sign in sign up
<<
Home , Viking 1, Viking 2, Viking program

'Docusiii RESUME

ED 161. 728 SEpiS194

mITHoR rrench, Bevan M.,

TITLE , : The Viking Discoveries.

- INSTITUTION Xational Aeronautics and Space Administration, iinshington, D.C. REPORT NO INASA -EP- 146 PUB. DATE Oct 77 NOTE 137p.; Not available in hard81), due to poor reproducibility of photographes AVAILABLE FROM Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402 (Stock No.

033-000-00703-5; $1.50) _ EMS PRICE/ MO-$0.83 Plus Postage. HC Not Available f-rom EDRS.. DESCRIpTCRSI *Aerospace. Education; Aerospace Techn§logy; AAstrotomy; *Earth SCieficeL ; *Instructional 2,Materials; Physics; *Science ActivitieSi' Science Education; Science Experiments; *Space Sciences IDENTIkiERS *Mars ti ABSTRACT This book :::rt describes the results, pf NASA's VViking on Mars. It is tended to be useful for the teacher of basic courses in earth, scie.w- space science, astronom physics, or A geology, but is also of inte :-t to the well-informed 1man. Topics include why we should ,study Mars; how the Viklpg spacec aft works, ..the winds of Mars, the chemistry of Mars, exp rimentt i ativit and the future of the Viking spacecraft. An appendix includes suggestions for further reading, classroom experiments'And activitiei, and suggested films. (BB)

.*********************************************************************, keproductions supplied by EDRS are the best that can-be made 4, from the original document. ************************************************** 3wk***********-***-- S. DEPARTMENT OP HEALTH. EDUCATION WELFARE HATIONALJNSTITUTE OP EDUCATION cHISDOCUMENT HAS BEEN REPRO. DUCED EXACTLY AS RECEIVED FROM THE PERSON OR ORGANIZATION ORIGIN. ATING IT POINTS OF VIEW OR OPINIONS STAYED DO NOT NECESSARILYREPRE SENT OFFICIAL NATIONAL INSTITUTEOF EDUCATION POSITION OR POLICY

I AI MI AMA -A

Mars: le VikingDiscoveries

.tip

by

Bevan M. French. Chief, Extraterrestrial MateriNrs PesearchPro ram Office of Lu and Planetary Programs Office of Sp ce Sciences, NASA

ERA 46 October 1977

NASA National Aeronautics and Space Administration, Tableof Contents

TO, New Arrival5

,,WhyrMars? 5 Viking to Seek AnsWers 6 The Viking SpaCe6raft 6 A Vikir-Eye View8 The Winds of Mars 12

The Chemistry of Mars 18

Three Chances for Life20

From Mars to Einstein22 ..

What Next?, 24

Appeqdix

,Suggestions for Further Reading32

Experiments and Activities 33 Suggested Viewing 36

Cover photo: Twilight on Mars; from , processed by compiler.*

Milder front cover: on Wit; Viking 1 orbiter photo frond early- morning fog filling this network of canyons on a high Mayian plateau.

For sale by the Superintendent-of Dbcuments, U.S. Government Printing Office Washington. D.C. 20402 Stock No. 033-000-00703-5 Prelate . Masrs.: The Viking Discoveries is the For assisting the author with 'helpful 17th NASA educational publication to advice, commenjs, and criticism, we outline the results oiNASA's*earch thank...thefollowing: Dr. Richard S: activities in spate Young, DireCtor, Planetary Bidlogy. and Prepared in a forMat that will be Quarantine; Office of Space Science,: useful to the teacher of basic Courses NASk, Loyal G. `Goff, Program iiiEarth science, 'Earth-space science', ScientiSt, and Wetter Jakobowski, astronomy, physics, and geology, they Manager, , (Nide of are also written in a style that will Space Science, NASA; Dr. Harry appeal to the well- informed, Herzer, Senior Specialist, NASA intellebtually curious layman. Aerbspace Education Services Project The author, Dr. BeVanM. French, is and faculty associate, California State a geologist who has studied Moon University, Chico; .Ms. Carolyn P. rocks and ancient terrestrial meteorite Schotter. Teacher of Earth Science, craters for more than 10 years. In 1973 Falls Church High School, Fairfax he helped discover a Brazilian impact County, Virginia:. and Ms. Jeanne ctiater 2,5 miles in diameter and-15.0 He;vitt, Departrrient of Geology, The million/years old. He now manages George Washington University. For NASA's program for scientific researc0 extensive editing. and revision, we on meteorites, lunar samples, and express appreciationto Mp. Mary-Hill other kinds of extraterrestrial materials; French as Chief. EXtraterrestrialMaterials Research Program, Office of Space October 1977 Science. Fjig'program is also helping National AeronauticSend Space NASA plan ahead for the return of Admiiistration cocks from. yet another worldMars: so that scientists can find out directly c what theRed..planet is reallylike.

I The New Arrival

Exactly 7 years after first Co trot Center at,the,NASA Jet. and its relatio the other.worlds we landed on the. Moon, a new inhabitant Pro ulsion Laboratoryin Pasadena, know. The scoveries 'did not rule out arrived on. Mars. On July 20, 1976, a Cal fornia. When the. applause and the po--ility-that-sOme-fOrm_ol.life top-shapedobject dropped from its : co I gratulations began on Earth, Viking mi exist on the diStant planet. Mars hundreds of kilometers above 1 a ready had been .studying Mars for a neither entirely dry and airless like Mars and streaked downward into the 20 minutes. Moments later, Earth's TV theMoon, nor watety and teeming with late afternoon Martian sky. About 40 sc pens` began.to show the first - life like' the Earth, What was Mars kilometers' above the' surface of the pi tures of Vikin9 l's footpad, fi y4 really like, and what could it tellus planet, the thin eirbegan.to grip and pl nted of, Mars gure 1). about the Earth and theNtOon? slow.the capsule. At an altitude of 6 Al.neW.era in oUr...,xplor ti e n of the EXploratioh of the solar system had, kilometers, a htige parachute unfiJrled, d Planet hadbeg 'earlier been established as a top a protective shell broke away, 'and the NASA goal for the Period after Apolo. metallic object inside began todrop to The, program was aimed, at abetter the ground more slowly At analtitude understanding of the sblar system's ' of 1.7 kilometers, three rocket engines origin and evolution, the origin of life, 56 fired downhard, slowing the jvl rs!has belNi in humanity's . and the planetary processes Wet. Spacecraft even more. The parachute Voughts.,since astronomy began. The affect life pn Earth. Because Mars, of- Was cut loose, and the object settled, Babylonians first began to follow the all the planets, most resembled the gently, to the proUrtd.. Therocket. motions of what to them was a Earth ang appeared the most likely to engines jmmediately shut Wandering red light in the 1ky, and harbor 'sd'rne form of life, it ]was. given.

Viking 1- Lander had arrived on,Mars..., ,.they named it Nergal after their god of top priority for scientific study. . With no more shock than a terfestriar,,.;.t:, war. Later, thelFlomans, honoring their Asspacecraft obserVed the planet skydiver in thercenter of his?:;'`f., ,own,war-god,gave the planet its(' in closer and closