Exploring Space

A GOLDEN GUIDE�

Complete your collection of Golden Guides and Golden Field Guides! GOLDEN GUIDES BIRD LIFE

BIRDS

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DINOSAURS FISHING

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BUTTERFLIES AND MOTHS

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EXPLORING SPACE

FLOWERS

INDIAN ARTS

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FOSSILS

INSECTS

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PLANETS

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FISHES

GEOLOGY

MAMMALS

POND LIFE

REPTILES AND AMPHIBIANS ROCKS AND MINERALS SEASHELLS OF THE WORLD SEASHORES

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SKY OBSERVER'S GUIDE

SPIDERS AND THEIR KIN TROPICAL FISH

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STARS

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TREES

VENOMOUS ANIMALS

WEATHER

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WEEDS

WHALES AND OTHER MARINE MAMMALS

GOLDEN FIELD GUIDES BIRDS OF NORTH AMERICA REPTILES OF NORTH AMERICA ROCKS AND MINERALS SEASHELLS OF NORTH AMERICA SKYGUIDE TREES OF NORTH AMERICA WILDFLOWERS OF NORTH AMERICA

Golden",

A Golden Guide", and Golden Press"

are trademarks of Western Publishing Company, Inc.

FOREWORD The author woul d like to tha n k many people for the i r con­ tributions to tbrs book: fi rst of a l l , Carol ine Greenberg and Remo Cosenti no at Golden Press for the i r ti reless help, expertise, and friendship; colleagues Bon ny Lee Michaelson, Dr. Robert E . Murph-y of NASA, Frederick I. Ordway, I l l , lan Pryke of ESA; Leo n a rd David, Dr. Glen P . Wilson, a n d com mercial"a stronaut Charles Wal ker for thei r assistance; other colleagues on the Boa rd of Di rectors a n d the staff of the National Space Society; Ron Miller for his a rtistic con­ tributions; and the people at the photo l ibraries of NASA Headquarters, Johnson Space Center, and Jet Propulsion Lab­ oratory, as wel l a s others who suppl ied photographs and assistance. Finally, I would l i ke to express my i ndebtedness to the late Dr. Wernher von Braun, whom I never quite had a chance to meet, but whose i deas and writings, many years ago, �rst inter­ ested me in space exploration. M.R.C.

©1991 Western Publishin

B Company, Inc . Illustrations © 1991 Ron M i ller. All rights reserved, including rights ot reproduction and use in any form or by any means, including the making of copies by any photo p rocess, or by any electronic or mechanical device, print­ ed or written or oral, or recording for sound or v isual reproduction or for use in any knowl­ edge retrieval system or device, unless permission in writing is obtained from the copyri g ht proprietor. Produced in the U .S.A. by Western Publishing Company, Inc . Published by Golden Press, New York, N . Y. Library of Congress Ca!olog Card Number: 91·070363. ISBN 0·307-24078-9

CONTENTS INTRODUCTION .......................... .. ... ....... ... ....... . . ..........5 .

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HISTORY OF SPACE FLIGHT ........ .. .... .............. ..... .......... ........ .9 .

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Early rockets; Spaceflight in science fiction; Space Age begins; Manned spaceflight; Lunar exploration; Apollo program; Space sta­ tions; Skylab; Planetary exploration THE SOLAR SYSTEM ..... ..... .... . .... ........ . . ... ............ ........22 .

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EARTH'S ATMOSPHERE ........... .... .................. .

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THE SPACE ENVIRONMENT ..... .. . ........... ... .. ............ ........26 .

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SPACE MEDICINE ........... ... .... .... ................... ............... .. ..31 .

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LIVING IN SPACE .................... .... ............ ... ............... ........34 .

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SPACESUITS AND EVA ... ........ .... ......... .... . .......... ............37 .

ASTRONAUTS .......... .... .

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WHAT KEEPS A SATELLITE UP? .... ................ ................... ....41 .

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Kepler's Laws; Orbits; Space navigation; Space tracking ROCKET PRINCIPLES ......... .... .... ................ ............. , ..........52 ..

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U.S. ROCKETS ........ ............... ............. . .. .. .... .............. , ...57 .

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Early rockets; Scout; Atlas; Delta; Titan; Space shuttle; Aerospace plane; Agena; Centaur; Payload assist module; Transfer orbit stage and advanced maneuvering stage; Inertial upper stage; Pegasus SOVIET ROCKETS . ................. . .. .... ... ... ... .... . . .. ..... ... .77 .

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A and B series; C and D series; F and J series; Energia; Space shuttle and spaceplane EUROPEAN ROCKETS... .......... .... . . .... ....... ....... . ... ...... .. 84 .

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Ariane; HOTOL; Hermes; Sanger/Horus

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JAPANESE ROCKETS

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Lambda, Mu, and N series; H series CHINESE ROCKETS

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INDIAN ROCKETS

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ISRAELI ROCKET

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OUT TO LAUNCH

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LAUNCH SITES

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Kennedy Space Center; Vandenberg Air Force Base; Wallops Island; Plesetsk; Tyuratam; Kapustin Yar; Tanegashima; Kagoshima; Jiuquan; Xichang; Guiana Space Center; Sriharikota; San Marco; Esrange SATELLITES

114

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Anatomy of a satellite; Research and applications satellites; Hubble Space Telescope; Galilee; AXAF; Ulysses; Phobos; CRAF; Commu­ nications satellites; Remote sensing satellites; Landsat; Spot; GOES; NOAA; Navstar; Manufacturing in microgravity 1 40

MIR SPACE STATION

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U.S. SPACE STATION

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MILITARY USES OF SPACE

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1 49 Lunar bases; Mission to Mars; Asteroid mining; Space settlements;

FUTURE SPACE MISSIONS

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Solar sails; Starflight 1 55 Space organizations; NASA facilities; Space museums and exhibits;

ORGANIZATIONS AND RESOURCES

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Books and magazines; Photo credits INDEX

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IN TROD UCTION The space prog ram is one of the most exciting and s i g n i fi ­ c a n t endeavors i n human h istory. W e have reached o u t i n p e r s o n t o E a rth o r b i ts a n d the Moo n , w i t h o u r robot spaceprobes beyond the edge of the solar system, and with our i n stru ments to the edge of the u n iverse. Although the Space Age began as a contest between the Soviet U n ion and the United States of America {and to some extent sti ll is}, many other nations a re now "space-capable," including Britain, France, India, Japan, China, and Israel. Sev­ eral more will gain that capabi lity soon. Hundreds of oper­ ational satellites and spaceprobes are in orbit right now, and the number is g rowing . Moreover, not only nations but private firms are now building and launching both rockets and satell ites. Over the past couple of decades, the Soviet Union has typ­ ically launched about 1 00 satell ites a year, the U . S . 20 to 25, and other nations combi ned another half dozen or so. Most of the Soviet launches are m i l itary in nature, a lthough that nation makes less of a distinction between m i litary and civi l ­ i a n spacecraft than d o West­ ern nations. The m a i n foc u s o f th i s boo k i s t h e c i vi l i a n space effort around the world. Much space hardwa re and term i ­ nology, however, came from mil i ta ry prog rams, and so a section on m i l ita ry uses of space i s a lso i ncluded .

Bootp r i n t i n the l u n a r d u s t NASA

COSTS OF SPACE EXPLORATION seem h i g h , but there a re a l so great rewa rds. In the United States, the enti re civi l i a n space budget cost less than 8/ 1 0 o f 1 percent of t h e federal budget yea rly d u ring the 1 980s. A major space endeavor, such as the Ga l i leo spaceprobe to Jup i ter, costs each per­ son in the U . S . o n ly about $ 4 . 50, about the price of a hamburger, fries, and a shake in 1 990. BENEFITS OF SPACE EXPLORATION are g reat but a re not easy to quanti fy . Besides the i ntel lectual rewa rds of explor­ ing and u ndersta n d i n g our place i n the u n iverse, there a re real economic benefits. What is the va l u e of a h u m a n l i fe saved by a sea rch-and-rescue satel l i te? How much money is it worth to know a h u rricane wi l l h it a certa i n city? What is it worth to mainta i n a lead i n h igh tech nology? Even more nebulous, how much is it worth to know a bout the satel­ lites of J upiter or the exi stence of black holes? While it is difficult to come up with definite numbers, it is clea r that space prog ra m s around the world have made it possible to manage better the p l a n e t t h a t h a s been ca l l ed " S pacesh i p E a rth , " a n d help make it a better, safer place to l ive. Ove r t h e n ext d e c a d e commerc i a l f i r m s , n o t j u st governments, wi l l beg i n to use the results of space pro­ grams to benefit everyone on Earth . Earth photographed from space NASA

OBSERVING ROCKETS AND SATELLITES can be exciti n g , but y o u h a v e t o be i n t�e right place at the right ti me. Rocket launches take place from on ly a few locations: I n the U . S . , the only one easily ava i lable to the public is the Ken nedy S p a c e Center i n Florida. Although the public is not a l lowed on the grounds during a l a u n c h , there a re many nea rby beach a rea s from which launches can be seen . Civi l i a n lau nches a re u s u a l ly a n n o u n ced i n adva nce; m i l ita ry lau nches a l m o s t n ev e r a re . N i g h t l a u n c h e s a re p a rtic u l a r l y spectacular. Once you have seen a real rocket launch you wi l l never forget it. Satell ites a re visible from Ea rth when they pass nearly over you r location . Only a Rocket launch NASA few are bright enough to be seen with the una ided eye. The best times a re near" dusk and dawn, when you are in darkness but the satell ite high a bove you is still in sunlight. Some local planetariums, observatories, space- interest g roups, and NASA facil ities offer information about satellite passages visible from you r a rea . Personal­ computer programs are available for trackin g satell ites, par­ ticu larly those satellites used by amateur radio operators.

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SPACE LAW There is no forma l legal defi n ition of where a i rspace ends and "outer" space beg i n s . There is, howev­ er, an operational defi n ition that is more-or-less accepted : 60 m i les up, the height at which a satell ite can make at least one orbit before a i r d rag makes it fa l l back to Earth . Spacecraft are subject to laws very different from those that apply to the most nearly analogous situations: flying in the air or sa iling on the h igh seas in international waters . Whereas there are admiralty laws dealing with flotsam , jetsam , and abandoned sh ips, no such laws apply in space. And while it is an accepted part of international law that a nation owns the earth below and the airspace over its borders, the same is not true of "outer" space. The U nited States and most space-faring nations are par­ ties to severa l space treaties. These deal with reg isteri ng space objects, the rescue of astronauts, liability in case a space­ craft does damage on Earth, and peacefu l uses of space. Another treaty, which the United States did not sign, claims that the Moon and other bodies in space are "the common her­ itage of mankind . " Many space entrepreneurs a re afraid this will be interpreted to mean that no one can mine the Moon, asteroids, or other planetary bod ies. Existing space treaties were written at a time when no one thought private compan ies could afford space activities, so the treaties do not recogn ize private enterprise. For instance, there does not exist in space the concept of a "common car­ rier." A nation that allows a launch, or whose citizens own the satellite, is liable for damages in case somethi ng goes wrong. Th is has had a dampen ing effect on private enterprise. It will be important to revise current space laws and make new ones that wi l l carry us into the 2 1 st century. As space becomes a place to do business, new laws and regu lations will be needed in such areas as patents, citizen ­ ship, taxation, and insurance.

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The Battle of K'ai-fung-fu

THE FIRST ROC KETS The principle of the reaction motor was known as far back as 360 B.C., when Aulus Gellius described a steam-pow­ ered model of a pigeon. A Greek named Hero is said to have i nvented a steam-d riven rotating "aeropi le" about 2,000 years ago. Most people credit the C h inese with the i nvention of the rocket itself, powered by burning black powder, a m ixture of charcoa l , saltpeter, and sulfur. Some h i storians clai m the Chinese had powder rockets a lmost 1,000 years ago, but it is certa i n that rocket-powered arrows were used by the Chi­ nese m i l ita ry in the 13th century. "Firearrows" drove off the attacking Mongols at the Battle of K'a i-fu ng-fu in 123 2 . Oth­ er a rm ies soon took up the idea, and in 124 1 Mongol tribes used the same kind of weapons at the Battle of Sejo ( neor pre­ sent-day Budapest) . Also in the 13th century, the English scientist Roger Bacon and the Arab scientist a I- Hasan ai-Rammah described black powder and rocketry. Soon th i s technology was i n use by armies th roughout Europe and Asia. 9

An aeropile

Wan Hoo's rocket-piled chair

A few non - m i l i tary uses were tried, including fi reworks. It is sa id that around the year 1 500 the Chinese Wan Hoo had 47 black-powder rockets attached to a sedan cha i r and ignit­ ed at the same time by 47 servants. He was not seen aga i n . B y t h e late 1 700s and early 1 800s, rockets carrying explosive warheads were a standard but small part of the arse­ nals of most countries. Sir William Congreve grea�y improved rockets for warfare. His rockets, carrying either incendiary or explosive warheads, Congreve rockets

cou l d be fi red a couple of m i les and wei g hed up to 60 pounds. They fi rst saw major use i n 1 806 . Congreve rock­ ets were later u sed by the British in the Wa r of 1 8 1 2, notably i n the n ight attack on Fort McHen ry. These were immortalized in the words of Francis Scott Key when he wrote of "the rocket' s red glare . " Later that century, Congreve' s rockets became obsolete because of advances in arti llery. Si mi lar rockets were adapt­ ed for use in throwing lifesaving ropes to stranded ships, and to some extent th i s is sti l l done today. Around the beginning of the 20th century advances in tech­ nology, and popular fantasies of trips to the Moon and life on other worlds, led to the work of the three great rocket pioneers and visionaries: Konstantin Tsiolkovsky in Russia, Hermann Oberth i n Germany, and Robert Goddard i n the U n i ted States. In the mid-twentieth century, rockets again entered the arse­ nals of most nations. The Bottle of Ft. McHenry

Spaceflight fantasies

SPACEFLIGHT in the imag i nation is thousa nds of years old. Science fiction, until the 20th centu ry, was much more fic­ tion tha n science. Lucian of Samosata , a Greek of the 2nd century A.D., wrote of a trip to the Moon by a sailing ship caught in a whi rl­ wind. In 1 0 1 0, the Persian poet Firdusi described a throne pul led to the Moon by eag les. The astronomer Johan nes Kepler wrote a fanciful tale of a lunar trip i n 1 634, and was perhaps the fi rst to realize that the air did not extend all the way to the Moon. About the same time, Engl ishman Francis Godwin wrote of men carried to the Moon by geese. Around 1 650 the famous writer Cyrano de Bergerac wrote stories of trips to the Moon and the Sun. His fi rst plan of travel was to tie bottles of dew to h is belt and thus rise into space when the Sun evaporated the dew! Another idea he had was to use fire­ works rockets. Around 1 705 Dan iel Defoe, better known for Robinson Crusoe, wrote a tale of lunar travel .

12

Only in the late 1 9th centu ry did such stories become more realistic. The father of modern science fiction is Jules Verne, who wrote From the Earth to the Moon i n 1 865. The concept of a manned space station and commercial naviga­ tion satellite comes from Edward Everett Hale and h i s 1 86 9 story "The B r i c k Moon . " One o f the earliest spaceAight motion pictures was Georges Mel ies' short fi l m A Trip to the Moon in 1 902. Most science­ Rction films have been little more than fantasies or "space west­ erns." Only a few fi lms have approached the subject realis­ tica l ly. The first such fi lm was The Woman i n the Moon, directed by Fritz Lang in 1 929. His technical advisors went on to establish the early German rocket progra m . This film made a permanent contribution to the space program when Lang invented, purely for dramatic purposes, the countdown before launch . In 1 950, producer George Pal made Destination Moon, a realistic depiction of what spacefl ight might be l i ke. T h e spaceship controls in the 1 939 film Buck Rogers

ORDWAY

THE SPACE AGE BEGAN on October 4, 1 957, when the Soviet U n ion lau nched the world's first artificial satellite, Sputn i k 1 . Though it weig hed only 1 84 pounds, was less than 2 feet in diam­ eter, and stayed i n its 1 40mile-high orbit on ly 92 days, its launch provoked shock waves o f p u b l i c rea c t i o n arou nd t h e world . Th i s f i rst s a t e l l i te wa s Sputnik 1 launched from the Tyurata m (Ba i konur) Cosmodrome on a Type-A rocket. It carried exper­ iments to study the density of the atmosphere at its orbital alti­ tude and the transm ission of radio waves through the atmo­ sphere. Its i nstruments were powered by batteries, which ran out three weeks after launch. Sputnik 2, weighing 1 , 1 20 pounds and carrying a live dog, was lau nched on November 3, 1 957. The U . S . did not launch its fi rst satell ite, Explorer 1, until January 3 1 , 1 958, a fter i n itiating a crash program i n an attempt to catch up with the Soviets, and after two attempt­ ed Vanguard satellite launch­ es had fa iled . The fi rst suc­ cessful Vanguard satellite went into orbit on March 1 7, 1 958. An Atlas rocket beca me the fi rst com mun ications satell ite later that yea r . ..fxplorer 1 model

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NASA

MANNED SPACEFLIGHT began on April 1 2, 1 96 1 , when Soviet Lt. Yuri Gaga rin made one orbit lasti ng 1 08 m i nutes, 250 m i les a bove Earth , in h i s Vostok- 1 spacecraft. The first American in space was Alan B. Shepard, who took a 1 1 5-mi le- h igh suborbital flight in a Mercury-Redstone cap­ sule on May 5, 1 96 1 . He was followed in another similar Right by Virg i l I. (Gus) Grissom on July 2 1 . On August 6, the Rus­ sian cosmonaut Gherman Titov spent 25 hours and 1 7 orbits in space aboard Vostok 2 . The fi rst American to orbit the planet was Joh n Glenn . On February 20, 1 962, he rode a Mercu ry-Atlas rocket that

John Glenn

NASA

Alan Shepard

NASA

made th ree orbits 1 60 m i les up in 5 hours. Scott Carpenter followed on May 24 i n a s i m i lar mission. The fi rst woman i n space was Va lenti na Teresh kova , aboard Vostok 6 on June 1 6, 1 963. She made 48 orbits i n 7 1 hours. N o other woman went into space until 20 years lat­ er, when astronaut Sally Ride was part of the five-member crew aboard the space shuttle Challenger on June 1 8, 1 983 . 15

Flight model of Surveyor craft

NASA

LUNAR EXPLORATION began when the Soviet Lu n i k 1 flew with i n 4,600 m i les of the Moon i n J a n u a ry 1 95 9 . That March the U . S . Pioneer 4 passed the Moon at a d i stance of 37,000 m i les. In September, Lun i k 2 became the fi rst man­ made object to h it the Moo n . Lun i k 3 , i n October, was the fi rst to ta ke photog raphs of the far side of the Moo n . Beg i n n ing in 1 964, U . S . Ranger craft crash-landed o n the Moon, photographing areas that might be used for later manned landings. Lun i k 9 in January 1 966 became the first craft to soft-land on the Moon, returning television pictures of the surface. U . S . Surveyor craft also soft- landed, taking photographs and digging trenches to analyze surface properties. Lunar Orbiters provided excellent photographs of most of the sur­ face. Severa l orbiti ng Soviet Lun i k craft a l so mapped the Moon. The Soviets sent severa l unmanned craft to the Moon to scoop up soil and return it to Earth . Some deployed a small roving veh icle cal led Lunokhod to sample lunar soi l over a wide a rea .

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FIRST VISIT TO ANOTHER WORLD was the goa l of the U . S . Apollo prog ram . A th ree-man spacecraft, consisti ng o f a command module attached to a two- section lunar mod u le, established orbit around the Moon. The l u n a r module car­ ried two men to the su rface, and its separable ascent stage brought them back to lunar orbit to rendezvous with the com­ mand module, which then retu rned to Ea rth . The first manned lunar orbit was achieved by Apollo 8 , launched December 2 1 , 1 968, carrying Frank Borman, James Lovell, and William Anders. Apollo 1 1 , lau nched J u ly 1 6, 1 969, made the fi rst manned lunar landing. Michael Col l i n s remained i n the command module while N e i l Armstrong a n d Edwin Aldrin landed o n the Moon's Sea of Tranquillity a t 4: 1 7 P.M EDT on J u ly 20. Neil Armstrong became the first human to set foot on another world at 1 0:56 P.M. Five more Apollo missions landed on the Moon. Apollo 1 3 encountered problems and retu rned to Earth after swi nging around the Moon. The successful missions did experiments and returned a lmost 850 pounds of lunar rocks for ana lysis.The last m ission was Apollo 1 7, in December 1 972. No one has been to the Moon since. Apollo 1 1 on the Moon

NASA

THE FIRST SPACE STATION was the Soviet Salyut 1 , launched April 1 9, 1 97 1 . Wei g h i n g over 25 tons, it had a tota l length of 47 feet and a maximum diameter of 13 feet. A crew of three were carried up to the station by Soyuz veh icles. Unfortunately, their Soyuz- 1 1 craft malfunctioned as the crew returned to Ea rth , and the th ree cosmonauts died. The Salyut- 1 station was shortly thereafter com manded to reen­ ter the atmosphere and burn up after only six months in orbit. Other Sa lyut stations followed . Salyut 6, lau nched i n 1 977, was a b i g step in Soviet spacefl ight. Over 4 9 feet long, weighing 4 1 ,000 pounds, and with docking ports for two Soyuz craft, th is space station was occupied by 33 different crewmen and docked with 30 different spacecraft during its 3-year-and-8-month lifetime. Unmanned Progress craft repeat­ edly carried suppl ies to the crews. Salyut 7, launched April 1 9, 1 982, was approximately the same size as its predecessor, but it had many improvements. Its crews have included the fi rst woman to "wal k" i n space, Svetlana Savitskaya . It fel l back to Earth in 1 99 1 .

Saylut 1

First U.S. space station

NASA

Inside Skylab

NASA

SKYLAB, in 1 973, was the fi rst and so fa r the only Ameri­ can space station . It was constructed inside the upper stage of a Saturn rocket, with two main rooms for experiments and l iving quarters. The weight of th is enti re 1 1 8 - foot- long, 2 1 foot-diameter station was a l most 200,000 pou nds. The fi rst 28-day m ission was followed by a nother a month later, when a th ree-man crew spent 59 days in space. The th i rd and last crew broke space-endurance records up unti l then ( 1 97 4) by stayi n g 84 days in orbit. The crews performed many important experiments in solar studies, space medicine, materia l s processing, and Ea rth studies. Atm o s p h e r i c d rag s l owly p u l led Skyl a b lower, a n d Cong ress cut fu nds that would have provided a booster engine to keep the station i n orbit longer. Finally, on July 1 1 , 1 979, Skylab fel l to Earth over the I ndian Ocea n . A few pieces landed in Australia without damage to property. Since then America has had no space station, and will not have one until later th is decade.

19

SPACEPROBES to the planets began i n 1 959, when Lun i k 1 became the fi rst man-made c raft to escape Earth perma­ nently. The first close-up pictures of Mercury and Venus came from the American Mariner-] 0 probe in 1 973. The U .S.S.R. also has many exploratory fi rsts for Ven u s : fi rst flyby, Ven­ era 1 i n 1 96 1 ; fi rst Venusian impact, Venera 3 i n 1 965; first Venus atmosphere probe, Venera 4 in 1 967; fi rst soil anal­ ysis, Venera 8 i n 1 972; fi rst pictu res from the su rface, Ven ­ era 9 i n 1 975. The Soviet Un ion also boasts the fi rst Mars flyby, by Mars 1 in 1 962; first Mars crash landing, Mars 2 in 1 97 1 ; and the first soft landing on Mars, Mars 3 the same year. First pictures of Mars from space came from the U . S . Ma riner 4 in 1 965, and the fi rst photographs from the surface were made by the two U . S . Viking landers in 1 976. The first close-up pictures of Jupiter and its moons came from the U . S . Pioneer- 1 0 probe i n 1 972, and of Saturn and its satellites by Pioneer 1 1 in 1 973 . Voyager-] and Voyager2 probes took more deta iled pictures. Voyager 2 went on to fly by U ranus in 1 986, and by Neptune in 1 989. The fi rst mission to a comet was by the U . S . Internationa l Cometary Explorer (ICE) to Comet Giacobi n i -Zinner i n 1 985. I n 1 986, the U . S . S . R . , the European Space Agency, and the Japanese a l l sent missions to rendezvous with Comet Halley. Th i s decade spaceprobes w i l l encounter asteroids, study Jupiter' s atmosphere, and study the Sun's poles. Venera 9

TASS

Venus' surface seen from Venera

TASS

Venus (middle) and Mercury's surface (right) seen by NASA

Voyager spacecraft (left); Jupiter (middle) and Saturn (right) seen by Voyager NASA

Above: Viking lander; Mars' surface seen by Viking Below: Giotto comet probe (left) Giotto (right) MPAE

NASA

ESA; Comet Halley as seen by

Our solar system

THE SOLAR SYSTEM The solar system is the region i n wh ich a l l our spacecraft, so fa r, have explored . Wh ile our earth ly and spaceborne tele­ scopes have probed to the depths of the u n i verse, our craft have gone only j u st beyond the edge of the p l a n eta ry system . The Sun is the center of the solar system, and has more than 99 percent of a l l its materia l . Orbiting the Sun a re n i ne major planets, more than five dozen satell ites, hundreds of thousands of minor planets (asteroids), and perhaps b i llions of comets. Except for the comets and some of the asteroids, these all revolve i n paths l i mited to a narrow disk around the Sun. Comets may have highly inclined orbits. Most are locat­ ed many bill ions of mi les from the Sun, only occasional ly plunging i nto the i n ner solar system where we can see them. Astronomers measure planetary distances i n terms of the Earth's d i stance from the Sun, called an astronomical unit (a . u . ) , equal to about 93 m i l l ion m i les. Pluto on average is more than 39 times this far from the Sun, but because of Pluto's 22

elliptical orbit, Neptune wi ll actually be the most distant plan­ et unti l March of 1 999. Another way to measure d i stance is the time it ta kes l ight or radio waves, moving at 1 86,000 miles per second, to trav­ el that d i stance. Light takes about 8 m i nutes to go 1 a . u . ; it takes 5 hours to get from the Sun to Pluto. The nearest sta r to our solar system is more tha n 4 light-years away, about 25 tri l l ion m i les. Spaceprobes have robotically explored all the planets except Pluto, although Pioneer 1 0 has passed the orbit of Plu­ to and is now more than 4 . 2 billion mi les away, the most dis­ tant man-made object. The limit of manned exploration, so far, is the Moon, only 240,000 m i les from Earth . I n pla n n i n g for space missions, a more i m portant factor tha n time or d i sta nce is the energy needed to get some­ where. Each planet has a strong g ravitational p u l l . A space­ craft going to another planet must first escape the gravitational field of Earth, travel to the planet, and then maneuver with ­ in its g ravitational field. Along the way, the craft is subject to the g ravity of the Sun. 23

EARTH'S ATMOSPHERE i s composed of about 78 percent nitrogen , 21 percent oxygen, and 1 percent trace gases such as water vapor, ca rbon d ioxide, and a rgon . THE TROPOSPHERE, the lowest 1 0 m i les of a i r, i s where a l l weather occu rs a n d a l l l i fe exi sts. A t the surface the pressure i s a l most 1 5 pounds per square i n c h . From the su rface upward the pressure and den sity of the a i r lessen rapidly. Only a few a i rcraft can fly h i g her than 1 0 m i les up, but the a i r here is sti l l much too th ick for an u npowered satell ite to orbit. Yet at th i s a ltitude, the a i r is too th i n for a person to l ive-except in a pressu re suit or a pressurized cabi n . THE STRATOSPHERE l ies from 1 0 m i les u p to a bout 30 m i les. A very few a i rcraft can fly th i s h i g h . H igher sti l l is the mesosphere, extending up to about 50 m iles, and above that the thermosphere. At 60 m i les above Earth the pressure is only a bill ionth, and the density is only th ree ten- m i l l ionths, what it i s at the su rface. THE EXOSPHERE i s the name sometimes g iven to the outer­ most ten uous atmosphere where it gradually blends into the vacuum of space. There is no legal or physica l "top of the atmosphere." But many people consider 60 miles up a practical l i mit, for at this altitude a small satell ite can make one orbit. Most satellites orbiting Earth are more than 1 00 m iles up, but even there the atmosphere exerts a resisting "drag" force which slows them down so that an orbit eventually "decays" and the satellite falls back to Earth . Usually it burns up l ike a meteor, but a few pieces of satellites have landed on Earth . The smaller, denser, and higher a satellite, the longer it will stay in orbit. Above a few thousand miles, a satellite experiences almost no atmo­ spheric drag. Structure of the atmosphere

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THE SPACE EN VIRONMEN T Space is a harsh environment. Our spacecraft designers m ust take i n to account these new conditions, wh ich d i ffer g reat­ ly from those on Earth . THE VACUUM OF SPACE causes many otherwise stable materia ls, such as rubber and many l ubricants, to turn i n to gas and d isperse. Such materials can only be u sed i n satel­ lites i f they a re enclosed . Materials l i ke g lass become more brittle i n a vac u u m . Humans must either work i nside pres­ surized conta i ners or use spacesuits for work outside. WEIGHTLESSNESS is the condition of a nyth i n g i n space that i s n ot u nder power; it is also cal led free fal l or " m icro­ gravity" or zero g, where the "g" stands for "gravity . " An Satellite after launch from shuttle

NASA

object sti l l has mass in space, even if it does not have any weight, so it sti l l ta kes work to sta rt it movi n g and to stop it. The lack of g ravity creates compl ications i n desig n i n g a spacecraft and i n l iving i n space. SUNLIGHT stri kes spacecra ft, producing heat. Above the absorbing atmosphere the Sun is stronger, and exposed sur­ faces may get hotter tha n the temperatu re of boi l i n g water. The lack of air means there is no convection to carry excess heat away from the satell ite; the on ly way a satell ite can get rid of heat is by radiation . On the other hand, when a satell ite is i n shadow its tem peratu re may fa l l to more tha n 1 00 degrees below zero Fahrenheit i n j u st a few m i n utes . Si nce tem peratu re extremes can damage spacecraft com­ ponents, thermal control is a n i m portant pa rt of sate l l ite design . Simulating zero g in a watertonk

NASA

COSMIC RAYS are charged atomic particles, many of them the n uclei of atoms. These come from the Sun as well as from the depths of space. They may give the spacecra ft an elec­ trica l charge, which can be damaging if it causes spa rks. They also g radua l ly reduce the efficiency of the solar cel l s (wh ich convert sunlight i n to electrical energy ) . Very h i g h ­ energy cosm ic rays may even penetrate the electronic chips in the satell ite' s control circuitry, causing tem porary or per­ manent cha nges i n the com mands g iven to the c raft. METEOROIDS are sol i d materials flyin g th rough space at tremendous speeds, usually many m i les per secon d . Most meteoroids a re smaller than a g ra i n of sand, and are called micrometeoroids. Over a typical 1 0- to 1 5-year l i feti me, a satellite wi ll get a few pinpricks a tenth of an i nch in size and a l i g h t "sa n d i ng" of its exposed su rfaces, i n c l u d i n g the Grabbing a satellite for repair

NASA

Distribution of space debris

sola r panels. So fa r we know of no large ( mea n i ng g reater tha n a few tenths of an inch i n diameter} meteoroids having h it satell ites. But the chances i ncrease with time and with the size and g reater n u mber of spacecraft we have i n space. Spacecraft have been hit by man- made space debris, how­ ever. SPACE DEBRIS in Ea rth orbit i s a serious and increasi ng problem. There a re now wel l over 7,000 trackable objects in orbit. On ly a few hundred are active satelli tes. There a re more than 35,000 objects the size of a marble, perhaps mil­ lions of smaller pieces. The debris consists of used third stages of rockets, the rem a i n s of exploded (accidenta l ly or i nten ­ tionally) spacecraft, chips o f paint knocked off satellites, hard ­ wa re l i ke bolts and spri ngs released when satel l i tes a re

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deployed , a n d pa rts knocked off satell ites by col l i sions. Much of the debris has come from the testi ng of a ntisatell i te weapon s . Even very sma l l objects are hazardous because they a re movi ng at speeds up to 25,000 m i les per hour. One of the space shuttles was h it on its windshield by a ti ny chip of alu­ minum pai nt, causing a small pit i n the glass. Several satel­ lites a re strongly suspected of having been destroyed by col ­ lisions. T h e Soviet space station Salyut 6 h a d some o f its external parts damaged by collision. The more satellites there are in space, and the more frequently they coll ide, producing stil l more fragments, the worse the problem wi l l become. Not until after the year 2000 wi ll we beg i n to have the tech ­ nology t o retrieve used-up satel lites a n d bring them back from high orbits. Space debris is becoming a problem for astronomers, too. I ncreasingly, debris shows up in photographs of the sky made with large telescopes, prompti ng fa l se d i scoveries . One reported discovery of a pulsar turned out to be sunlight reflecting off the solar cel ls of a dead satellite!

Debris caused this pit in shuttle window

NASA

SPACE MEDICINE When a human enters space there a re physiolog ical and psychologica l changes. Some body fu nctions conti n u e to alter as long as she or he i s we i g h tless; others reach a steady level with i n days or weeks. Upon retu rn to Ea rth most body functions retu rn to normal. S i nce the longest conti nuous period a cosmo­ n a u t h a s spent in we i g ht­ lessness i s about a yea r, we sti l l do not know if some of these changes might become permanent a fter a very long stay i n zero g. S PAC E S I C K N E S S , c a l l e d " s p a c e a d a p ta t i o n s y n ­ d rome" by NASA, a ffects about half of all people who Astronaut Don Williams exercis­ g o i n to s p a ce. L i ke oth e r es a b o a r d t h e s p a c e s h u tt l e forms of motion sickness, i t NASA arises i n the astronaut' s i nner ear, the mechanism that senses orientation and acceleration . The symptoms i nclude cold sweating, nausea, and vom iting. These could be dangerous to an astronaut i n a spacesu it. Most people who get spacesick get over i t i n a couple of days. A few a stronauts have briefly reexperienced it after thei r retu rn to Earth.

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C HANGES I N THE BODY i nclude a loss of body flu id s and sol id materia l . I n space, an astronaut' s bones are no longer n eeded to support the body and so beg i n to wea ken . The hea rt pumps faster; it g rows larger but pumps less blood . Muscles g row wea ker si nce they have less work to do. The n u m ber of red cel ls i n the blood decreases wh i l e the n u m­ ber of white cells i ncreases. After return to Earth it takes from weeks to months to bring blood cel l s back to pre-fl ight lev­ els. Astronauts regularly exercise while in space to try to min­ i m ize these problems. RADIATION i s another problem in space. Wh ile not too seri­ ous i n low Ea rth orbits, the h igh-energy particles trapped i n the V a n Allen belts a round Ea rth a re a danger. O n e belt extends from about 300 miles to about 750 m iles up, the oth­ er from 6,000 m i les to a height dependent on the activity of the S u n . Some rad iation leaks th rough to lower a l titudes. Van Allen radiation belts

A m e d i c a l c h e c k u p in s p a c e NASA

Testing the effects of space on the body

NASA

Astronauts head ing away from Earth must pass quickly through these radiation zones to minimize exposure. Outside the Van Allen belts, space travelers are exposed to a contin ­ u a l dosage o f radiation . Long-duration space m issions must carry heavy shielding of some sort. Once in a wh ile the Sun produces a solar flare that could give a lethal dose of rad i ­ ation to a n unprotected astronaut. PSYCHOLOGICAL PROBLEMS come from lengthy confi ne­ ment, living in an unnatural environment, close quarters, lack of privacy, and the ever-present hazards of l iving in space. Using stud ies of s i m i la r situations-for i n sta nce, aboa rd subma rines-space- mission plan ners try to m i n i m ize poten­ tial problems. It will be i mporta nt to provide many forms of recreation and relaxation for crews on long m i ssions aboard space stations and man ned m i ssions to other pla nets . M U C H RESEARCH i s needed to determine h u m a n toler­ ances for extended m i ssions either i n low orbits or to the planets . Th i s wi l l be one of the more i m porta nt goa ls of the projected U.S . space station later th is decade.

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LIVING IN SPACE Weightlessness comp l icates even s i m p l e ta sks in space. Spacecraft need spec i a l systems to p rov i d e the th i n g s req u i red for l i fe. OXYGEN for breath ing is carried i n tanks. Some spacecraft use a reduced atmospheric pressure enriched in oxygen . Oth­ ers have an envi ronment much l i ke natural a i r. Exhaled carbon d ioxide is a bsorbed by chemical filters a n d the purified air i s rec i rc u lated . Air m u st be in motion at a l l times i n a spacecraft: a n un movi ng astronaut cou ld suffo­ cate in a bubble of her own exhaled breath because, with­ out a i r c i rcu lation, it wou ld not move away from her body. EATING in space can be messy. Free l iq u i d wou l d float out of an open g lass and cou ld be a hazard if it escaped . Thus d ri n ks come i n squeeze bottles. Foods may be sol i d s and pastes. Sauces a re often used to ma ke the foods stick to p l a tes. Mea l s a re u s u a l ly p re p a r e d o n E a r t h a n d stored for fi n a l preparation as needed . WATER for d r i n k i n g , cook­ ing, and wash i n g i s carried in tan ks, may be produced on boa rd by fuel cel ls, and may be recycled from body waste. Excess water is a l so filtered out of the a i r.

Eati ng in space can be a chal­ lenge NASA

The space shuttle's galley area NASA

Taking a space shower aboard Skylab NASA

S a l l y R i d e s l e e p s a board the space shuttle NASA

The toi let of the s pace s h u ttle NASA

BODY-WASTE ELIMINATION is more com p l i cated . I n early spacecraft {and sti l l in spacesuits} urine wa s col lected by a tube and held i n a bag . Sol id waste was el i m i nated into a plastic bag held to the body with adhesive, and then stored unt il the end of the mission. The space shuttle, a n d the futu re space station, have a specially designed zero-g toilet. Th i s uses a i r to pull the waste materia l into the toi let where a rotati ng fan sepa rates the solids from the l iq u i d s . The l i q u id may be either steril ized and recycled or expelled from the spacec raft. Sol i d waste is dried and stored for retu rn to Ea rth . IN WEIGHTLESSNESS, as in a pool of water, the relaxed body n atura lly assu mes a slig htly curled - u p position, with arms and legs floati ng freely i n front of the body. An astro­ naut cannot l ie on a bed to sleep; instead he zips himself into something much l i ke a sleeping bag, which may be attached to a wa l l or cei l i ng or someplace else out of the way. ORIENTATION can be a problem . The terms "wall" and "ceil­ ing" have much less mea n i ng i n zero g . I n the space sh ut­ tle the su rface that is the floor when the shuttle is on the ground is sti l l often thought of as "down" with i n the space­ craft. When th i n ki n g about th ings outside a spacecraft i n orbit a round a planet, it i s most natura l to th i n k o f "down" as the d i rection toward the planet. Future space stations and space settlements will probably i nclude growi ng plants, and possibly a n i mals, as pa rt of the ecosystem. Some types of algae d igest waste products, and others produce oxygen . Large space structures may revolve to provide an "artificial gravity" that will eliminate many of the problems caused by weightlessness (although it wi ll introduce some problems of its own } .

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SPACESUITS AND EVA Spacesuits a re designed to provide the a stronaut with a self-contained environment for severa l h o u rs of work outside the pressurized cab­ in. Th is is cal led extravehic­ ular activity, or EVA. The suits supply oxygen , absorb ex h a led ca r b o n d i ox i d e , a n d provide for some body­ wa ste e l i m i n a ti o n . S o m e p rov i d e wate r th rou g h a tube in the suit's helmet. Sen­ sors i nside the hel met g ive the a stro n a u t i n formation about the suit' s status, such as the amount of rema i n i n g Spacesuit and Manned Maneu­ oxygen . vering Unit N ewe r s u its a l l ow fu l l atmospheric pressure, rather than the reduced pressu re used in older ones. The suits a re in several parts: the lower pa rt, or legs, attached to the upper part with airtight seals, and the helmet. The spacesuited astronaut may attach himself to a large backpack unit containing oxygen, or be tethered to the space­ craft by an umbilical hose. Once outside the cabin, astronauts move a round by p u l l i n g and push ing themselves on the spacecraft. NEWER SPACESUITS, lighter and more flexible tha n present ones, a re bei n g designed to make it easier for astronauts to work i n space for extended periods of time.

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MANNED MANEUVERING UNITS (MMUs) a re jet-pow­ ered backpacks for excur­ sions away from the craft. A h a n d contro l ler m u c h l i ke o n e o n a v i d e o a rc a d e game i s used to fire the j ets in a ny com b i nation of s i x d i rections, a l lowi ng motion or turn i n g in any d i rection. A s t ro n a u ts u s i n g M M U s don't have to b e tethered to the spacecraft. S h o u l d a n astronaut get i n to trouble, the spacecraft can a lways go after h i m . One complication o f zero g is that special tool s must often be used because if, say, Astronaut uses a Manned Maneuvering Unit NASA an astronaut tries to turn a sc rew, s h e w i l l a l so tu r n , obeying Newton's Third Law (see p. 4 1) . She must either brace herself against the craft, or use so-called "reaction less" tools. One way to m i n i m ize th is problem is to attach the astro­ naut firmly to part of the spacecraft, usually by clamps on the boots. For EVA on the space shuttle, astronauts are often attached to the Remote Manipu lator Arm (see p. 67). WALKING ON THE MOON, and in the futu re o n other sma l l planets, can present other problems. For i nsta nce, the Moon's g ravity is only a sixth of Earth's, and the Apol­ lo astronauts found that a bouncing, loping kind of gait was the best way to get a round there.

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ASTRONAUTS The U n i ted States and many other nations call space trav­ elers "astrona uts," the Sovi­ et U n ion calls theirs "cosmo­ nauts," and the French term is "spationaut." Most a s t ro n a u t s h a v e come from the m i l i tary ser­ vices and have had tra i n i ng as test pilots. The fi rst astro­ nauts had little control over their craft. Later, especially in the space shuttle, the pilots have actually controlled the spacecraft much of the ti me. I n the m i d - 1 960s, the U . S . began recruiting non-pilot sci­ enti sts and e n g i n eers from un iversities and industry for space miSSions. Training for a spaceflight in a For the space shuttle the simulator NASA crew consists of two pilots and up to five Mission Specialists and Payload Specialists. These latter have responsibility for deploying satellites, conducti ng experi ments, and other non-piloting tasks. Most of the crew of the future space station wi l l not be pilots. All astrona uts go th rough long and rigorous tra i n i n g . They must understand everything about their spacecraft, its mis­ sion, its payload {cargo) , and what to do i n case of emer­ gencies. Th is i s i n addition to their particular a reas of exper­ tise, such as m ed i c i ne, physics, astronomy, materials pro­ cessing, and so o n . 39

A payload specialist at work

NASA

The best preparation for being an astronaut, say the cur­ rent astronauts, i s becom ing good in whatever field you l i ke. Later you can apply that expertise to space. NASA periodically advertises for astronauts to fi l l vacan ­ cies. Applicants are given several aptitude, psychological, and physical exam ination s . Those that are accepted become astronaut-candidates, and then finally astronauts when they have completed about a year of trai n i n g . They get their astronaut wings upon completion of their fi rst spaceflight. (The U . S . awards astronaut wings to anyone who has been more than 50 miles up; thus several pilots of the X- 1 5 research plane are techn ically astronauts although they have not flown in spacecraft. ) There are usually 50 to 1 00 men and women i n the U . S . astronaut corps a t any one time. 40

WHAT KEEPS A SATELLITE UP? The motion of a ny object i n space, whether that object is a micrometeoroid or the S u n , is controlled by the l aws of physics. NEWTON'S LAWS OF MOTION describe how a n object moves: I. A body at rest remains at rest, and a body i n motion remains i n motion, u nless acted on by a n outside force. II. The change i n the motion of a body is in the d i rection of, and proportional to, the strength of the force applied to it. Ill. For every action, there is an equal and opposite reac­ tion . THE LAW OF GRAVITY descri bes the major force acti ng i n space: The g ravitational attraction between two objects p u l l s them together with a force that is proportional t o the p rod­ uct of the i r masses and i nversely proportional to the square of thei r separation .

The Law of Gravity

An orbit is a balancing of forces

Newton's imaginary cannon

AN ORBIT is the motion of one object a bout another. An object remains i n orbit because the momentu m of its forward motion balances the gravitationa l pull between it and the oth­ er object. It is similar to the way ou can swing a ball on the end of a string: the inward pull o the string balances the out­ ward momentum of the ba l l . A satellite once placed in orbit (outside the atmosphere, which causes d ra g on a i rcraft and low-orbit spacecraft} can conti nue i n that orbit without having to conti n u a l ly fire its rocket engines. Newton gave the fol lowing example: suppose there were no atmosphere a round the Earth to slow th ings down . A cannon on top of a very h igh mounta i n could fire a bal l that goes some d i stance. As the bal l travels, it falls toward the ground, but the curvature of Earth makes the ground "fall away" under it. I f the cannon fires with sufficient energy, the bal l can be made to travel at such a speed that the Earth falls away at the same rate that the bal l falls toward Earth . I n oth­ er words, the ball will never touch the ground: it will be in orbit.

r

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ESCAPE VELOCITY is the min imum velocity needed to escape permanently from a planet. The speed req u i red depends on the mass of the planet and the d i stance of the satel l i te from it. At any d i stance it wi l l a lways be 1 .4 times the speed nec­ essa ry for a c i rcu lar orbit. KEPLER'S LAWS, d iscovered a rou n d 1 6 1 0 by Johannes Kepler, describe any orbita l moti o n : I . T h e orbit of each pla net is a n ellipse, with the Sun at one focus of the ellipse. I I . There is a u n ique relationship between the distance of a planet from the Sun and how fast it moves: its speed wil l be slower when far from the Sun and faster when nearer the Sun. I l l . The average distance between the Sun and a planet, a, is related to the time it takes the planet to orbit the Sun once, t. Expressed mathematically, it is t 2 = a3. I f you substitute the word "satelli te" for "planet" a n d "Earth" for "Sun," the laws a re sti l l true. Kepler' s Laws describe orbits

How to draw an ellipse

Types of open and closed orbits

AN ELLIPSE is a closed cu rve that can be made by sticking two pins i nto cardboa rd, looping a string a round them , and then, keeping the string taut with the tip of a pencil, mov­ ing a round the p in s . The penci l w i l l draw an e l l i pse. The points with the pins are called the foci (singular, focus) of the ell ipse. The fa rther apart they a re, the more eccentric the e l l i pse w i l l be. I f the pins are moved together, the ell ipse becomes a c i rcle. The Sun wou ld be where one of the pins is; the other focus is vacant. The long dimension of the ellipse is called the major axis; half of it is the semi major axis, which is the aver­ age distance between the Sun and a planet. Circular and ellip­ tical orbits are called "closed" orbits. If a satellite has reached escape velocity, its orbit will have the shape of a parabola or hyperbola , which a re examples of "open orbits" since they don't repeat. Actual ly, no orbit is perfectly elliptica l because the grav­ itationa l pulls of a l l the other objects in the solar system also affect the motion . These smaller forces are called perturbations, and can be very compl icated .

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ORBITAL PARAMETERS describe an orbit i n space. The size is described by the sem i major axis (half the long axis of the e l l i pse), which is the average d i stance from the center of Earth . ECCENTRICITY descri bes the shape of the orbit. For closed orbits th is is a nu m ber between 0 ( for a perfectly c i rcu lar orbit) and 1 (a parabolic escape orbit) . A hyperbolic escape orbit has eccentricity g reater than 1 . INCLINATION is the angle the orbit makes with the equator. An orbit lyi n g over the equator has an i n c l i nation of 0 deg rees; for one flyi ng over the poles the i ncli nation is 90 degrees. A satell ite with inclination between 90 degrees and 1 80 deg rees is going from east to west, and is said to have a retrograde orbit. Several other nu m bers descri be the ori ­ entation of the orbit i n space. PERIOD, the length of time it takes to orbit once, depends on the altitude of the satell ite . The space shuttle, orbiti ng a cou ple h u n d red m i les h i g h , has an orbital period of about 90 m i n utes. Elliptical orbits come in many shapes

Inclination of an orbit to the equator

PERIGEE is the point on the orbit where the sate l l ite is clos­ est to the Ea rth ( from "peri -" mea n i n g "close" and "gee" mea n i n g "Earth" ) . A satel lite moves fastest at perigee. APOGEE is the point i n an orbit farthest from the Earth . Here a satell ite moves slowest. TRAJECTORY is a term someti mes used to describe a path from one orbit or pla net to a nother. "Tra n sfer orbit" i s another term for the same th i n g . T o go from o n e orbit to another one, you must fire a rocket to speed u p the satel­ lite (to get to a higher orbit) or slow it down (to get to a low­ er one) . Th is will place the satell ite in a transfer orbit. When it gets to the new orbit, you must aga i n fi re a rocket to g ive the satel l i te the correct speed for the new orbit. LOW EARTH ORBITS a re those with i n a few hundred m i les of the surface of Earth. The lowest practical orbit is about 1 00 m i les u p . _

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HIGHER ORBITS are those above about 1 ,000 m i les. The h igher the orbit, the longer the period (the time it takes to complete an orbit), and more of the Earth's su rface that can be seen from the satell ite. GEOSYNCHRONOUS EARTH ORBIT is a special orbit 22,300 m i les above Earth' s su rface. Here a satell ite has a period of 24 hours, the same time it takes the Earth to rotate once. GEOSTATIONARY ORBIT is a geosynchronous orbit with zero incl ination . In th is special case the satell ite w i l l seem to be stationary in the sky as seen from Earth . An antenna on Earth pointed at such a satell ite would not have to move at all . The u sefu lness of such an orbit for com m u n i cations satell ites (commsats) was pointed out in 1 945 by author-eng ineer Arthu r C . Clarke. This orbit is often cal led a "Clarke orbit" in h i s honor. SUN-SYNCHRONOUS ORBITS cause the satellite to pass over every place on Earth at the same local ti me of day. Th i s i s done by choosing the proper inclination for the orbit. A satel­ l i te i n low orbit will have a Sun-sync h ronous path i f its inclination is about 98 deg rees. Several types of orbits

Relationship of distance and peri­ od of orbits

I NTERPLANETARY ORBITS a re those a round the S u n . The n u m bers that describe these path s a re s i m i l a r to those of Earth orbits, but d i stance is measu red from the Sun, and the incli nation is measured compared to the Earth's orbit a round the S u n . The nea rest and fa rthest poi nts i n orbit a re called "perihelion" and "aphel ion . "

Geostationary, o r Clarke, orbit

A "slingshot" trajectory

SLINGSHOT ORBITS, which are also called g ravity-assist tra­ jectories, a re those in which a spacecraft is sent close to a pla net i n order to use the gravity of the planet to slow down or speed up the craft {usually to speed it u p ) , changing its tra jectory. In th is way we can send spaceprobes on m issions we could not otherwise accompl ish because of the limited fuel capacity and power of our space veh icles.

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SPAC E N AV IGATION Finding one's way around in space is more complicated than it is on Earth . Si nce a spacecraft ( l i ke a n a i rplane) can move i n th ree sets of d i rections ( forwa rd,backwa rd , right­ left, a n d up-down } , there a re th ree n u m bers needed to determine one's position . On a surface such as the Earth, with no up-down d i mension, you need j u st two, such as latitude and longitude. RA D I O N AV I G A T I O N 1 s com monly u sed for satel l i tes in orbit a round Ea rth . They a re trac ked by ra d i o a n d radar (and sometimes optical telescopes) , and thus ground control lers conti n u a l ly know thei r position . C E L E S T I A L NAVIGAT I O N i nvolves observing the rela­ tion s h i p of the sate l l i te to sta rs, planets, and the S u n . Star trackers, which are actu­ a l ly s m a l l e l ectro n i c te le­ scopes, keep known sta rs i n view, a n d the satel lite' s com­ puter system ca l c u l ates i ts position and orientation from the directions to several stars.

Stee ring by the stars and by radio

INERTIAL NAVIGATION is a system of devices i n the satel­ lite that measures all changes i n motion and orientation . It computes where the satellite is based on where it was at some other ti me.

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ATTITUDE is the term used to describe the orientation in space of a satell ite. Satellites must know their orientation for poi nt­ ing a camera to take pictures or for pointing a radio anten­ na back to Earth . Li ke a n a i rplane, there a re th ree axes a round which the craft can tu rn . Motion a rou nd the axis poi nti n g i n the d i rection of fl ight i s cal led rol l . Up-and­ down motion, with respect to the orbit, is cal led pitc h . Side­ to-side motion i s cal led yaw. TRACKING NETWORKS of large antennas a round the world a re used to detect and communicate with spacecraft. Some­ times satel lites may be used to locate other satel l i tes, and to relay data from widely spaced Ea rth stations to a central tracking fac i l ity. For NASA, the focus of all tracking activ­ ities is at the Godda rd Space Flight Center in Ma rylan d .

Principles o f i nertial navigation

SPACE TRACKING i s an a round-the-g lobe, a ro u n d -the­ clock activity. Both the U . S . and the U . S . S . R . m i l i tary have extensive networks that not only track thei r own spacecraft but have the additional duty of watching for missile attacks. To do th i s they must know what i s i n orbit and where, and they must monitor every lau nch . Not much is known ( i n the non-classified world) about the Soviet tracking system. The U . S . system has its focus i n side Cheyenne Mou nta i n , nea r Colorado Springs, at the joint headqua rters of the North American Aerospace Defense Command and the U . S . Space Command . They use a world ­ w i d e network of optical and radar tracking equipment that sends in over 45,000 sightings a day for identification and analysi s.The optica l system is called GEODSS, for Grou nd­ based Electro-Optical Deep-space Surveillance, which uses electronic telescopes located in New Mexico, Hawa i i , Korea, Portuga l , and Diego Garcia Island in the Indian Ocea n . It i s sa id these c a n detect space objects o n l y a few inches across in low orbits, and only the size of a footba ll in orbits out to about 25,000 m i les. A system of 26 radio and radar sites spaced a round the Earth contributes information on objects in orbit. These include the U . S . Navy' s Space Surveil lance System . In the future, space objects will increasingly be mon itored from space by orbiting surve i llance satell ites. Private satell ite operators-for instance, of commsats- may have thei r own tracking and control faci l ities for their satel­ lites, and may perform these functions under contract for other satellite owners as well . Such systems are of course much less elaborate than the m i l itary systems. Low-orbit satellites someti mes relay their signals th rough higher-orbiting satellites. For interplanetary probes, NASA uses its global Deep-Space Network of very large antennas.

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ROC KET PROPU L SION Rockets a re the technology used for spacefl ight. A rocket is a device that carries its own fuel and oxidizer so it can work in a vacuum, u n l i ke a jet eng i ne that u ses the oxygen in the a i r to burn its fuel . A roc ket motor works because of New­ ton's Third Law of Motion {p. 4 1 ) . The combustion of the fuel and oxid izer produces a force in a l l d i rections i nside the rocket chamber. One end of the chamber-the nozzle-is open. The burn i ng gases escape out the nozzle, creating an unbalanced force push ing the rocket forward . A toy bal loon blown up and released works the same way, with a i r rush­ ing out one side and the bal loon going i n the opposite d i rection . Rockets do not work because their exhaust pu sh­ es aga i n st the a i r; i n fact, they work better i n a vacuum because they do not have air to push out of the way. I n some very small rockets, such as those used for m i nor maneuver­ ing and orientation of a spacecraft, the rocket {often cal led a thruster) is simply a jet of pressu rized {someti mes heated ) gas escaping th rough a nozzle. Action a n d reaction make a rocket work

THRUST of a rocket is the amount of push it has, usually mea­ su red in tons or pounds of force. For a rocket to be able to ta ke off, the thrust of the motor must be g reater than the weig h t of the rocket. The time during which a rocket is th rusti ng is someti mes cal led a "burn . " SPECIFIC IMPULSE measures h o w efficient a rocket fuel/oxi­ d izer comb i n ation i s . Th is i s the time during which one pou nd of fuel can produce one pound of th rust. The most powerfu l combination in use is l i q u id hyd rogen and l iq u i d oxygen; its spec i fic impulse i s a round 3 5 0 seconds. SOLID-FUEL ROCKETS use a solid mixtu re of fuel and oxi ­ dizer. The ea rliest sol i d fuel w a s gunpowder, a m ixtu re o f sulfu r, charcoa l , and saltpeter. Today' s sol id fuels a re m ix­ tu res of rubbery materia l s conta i n i n g powdered a l u m i n u m and oxidizer chemicals. They are usually m ixed i n l iquid form and then pou red into the rocket casi ng, where they sol i d i ­ fy. T h e thrust of a sol id-fuel rocket depends on t h e a m o u n t burn i ng at one t i m e , w h i c h can b e control led b y design i ng the inside of the rocket properly. Once a sol id-fuel rocket is ign ited , it can not be shut off; it burns until a l l fuel is gone. LIQUID-FUEL ROCKETS use a mixtu re of l i q u i d fuel and a n oxidizer as propella nts . Some chemicals must be ign ited by a flame or a spark. Others spontaneously i g n i te when they come i n contact; these a re cal led hypergol i c propella nts. Some common liquid fuels are alcohol, purified kerosene, l iq­ uid hydrogen , and hyd razi ne. Common oxid i zers i nclude n i trogen tetroxide and nitric acid, as wel l as l iq u i d oxygen . A liquid-fuel engine can be controlled in power, shut off, and restarted at will. Supercold propellants l i ke liquid hydrogen and oxygen, cal led cryogen ic fuels, are tri c ky to handle, requiring the h i ghest tech nology, but a re very powerfu l .

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I on rocket

Types of rocket engines

ELECTRIC PROPULSION, someti mes cal led an ion rocket, i s a technique n o t yet perfected . It works b y plac i n g a n elec­ trical charge on the molecules of a single fuel, which can be water, hydrogen, mercury, or many other chemicals. There is no combustion , so no oxidizer is needed . The charged molecu les ( ions) a re propelled out of the rocket by a strong electrical field, producing th rust. The tota l thrust produced by ion rockets is very low, but they use fuel with g reat effi­ ciency and can function for a long time. I n the futu re they may be used for interplanetary and maybe even interstellar probes. MASS RATIO i s the ratio of the weight of the payload {what you want to get into space) to the total fueled weight of the rocket. This is often very sma l l , only a few percent. For th i s reason , rockets a re usua l ly built t o operate i n stages.

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STAGING is the tec h n ique of building a rocket i n sections, or stages, each of wh ich provides thrust for a time and then i s d i scarded . The reason for th is is to save weight, for the fuel tan ks and rocket engi nes themselves a re very heavy. Typical rockets (often cal led lau nchers) have two to fou r stages. The first stage usually burns for only a couple o f m i n ­ utes, getti ng t h e rocket going a n d l i fting it u p several m i les through the th ickest layers of the atmosphere. After its fuel tanks are empty, it d rops away and a second, smal ler stage ignites, carrying the rocket h igher and faster. Third and fourth stages may be used to continue the process until the payload reaches the proper altitude and speed for its m ission . Stages after the fi rst one a re cal led u pper stages. EXPENDABLE LAUNCH VEHICLES ( E LVs) are lau nchers, or rockets, that a re used once and their pa rts d i scarded . Most launchers fal l into th is category. Most a re l a u nched from launch pads; a few small rockets are launched from a i rcraft. So fa r, the U . S . and Soviet space shuttles a re the only reuseable spacecraft. TO ACH I EVE ORBIT the sate l l i te must get both h i g h enough and fast enough to stay there. For th is reason there is often a period of coastin g between the burn ing of the rocket' s stages. To place a com m u n i cations satel lite i n a geosyn­ chronous orbit, a rocket will typically use three stages to fi rst place it in a h i g h ly ell iptica l tran sfer orbit with a perigee of 200 m i les and a n apogee at the geosynchronous altitude of 22,300 m i les. The th i rd stage may be called a perigee kick motor or a Payload Assist Module ( p . 7 3 ) . After the satel­ l i te has been checked out fol lowi ng several of these orbits, and after it has reached its a pogee, a sol id-fuel rocket fi res to c i rcula rize the orbit at the proper altitude. Th i s rocket i n the base o f the sate l l ite i s called a n a pogee k i c k motor.

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G FORCE is a measure of the acceleration produced by a rocket. One g, or "gee," is the force of gravity. The space shuttle crews and ca rgo experience a pea k force of about 3 g' s. An unman ned rocket may reach 1 1 g' s or more. COST OF LAUNCHING is still very high. In the 1 980s, it cost rou g h l y $25 to $ 1 50 m i l l ion to place a few-thousand­ pou n d expendable- rocket sate l l i te i n to E a rth orbit. This translates into costs of $ 1 0,000 to $50,000 per pound. And th i s covers only the costs of building the rocket, the fuel, the payload preparation, and so o n . It doesn ' t incl ude the cost of the payload itself, or such developmenta l costs as design­ ing the rocket or building the launch pad . One of the major goals of a l l space progra ms is to reduce the cost-per-pound to orbit. Several stages o r e used t o reach orbit

U .S. LAU N C HERS At the end of World War I I , both the U . S . a n d the U . S . S . R . captured German rockets, rocket parts, a n d rocket scientists and engineers. These then became the basis of both nations' rocket prog rams. THE V-2 ROCKET, also ca l l ed the A-4, i nvented i n the ea r­ ly 1 940s by a team of German engi neers working under Dr. Wern her von Bra u n , was the world's fi rst rocket to reach space . It was 46 feet h i g h and 66 i nches i n d i a meter, weighed 27,000 pounds, and used alcohol and l i q u i d-oxy­ gen fuel to generate a thrust of 56,000 pounds, carryi ng V - 2 rocket ORDWAY a one-ton payload 200 miles down ra n g e a n d 60 m i l e s h i g h . D u r i n g t h e last yea rs of World War II it was used to bombard England. Later, U . S . scienti sts used severa l to set new altitude records. JUPITER-C, or Juno I , put the f i r s t A m e r i c a n s a te l l i t e , Explorer 1 , i n to orbit Jan­ uary 3 1 , 1 958, and carried the fi rst two U . S . m a n ned suborbita l spacefl i ghts . Juno I wa s 7 1 feet h i g h a n d almost 6 feet i n d i a meter. It had a liquid-fueled , 83,000pou nds-of-thrust fi rst stage, and th ree solid-fueled upper stages.

VANGUARD was the second U . S . rocket to orbit a pay­ load . It stood 72 feet h i g h , 3 . 7 feet i n diameter. The first stage used kerosene and liq­ u i d o x y g e n to p r o d u c e 2 8 , 000 p o u n d s o f th rust, topped by a secon d stage using fum i n g n itric acid and d i methyl hyd razine propel ­ lants and a sol id-fueled th i rd stage. S AT U R N R O C K E T S w e r e developed for the m a n ned space prog ra m . The Satu rn lb, with 1 . 3 m i l l ion pounds of thrust, placed the Apol lo7 c rew i n to Ea rth orbit, and later lau nched th ree Skyla b crews. The th ree-stage Saturn V, the largest rocket ever made by the U . S . , was 363 feet high, 33 feet in diameter, and produced 6 . 4 m il l ion pounds of thrust. It was used for the Apo l l o p ro g ra m o f l u n a r fl ights, and a converted th i rd sta g e beca m e the S kyl a b space station .

A Jupiter-C rocket

NASA

Vanguard launcher

NASA

S a t u r n V, the A p o l l o r o c k e t NASA

ROC KET LAU NC H E RS

Scout Ariane-4

H-2

on g March

U.S. shuttle

Titan 4

Energia/Buran

Proton

SCOUT i s the smal lest U . S . satell ite launch veh icle. It is a lso u sed as a sou n d i n g rocket-those that ta ke sma l l payloads above the atmosphere a n d back aga i n . I t was the fi rst America n a l l - so l i d - p ropellant lau ncher. There a re many versions of the Scout, but a typical confi g u ration has fou r stages a n d sta n d s 7 5 feet h i g h , 3 . 7 feet in diameter, and weighs 47,000 pounds. The fi rst stage has 1 09,000 pounds of th rust; the second s ta g e p ro v i d e s 6 4 , 0 0 0 pou n d s of th rust; the th i rd stage is an 1 8, 700- pou nd­ thrust motor; and the fou rth s ta g e p ro d u c e s 5 , 7 0 0 p o u.)l d s o f t h r u s t . I n th i s a rrangement, Scout c a n place a payload o f a bout 425 pounds i n to a n orbit 300 m i les h i g h . Its fi rst successfu l launch was of Explorer 9 i n 1 96 1 . S c o u ts h ave c a r r i ed s u c h satel lites a s the Small Astron ­ omy Satell ite , the Meteoroid Technology Satellite, ond sev­ eral amateur radio satell ites. Scouts have been launched from a l l U . S . l a u nch s i tes, most often Wa l lops I sland, and from many other nations.

Scout launcher

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NASA

Atlas launcher

NASA

ATLAS was the fi rst opera­ tional U . S . ICBM ( I n tercon ­ t i n e n ta l B a l l i st i c M i s s i l e ) , beg i n n i n g i n 1 95 9 . These missiles were gradually with­ drawn from service and con­ verted to satel l i te launchers. Atlas i s cal led a "stage­ and-a-half" rocket because it uses a s i n g l e m a i n eng i n e together with two booster engines; a l l are powered b y liquid fuel . The three engines are ignited on l i ft-off, and the boost­ ers fal l away halfway through the fi rst-stage burn . An Atlas-D launched America's first manned orbita l flight with John Glenn i n 1 962. Others have carried such satellites as Mari ner, Ranger, Su rveyor, High Energy Astronomical Observatory, and many m i l itary payloads. Severa l versions of Atlas carry either the Agena or Cen­ taur u pper stage. The Atlas­ Centaur configuration is the cu rrent commerc i a l l a u n c h veh icle. A n Atlas-Centaur i s 1 3 2 feet h i g h , 1 0 feet i n d i a m ete r , a n d c a n p l a c e 1 3,000 pounds into low orbit, 4,900 pounds into a transfer orbit, or send 2,600 pounds i nto an interplanetary orbit.

Mercury-Atlas

NASA

D E LTA l a u n c h ers come i n several confi g u rations, d i f­ feri ng m a i n ly i n the number of solid-fuel strap-on booster rockets, and in what u pper s ta g e is u s e d . T h e D e l ta 3 9 2 0 u s es n i n e stra p - o n m o to r s tota l i n g 7 6 6 , 000 pounds of thrust on the liq­ u id-fueled fi rst stage, which i ts e l f p r o d u c e s 2 0 5 , 0 0 0 pou nds of thru st. T h e l iq ui d­ fueled second stage provides 9,800 pou nds of thrust. The th i rd stage produces 1 8,500 pou n d s . The payload itsel f may contain a Payload Assist Mod ule ( p . 73 ) . Overal l , the rocket stands 1 1 6 feet h i g h , i s 8 feet i n diameter, a n d when fueled weighs 426,000 pounds. It can place 2,750 pounds of payload into geostationary transfer orbit and more into low Earth orbit. An improved Delta model is n o w in u s e as t h e A i r Force's Medium Launch Veh i­ c l e a n d fo r c o m m e rc i a l launches. A De lta commercial launcher MDSSC

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TITAN rockets, which began flying i n 1 959 as ICBMs, are cu rrently the most powerfu l u n m a n ned U . S . l a u n chers . The Tita n Model 3 B has two ma i n stages and a n upper stage that depends on the payloa d . Tita n - 3 C and - 3 D add tw o solid-fuel boosters to the fi rst stage. Tita n - 3 E is a NASA version used to h u rl the Viking and the Voyager i nterp l a n eta ry p robes i n to escape orbits. The Tita n 4, also known as the Tita n 34D-7, is 204 feet long, with a payload 40 feet long and 1 6 feet in diam­ eter. It i s capable of l i fting 40,000 pounds to low orbit or 1 0,000 pounds to transfer orbit. Its two fi rst-stage solid booste rs h ave 1 .6 m i l l io n pounds o f th rust each, added to 546,000 pou nds for the liquid-fueled eng ine. Second s ta g e p ro v i d e s 1 0 4 , 0 0 0 pou nds of th rust, and a Cen­ taur upper stage adds 33,000 pou nds of thrust. Tita n can also carry i nstead an I nertial Upper Stage (p. 75) . The Titan launcher

NASA

Space sh uHie an its crawler transporter

NASA

SPACE SHUTTLE, officially cal led the Space Transportation System, is the world's fi rst largely reusable spacecraft. There are th ree major components . T H E ORBITER veh icle looks l i ke a n ai rplane a n d i s about the size of a Boeing 737 jet, with a length of 1 84 feet and a wingspan of 78 feet. A two-level c rew com partment i n the nose holds up to seven crew members . Amidsh i p there is a 60-foot- long, 1 5-foot-wide cargo bay (big enough to hold a bus, or fou r medium-sized commun ications satell ites} that Cc:.:!n carry up to 65,000 pou nds of payload i n to a low­ i n c l i nation orbit or 3 2,000 pou nds i nto a polar orbit. Typ-

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ical fl ight altitudes a re 200 m i les up, with a maxi m u m of about 600 m i les. An a i rlock exits into the payload bay so astrona uts can perform tasks i n space. A Canad i an-b ui lt Remote Ma n i pu lator A r m is used to pick u p and retrieve satell ites from the ca rgo bay. The orbiter is powered on launch by th ree liquid-fueled motors, provid i n g 375,000 pounds of th rust each, as wel l as by smaller rockets for ma neuveri ng i n space. SOLID ROCKET BOOSTERS (SRBs), each provid i n g 2 . 6 5 m i l l ion pou nds of th rust, a re ignited at l i ft-off along with the space shuttl e ' s main engi nes on the orbiter. They burn for a little over two minutes, by which time the shuttle is about 28 m i les up. Then they detach and parachute into the ocean , to be recovered by ships, towed to shore, refurbished, and used aga i n . Each booster is 1 50 feet long, holds 1 . 1 m i l l io n pounds of fuel, and is designed t o b e used about 20 times. Inside the space shuttle

THE EXTERNAL TANK holds the liquid hydrogen and oxy­ g e n fuel fo r the o r b i ter' s engines. Both the orbiter and the solid rocket boosters are attached to it, and it is the only major pa rt not reused . After 8 . 5 m i n utes of flight, the ta n k i s empty and is jet­ tisoned to fa l l back into the ocea n and s i n k . The ta n k i s A space shuttle heads into space made of aluminum; it is 1 55 NASA feet long, 28 feet i n d iame­ ter, and 1 . 65 m i l l ion pounds when fueled . A shuttle is assembled in the Vehicle Assembly Building sev­ era l m i les from Launch Pads 39A and 39B at the Ken nedy Space Center, or at Vandenberg Ai r Force Base. The orbiter and the external tank are attached to the boosters, which stand on a Mobile Launch Platform . The whole "stacked" shuttle is then moved by a giant tractor to the launch pad . At 6 . 6 seconds before l i ftoff the m a i n engi nes ign ite Space shuttle lands like an air­ and b u i l d up to fu l l thrust, plane NASA which signals the boosters to ign ite, and the shuttle takes off. The boosters d rop away two m i n utes later, a n d the s h u tt l e c o n t i n u e s to c l i m b using its main engi nes. The tank separates at eight min­ utes into the fl ight, falling into the ocean , wh ile the orbiter conti nues on i nto orbit using its small Orbital Maneuver-

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ing System rockets. When its m ission is complete, the shut­ t l e is tu r n e d a ro u n d : t h e m a n euveri n g e n g i nes a re fired to slow it down, then the orbiter flips over to point nose fi rst. The sh uttle then reenters the atmosphere, getting very hot as it reduces speed using the d rag of the air. It is com­ pletely un powered , but has the abil ity to fly severa l hun­ d red m i les to either side of its orbita l path . It lands l i ke a gl ider on a runway. After landing, unused fuels a re removed and the orbiter is refu r b i s h ed fo r a n other fl ight. I f the shuttle must be tran sferred some other place for launch, it i s carried on the back of a mod ified 7 47 a i rplane. The d e s t r u c t i o n o f t h e space shuttle Challenger and death of its c rew on January 28, 1 986, led to a several­ yea rs halt i n the shuttle pro­ g r a m a n d l eft o n l y th ree operational orbiters, named Col u m b i a , D i s covery, a n d Atlantis. A new one, Endeav­ our, has now joi ned them .

A space sh•.ottle seen by a nearby satellite NASA

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THE NATIONAL AEROSPACE PLANE now under study is planned as a hypersonic wi nged craft that could take off like an a i rplane from a runway, accelerate to orbita l velocity, maneuver in low orbit, and then retu rn to Earth, landing l i ke a n a i rplane aga i n . Such a veh icle cou ld provide access to low orbits at a cost per pound of payload much lower tha n ord i n a ry rockets or the space shuttle. A com mercial ve.rsion of it may be used as a transoceanic a i rplane, nicknamed the "Orient Express," able to travel from San Francisco to Tokyo in about th ree hours. Req u i ring very h igh-strength, lightweight, heat- resistant materials, several designs are being stud ied for construction in the late 1 990s. One calls for using methane as a fuel, with atmospheric oxygen wh ile in the lower atmosphere, then switching to l iquid hydrogen and liquid oxygen at h igher alti ­ tudes. Other plans consider the use of ramjets and supersonic combustion ramjets {called scram jets ) . Conception for a U . S . aerospace plane

AGENA i s the oldest U . S . u p p e r sta g e , u s ed s i n c e 1 959 more than 300 times with g reat su ccess . I t h a s been used a s the u pper stage for Atlas, Thor, a n d Tita n 3 B l a u nchers. Several m i l itary spy-satel­ lite payloads a re based on Agena . An Agena was the fi rst space-doc k i n g ta rget, and other Agenas launched s u c h p a y l o a d s as t h e Mariner-Ma rs and Mari ner­ Ven us probes. T h e l a test vers i o n , t h e Agena-D, c a n b e used with a wide vari ety of payloa d s , a n d its liquid-fueled engines can be stopped and restarted in space for versatile maneu­ ven ng. Some Agena stages have been used for missions lasting more than six months in orbit. This stage is 23 feet long, 5 feet in diameter, and weighs 1 5,000 pounds, 9 1 percent of which is fuel .

Atla s rocket with Agena u pper stage NASA

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CENTAU R upper stage has been used with Atlas and Tita n launchers to orbit such Earth -orbit payloads as large com­ m u n i cations satellites and orbiting astronomical observato­ ries. It has a l so been used for many i nterplaneta ry mis­ s i o n s , i n c l u d i n g P i o n ee r , V i k i n g , Mari ner, and Voy­ ager. A typical Centaur stage is 30 feet long and 1 0 feet in diameter; it burns 3 1 ,000 pounds of cryogenic fuel in its two e n g i n e s , p ro d u c i n g 3 3 ,000 pou n d s o f thrust. These engines can be restart­ ed in space for maneuver­ ing. Centaur, when used as the upper stage with an Atlas booster, is capable of putting 1 3,000-pound payloads into low orbits, 4,900 pounds into a geostationary transfer orbit, and , with the add ition of a sma l l " k i c k m otor" on the payload, 2,600 pounds into an escape tra jectory. The Centa u r conta i n s a very capable guidance, nav­ igation, and systems-control computer that governs not only the Centaur itself, but also the Atlas booster. Atlas with a Centaur upper stage NASA

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PAYLOAD ASSIST MODULE ( PAM) is designed as a small sepa rate upper stage attached to satell ite payloads on Delta and Atlas rockets, and for boosti ng payloads from the low orbit of the space sh uttle to geostationary tra n sfer orbit. When used with the shuttle it is someti mes cal led the Spinn ing Solid Upper Stage because directional stabil ization is achieved by spinning the PAM and its payload about 50 revolutions per m i n ute. When used in the shuttle, the spinning is started by elec­ tric motors on the structure holding the PAM and its payload . They a re then ejected from the shuttle' s payload bay by springs, and then a l lowed to drift many mi les away from the shuttle (for safety) before the PAM is ignited to carry the payload h ig her into space. When used with expend­ able rockets, small th ruster jets a round the PAM cause the spi n n i n g . T h e fi rst PAM was used i n 1 980 with a Delta launcher. PAMs come in d i fferent versions for use with shuttle a n d expen d a b l e roc kets . PAMs fo r s h u ttle u se h ave slightly shorter rocket nozzles so they will fit with i n the car­ go bay. The PAM is capable of taking al most 3,500 pounds of payload from low orbit to a Clarke orbit. Payload Assist Module attached to a satellite NASA

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TRANSFER ORBIT STAGE was developed with private fu nds to provide a n upper stage between the capabil ities of the PAM, the Centaur, and the I nertial U pper Stage. Weighing 24,000 pounds when fu l ly fueled, it is 1 1 feet long and 1 1 feet i n dia meter, and can ta ke payloads i n the ra nge of 6,000 to 1 3,000 pounds from shuttle orbit to geostationary tran sfer orbit. Its rocket engine provides 60J50 pou nds of thrust. It can also be used as the upper stage for a Titan, tak­ ing a payload capacity of 9,000 pounds to Cla rke orbit. APOGEE AND MANEUVERING STAGE is an upper stage 1 0 feet i n dia m eter and 5 . 6 feet i n length , wei g h i n g 9,400 pounds. When used by itself as an upper stage from the shut­ tle, it can boost 5,300 pounds from low orbit to geostationary orbit. It will also be used for ferrying payloads from the shut­ tle to the space station . Combi ned with the Tra n sfer Orbit Stage, the payload capacity to high orbit is increased to 1 8 ,600 pou nds. Transfer Orbit Stage

OSC

INERTIAL UPPER STAGE was designed by NASA and the Ai r Force to launch heavy payloads from both the shuttle and the Titan . It was fi rst u sed with a Titan in 1 98 2 . I t is a two-stage solid-fueled vehicle, 1 6.5 feet long and 9.6 feet in diameter. Its first stage provides 42,600 pounds of thrust and is connected to the second stage by a structure called the interstage. The second stage g ives 1 7,430 pou nds of thrust. The payload , attached to th is, contains a sop h isticated gu id­ ance and control computer. Total weight (without payload) is 32,000 pounds. It can carry a 5,000-pound payload from low orbit to C larke orbit. The Inertial U pper Stage

NASA

;

Pegasus air-launched racket

OSC

PEGASUS is the newest and smallest of U nited States launch­ ers. It is u n ique i n severa l ways. Fi rst, it is the o n ly launch­ er developed purely by private industry, a l beit using many pa rts from previous spacecraft. Second ly, it i s l a u nched not vertically from a launch pad , but horizonta l ly from under the wing of an a i rplane. Pegasus is designed to car­ ry sma l l payloads-someti mes called sma l l sats, or l ight­ sots, or cheapsats-of less tha n about 950 pou nds inex­ pen sively i nto low orbits a few hundred m i les u p . The th ree-stage, solid-fueled, 50-foot- long Pegasus rock­ et is attached under the wing of a B-52 bomber and flown to an altitude of about 40,000 feet over the ocean . Pegasus is then d ropped from the a i rplane and its fi rst-stage motors ign ite, provid ing 1 09,000 pounds of thrust. When the first stage is empty, it d rops away and a second stage provides 27,600 pounds of thrust for severa l m i n utes before it, too, d rops away. A th i rd stage, with 9,800 pounds of thrust, puts the satell ite into low Ea rth orbit.

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SOVIET LAUNC HERS Like the U . S . , the Soviet rocket program followi ng World War I I got its sta rt using captu red German scientists and rockets . U n l i ke the U n i ted States prog ra m , however, the Soviet pro­ gram was carried on in great secrecy, some of which still sur­ rounds it today. For exa mple, photog ra phs of some Soviet rockets were not made publ ic until 20 yea rs after they were used , and, until recently, some launch sites officially did not exist. Soviet boosters have tended to be capable of putti ng heavy payloads into orbit. One reason for this seems to be that Soviet scientists were not able, in the early days of ICBMs, to reduce the weight of their bombs and so had to use more pow­ erfu l rockets. It also req u i res more powerfu l rockets to place satellites into low- incli nation orbits from the Soviet high -lati ­ tude launch sites. A continuing reason may b e that Soviet microminiatu rization tech nology is less advanced, meaning thei r satellites are heavier. At the present ti me, they have the 77

world's most powerful boost­ er, Energia, as part of their fleet. There a re th ree d i fferent nomenclatures for Soviet rock­ ets. The Library of Congress system u s e s l ette rs of the alphabet roughly i n order of appeara nce. Another system, used by the U . S . Department of Defense, uses the prefix SL, meaning "satell ite launcher," and a number. Then there is what the Soviets cal l them . SOVIET A SERIES launchers, ori g i n a l ly I C BMs, lau nched the fi rst th ree Sputn i ks, and incl ude the A 1 (or SL- 3 , or Vostok), now being replaced with more adva nced mod­ els. Used for heavy spy satel­ l ites, they stand 1 25 feet ta l l a n d ca n p l a ce s i x ton s i n orbit usi ng a main-core rock­ et and fou r boosters . A2 (SL-4), cal led Soyuz by the Soviets, h a s been ex­ ten s ively u sed for m a n ned launches of Soyuz spacecraft a n d Progress supply veh i The Soviet A 1 rocket, Vostok

78

des. It stands 1 63 feet h igh and can place 7 . 5 tons into low orbits. A2e ( S L - 6 ) a d d s an a d ­ ditional u pper stage to pro­ pel payloads to escape orbit. It has been u sed for i n ter­ planetary probes, but is now u sed mostly fo r com m sats and deep-space probes. THE 81 LAUNCHER, or SL7, i s no longer u sed . It was used to place sma ll payloads i n the Kosmos and lnterkos­ mos series i n to orbit. These s a te l l i t e s h a d m a x i m u m we i g h ts o f a bo u t 1 , 300 pou nds. THE Cl (SL-8) booster i s the only one of the many Soviet l a u n c h e r s k n ow n to b e launched from a l l th ree Sovi­ et launch sites. The fi rst stage develops 1 7 6 tons of thrust. Overa l l length is about 1 05 feet. They are primari ly used now for navsats ( n avigation s a te l l i t e s ) a n d c o m m s a t s (comm u n ications satel l i tes } . Soyuz

TASS

The Soviet D 1 launcher

D SERIES lAUNCHERS have six fi rst-stage engi nes pro­ ducing a m i l l ion pounds of thrust. D 1 (SL- 1 3 ) adds an additional u pper stage. Th is workhorse booster lau nched the heavy Salyut a n d M i r space sta t i o n s , a s wel l a s many heavy Kosmos satel­ lites. It can place 20 ton s in low orbit. PROTON, a l so cal led D 1 e and SL- 1 2, is the D 1 with an added u pper stage to a l low escape from Ea rth orbit. I t can ca rry 5 . 7 tons as fa r a s the Moon, 5 . 3 tons to Ven us, 4.6 tons to Mars, and 2 tons to C l a rke orbit. The Soviet U n ion has tried to make th is launcher ava ilable as a com­ mercial veh icle. There are no Series E, G, or H Soviet launchers . F S E R I E S LA U N C H E R S i nclude the F 1 (SL- 1 1 ), which w i t h an u p p e r sta g e c a n p l a c e u p t o a b o u t 9 , 000 pounds i n low orbit. It stands

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Proton

NOVOSTI

1 49 feet h ig h , is 1 0 feet i n d ia m ete r, a n d prod uces a thrust of 494,000 pou nds i n t h e f i r s t s ta g e , 2 2 0 , 0 0 0 pounds i n t h e second stage. Th is lau ncher has been used a l most exc l u s i vely for m i l i ­ ta ry payloads. T H E F 2 ( S L- 1 4 ) a d d s sti l l another upper stage, so that t h i s l a u n c h e r c a n ta k e 1 2 ,000 pou nds to low Ea rth orbit. It is a bout the same size as the F 1 , but with slight­ ly i m p roved th rust. Typ ica l payloads i nclude the Meteor series weather satell ites and p roba bly heavy e l ectro n i c spysats (spy satell ites) . THE MEDIUM-LIFT VEHICLE, also known as the J 1 , the SL1 6, and the S L-X, i s a newer Soviet launcher that fi l l s the payload-capacity weight-gap between the capa b i l i ties of the A2 and the D 1 . Its fi rst launch was in 1 985. It can boost 1 5 to 20 tons into low orbit.

ENERGIA, or SL-W, fi rst lau nched in 1 987, is the world' s most powerfu l launch veh icle. It is capa ble of putti ng about 220,000 pounds into low Ea rth orbit. The lau ncher stands 1 98 feet ta l l , weig h s 4.4 m i l l ion pounds, and has 6.6 million pounds of thrust from its first stage. This consists of a core tank, much l i ke the external tan k of the spoce shuttle, with four liquid-hydrogen/liquid-oxygen engines. Around the core are four boosters using kerosene and liquid oxygen . There are versions of the Energia for use with unmanned payloads and for the Soviet space shuttle and spaceplane. The payload is carried piggyback on the side of the core veh icle. With the add ition of upper stages Energia may be used to build a large Soviet space station i n the 1 990s. The booster rockets are reuseable. They separate from the core stage when the launcher reaches about five times the speed of sound. They parachute to Earth and are refurbished for use. THE SOVIET SPACE SHUTTLE (or SL-W Shuttle, si nce it is launched on the Energia booster) i s very s i m i lar to the U . S . shuttle. T h e Soviet Un ion made much u s e o f America n tech­ nology and experience. The fl ight of the fi rst Soviet shuttle, named Bura n ( "Bl izzard" ) , was in November 1 98 8 . There are several differences between the Soviet shuttle and the America n one. The Soviet shuttle carries its main-stage engines on the external tank, g iving improved performance to the orbiter because of reduced weight. The boosters are l iq­ uid-fueled . The Soviet shuttle can operate either with a crew or as an unmanned vehicle. For transport between launch sites both the orbiter and tank can be carried piggyback on an air­ pla ne, s i m i lar to the way the American orbiter is carried on a Boeing 747.

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THE SOVIET SPACEPLANE is a smaller veh icle, designed proba bly fo r a th ree- m a n c rew, a n d capable of ra p i d launch . It w i l l b e used for replacing Mir space-station crews, servicing sate l l i tes in low orbit, and for man ned reconnais­ sance m ission s . The U.S. Depa rtment of Defense ca l l s it a "space fighter." The Soviet Energia o n d Buran space shuttle

EU ROPEAN L AU N CHERS THE EUROPEAN SPACE AGENCY ( ESA) is a consortiu m of more th a n a dozen nations that pool th e i r money a n d expertise on space projects . The biggest contributors to ESA are the U n i ted Ki ngdom, France, Germany, and Ita ly. Having no launch sites for large rockets in Europe, ESA uses the French Guiana Space Center. The Ariane, ESA's launcher, had its fi rst Flight i n 1 979 and became operational i n 1 98 2 . Si nce then it has captu red about half of the world's commercial launch market. ARIANE-3, one of the versions recently used, stands 1 62 feet high; it uses fou r l iq u id-fueled eng i nes plus two solid-fueled strap-on boosters. The second stage has a si ngle engine sim­ ilar to those i n the fi rst stage, and the th i rd stage uses cryo­ gen ic fuels. Tota l launch th rust is 850,000 pounds, and the veh icle weighs 530,000 pou nds. It can place 5,700 pounds i nto a geostationary transfer orbit, or 3, 800 into an escape orbit. ARIANE-4 i s the latest version . The fi rst stage is si mi lar to the Ariane-3, but it is 23 feet longer in order to hold more fue l . B y itself it has a th rust from its fou r eng i n es of 60 1 ,000 pou nds. The second and th i rd stages a re strengthened ver­ sions of those from the Ariane- 3 . Aria ne-4 comes i n severa l configurations. Model 42P, with two sol id-fuel boosters, can place 2 . 6 tons into Cla rke orbit. Model 44P uses four solid boosters for a payload capacity of 3 tons. Model 42L uses two new liquid-fueled boosters for 3 . 2 tons of payload. Modei 44LP uses two sol id­ and two liqu id-fueled strap-ons for a 3 . 7-ton capacity. Mod­ el 44L, using fou r l iquid-fueled boosters with a lift-off thrust of 1 . 2 m i l l ion pounds, can send 4 . 2 tons to geostationary orbit.

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Ariane-3 launcher

ESA

Ariane-44LP launcher

ESA

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HOTOL spaceplane concept

BAe

HOTOL, for HOrizonta l Ta ke-Off and La n d i n g , is a British proposa l fo r a s i n g l e - stage-to-orbit, 200-ton u n p i l oted spaceplane that will take off l i ke an a i rplane from a runway on a rocket-assisted trolley. It wi l l burn l i q u i d hyd rogen from on-boa rd ta n ks with atmospheric oxygen d u ri n g fl ight i n the lower atmosphere. When the a i r becomes too th i n at higher altitudes, it will switch to on-board tanks of liquid oxy­ gen . Its ca rgo bay w i l l be about the size of that of the U . S . space sh uttle, a n d the cargo load around 1 0 ton s . When used to carry people, a crew compartment will be fitted into the cargo bay. After del ivering its payload to low orbit it will reenter the atmosphere and land l i ke an a i rplane. It could be mod ified to be a hypersonic commercial airl i ner. HOTOL may be fly­ ing by the end of the 1 990s.

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HERMES is the Europea n Space Agency' s project for a reusea ble, small space-shuttle veh icle. Present plans ca l l for a three-person crew. Hermes will carry 3 tons o f payload . Its overa l l weight will be around 2 1 tons. ARIANE-5, now i n the planning stages, w i l l become the launch veh icle for Hermes in the late 1 990s . It will also ca r­ ry u n m a n ned satell ite payloads, capable of ca rryi ng 1 5 tons to low Ea rth orbit and 8 tons to geosynchronous orbit. A single cryogen ic fi rst-stage eng ine will provide 80 ton s o f thrust. Two sol id-fuel stra p-on boosters wi l l each add another 500 tons of thrust. At lift-off the launcher wi l l weig h about 1 45 tons. For small- to medium-sized payloads there will be a second stage. For m i ssions that requ i re more pow­ er, a th i rd stage developed from the Ariane-3 will be used . For manned m issions, the Hermes space shuttle is to be the upper stage. Hermes spaceplane on Ariane-5

ESA

Songer and Horus concept

ESA

SANGER/HORUS is a proposed Germa n two-stage space­ plane that is to be fully reuseable. The fi rst-stage Sanger veh i­ cle itself will be a hypersonic ai rcraft powered by turbo ram ­ jets with a n 83-foot wi ngspa n , a length o f 1 65 feet, and a ta keoff weight of about 350 tons. It w i l l ca rry the Horus orbita l veh icle piggyback, ta king i t to a n altitude of about 20 m i les and a speed of 7,500 m i les per hour. Sanger will then sepa rate from the orbital veh icle and fly back to land at a n a i rport for reuse. Horus, weighing 50 tons, will then conti nue into space. Payload capacity to low orbit i s planned to be either 9,000 pounds of cargo or 4,500 pounds of cargo and a crew of ten . Its mission over, Horus would reenter the atmosphere and land l i ke an a i rplane.

88

JAPAN ESE L AU NC HERS J a p a n beca m e the fo u rth space nation i n 1 970 . LAMBDA SERIES rockets are sma l l , unguided sol id-fueled launch veh icles with a fi rst­ s ta g e t h r u s t of 8 1 , 0 0 0 pounds. M U S E R I E S LAU NC H E R S i nclude the th ree-stage Mu3S, which has two stra p-on so l i d -fu el boosters, has a ta ke-off th rust of 43 1 ,000 pou nds, and can place 1 , 700 pou nds i n low orbit or 300 pounds i n an escape orbit. It l a u n c h ed J a pa n ' s fi rst deep-space m i ssion to Comet Hal ley. N-SERIES LAU NCHERS use a l i censed derivative of the U . S . Delta rocket as a fi rst stage. The second stage uses l i q u i d fuel, the th i rd stage i s sol id-fueled . T h e N - 2 h a s a tota l l i ft - o f f p o w e r o f 638 ,000 pou nds. It can l i ft 770 pou nds to Cla rke orbit. The Japanese Mu launcher

THE H- 1 LAUNCHER, l i ke the N-series, uses a Thor-derived fi rst stage with n i n e strap-on sol id-fuel boosters. Tota l l i ft­ off thrust is 640,000 pounds. The second stage uses an a l l Japa nese-design cryogen ic­ f u e l e d e n g i n e p ro d u c i n g 2 2 , 000 p o u n d s o f th rust. Th i rd stage i s sol id - fueled, with 1 7, 600 pou n d s of thrust. I t stands 1 32 feet h igh, and can place 7, 1 00 pounds into low Earth orbit, or 1 ,200 pou n d s i n to geostationary orbit. T H E H - 2 LA U N C H E R , designed for use after 1 992, w i l l use a c ryog e n i c f i rst s ta g e w i t h two s t r a p - o n boosters for a tota l launch thrust of about 1 30 ton s. The s e c o n d s ta g e w i l l be the same stage as i n the H - 1 . It w i l l be capable of placing 4,400 pounds i n to C l a rke orbit, a n d wi l l be J a p a n ' s most powerful launch veh icle wel l into the 2 1 st century.

Japanese H-2 launcher

90

C HIN ESE LAUNC HERS The People's Repu bl ic of C h i n a became the fi fth space­ capable nation on April 24, 1 970 . Si nce then C h i n a has launched two to th ree m i ssions a yea r. Its fi rst com m u n ica­ tions sate l l ite i n Cla rke orbit was lau nched Apri l 8 , 1 98 4 . The C h i nese have spec i a l i zed i n recoverable u n m a n ned satel l i tes. Some of these have conta i ned experi ments per­ formed in weightlessness, and others seem to have been recon n a i ssance satell ites. LONG MARCH 1 , known a l so as the CZ- 1 {Chang Zheng1 ) and by the Western nations as CSL- 1 , was the ea rliest booster. It was derived from a n I RBM { I n termed i ate Range Bal l i stic Missi le) . It has two l iquid-fueled stages and a sol id­ fuel upper stage, together 97 feet tall, capable of putting 660 pounds into low Earth orbit. The CZ- 1 C is a slightly improved version with a payload capacity of 880 pou nds. Chinese CZ-2C launcher

© Xinhua and New China Pictures

THE FB- 1 ROCKET stands for " Feng Boo," wh i c h mea n s "Sto rm Booste r . " O v e r a dozen sate l l i tes h ave gone up on th i s series of rockets. It is a two- stage l i q u id-fueled rocket that can place 5,500 pounds in a low orbit. LONG MARCH 2 (CZ-2 ) is a two- sta g e roc ket, the fi rst stage developing 6 1 7,000 pou nds of th rust from fou r l i q u i d - fu e l e n g i n e s . These can put 6, 600 pou nds i n to low Earth orbit. THE LONG MARCH 3 (CZ3), fi rst flown i n 1 984, i s a th ree- stage rocket with the same fi rst stage as the CZ-2 . It i s 1 42 feet h i g h , weighs 202 to n s , and can p l a c e 3, 1 00 pou n d s i n to a geo­ stationary tra nsfer orbit. " W E AV E R G I R L" ( Lo n g Ma rch 4 ) i s the newest C h i ­ nese lau ncher, fi rst tested i n 1 98 8 .

"Weaver Girl"-the Chinese Long March 4 l a u n c her © X i n h u a a n d New C h i n a Pictures

IND IAN LAUNC HERS India entered the Space Age in J u ly 1 980. India has used the launch services of both the U . S . and U . S . S . R. SLV-3, India's fi rst successfu l lau ncher, i s s i m i l a r to the U . S . Scout rocket. It placed th ree satellites i nto low Ea rth orbits in the early 1 980s. ASLV, or Augmented Satellite Launch Veh icle, is a 75-foot­ high, all-solid-fuel, four-stage roc ket c a p a b l e of plac i n g about 3 3 0 pounds into low orbit. It has a lift-off weight of 3 9 to n s a n d a t h r u s t o f 365,000 pounds. GSLV, Geostationary Satell ite La u n c h V e h i c l e , i s i n t h e pla n n i ng stages for opera­ tion i n the m i d - 1 990s . The c u rrent d es i g n ca l l s fo r a cryogenic-fueled rocket able to p l a c e 2 , 8 0 0 to 3 , 700 pou nds i n to a geostationary tra n sfer orbit.

India ' s SLV

ISRAELI L AU N C HER I s rael beca m e t h e e i g h th space-ca pable nation on September 1 9, 1 988, with the launch of its fi rst satel lite aboa rd the Shavit { "Comet" ) launcher. SHAVIT is thought to be a derivative of the two-stage sol i d - fueled Jericho- 2 m i l i ­ ta ry ba l l istic m i s s i le, wh ich was in tu rn d e r i ved fro m French rocket resea rch . As a m i ssile it has a range of about 400 m i les. As a sate!lite launcher it placed its fi rst payload into an elliptical retrograde orbit with a perigee of 1 55 m i les and an apogee of 7 1 7 m i les . The launch was unu sual in that i t was towa rd the northwest, over Europe, so that the rocket wouldn ' t fly ove r A r a b n a t i o n s . T h e l a u n c h s i te wa s t h e Pa l ­ machim Air Force Base. The 343-pound satellite, named Offeq- 1 { " Horizon1 "L is 8 feet long and 4 feet in diameter, and it contains several scientific experiments.

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T h e Israeli launcher

IAI

First Israeli satellite

IAI

OUT TO LAUN C H TH E LAUNCH PAD, o r launch complex, i s the location and assem blage of components that holds the rocket ready for launch and suppl ies the necessa ry faci l ities for fuel ing, elec­ trical power, payload installation, and other support services. Most rockets a re attached to the pad by su pport structu res at the base of the fi rst stage. The U . S . space shuttle rests on its sol i d rocket boosters. Some rockets, such as the American space sh uttle, the European Ariane-4, and many Soviet rockets, a re assembled in a separate vehicle-assembly building and then moved to the launch pad severa l m i les away. Most Soviet rockets a re car­ ried horizonta l ly on ra i lcars. The American shuttle and the European Ariane-4 are carried vertically. Some other launch­ ers are "stacked" on the pad, and the payload is then installed i n the top stage. Launch pads need to withstand the tremendous heat and vibration of launch . Often huge streams of water are sprayed over the pad during the l i ft-off. Beneath the pad a re flame troughs to carry the rocket flames harmlessly away from the pad . THE GANTRY is the ma i n structu re of the pad , usually h i g h ­ er tha n t h e rocket itself. It provides work platforms at many levels, and these can be moved to encase the rocket for work on it and to provide protection from the weather. S i m i l a r moving structures, which d o not surround the rocket but allow workers a n d crews access to it, a re often cal led "swi ng a rm s . " From the gantry come umbilical lines carrying fuel, air, and electrical power to the rocket and its payload, and carryi ng back to g round controllers telemetry signals g iving the status of all the rocket and payload functions.

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COUNTDOWN is the process of prepa ring the rocket and its payload for l a u n c h i nto space. Fuel i n g of l i q u i d - fueled stages is a lways done on the pad, whereas the sol id-fuel motors a re brought to the pad ready for fl ight. Because the very cold cryogen ic fuels boi l off, such fuel tan ks need to be "topped off" conti n u a lly until a few m i n u tes before launch . Because fuels are explosive, it is often necessary to vent away a ny escaping gases. The external ta n k of the space sh uttle has a "bea n i e cap" that fits over its nose during launch prepa ration and performs th is function . The launch process is controlled from a launch control cen­ ter, often called a blockhouse because it is usually underground and built with very th ick wa lls to withstand an explod ing rocket. In side, launch crews mon itor the preparation of the rocket and the status of the payload. Th is information is car­ ried from the pad via wi res before launch, and via radio telemetry after launch. The checkout and the launch of a rocket a re usually

c o m p u te r - c o n t ro l l e d , beca u s e there a re te n s of t h o u ­ sands o f measu rements that must b e made continually. A typica l countdown may take about a day. In the last few m i nutes before launch the safety mechan isms, which prevent the rockets from firing accidenta lly, a re set to a llow for i gni ­ tion, l iquid-fuel tan ks have their vents closed so pressure that will force the fuels into the eng ine can bu i ld up, and the rocket goes on i nternal battery power. At ign ition , cal led "T-0," the rockets a re ignited and the cables con necting the rocket with the launch pad a re dis­ connected. Often it takes several seconds for liquid-fueled rock­ et engi nes to bu i ld up to ful l thrust. Then sol id-fueled boost­ ers a re ign ited and the rocket begins to "lift off," taking sev­ era l seconds to "clear the tower." Several seconds later the rocket turns to the desi red d i rec­ tion and angle of fl ight and conti nues to climb. As it ascends th rough the thick lower layers of the atmosphere it i s subject to a g reat deal of stress, so often the engines a re reduced i n power for a few seconds to avoid over-stressing the rocket. During this stage the rocket is accelerating at several times the force of g ravity. After a m i n ute or two, booster rockets burn out and fal l away. When the fuel in the fi rst stage is gone, it drops away, usual ly fal l i ng into the ocea n . The second stage ignites and continues to th rust the rocket toward space. Once the rocket is above the th icker parts of the atmosphere, aerodynam i c strea m l i n ing is no longer needed, s o to save weight t h e nose cone of the rocket, called the payload fa i ring, is jettisoned . When the second stage is empty, it separates, and the rock­ et may coast upwa rd for a while before the th i rd stage fi res. The burn ing of the th i rd stage places the payload into orbit, and it then separates from the rocket. Often small rockets move the th i rd stage aside to prevent its bumping into the payload .

97

SPAC EPORTS Since the most dangerous portion of a launch is the first-stage burn , there must be unpopulated areas in those direction s from the launch site toward which rockets are sent. For low- inclination orbits, this means roughly toward the east and southeast; for h ig h - incl ination satellites, particularly polar orbits, the d i rection of lau nch is toward the north or south . The latitude of the launch site partially determines how much fayload a rocket can carry to low-inclination orbits. A launch eastward from a site close to the equator means a given rocket can carry a greater payload . If two identical rockets were launched from NASA' s Kennedy Space Center in Flori­ da ( latitude 28 degrees) and from the Gu iana Space Center (5 degrees), the latter could carry about 1 5 percent more pay­ load to Clarke orbit. 98

THE WORLD'S MAJOR LAUNCH SITES 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Launch Site Kennedy Space Center Wallops Flight Center Vandenberg Air Force Base Guiana Space Center Tyuratam (Baikonur) Kapustin Yar Plesetsk Jiuquan Xicheng Tanegashima Space Center Kagoshima (Uchinoura) Sriharikota Launching Center Thumba San Marco Equatorial Range Esrange

Latitude 28.5N 37.9N 34.7N 5 . 2N 45.6N 48.4N 62.0N 40.6N 28 . 1 N 30.4N 3 1 .2N 1 3. 8 N 8.5N 2.9S 67.8N

Longitude 8 1 .0W 75 .4W 1 20.6W 52.8E 63.4E 45.8E 40. 1 E 99. 8 E 1 02 . 3 E 1 3 l .OE 131.1E 80.4E 76.9E 40.3E 20.2E

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KENNEDY SPACE CENTER ( KSC) is NASA's major spaceport, located on the east coast of Florida on Merritt I s l a n d . Next to it is the Cape Canavera l Air Force Station, launch site for the Air Force Eastern Space and Missile Test Range, wh ich extends southeastward across the Atlantic. KSC itself has only two launch pads, 39A and 39B. These were used for all but one of the Apollo lau nches and for all the shuttle lau nches so fa r. All expendable roc ket lau nches and all pre-Apollo man ned launches were from the Air Force Statio n , where most of the pads have now been deactivated . KSC also has a giant veh icle-assembly bu i l d i ng and related process­ ing buildings and firing rooms, as well as a 1 5,000-foot run ­ way for retu rn ing space shuttles. The non-operational areas of KSC are a wildlife preserve. Public tou rs of KSC are ava i lable from the Visitor' s Informa ­ tion Center located near the entrance on NASA Causeway. The Center has extensive displays of rockets, satellites, and edu­ cational exh i bits. VANDENBERG AIR FORCE BASE (VAFB), also known as the Western Test Range, is located nea r Lompoc, Californ i a . It has been the site of many m i l i ta ry missile launches, and of NASA lau nches of satel l i tes intended to go i n to h i g h incl i­ nation or polar orbits. VAFB has a safe launch d i rection for polar orbits towa rd the south , over water. VAFB cannot launch satel l i tes towa rd the east beca use fi rst stages wou l d fa l l i n populated a reas. Launch and landing faci l ities that enable polar orbits for the space shuttle were built here but then deactivated follow­ ing the Challenger accident in 1 986. They will be reactivat­ ed sometime in the 1 990s. VAFB is also the site of many operationai iCBMs, and of test launches across the Pacific . Hence, th is is a heavily clas­ sified area not open to the public.

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NASA ' s Kennedy Space Center

NASA

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NASA ' s Wallops Island Facility

NASA

WALLOPS FLIGHT CENTER is located on Wa l lops Island off the Del marva Pen insula on the coast of V i rg i n i a . It was one of the earl iest U . S . launch sites, dati ng from 1 945. Ma ny tests of boosters and other rocket systems occu rred there in the early days of the space prog ra m . It has safe launch d i rections to the east and southeast. Wh i l e many of the fl ig hts a re of sou n d i n g rockets, des igned to go up and right back down aga i n , many small sate l l i tes have been launched from here using Scout rockets. NASA has launched severa l non - U . S . sate l l i tes from th i s site . OTH E R NASA CENTERS, w h i c h cond u c t p rog ra m s a n d resea rch b u t do n o t have l a u n c h sites, i nclude t h e Goddard Space F l ight Center, Greenbelt, Maryland; Johnson Space Center, Houston, Texas; Ames Resea rch Center, Mounta i n ­ view, Ca l i fornia; Lewis Resea rch Center, Cleveland, Ohio; Jet Propu lsion Laboratory, Pasadena, Ca l i forn i a ; Langley Resea rch Center, Hampton , Virg i n ia; and severa l that con­ duct mostly aeronautical research . Some have visitor centers open to the public.

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PLESETSK, known a l so as the Northern Cosmodrome, i s located 1 00 m i les south o f Archangelsk, U . S . S . R . , nea r the town of Plesetsk. It is the Soviet equivalent of Vanden berg Air Force Base and is the major Soviet m i l ita ry launch site; i t i s heavily defended by m issile emplacements. Plesetsk i s b y fa r t h e world's busiest spaceport, havi n g lau nched wel l over 1 ,000 m i ssions, typically 5 0 to 7 0 a yea r. The site i s at least 60 m i les l o n g , w i t h dozens of launch p a d s as wel l as research faci l ities. It is idea l ly pos itioned for launch i n g polar-orbiting satell ites, typically toward t h e northeast, a n d i t i s from here t h a t Soviet recon n a i ssance sate l l i tes are launched. The exi stence of th is cosmodrome was un known until a group at a British boys' school tracked a lau nch in 1 966 and calculated that it must have come from th is reg ion, not from one of the other space centers then known .

TYU RATAM ( a l so c a l led Ba i ko n u r beca use the Sovi ets clai med for many yea rs it was near that town) i s rea l ly more tha n 200 m i les southwest i n Kaza khsta n , j ust east of the Ara l Sea . It i s near the Sar-Darya R iver. A newly bu i lt city for the base workers, Len i nsk, is nearby. Th i s huge spaceport has more tha n 80 launch pads, and was the location from wh ich both Sputn ik 1 and Yuri Gagarin were launched . Typica l ly, more than a dozen fl i ghts a yea r are launched from Tyu ratam, which is the second busiest spaceport in the Soviet Union. All Soviet manned missions, and a l l i nterplanetary probes, are launched from here. This is also the site for launches of the Energia booster, and new facil­ ities are being developed for launches of the Soviet shuttle and spaceplane. KAPUSTIN YAR, also known as the Volgograd Station, is the oldest of the Soviet launch bases; it is located on the Volga River not far from the city of Volgograd . It was here the Sovi­ et and German engineers launched the V-2s captured at the end of the war. Th i s was the fi rst- known of the Soviet rock­ et bases, ea rly m i ssile lau nches havi ng been tracked by radar from Tu rkey to the south . This spaceport is largely used for m i l ita ry m issile tests (particularly antiballistic missile targets), for small scientific satel­ lites in the Cosmos series, and for sounding rockets. Most orbital launches from here have used the B and C series of rockets. More recently it has been the launch site of the small Soviet spaceplane (p. 83). Th is may signal a coming increase in the usua l ly sma l l launch-rate from Kapusti n Yar, depend ­ i n g on whether on ly the test fl ights or the operational fl ights will be made from here. KALININGRAD is the main control center for Soviet manned space m issions.

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TANEGASHIMA SPACE CENTER, with its Osaki and Takesaki launch sites, i s located on Ta negashi ma Island, about 600 m i les southwest of Tokyo, Japa n , and 50 m i les south of the southern tip of Kyushu, southernmost of the Japanese ma jor islands .The Takesa ki site is used for small sou n d i n g rockets on resea rch fl ig hts. The Osaki launch site is used for orbital lau nches of larger veh icles. It was fi rst used i n 1 97 4 as the launch site of an N-series launcher, and is the site for the new H- 2 veh icles. The island is in the m iddle of one of Japan's richest fish­ ing areas, and fa l l i ng fi rst stages of rockets cou ld produce a hazard to fish ing boats, requiring the down range areas to be evacuated for each launch . Hence, an agreement between the Japanese government and the fishi ng i ndustry restricts launch­ es to February and August. Typical ly, one or two launches a year are carried out here, but th is number may rise as the H2 launcher comes into operation . KAGOSHIMA, also cal led Uchi noura, is on the southern tip of Kyushu Island . It was inaugurated by a first launch in 1 964 of a Lambda soun d i ng rocket. ( Severa l ea rlier Japa nese sou n d i ng rockets had been launched from the nea rby Aki­ ta Rocket Range. ) Japan's first six satellites were launched from Kagosh ima, beginning in 1 970. The la rgest rockets launched from here are the Mu-series. All launches have been of sci ­ entific payloads, both sounding rockets and several orbital mis­ sions. Typically, there is one launch a year from th i s base. OTHER JAPANESE SPACE FACILITIES a re at the Tsu kuba Space Center north of Tokyo and near Tanegashima; down­ range are tracking stations at Okinawa and Ogasawara on C h i c h i -J i ma Island, and a mobi le station that can be set up either on Kwajalein Atoll or Chri stmas Island . Tanegashima launch site

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JIUQUAN , previously referred to as Shuang Chen -Tse, or " E ast W i n d Center," is in n o rthwest C h i n a , in Ga n s u Provi nce, near the border with Mongolia. It was first used i n t h e late- 1 960s to l a u n c h m i l itary rockets, some possi bly with nuclear warheads, i nto a test range i n the Gobi Desert. From here was launched C h i na's fi rst satellite, C h i n a- 1 , i n 1 970. Most lau nches are toward the southeast. Typical payloads now lau nched from J iuquan a re Earth resou rces satellites and those with recoverable payloads. The latter are lau nched into low orbit for days to weeks, and then reenter under controlled conditions so they may be found and the speci mens aboard studied . Because the Chinese d o not have any territories outside their borders for tracking satel lites down range, they use tracking sh ips sent out into the Pacific. XICHANG, ea rlier cal led Chengd u, i s located i n China's Szechwan province. The site i s more su itable for lau nches to geosynchronous orbits than J iuquan i s since it has a lower latitude, and a l l such lau nches a re now made from here. Although small compared to some of the giant American and Soviet bases, Xichang is being expanded to serve as the launch base for Long March 2 and 3 rockets. China now offers its launch services to other nations and firms need i n g to place satellites into orbit. Li ke the Soviet U n ion, China has on ly land- locked launch sites, which restricts the d i rections i n which they can launch their rockets. Despite the apparent availability of seacoast sites, they seem to prefer to keep their launch bases inland for secu­ rity reasons .

Xichang launch site

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© Xinhua and New China Pictures

GU IANA SPACE C E NTER, known by its French name C e n tre S p a ti a l Guya n a i s (CSG) a n d by the name of the nea rest town, Kou rou , is located i n French Guiana, on the n o rtheast coast of South America. It was estab­ l i shed by France with a fi rst l a u nch i n 1 96 8 . It is now used by the European Space Agency and its commercial launch orga n i zati o n , Ari­ anespace, to launch Ariane rockets . ELA- 1 rockets are assem­ bled on the launch pad . The n ewer E LA - 2 , as wel l a s futu re E LAs under construc­ tion for the Ariane-5, use a vehicle-assembly building, in which the enti re vehicle is put together on its launch plat­ form and checked out by a sop h isticated computerized system . The p l a tfo rm a n d roc ket a re then carried by ra i l a b o u t a m i l e to t h e launch site. There a re also plans for a landing strip for use with the Hermes space­ plane. Centre Spatial Guyanais

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ESA

India ' s Shar spaceport

SRIHARIKOTA LAUNCHING CENTER, cal led Shar, is I ndia's major launch site, located on the east coast north of the city of Madras on the Bay of Benga l . Shar began with sounding rocket launches i n 1 97 1 , and si nce then has been the site of most of I ndia's satell ite launches. Shar is also responsible for administering several other m i nor launch sites, i ncluding Bal­ asore Rocket La u n c h i n g Station, located on I n d i a ' s east coast, south of the city of Calcutta . Bala sore' s more north­ ern latitude makes it less suitable for orbita l lau nches. THUMBA Equatoria l Rocket La unching Station is located just north of the city of Trivandrum near India's southern ti p. Thumba i s now a d m i n i stered i n cooperation with the U n it­ ed Nations and is used for atmospheric sou n d i n g - rocket resea rch by many nations, i n c l u d i n g Fra n ce, Germany, Japa n , and the U n i ted States.

111

SAN MARCO EQUATORIAL RANGE is operated by Italy and the U n i ted States. It i s located i n Formosa Bay, th ree m i les offshore from the coast of Kenya . The San Marco launch platform is a 3,000-ton, 98- by 382-foot steel structure standing on 20 legs embedded in the seafloor. Scout rockets are assembled and tested in a hori­ zontal position, then ra ised to a vertical position for launch. About 4,000 feet from San Ma rco and connected to it by 23 electrical cables is the Santa Rita control platform, a tri ­ angular "Texas Tower" -type platform l i ke those u sed for oil­ drilling rigs. It is 1 37 feet on a side. A crew of 80 controls and tracks launches from here. Both platforms generate thei r own electricity. The most famous satel lite lau nched from San Marco, and the first U.S. satell ite launched by another nation, was Explor­ er 42, better known as "Uhuru/' in 1 970. During its very suc­ cessfu l m ission it sca nned the sky for X-ray sou rces, and identified the fi rst suspected black hole. WHITE SANDS TEST FACILITY is a NASA resea rch labora­ tory nea r Las Cruces, New Mexico, next to the U . S . Army's White Sands Missile Test Range. Here NASA tests rocket engi nes and power systems, particula rly for the space sh ut­ tle. No lau nches are made from the NASA faci l ity, but sub­ orbita l launches are made from the Army ra nge. These a re sounding rockets for both civi l ian and defen se research . The fi rst captu red V-2 rockets were launched from here . WHITE SANDS SPACE HARBOR, a l a n d i n g stri p for use by the retu rn i n g space shuttle, is also located here. It is for u se if the other shuttle landing sites at the Ken n edy Space Cen­ ter and Edward Air Force Base, i n Cali forn i a , have bad weather.

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Sweden ' s Esrange launch site

ESRANGE is the world's most northerly launch base, locat­ ed near K i ru n a i n northern Sweden, above the Arctic C i r­ cle. It is operated by the Swed ish Space Corporation and i s used by Sweden and m a n y Europea n nations to launch sou n d i ng rockets .There a re six launch pads ava i lable for use; from these sounding rockets can reach altitudes of at least 300 m i les . Many of these a re designed to study the upper atmosphere, polar phenomena, and the interaction of the Sun and the Ea rth's magnetic field. About half of the rockets are recovered . Associated with the launch pads are tracking and control facilities, as well as a receiving station for Landsat and Spot photog raphs. The broadcast satell ite for Scandinavia n television i s a l so controlled from here.

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AN ATOM Y OF A SATEL L ITE Every satell i te and spaceprobe has a m ission to perform . It wi l l therefore conta i n va rious components that enable it to perform its mission . These may i nclude cameras, telescopes, other sensors, rad io receivers and tra n s m i tters , or other instruments. I n addition , whatever the mission, there will also be a number of subsystems common to a lmost all spacecraft. Beca use most satel l i tes can not be repa i red once in space, many of the systems are red unda nt: they have m u ltiple, dupl icate components that can be switched i n and out as needed i n case one fa ils. Spacecraft components, as wel l as the enti re assembled craft, are subjected to severe tests to ensure rel i a b i l ity once i n space. Pioneer 1 0, for exa mple, launched i n 1 972 and now outside the solar system, i s sti l l sen d i ng back data . T H E STRUCTURAL SUBSYSTEM i s t h e body of t h e satel l ite . Other components are attached to it. Once i n space a satel­ lite has no weig ht, but it must nonetheless be desig ned to withstand forces many ti mes the force of gravity during launch and during orbital maneuvers. Consequently, large, fl i m sy, extended structures, such as antennas or arms hold­ ing solar cells, are often not extended to their fu ll length until the craft is on-station or all major propulsive events are over. POWER SYSTEMS provide electrical energy to the other systems. In almost all satellites the power comes from the Sun, and i s converted to electricity by sola r cells. These a re heavy and may be a major pa rt of the tota l weight of a spacecraft. It takes about a square yard of solar cel ls to pro­ duce 1 00 watts of electricity. Solar panels m ust often rotate to face the Sun, and the bearings that a l low th i s a re critica l components.

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BATTERIES supply power to the sate l l i te d u ri n g l a u n c h , between the time o f launch and when the solar cells become usefu l, and d u ring a ny periods i n which the Sun i s ecl i psed . NUCLEAR POWER SUPPLIES have been used i n a few spe­ cial spacecraft, such as Soviet m i l ita ry ocea n-observation satell ites that need very large amou nts of power for the i r radar systems. Spaceprobes s u c h as Voyager, desig ned to explore p l a n ets fa r from the S u n , where the s u n l i g h t i s wea k, u s e radioi sotope thermal generators that convert the heat of rad ioactive materials into electricity. Voyager spacecraft

Radio antenna

Functional diagram of a spacecraft

THERMAL-CONTROL SYSTEMS keep a spacecraft at the proper temperatu re. Every square ya rd of a rea exposed to the Sun p icks up over 1 , 300 watts of heat, about the same wattage as a stea m i ron . Spacecraft systems also generate heat. I n the vacuum of space there is no a i r to ca rry heat away by convection; a craft can only radiate heat away. The spacecraft components must be kept with i n fai rly narrow tem­ perature ranges, usually between about 40 and 1 00 degrees Fahrenheit. Passive therma l-control measures include painting the out­ side a highly reflective wh ite; covering parts with m i rrors or gold-plated foi l , which i s very effective at reflecti ng solar infrared rays; and pa i nting areas black so they will pick up heat when facing the Sun and radiate heat away when fac­ ing away from the Sun .

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Active thermal control includes havi ng moveable louvers, white on one side and black on the other, wh ich are turned to control the heat gained or lost. To keep satellite systems wa rm during ecl ipses, batteries supply heaters . Some satel­ lites spin conti nually, a method cal led "barbecue mode," to keep one side from getting too hot. THE NAVIGATION SUBSYSTEM i s responsi ble for deter­ m i n i n g the position and attitude of the spacecraft, and for sending signals to the propulsion system for correctio n . For Ea rth -orbiting sate l l i tes, position i s often determ i ned by grou nd-track i n g , but deep- space probes also use stel lar navigation . Objects sighted to determ ine orientation include the Sun, Earth , planets, and stars. For satell ites that must keep antennas pointed toward Earth, such as commsats, an Earth­ horizon sensor i s often used . Someti mes d i rectional anten­ nas on the satell ite track radio transmitters on Ea rth . A PROPULSION SUBSYSTEM is requ i red for station keeping, keepi n g the spacecraft i n its proper location or tra jectory, and for orientation, keepi ng the craft pointed correctly. Usual ly these are very sma l l rocket motors that each provide only a few pou nds of thrust. They a re a rra nged a round the spacecraft i n such a way that they can be used either to move the craft i n a pa rticular d i rection or to rotate it a bout some axis. More powerful systems may be used to change the orbit or tra jectory of the craft. FUEL used for station keeping is usually hydrazine. It does not burn as does the fuel for large rockets, but merely escapes under pressure from the rocket nozzles. To provide slig htly more thrust, it may be heated in the nozzle. Hydrogen per­ oxide has a l so been used .

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Pitch adjustment

Lateral motion

Roll adjustment

Satellite thrusters

TRACKING, TELEMETRY, AND CONTROL (TI&C) is the sys­ tem by which the satell ite's operators know where the satel­ l i te i s and what it i s doing, and can com mand it to do th ings to fu lfi l l its m ission . The telemetry systems monitor the electrical voltages, currents, temperatures, and switch settings with i n the satel lite and report these to control stations on Ea rth by rad i o . They may a l so reco rd data acq u i red by the satellite for relay to Earth at convenient times. The system uses a special o m n i d i rectional anten na that ensures that, even if the satellite goes out of control and starts tumbling, its oper­ ators can always stay i n touch with it. When a satell ite is on­ station and is properly oriented , telemetry signals may also use larger anten nas pointed at Ea rth to a l low more data to be sent faster. TI&C signals are received by a worldwide network of tracking stations. Signals from low-orbit satel l i tes can be received by anten na "dishes" only ten or twenty feet in diam­ eter. Very d i stant spaceprobes such as Pioneer 1 0-now close to 3 bill ion m i les from Earth-requ i re d i shes a hundred • feet in size.

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RESEARCH SATELLITES have an unobstructed view of Earth , the planets, the Sun, and the cosmos. They include such pas­ sive satellites as Lageos, designed to reflect laser beams from Earth in order to determ ine precisely our planet's shape, and upper-atmosphere research probes that release clouds of gas­ es to stream along the lines of force of Earth's magnetic field . At the other end of the complexity sca le a re the sem iau­ tonomous robotic planeta ry probes desig ned to work for yea rs b i l l ions of m i les from Ea rth . "Particles and fields" probes study the i nterplanetary elec­ trical and magnetic fields, and detect cosmic rays and the solar wind-the stream of high-energy atomic particles th rown off by the Sun. Orbiting observatories study the cosmos in the visible and invisible wavelengths of the spectru m, most of which never make it th rough the atmosphere to su rface observatories. (Different physical processes produce l ight of different wave­ lengths, so each new "window" in the spectrum gives impor­ tant new information about the un iverse. ) Planetary probes visit our cosmic neighbors, sending back beautiful photog raphs as well as data a bout the enviro n ­ ments near them . Solar probes study the sta r upon which o u r l ives depend . Earth-orbiti ng satellites

APPLICATIONS SATELLITES make use of the a i rlessness and wei g htlessness of space for practical pu rposes. Remote sensing satel lites provide data for better weather forecasts, crop forecasts, the mon itoring of forest fi res, and other practical uses. Navigation satel lites a l l ow s h i ps, a i rcraft, trucks, and trains to determine their positions very accu rately. Com m u n ications satellites carry ten s of thousands of tele­ phone ca l l s and hundreds of television signals a round the g lobe. I n the future, appl ied research aboard satell ites and space stations will a l low the creation of space factories to produce materials of great economic benefit to Ea rth . Among the things we may develop are new pharmaceuticals for medicine, purer c ry stals for electron ics, and new a l loys for building. The fol lowing pages show a few representative space­ craft from a variety of nations.

The Hubble Space Telescope

NASA

THE HUBBLE SPACE TELESCOPE (HST) has been called "the most importa nt scientific i nstru ment ever flown . " It i s named for astronomer Edwin Hubble, who d iscovered the expa n­ sion of the u n iverse. HST, launched in 1 990 by the space shuttle to an orbit about 370 m i les up with an i nclination of 2 8 . 5 deg rees, can peer into the un iverse seven ti mes fa rther tha n any previous man- made i nstrument. It can detect objects 1 /50 the bright­ ness detectable from grou nd-based telescopes. Five sensitive i nstru ments share the l ight collected by the telescope' s 8foot-diameter main m i rror. Despite some i n itial optical prob­ lems, HST is return ing much valuable data . HST weighs more than 20,000 pounds a n d is 1 5 . 5 feet i n diameter and 48 feet long . Two large solar panels provide 4,000 watts of electricity. Every few years HST will be visit­ ed by the shuttle for refuel ing, refurbish ing, and upgrading. HST takes electronic pictures and measurements and relays them to the Space Telescope Science Institute located in Bal­ timore. Here astronomers record the observations and d i rect its activities.

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Atmosphere probe

Radioisotope power supply

The Galileo J upiter spaceprobe

'

GALILEO is now on its way to Jupiter. Ga l i lee' s path ta kes it fi rst into a long elliptical orbit .a bout the Sun, which swings it back months after launch to pass closely by Ea rth once again to pick up more energy i n a slingshot tra jectory. It then heads out to Jupiter. About 1 00 days before encounteri ng that giant planet in 1 995, it wi l l sepa rate into two parts. One goes into orbit around Jupiter, approximately following the orbit of the satel­ lite Ganymede, with a period of about seven days. During 1 1 orbits it will take close-up photog raphs of Jupiter and many of its satel l ites. The second part of Gal i lee is an atmospheric probe. It wi ll plunge into Jupiter's atmosphere at a speed of 1 00,000 m i les an hour. A heat shield and then parachutes will slow it down . As it drifts slowly downward , it will radio back a pro­ fi le of the atmosphere.

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The Advanced X- Ray Astrophysics Facility (AXAF)

NASA

AXAF {Adva n ced X- Ray Astrophysics Fac i l i ty) w i l l explore the depths of the u n iverse by looking for X rays from cosmic sou rces . {These wavelen g ths never m a ke it th ro u g h the atmosphere to Earth ' s su rface observatories . ) It will conti n­ ue studies beg u n by the ea rlier sate l l i tes U h u ru and the High Energy Astrophysics Observatories. It will comple­ ment the observations of the Hubble Space Telescope . AXAF will be 1 4 feet in diameter, 43 feet long, and weigh 1 0 tons in orbit 300 miles above the Earth . Its main instrument wi l l be an X- ray telescope 4 feet in diameter with 1 00 ti mes more sensitivity to fa int X-ray sou rces than earl ier satellites. It will be able to pinpoint the position of sources four times more accu rately in the sky as wel l . Th rough i nternational cooper­ ation with NASA, instruments from researchers in the Nether­ lands and the U n ited Ki ngdom a re being provided . This space observatory is designed to last severa l yea rs.

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U LYSSES i s a spaceprobe designed to explore a never­ before-vi sited reg ion of our solar s stem, the h uge vol u me lyin g a bove and below the plane o the Earth ' s orbit (ec l i p­ tic) and the polar reg ions of the S u n . All previous inter­ planeta ry m i ssions have been confined to the n arrow disk with i n which a l l the planets orbit. The 800-pound spacecraft, provided by the European Space Agency, was launched in 1 990. The U . S provided the launch services, the 260-watt power supply, some experiments, and tracking using NASA's large-dish anten nas. The craft i s head ing toward Jupiter, using a s l i ngshot orbit over the giant planet's pole to swi ng it into a tra jectory that wi l l take it over the poles of the Sun in 1 994 and 1 995. Thi s m i ssion is designed to last about five years and g ive us important new information about the three-d imensional struc­ ture of interplanetary space around the Sun .

r

Soviet Phobos spacecraft photog raphs that satellite

PHOBOS, launched in 1 988 by the Soviet Un ion, was a pa ir of 1 0,000-pound spacecraft sent to study Mars and i ts two satellites, thought to be captu red asteroids. They had been fi rst photog ra phed by Mariner 9 in 1 97 1 . Cooperative experiments on board came from researchers in France, Aus­ tria , West Germany, and Sweden . Phobos 1 fa iled en route to Ma rs due to a controller's error. Phobos 2 entered orbit around Mars early i n 1 989. The craft was to have studied Ma rs' i n ner satelli te Phobos, a sma l l world with a very low escape velocity. Lasers from the probe were planned to vaporize a small portion of the surface for chemical analysis. Later the craft was to release two lan­ ders, one to d rive a probe into the satellite's su rface i n order to test its properties, another to hop from place to place across the su rface for a more complete su rvey. Unfortunate­ ly, the spacecraft fa i led after send ing back only a few pho­ tographs and before it made any close studies of the satellite.

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Comet Rendezvous/ Asteroid Flyby space mission

NASA

C RAF ( Comet Ren dezvous/ Astero i d F lyby ) , a l so ca l l ed Mariner Tempel-2, wi l l be the fi rst to use a new mu ltipu rpose spacecraft structu re to wh ich the specific i n stru ments need­ ed for the m i ssion are to be attached . Plans are to launch CRAF aboard a Tita n - Centaur i n 1 993. It will fly b y Venus that Aug ust, then swing b y Earth aga in on a s l ingshot tra jectory, picking up speed for its trip outward . I n early 1 995 it will fly by the asteroid Hestia, g iv­ ing us our fi rst close look at one of these m i nor planets. I n 1 996 CRAF wi l l approach to with i n 3,000 m i les of Comet Tempel-2. It will then close to with in about 600 m i les, then down to 20 m i les, and fi re a penetrator probe into the icy n ucleus of the comet to measure its properties. Fol lowing the comet as it heads inward toward the Sun and heats up, l i berati ng gases and dust, CRAF will move slowly away from the comet, traveling down the comet' s ta ils.

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COMMUNICATIONS SATELLITES (com msats} are the most widely used appl ications satellites so fa r, a multi - b i l l ion-dol­ la r-a-yea r b u s i ness . Al most all commsats-over 1 00 of them-a re i n Clarke orbit 2 2 , 300 m i les above the Earth ' s equator. A t th is distance they orbit the Earth i n 24 hours, the same time it ta kes Earth to revolve once. As seen from Earth they appea r to be stationary i n the sky. Thus anten nas on the g round do not need to fol low them across the sky. Each satell ite receives rad io signals from a n Ea rth station antenna, shifts the frequency, amplifies them, and sends them back to Earth . The circuit aboard the satell ite that does th is is cal led a transponder or repeater. Transponders have powers ranging from a few watts to a few hundred watts . Although only about a thousandth of a billionth of a billionth of the pow­ er rad iated by the satellite ma kes it to the antennas on Earth's su rface, receivers are sensitive enough to al low even small anten nas to be usefu l .

The larger satel lites, such as those of the I nternational Teleco m m u n ications Sate l l i te Org a n i zation ( I n tel sat} , a re intended to relay telephone calls, dig ital data, and television across the ocea ns. One large satellite can ca rry 100,000 telephone ca lls simu ltaneously, plus severa l televi sion sig­ nals. Other D i rect Broadcast Satellites carry television signals d i rectly to smull antennas on people's homes. Sti l l others connect ships at sea and ai rcraft with telephone systems any­ where in the world . Commsats may have antennas designed to send their sig­ nals to the 42 percent of the globe they can see from their orbit, or the antennas may be "spot beams" designed to focus on sma l l areas of the Earth . Commsats range in cost from a few tens of m i l l ions of dol­ lars for the smallest ones to several hundreds of mill ions of dol­ lars for the la rgest, most powerful ones. Th is does not i nclude

An l n telsat VII commu nications satel lite INTE LSAT

Spacenet commsat i n the Clarke orbit GTE

Molniya satellite over northern regions

the additional tens of millions of dollars needed to launch them, or to operate them once in orbit. There are severa l commsats not i n Clarke orbit. Because it is difficult for a satellite over the equator to communicate with areas at h i g h latitudes, the Soviet Un ion has a series of commsats, known as Molniya, in long, looping orbits that take 1 2 hours to go around once. Several of these are spaced around one orbita l path, and each is used in tu rn when it is near its apogee poi nt and hence moving slowly. An Earth sta­ tion tracks each one for severa l hours unti l it beg ins to move too fast, at which time commun ications traffic is switched off to another Moln iya then nearing its apogee. The U . S . military has a s i m i lar satellite system for commun icati ng with its sub­ marines and a i rcraft when they are near the North Pole.

1 29

REMOTE SENSING is the techn ique of studying someth i n g from a d i stance b y analyzing l ight. Everyth i n g emits and reflects l ight u n i quely, depending upon its chemical com­ position , tem perature, pressure, and other properties. Remote sensing satellites {sometimes cal led sensats) have a bird's-eye view of Earth and can examine the entire surface every few days to weeks, enabl ing us to detect changes. Sensor i nstruments provide data that allows scientists to deter­ mine if a crop is under stress, roughly predict crop yields, find the boundaries of a forest fire or a Rood, detect minerals, and study the effects of flooding, pollution, or u rbanizatio n . Sea-sensing satellites c a n determine temperature, wave height, wind d i rection, and sea level. By knowing the tem ­ perature o f water preferred b y certa i n f i s h , satel lites c a n g u i d e fishing fleets to schools o f fish quickly. Weather or meteorolog ical satell ites (metsats) provide the photographs you see on television weather reports. They can determine the temperature, winds, weather fronts, cloud pat-

Remote sensing satellites detect radiation from Earth

terns, and moisture in the air. They are especially important since most of Earth' s surface is ocean , a n d much of our weather orig i nates there. RESOLUTION, the a b i l ity to detect sma l l objects and tel l them apart, i s a n i m portant characteristics of a sensat. La ndsat 5 has a resol ution for one of its sensors of 240 feet. Th is means it can detect a reas an acre in size, and tel l one acre from another. The economic benefits of sensing satel l i tes are hard to calculate, but certa i n ly large.

Studying Earth from space

Radar " photog raph" of Earth from Seasat

NASA

LANDSAT is the series of U . S . remote land-sensing satellites. The fi rst one wa s l a u nched in 1 97 2 . In the m i d - 1 980s Congress decided to transfer the Landsat program to p rivate i n d u stry. The cu rrent sate l l i te is La ndsat 5, l a u nched i n 1 984. Landsat is i n a polar orbit at an a ltitude of 438 miles, ori­ ented so that it looks down and takes photog raphs of areas 1 1 5 m iles square. The orbit changes orientation slowly and continually so that it always passes over parts of Earth that have a local time of about 9 : 30 A.M. Th is is so that the i l lumination angle of the Sun is a lways the same, which a l lows for com­ parisons between photographs taken on d i fferent days. In 1 8 days Landsat scans the entire Ea rth and then beg ins aga i n . Landsat weighs almost 4,300 pounds, a n d is 1 3 feet long, 6 feet wide, and 1 2 feet h igh including its solar panel and antenna. The sensors are ( 1 ) a Multispectral Scan ner, wh ich detects l ight i n fou r d ifferent wavelength bands with a reso­ lution of 260 feet, and (2) a Thematic Mapper, sensitive to sev­ era l other wavelengths of light, with a best resolution of 1 00 feet. Most La n d s a t p h o ­ tographs a re printed i n false colors to enhance visibil ity. Water shows up as black or blue, u rban a reas are gray, growing plants a re pink or red, desert areas are brown.

A Landsat remote sensing space­ craft NASA

A Landsat photograph

NASA

SPOT, sta n d i n g for System Probatoire d'Observation de I a Terre, i s a n E a rth re s o u rces s a te l l i te of t h e E u ropea n Space Agency . l t w a s first l a unched i n 1 986 by a n Ariane rocket, the first polar launch for that rocket. Spot is roughly cubical in s h a pe , a b o u t 6 . 5 feet o n e a c h side. Extend i n g from this main body are solar pan­ els about 50 feet long that provide 1 , 800 watts of pow­ er to the satell ite. It weighs 4,000 pounds. Spot i s i n a n orbit 522 m i l e s up, and repeats i ts ground track every 26 days. Each image covers a n area about 38 m i les on a side, with a resolution of 33 feet for black-and-white pictures and 6 6 feet for color pi ctures, much better tha n La ndsat. Thi s a llows finer deta i l to be seen on Earth . Newer, more capable ver­ sions of Spot, with higher res­ o l ution a n d more deta i l ed light analyzers, a re planned for the 1990s.

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The Spot remote sensing satellite © 1 990 CNES. Provided by SPOT Image Corporation A photograph of part of Earth from Spot © 1 990 CNES. Pro­ vided by SPOT Image Corporation

GOES is a series of Geostationary Operational Environmenta l Sate l l i tes. Severa l G O E S a re i n orb i t 2 2 , 3 00 m i les u p , spaced t o g ive ful l coverage of the Earth ' s weather. These sate l l i tes a l so mon i to r rad i o reports from thousa n d s of u n m a n ned weather-observ i n g stations and h i g h - a l titude meteorological bal loons, relaying the data to weather cen · ters on Earth . The older GOES spacecraft are shaped l i ke hat boxes, about 7 feet in diameter and 1 1 feet high including their anten · nos. On orbit they have a weight of 86 1 pounds. They a re spin-stabilized, mainta i ning their orientation i n space l i ke a gyroscope. Their sensors scanned across the Earth's surface as they turned . The newer GOES satellites are a very different design. They are three-axis stabilized, so they do not spin and their instru · ments a re continually pointed down at Ea rth . They weigh almost 2, 900 pounds. The i nstruments include new sensors to examine a wider portion of the spectrum; they are more sen· sitive than those on earlier satellites.

A newer GOES weather satellite NOAA GOES photog raph of E a rth ' s weather NOAA

A NOAA weather satellite

NOAA

NOAA is a series of low-orbit weather satel l i tes na med after the U . S . National Oceanic and Atmospheric Agency, wh ich manages a l l metsats . They complement the GOES satellites by providing closer, more detailed photographs and mea s u rements of the atmosphere. NOAA sate l l ites a re about 500 m i les up i n polar orbits that take them over a l l of the Earth . They weigh about 2,000 pounds and a re about 1 3 feet long, not including the sola r pa nels, wh ich supply 1 ,500 watts . Thei r i nstru ments i ncl ude h ig h - resol ution cameras and devices to determ ine atmospheric temperatu re. They also relay reports from weather bal loons and buoys, and from remote stations. Aboard the later NOAA satellites a re receivers for the Sea rch and Rescue system. These detect d istress signals from ai rcraft that may have c r a s h e d i n rem ote a re a s beyond the range o f the usu­ al d istress receivers on Earth . NOAA image of Earth

NOAA

Navstar/GPS navigation satellite

NAVSTAR, or GPS, the Global Position i n g System, i s a g roup of navigation satellites designed for use by the U . S . m i l ita ry but a l so usable by civi l ia n veh icles. There a re 1 8 operational Navstar satellites, six spaced around i n each of th ree 1 2,500- m i le- h i g h orbits with d i fferent i n c l i nations, each with a period of 1 2 hours. User equipment ranges from small hand-held receivers to larger receivers carried aboa rd ships and a i rcraft. These receivers automatically pick up signals from the several near­ est Navsta rs to calculate the receiver's position to with i n 50 feet in three d i mensions, and velocity to with i n a fraction of a mile per hour. The current Navstars are about 1 ,700 pounds i n weight, use 700 watts of power from solar cel ls, and a re "hard ­ ened" aga inst radiation from nuclear blasts. They also have nuclear detection devices aboard, and can detect if someone has tried to tamper with them either by hitting them or by shin­ i ng a laser at them .

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MANUFACTURING IN MICROGRAVITY is stil l i n its i n fancy. The advantages of space are that it is a n a l most weightless envi ronment and a better vacuum tha n we can produce on Ea rth . More experimenti ng than actual commercial manufactur­ ing has gone on so far. The National Institute of Standards and Technology does sell tiny, perfectly spherical plastic beads {for cal ibrating instruments} that are made in space. Pharmaceu­ tical compan ies have used a techn ique called electrophore­ sis to purify drugs. {Much of the cost of a d rug comes in the purification process, which can sometimes be done more efficiently i n space because gravity doesn't i nterfere . } Semiconductors for the electronics industry must b e excep­ tiona l ly pure to function . Many i mpu rities come from the conta iner i n which ingredients are processed . In the zero-g

Experimental drug processing in space "1

NASA

-' -----=

environment of space, mate­ rials can be processed with­ out conta iners, levitating them with magnetic fields or sound waves to a l low p u rer pro­ cessing. It may be possible to pro­ duce a l loys in space from materials that won't m ix on Earth because one floats on another, or to make l ight but strong foa med meta l s that h ave t i n y b u b b l e s eve n l y d i spersed th ro u g h o u t t h e materia l . Manned spacecraft in free fall are not totally weightless, as the crew moves a rou n d a n d s m a l l th rusters keep the craft in the proper orienta­ tion . Someti mes, too, waste prod u c ts a re v e n ted i n to space. Therefore some mate­ rials processing wil l probably be done in separate, free-fly­ i ng platforms that a re visited by astro n a u ts i n order to renew supplies and remove fin ished materials. I t is p ro b a b l e that the greatest benefits from mate­ r i a l s p roces s i n g in m i c ro­ g ravity will come from th i ngs we can't even imagine yet.

Perfect spheres made in zero g NASA

I . L

Astronaut Guion Bluford prepares an expe r i m e n t on the s h u ttle NASA

1 39

MIR i s the world's on ly operationa l space statio n . It fol lows the Soviet Salyut series first placed in space in 1 97 1 . The first 20-ton component of Mir, wh ich means both "peace" and "world" i n Russ i a n , wa s lau nched February 20, 1 986, aboard a Proton rocket from the Tyuratam spaceport. Its orbit is i n c l i ned about 52 deg rees at an altitude of a round 200 m i les. Becau se of its size it is very bright and can easily be seen from Ea rth . The station has been increased i n size several times since launch . The ori g i nal 43-foot- long, 1 4-foot-d iameter, 2 1 -ton station has had a 20-foot- long, 1 0. 6-ton Kvant ( "Quantum"} astrophysics research module added on to it. The station has five docking ports, which allow both manned and unmanned resupply vessels to attach to the station . Three large solar pan­ els supply electricity. Mir can accommodate a crew of up to six cosmonauts, but usually there are only two or three aboard except during crew changes. Several cosmonauts have spent over 200 days each in space aboard Mir. Robotic Progress tan ker craft are launched and automatically rendezvous and dock with Mir to bri ng water, food, and suppl ies, and to retrieve materials from the experi ments bei ng conducted aboard . More add itions are l i kely. Among the activities ca rried out in Mir are astronomy observations, materials processing { i ncluding purification of drugs similar to the electrophoresis equipment carried aboard the space shuttle}, manufacturing experimenta l a l loys, Ea rth observations, studying the biomed ical effects of zero g, and m i l itary researc h . T h e large size a n d low orbit o f Mir mean that it i s subject to much atmospheric drag. Rocket engines aboard the Progress tan kers are used to re-boost the station to h igher altitudes.

Mir, the Soviet space station

1 40

THE U.S. SPACE STATION, na med "Freedom , " w i l l p rovide a permanently manned space research facility by the end of the 1 990s . The basic design has one or more long beam s with large solar panels and heat radiators to provide elec­ tri c i ty. Severa l cy l i nd r ica l mod u l es-i n c l u d i n g o n e from Europe and one from Japan-wi l l serve as a dorm itory for crew, l aboratories, and detachable log istics modu les for sto r i n g foo d , fue l , a n d suppl ies. Canada wi l l su pply a mob i l e robot a rm for use i n construction a round the sta­ tion .The design cou ld change. By 2000 the station should be complete and capable of per­ manent manned occupancy. After that, a second phase of con­ struction will add more large beams, solar-dynamic power sup­ plies to increase the available electrical power, and more mod­ ules. A service bay will enable astronauts to construct space­ craft or to perform maintenance on spacecraft. FREE-FLYING PLATFORMS near the m a i n station wi l l a l l ow microgravity experi ments. Possibly separate astronomy plat­ forms w i l l be bui lt. Later, a co-orbiting small station may be built by the Euro­ pean Space Agency and launched by the space shuttle for more m icrogravity work. Scientists will commute from the station to the platforms. A separate polar-orbitin g platform is planned for Earth-observation missions; it will be smaller than the main station . SPACETUGS, or space ferries, a re bei n g developed to car­ ry payloads from one orbit to another, or from one space­ craft to another. Spacetugs may be automated or piloted. Fur­ ther i n the future we may have lunar shuttles to ferry crews and supplies between Earth orbit and a lunar base.

One concept of a U.S. space station

1 42

NASA

MILITARY U SES OF SPACE Most of the technology now used in civi l i a n space pro­ g rams came out of m i l ita ry resea rch , j ust as did most avi­ ation tech n ology before it. Most rockets were ori g i n a l ly des ig ned to ca rry wa rheads. Many of the i n stru ments used in astronomy and in Earth-observing satellites were designed for spy satell ites (spysats} . To national leaders concerned with thei r nations' defense, space is the "high grou nd" that must be used and occupied. Other tha n anti satell ite weapons and the rockets that car­ ry conventional and n uclear warheads, much of the m i l itary use of space promotes world stabi l i ty. The abil ity to see from space m i l ita ry movements and factories m a k i n g m i l i ta ry equ ipment, or even to eavesdrop on a potential enemy's communications, ma kes su rpri ses and uni nformed reactions less l i kely. Some details are known about U . S . m i l itary satel lites from unclassified sou rces. Most Soviet satellites a re h idden under the catchall phrase "Kosmos," and much less is known about them by the public. MILITARY COMMUNICATIONS SATELLITES a l low world­ wide coverage. Most U.S. long-dista nce m i l i ta ry com m u n i ­ cation u ses satell ites. Si nce geostationary satel l i tes are not useful from latitudes greater than 77 degrees (they would be too close to the horizon to get a good signal th rough the atmosphere}, both ma· or powers have non-geostationa ry commsats i n orbits i nc ined about 63 deg rees . The Soviet satell ite system is cal led Moln iya; the U . S . has the Satellite Data Syste m . Such satel l i tes allow nations to stay i n touch with thei r nava l and air forces i n polar reg ions, and to relay data from spysats .

l

1 44

METEOROLOGY SATELLITES (metsats) provide mil itary forces with important information on weather conditions worldwide. They can g ive data on clouds, icebergs, and prec i pitation, and they can track large, dangerous storms. Th i s i s i m por­ ta nt to troops and vessels, and it also helps target spy satellites to areas with l ittle cloud cover. The U.S. m i litary met­ sat system is cal led the Defense Meteorological Satel l i te Prog ra m . NAVIGATION SATELLITES ( n avsats) provide m i l i ta ry users such as ground troops, ships, aircraft, and m i ssi les with very accu rate position determ i nation. The cu rrent U . S . system i s called Navsta r or Globa l Position ing System (see p . 1 37 ) . OCEAN SURVEILLANCE satellites track ships, a n d c a n even detect some submerged submarines. The U . S . cu rrently has no such satell ites. The Soviet Union has for many yea rs used a series of Radar Ocea n Reconnaissa nce Satell ites. MILITARY RESEARCH SATELLITES carry i nto space scientific experiments of interest to the defense forces, including work on new sensors, propu lsion, and even sop h i sticated manu­ facturing tec h n iques. Space shuttles a re used both for m i l­ itary and civi l ia n resea rch m i ssions; the space station may be as wel l . EARLY WARNING SATELLITES provide national command forces with i n formation on possible m issile attacks and ene­ my m i l i ta ry satell ites . The cu rrent U . S . system is called the Defense Support Program , a series of th ree geostationary satell ites stationed over the Atlantic, I n d i a n , a n d Pacific ocea n s watc h i n g for ba l l i stic missile lau nches from land bases or from submarines.

1 45

N U C LEAR DETECTION SATELLITES watch from orbit fo r the i n te n se f l a s h e s of n uclear bombs as a way of enforcing test bans. The ear­ l i est U . S . detection satel l i tes were ca l led Vela . Now that function is a l so performed by the I n teg rated Opera­ tional Nuclear Detection Sys­ tem carried piggyback on Navsta r sate l l i tes. ELECTRONIC INTELLIGENCE SATELLITES a re some of the most secret satel lites used by defense organizations. Often called ferret satell ites, they a re u sed to eavesd rop on rad i o a n d rad a r tra n s m i s­ s i o n s a n d c a n repo rted ly even pick up, from low orbit, telephone c a l l s carried on terrestrial m icrowave l i n ks. Others a re i n geostationary orbits. The fi rst U.S. series was c a l l e d R h y o l i te . M o re advanced satellites reported­ ly h ave c o d e n a m e s l i ke Aquacade, Magnum, Chalet, and Jumpseat.

1 46

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. . "/2. ��� ��-. . M i l i ta ry n a v i g a t i o n s a te l l i te NASA

Soviet Radar Ocean Surveillance Satellite

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SPY SATELLITES (spysats) a re a lso h i g h ly secret. They a re placed i n low orbits, and have maneuveri n g eng i n es that a l low them to swoop even lower for closer photog raphs, to return to higher orbits, and to change orbits i n order to scan d i fferent target a rea s . Fol lowing t h e ea rly U . S . Discoverer series, t h e "Big B i rd" satell ites, a l so known as KH("Keyhole" )-9, were launched between 1 97 1 and 1 984. These huge spysats were 50 feet long, 1 0 feet in diameter, and weighed 25,000 pounds. They conta i ned long-focal - length cameras. (They also someti mes contained some electron ic eavesdropping capabil ities . ) Pho­ tographs were developed in the spacecraft automatical ly. Some were scan n ed electro n ical ly and the pictures sent back to receiving stations on Ea rth by rad i o . For the high­ est-resol ution pictures, the fi l m was transferred to one of six pods that were then jettisoned and retu rned to Ea rth by parachute, being caught in m i da i r by a i rplanes. Unofficial sou rces claim Big Birds could recognize objects as smal l as a foot across from 1 00 m iles up. A standing joke is that the CIA has n ickna mes for every Russian truck d riv­ er. Big B i rds were exploded in orbit or commanded to reen­ ter and burn u p at the end of their operational l ives to pre­ vent them from fa l l i n g into foreign hands. The Tita n - 3 launcher was specifical ly developed to launch the Big B i rds. Current spysats are launched by newer Tita n models or b y t h e space shuttle. Big B i rd u sed t h e Agena upper stage, wh ich remained attached to it to enable it to maneuver over different geographical areas of interest. The newer U . S . spysats, beg i n n i ng in the m i d - 1 980s, a re the KH- 1 1 and KH- 1 2, supposedly with ever- better res­ olution and longer operational l i feti mes in orbit. Tech nolo­ gy has i mproved, so fi l m retu rn is no longer necessa ry.

1 47

Artist's conception a Big Bird spysat

LACROSSE is the name of a new radar spysat fi rst lau nched aboard a space shuttle in 1 988. It is the first U . S . active radar satell ite, capable of making i mages of what it "sees" with rad io waves. The rad a r i s capable of peer i n g th rough clouds and of being used at n ight as wel l . Lacrosse satellites are about 1 50 feet across, and a re placed in orbits about 400 miles up. Unclassified sources claim they can resolve objects as small as about 3 feet across. Their connection with the new KH- 1 2 spysats is not known out­ side the m i l i tary.

1 48

FUTU RE SPAC E MISSIONS So fa r our space m issions have been confi ned to the solar system, and even that we have explored o n ly spottily. Only the Moon has been visited by humans i n perso n . We a re techn ically limited in o u r explorations by the pow­ er of our rockets, by our abil ity to carry food and fuel, and by one appa rently insuperable physical l i m itation : the speed of l i g ht. No object or signal we now know of can travel faster than 1 86,000 m i les per second . Further exploration and exploitation of space will depend upon more powerfu l and efficient rocket engines. Among the possibilities are ion engines, wh ich, although they produce only a small th rust, can provide power for a long time and make very efficient use of fuel. Other low-thrust techniques such as solar sails may be used. Tech nolog ies such as fusion ra mjets a re fa r in the futu re. Such fanciful ideas as anti-gravity, "wa rp drive," and so on a re l i kely to rema i n i n the rea lm of science fiction, a lthough we should never underesti mate the potential for resea rch breakth roughs. Much will be done robotical ly, sending "smart" machi nes into distant and dangerous environments. Robots will become i ncreasingly autonomous. This is especially i m porta nt the farther from Earth our probes go, and thus the longer it takes to communicate with them via radio. The next few pages outl ine several possible futu re space activities, some almost certa i n to occur with i n the next couple of decades, some that will perhaps never occur. Whether any particular project happens i s not so i m por­ tant as the fact that, just as the 20th centu ry saw terrestrials take the fi rst tentative steps off our planet after 5 bill ion years of evolution, the 2 1 st century will see the permanent expan ­ s ion of human beings into the solar system and t h e u n iverse beyond .

1 49

A future base on Mars might look like this

LUNAR BASES will be among the next manned space activ­ ities. The Moon cou ld be m i ned for materials to be used i n b u i l d i n g space settlements and spacecraft, and for fue l . The Moon i s a good site for astronomical rad io a n d optical observatories. Lunar orbit may be a good place to a ssem­ ble huge spacecraft for planetary m issions. A MAN NED MISSION TO MARS i s among the progra m s being considered b y the U .S. a n d the Soviet U n i o n , perhaps as an i nternationa l venture that includes Europe and Japa n . Because the Moon a n d Ma rs have no or l ittle protective atmosphere or magnetic field, bases there would have to be dug several feet below the surface to avoid cosm ic rays and meteoroids. Humans would need to wear pressure suits for work on the surface. With i n a couple of decades there may even be tourist visits to the Moon. The first true extraterrestrial human i s l i kely to be born in a lunar base with i n the next couple of decades.

1 50

ASTEROI D M I N E S may become practic a l i n the futu re. Although the asteroid belt between Mars a n d Jupiter seems very d istant, it ta kes only a bout the same amount of ener­ gy to bring a pou nd of asteroidal material from there to a near- Earth orbit as it does to bring a pound of materia l from Earth' s su rface to orbit up th rough the Earth ' s strong g rav­ itational fiel d . A small n ickel-iron asteroid, one mile in diameter, contains about a decade's worth of the total output of a l l i ron smelters in the entire world, and it is a l ready refined to a bout 95 per­ cent purity! The silicon, oxygen, and other elements in the rocky asteroids would be valuable on the Moon, on Mars, or in space settlements. It would take several years to ferry asteroidal material eco­ nomically back to near-Earth, perhaps usin g solar sails or ion rockets uti l izing the asteroid itself as fuel . A few asteroids pass close to Earth, and we may be able to rendezvous with them .

Mining an asteroid

Concept for a space colony

Inside a space colony

SPAC E SETTLEME NTS, or space colon i es, w i l l be huge "cities" built i n space using mostly extraterrestrial materials. The most l i kely location would be i n the Moon's orbit, 60 deg rees a head of or beh ind it, at the location s cal led by space scienti sts L4 and L5 . These settlements wou ld be spheres or cyl i n ders m i les across i n size, with ful ly self-contained, self-susta i ning ecosys­ tems, including houses, animals, plants, lakes, agriculture, and everyth ing else needed to support thousands of people i ndef­ i n itely. Day and night cycles would be provided by rotati ng the settlement and by open ing and closing shutters. Rotation would a lso provide a kind of "artificial gravity." The space settlers may be employed i n research, manu­ factu re of spacecraft, refin i ng lunar materials, and many other activities. Some may come to reti re i n the reduced "gravity" of the settlement. Others may come to vacation. While such settlements are at least several decades away, there are now many people who wou ld l i ke to l ive in one.

1 52

SOLAR SAILS, or l ight sails, use the power of sunlight to move a spacecraft. Only Earth-bound experimental models have been built so fa r, but one day they may be u sed to transport cargo across vast distances. Although their thrust is extreme­ ly low, they need carry no fuel and no eng i nes . Sunlight exerts a slight pressure, the same force that makes a comet's gaseous ta i l stream away from the su n . A large lightweight sail, miles across, made of aluminized plastic, could use th is light pressure to provide a few pounds of force. They would be control led much as a sa i l boat on a lake is, by altering the position of the sa i l to slow down or speed up as needed . At d i stances that a re much fa rther from the Sun than the asteroid belt, there would be too l ittle sunlight to work wel l . Such a technique could b e used to ferry materials from asteroids to near- Earth . Although the journey wou ld take many years, it would be inexpensive. There are plans for a solar-sa i l trial race in the 1 990s.

A fusion ramjet storship

INTERSTELLAR FUGHT is a dream out of reach for some time. Even at the speed of l ight it wou ld ta ke 4 . 3 years to reach the nearest star system. I t now seems impossible to travel faster than l ight. The Hubble Space Telescope may tel l us if any of our neighboring stars have planets around them. Robotic probes could journey there, taking decades and sending findings back by radio or laser beams. Manned starAight is much further i n the future, and fl ights would probably take so l o n g they would be one-way voyages. One technology imagined for such a futuristic mission is the fusion ramjet, which generates a miles-wide funnel-shaped magnetic field in front of it. Its motion th rough the th i n inter­ stellar gas would capture hydrogen atoms, which would then be compressed and expel led out the rear. As yet no one knows how to make such a craft. Still, it is exciting to consider that someday h uman s may jou rney among the stars.

1 54

ORGANIZATIONS AND RESOURCES SPACE ORGANIZATIONS con give you information on what is happening in

the space program. They usually publish informative magazines and hold meet­ ings, and they may actively promote space activities. The major ones a re : Notional Space Society 922 Pennsylvania Avenue, SE Washington, DC 20003

British I nterplanetary Society 27/29 South Lambeth Rood London SW8 1 SZ, England

Planetary Society 65 North Catalina Avenue Pasadena, CA 9 1 1 06 NASA FACILITIES often hove public visitor centers, and some offer special

resources lor teachers. If you live or visit near one of these, contact them ahead of time for more information . Visitor Information Center Goddard Space Flight Center Greenbelt, MD 2077 1

Public Affai rs Office Lewis Research Center Cleveland, OH 44 1 35

Public Affai rs Office Johnson Space Center Houston, TX 77058

Public Affai rs Office Ames Research Center Mou ntoi nview, CA 94035

Visitor Information Center Kennedy Space Center Merritt Island, FL 32899

Public Affai rs Office Jet Propulsion Laboratory Pasadena, CA 9 1 1 03

MAJOR SPACE MUSEUMS AND EXHI BITS:

Notional Air and Space Museum

Alabama Space and Rocket Center

6th and I ndependence Ave. , SW

1 T ronquility Bose

Washington, DC 20560

Huntsville, AL 35807

BOOKS AND MAGAZINES Following o re recommended books about a variety of space activities:

Blonstein, Lorry. Communications Satellites. John Wiley, New York, 1 987. Chochron, Curtis D. , Dennis M. Gorman, and Joseph D. Dumoulin, eds. Space Handbook. Ai r Un iversity Press Publ ication AU- 1 8, U . S . Government Printing Office, Washington, DC, 1 985.

1 55

Gotland, Kenneth . The Illustrated Encyclopedia of Space Technology. Harmo­ ny Books, New York, 1 98 1 . Goldman, Nathan C. Space Commerce. Boll inger Publishing Company, Com­ b ridge, MA, 1 985. Hobbs, David. An Illustrated Guide to Space Warfare. Salamander Books, New York, 1 986. Sheffield, Charles. Eorthwotch: A Survey of the World from Space. Macmillan Publishing Co. , Inc., New York, 1 98 1 . Turn i l l , Reginald, ed . Jane's Spaceflight Directory for 1 987. Jane's Publishing Inc., 1 1 5 Fifth Avenue, New York, 1 987. Von Bro u n , Wern her, Frederick I . Ordway, David Dool ing, and Fred C . Durant. Space Trove/: A History. Harper & Row, New York, 1 985. Space events happen faster than books can keep up with them. Magazines are indispensable for keeping up-to-dote. These ore the major ones:

Ad Astra

Spaceflight

National Space Society 922 Pennsylvania Avenue, SE Washi ngton, DC 20003

British I nterplanetary Society 27/29 South Lambeth Road London SW8 1 SZ, England

Aviation Week & Space Technology

P. 0. Box 1 505 Neptune, NJ 07753

PHOTO CREDITS: We are i ndebted to the fol lowing institutions and individ­

uals for the photographs used in th is book. British Aerospace ( BAe) : 86; Euro­ pean Space Agency ( ESA) : 2 1 bottom left, 85, 87, 88, 1 1 0; GTE Spocenet Corporation (GTE) : 1 28 right; Israel Aircraft Industries (IAI): 94; I nternational Telecommunications Satell ite Organization ( I NTELSAT): 1 28 left; McDonnell Douglas Space Systems Company (MDSSC ) : 64; Mox-Pia nck- l n stitut fur Aeronomie (MPAE), Lindau/Harz, FRG, © 1 986. Photo by Hol ley Multicolour Camero on ESA'S Giotto spacecraft. Courtesy Dr. H. U. Keller: 21 bottom right; National Aeronautics and Space Administration (NASA): 5, 6, 7, 1 4, 1 5, 1 6, 1 7, 1 9, 2 1 fi rst three rows, 26, 27, 28, 30, 3 1 , 3 2 , 33, 34, 35, 38, 39, 40, 58, 59, 62, 63 , 65, 66, 68, 6� 7 1 , 72, 73, 75, 96, 1 0 1 , 1 0� 1 2 1 , 1 2� 1 26 , 1 3 1 , 1 3 2, 1 33 , 1 38 , 1 39, 1 43 , 1 46 top; Notional Oceanic and Atmospheric Adm i n i stration (NOAA) : 1 35 , 1 36 ; Novosti Press Agency (NOVOSTI): 8 1 ; Ordway Collection, Space and Rocket Center, from the col­ lection of Frederick I. Ordway Ill (ORDWAY): 1 3 , 57; Orbital Sciences Cor­ poration (OSC ) : 74, 76-77; SPOT Image Corporation: 1 34; TASS: 20, 79, 1 03 , 1 05; Xinhua News Agency and New China Pictures: 9 1 , 92, 1 09

1 56

IN DEX Advanced X -Roy Astrophysics Facility, 1 23 Aeropile, 9, 1 0 Aerospace plane, 70 Ageno upper stage, 63, 7 1 , 1 47 Aldri n, Edwin, 1 7 AI-Hoson oi-Rammoh, 9 Ames Research Center, 1 02 Anders, William, 1 7 Antiballistic missi les, 1 04 Anti-gravity, 1 49 Antisotellite weapons, 30 Aphel ion, 48 Apogee, 46 Apogee and Maneuvering Stage, 74 Apogee kick motor, 55 Apollo program, 1 7, 59 Applications satellites, 1 20 Arione rockets, 60, 84, 85, 87, 95, l l 0, 1 34 Arionespoce, l l 0 Armstrong, Neil, 1 7 A-series rockets, 1 4, 78, 79 ASLV, 93 Asteroids, 20, 22, 1 5 1 , 1 53 Astronauts, 3 1 , 32 , 33, 37, 39-40 Astronomical un it, 22 Atlantis, 69 Atlas rockets, 1 4, 60, 63, 7 1 , 72, 73 Atmosphere, Earth's, 24, 97, 1 36 Augmented Satellite launch Vehicle, 93 AXAF, 1 23 Bacon, Roger, 9 Boikonur, 1 4, 99, 1 04 Bolosore Rocket launching Station, 1 1 1 Batteries, 1 1 5 Big Birds, 1 47, 1 48 Bluford, Guion, 1 39 Booster rockets, 63, 65, 67 Borman, Fronk, 1 7 B-series rockets, 79, l 04 Buran, 6 1 , 82, 83 Cope Canaveral, 96, 1 00

Carpenter, ScoH, 1 5 Celestial navigation, 49 Centaur upper stage, 63, 72, 74, 1 26 Challenger, 1 5, 69 Chong Zheng- 1 rocket, 91 Cheapsots, 76 Chino, 5, 9 l , 1 08 Chi nese rockets, 9 1 -92 Clarke, Arthur C., 47 Clarke orbit, 47, 48, 1 27 Collins, Michael, 1 7 Colonies, space, 1 52 Columbia, 69 Comet Giacobini-Zinner, 20 Comet Holley, 20, 2 1 , 89 Comet Rendezvous/Asteroid Flyby, 1 26 "Comet" rocket, 94 Comet Tempel-2, 1 26 Commsats. See Communications satellites Communications satellites, 47, 55, 66, 1 20, 1 271 29, 1 44 Cosmic rays, 28 Cosmodrome, l 03 Cosmonauts, 39, 1 05 Countdown, 96 CRAF, 1 26 Cryogenic fuels, 87, 90, 96 (-series rockets, 79, 1 04 CSL- 1 rocket, 9 1 CZ-series rockets, 9 1 , 92 Debris, space, 29-30 Deep-Space Network, 51 Delta rockets, 60, 64, 73, 89 Discoverer satellites, 1 47 Di scovery, 69 Drag, atmospheric, 1 9, 24 D-series rockets, 80, 8 1 Earl y warning satellites, 1 45 Earth, 5, 42, 1 1 8, 1 1 9, 1 23, 1 34 Earth sensing satellites, 1 1 9 Eating in space, 34 Eccentricity, 45 Edwards Air Force Base, 1 12

Electric propulsion, 54 Electronic intelligence satellites, 1 46 Ellipse, 43, 44 ELY, 55, 56 Endeavour, 69 Energia, 6 1 , 78, 82 Energia/Buran, 6 1 , 82, 83 ESA. See European Space Agency Escape velocity, 43 Esronge, 99, 1 1 3 European Space Agency, 20, 84, 87, 1 24, 1 34 EVA, 37 Exosphere, 24 Expendable launch Vehicles (ELY). 55, 56 Explorer satellites, 1 4, 62 Extravehicular activity ( EVA). 37 FB- 1 rocket, 92 Feng Boo rocket, 92 Ferret satellites, 1 46 France, 5, 84, 1 1 0, 1 1 1 Freedom spocestotion, 1 42 Free fall. See Weightlessness Free-flying p latforms, 1 42 F-series rockets, 80, 8 1 Fuel, rocket, 52, 53, 96 Fusion rockets, 1 49, 1 54 G, 56 Gogorin, Yuri, 1 5, 1 04 Gali lee spocecroh, 1 22 Gantry, 95 Ganymede, 1 22 Gee, 56 Gelli us, Aulus 9 Geodesy satellites, 1 1 9 GEODSS, 5 1 Geostationa ry Operational Environmental Satel­ lites, 1 35 Geostationary Orbit, 47, 48, 90 Geostationary Satellite launch Vehicle, 93 Geostationary transfer orbit, 84, 93

1 57

Geosynchronous Earth orbit, 47 Germany, 57, 84, 88, 1 1 1 , 1 25 GioHo comet probe, 2 1 Glen n , John, 1 5, 63 Global Positioning System. See Navstor Goddard, Robert, 1 1 Goddard Space Flight Center, 50, 1 02 GOES satellite, 1 35 GPS. See Navstar Gravitational fields, 23 Gravity, 23, 26, 27 "artificial," 36, 1 52 force of, 42, 97 law of, 4 1 Gravity-assist trajectories, 48 Great Britain, 5 Grissom, Virgil I. !Gus). 1 5 Ground-bosed Electro-Optical Deep Space Surveillance, 5 1 GSLV, 9 3 Guiana Space Center, 84, 98, 99, 1 1 0 H - 1 rocket, 90 H-2 rocket, 60, 90, 1 06 Hale, Edward Everen, 1 3 Hermes, 87, 1 1 0 Hestia, 1 26 High Energy Astronomical Observatory, 63 High Energy Astrophysics Observatory, 1 23 Horizon- ] satellite, 94 Horizontal Take-off and landing IHOTOL). 86 Horus. See Si:inger/Horus HOTOL, 86 HST, 1 2 1 Hubble, Edwin, 1 2 1 Hubble Space Telescope I HST). 1 2 1 , 1 23 , 1 54 Hyperbolic orbits, 45 Hypergolic propellants, 53 ICBM. See Intercontinental Ballistic Missi les ICE, 20 Inclination of orbit, 46

1 58

India, 5, 93, 1 1 1 Indian rockets, 93 Inertial navigation, 49 Inertial Upper Stage, 65, 75 lntelsat, 1 28 Intercontinental ballistic mis­ siles !ICBM). 63, 65, 77, 78, 1 00 lnterkasmos satellites, 79 International Cometary Explorer liCE). 20 International Telecommuni­ cations Satellite Orga­ nization, 1 28 Interplanetary orbits, 48 Interstellar probes, 54, 1 54 ion rockets, 54, 1 49 IRBM, 9 1 Israel, 5 , 94 Israeli rocket, 94 Italy, 84, 1 1 2 J l rocket, 8 1 Japan, 5, 20, 89, 90, 1 06, 1 1 1 , 1 42 Japanese rockets, 89-90 Jericho-2 rocket, 94 Jet Propulsion Laboratory, 1 02 Ji uquan, 99, 1 08 Johnson Space Center, 1 02 Juno I, 57 Jupiter, 20, 2 1 , 23, 1 22, 1 24, 1 5 1 Jupiter-( rocket, 57, 58 Kagosh ima, 99, 1 06 Kaliningrad space control center, 1 03 , 1 04 Kapustin Yor, 99, 1 04 Kennedy Space Center I KSC). 68, 98, 99, 1 00, 1 1 2 Kepler, Johannes, 1 2 Kepler's laws, 43 Keyhole satellites, 1 47 KH-9, - 1 1 , - 1 2 satellites, 1 47, 1 48 Kick motor, 72 Kosmos satellites, 79, 80, 1 44 Kourou launch site, 1 1 0 KSC. See Kennedy Space Center

l4, L5 paints, 1 52 lacrosse satellite, 1 48 lageos satellite, 1 1 9 lambda rockets, 8 9 landsat, 1 1 3, 1 3 1 , 1 32, 1 34 land sensing satellites, 1 321 33 Longley Research Center, 1 02 launchers. See Rockets launching, costs, 56 launch pad, 95, 96 launch sites, 9 8-1 1 3 lewis Research Center, 1 02 light, speed of, 23 lightsats, 76 liquid-fuel rockets, 53 living i n space, 34-36 long March rockets, 60, 9 1 , 92, 1 08 lovell, James, 1 7 lunar boses, 1 50 lunar module, 1 7 lunar Orbiter, 1 6 lunik spacecrah, 1 6 lunokhod, 1 6 Manned Maneuvering Unit IMMU). 37, 3 8 Manufacturing i n space, 1 38 Mariner program, 20, 2 1 , 63, 71 ' 72, 1 25 Mariner Tempel- 2, spaceprobe, 1 26 Mars, 20, 2 1 , 22, 1 25, 1 50, 1 5 1 Mass ratio, 54 Medium launch Vehicle, 64 Medium-lih vehicle, 8 1 Mercury, 20, 2 1 , 22 Mercury-Arlas, 1 5 Mercury-Redstone, 1 5 Mesosphere, 24 Meteoroids, 28-29 Meteoroid Technology Satellite, 62 Meteorological satellites, 1 30, 1 45 Meteor satellites, 8 1 Metsats, 1 30, 1 45. See Weather satellites Microgravity, 26, 1 38, 1 39

Mil itary uses of space, 1 40, 1 44 - 1 48 Mir, 83, 1 40- 1 4 1 Mission Specialists, 39 MMU. See Manned Maneu· vering Unit Mobile launch Platform, 68 Malniya satellites, 1 29, l M Momentum, 42 Moon, 5, l l , 38, 1 49, 1 5 1 exploration, 1 6 rocks, 1 7 Mu·series rockets, 89, l 06 NASA (National Aeronau· tics and Space Admin­ istration). 7, 40, 50, 75, 98, l 00, l 02, 1 1 2, 1 23, 1 24 National Aerospace Plane, 70 National Oceanic and Atmospheric Adminis­ tration (NOAA). 1 36 Navigation, 49 inertial, 49, 50 Navigation satellites, 1 20, 1 45 Navstar, 1 37, 1 45, 1 46 Neptune, 20, 23 Newton's Laws of Motion, 38, 4 1 , 52 NOAA satellites, 1 36 North American Aerospace Defense Command, 51 N-series rockets, 89, l 06 Nuclear detection satellites, 1 46 Nuclear power supplies, 1 15 oberth, Hermann, l l Observatory satellites, 1 1 9 Ocean surveillance satellites, 1 45, 1 46 Offeq- 1 satellite, 94 Orbital Maneuvering Sys­ tem, 67, 68-69 Orbits, 42-48 period, 45, 47 reaching, 55 transfer, 46 Orientation, 50, 1 1 7

Osaki launch site, l 06 Oxidizer, 52, 53 Oxygen, 34 Palmachim, 94 PAM. See Payload Assist Module Particles and fields satellites, 1 19 Payload, 39, 56, 95 Payload Assist Module (PAM). 55, 64, 73, 74 Payload Specialists, 39, 40 Pegasus rocket, 76 Perigee, 46 Perigee kick motor, 55 Perihelion, 48 Period of orbit, 45 Phobos spaceprobes, 1 25 Pioneer program, 1 6, 20, 23, 72, 1 1 4, 1 1 8 Pitch, 50 Planetary m ission, manned, 33 Planets, 22, 1 1 9 Plesetsk, 99, l 03 Pluto, 22, 23 Progress rocket, 78 Propellants. See Fuel, rocket Propulsion, rocket, 52, 54 Proton, 6 1 , 80, 8 1 , 1 40 Radar Ocean Reconnaissance Satellites, 1 45 Radar satellites, 1 3 1 , 1 48 Radiation, 3 2 Radio navigation, 4 9 Ramjets, 70, 88, 1 54 Ranger spacecrak, 1 6, 63 Reconnaissance satellites, 91 Remote Manipulator Ann, 38, 67 Remote sensing satellites, 1 30- 1 36 Resolution, l 3 1 Rhyolite satellite, 1 46 Ride, Sally, 1 5, 35 Robots, 1 40, 1 49 Rockets, 52, 60-6 1 . See also rocket names and individual countries. early, 9 observing, 7

Rockets (continued): propulsion, 52, 54 sounding, 62, l l l , 1 1 2 stages, 55 Roll, 50 Salyut space stations, 1 8, 30, 1 40 Sanger/Horus, 8 8 S a n Marco Equatorial Range, 99, 1 1 2 Satellite Data System, l M Satellites, 24, 42, 46, 1 1 4 a mateur radio, 7, 62 anatomy of, l 1 4- 1 1 8 applications, l 20 first, 1 4 fuel, 1 1 7 natural, 22 navigation subsystem, 1 17 observing, 7 power, 1 1 4 propulsion subsystem, 1 17 research, l 1 9 thermal control, 27, 1 1 6 tracking, l 1 8 Saturn, 20, 2 1 , 22 Saturn rockets, 1 9, 59, 60 Savitskaya, Svetlana, 1 8 Scout rockets, 60, 62, l 02, 112 Scramjets, 70 Search and Rescue System, 1 36 Seasat satellite, 1 3 1 Sea-sensing satellites, 1 30 Sem imojor axis, 45 Sensats. See Remote sensing satellites Settlements, space, 36, 1 52 Shar. See Sriharikota Shavit rocket, 94 Shepard, Alan B . , 1 5 Shuttle. See Space shuttle Single-stage-to-orbit, 86 Skylab, 1 9, 35, 59 Slingshot orbits, 48, 1 26 Sl-series rockets, 78- 8 1 SLV-3 rocket, 9 3 Sl-W rocket, 8 2 Sl-X rocket, 8 1 Smallsats, 76 ·

1 59

Solar cells, 2 8, 1 1 4 Solar probes, 1 1 9 Solar sails, 1 49, 1 54 Solar system, 22, 1 1 4 Solid-fuel rockets, 53, 97 Solid Rocket Boosters, 67 Sounding rockets, 62, 1 02, 1 1 1 , 1 1 2, 1 1 3 Soviet Union, 5, 1 4, 1 6, 1 8, 9 3 , 1 03 - 1 04, 1 08, 1 25, 1 29 first manned flight, 1 5 first woman in space, 1 5 first woman spacewalker, 18 rockets, 1 4, 57, 77-83, 95, 1 40 spoceplane, 83, 1 04 space shunle. See Energia/Buran space stations, 1 8, 30, 82, 1 40- 1 4 1 tracking, 5 1 Soyuz rockets, 1 8, 78, 79 Space adaptation syndrome, 3 1 Space Age, 5, 1 4 Space fighter, 83 Spoceplanes, 70, 83, 86, 87, 1 1 0 Spaceport. See Launch sites Spoceprobes, 20, 23, 1 20 Space shunle (Soviet). See Energia/Buran Space shunle (U. S.), 1 5, 35, 38, 39, 45, 55, 6 1 ' 66-69, 73, 75, 95, 1 2 1 , 1 45 external tank, 68 orbit, 25 orbiter, 66, 68 payload bay, 67 Space sickness, 3 1 Space stations (Soviet), 1 8, 82, 1 40- 1 4 1 Space stations (U.S. I, 1 9, 1 42 - 1 43, 1 45 Spacesuits, 3 1 , 37 Space Surveillance System, 51 Space Transportation Sys· tern, 66 Spocetugs, 1 42 Spotionauts, 39

1 60

Specific i mpulse, 53 Spectrum, 1 1 9, 1 35 Spinning Solid Upper Stage, 73 Spot satellite, 1 1 3, 1 34 Sputn ik, 1 4, 78, 1 04 Spy satellites, 71 , 8 1 , 1 44, 1 47, 1 48 Sriharikota, 99, 1 1 1 Stages, 5 5 , 9 7 Stars, 23, 1 1 9, 1 54 Storm Booster rocket, 92 Stratosphere, 24 Sun, 20, 22, 44, 1 1 4, 1 1 5, 1 1 9, 1 22, 1 24 Sunl ight, 27 Sun-synchronous orbit, 47 Su rveyor crak, 1 6, 63 Sweden, 1 1 3, 1 25 Swing arms, 95 Takesaki launch site, 1 06 Tanegashima Space Center, 99, 1 06 T ereshkova, Valentina, 1 5 Thermos here, 24 Thor roc et, 7 1 Thrust, 53 Thrusters, 52 Thumba , 99, 1 1 1 Titan rockets, 6 1 , 65, 7 1 , 72, 74, 1 26, 1 47 Titov, Gherman, 1 5 "T-0," 97 Toilet, zero-g, 36 Tracking, 7, 50, 5 1 , 1 1 8 Tracking, Telemetry, and Control, 1 1 8 Training, astronaut, 39 Trajectory, 46, 48 Transfer orbit, 46 Transfer Orbit Stage, 74 Transponders, 1 27 T reoties, space, 8 Troposphere, 24 Tsiolkovsky, Konstantin, 1 1 T sukuba Space Center, 1 06 n&c, 1 1 8 Tyuratam, 1 4, 99, 1 04, 1 40

�

Uchi noura, 99, 1 06 Uhuru satelite, 1 1 2, 1 23 Ulysses spoceprobe, 1 24

Umbil ical l ines, 95 United Kingdom, 84, 1 23 United Nations, 1 1 1 United States, 5, 6, 7, 1 4, 1 6, 1 7, 1 9, 1 32 first manned mission, 1 5 rockets, 1 4, 1 5, 57-76, 95 Space Command, 5 1 space shunle. See Space shunle ( U . S . ) space stations, 1 9, 1 42 1 43 , 1 45 tracking, 50, 5 1 , 1 1 8 United States Air Force, 64, 75 Uranus, 20, 23 U.S.S.R. See Soviet Union V-2 rocket, 57, 1 04, 1 1 2 Vacuum of space, 24, 26 Van Allen belts, 32, 33 Vandenberg Air Force Base, 68 , 99, 1 00 Vanguard, 1 4, 59 Veh icle Assembly Building, 68 Vela satellites, 1 46 Venera spaceprobes, 20 Venus, 20, 2 1 , 22, 1 26 Viking, 20, 2 1 , 72 Volgograd Station, 1 04 Von Braun, Wernher, 2 , 57 Vostok rockets, 1 5, 78 Voyager spoceprobes, 20, 2 1 , 72, 1 1 5 Wallops Flight Center, 99, 1 02 Waste elimination, 36 Weather satellites, 8 1 , 1 30, 1 35, 1 36 'Weaver Girl" rocket, 92 Weightlessness, 26, 3 1 , 34, 36, 38, 1 38 - 1 39 Western Test Range, l 00 White Sands, 1 1 2 X- 1 5 rocket plane, 40 Xi chang, 99, 1 08 Yaw, 50 Zero g. See Weightlessness

BCDEF

EXPLORING SPACE A GOLDEN GUIDE® MARK R. CHARTRAND, Ph . D. , is an astronomer and a science writer and lecturer. He wrote the Golden Field Guide Skyguide, and revised and updated the Golden Guide Stars . He was for many years Chairman of New York City's Hayden Plane­ tarium, and has been Executive Director of the National Space Society. In addition to teaching at several universities, he has been widely published in popular science magazines, and appears fre­ quently on radio and television . RON MILLER graduated from the Columbus Col­ lege of Art and Design and has spent 15 of the 20 years since then specializing in scientific and astro­ nomical subjects . His work has appeared in numer­ ous publications worldwide, in motion pictures, and in a series of best-selling books he has co­ authored . His original space art has been exhibited internationally and hangs in many private and pub­ lic collections . He is considered one of the most prolific and influential space artists now living. He lives with his wife, daughter, and six cats in Fred­ ericksburg, Virginia . GOLDEN PRESS NEW YORK •

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A GOLDEN GUIDE 1\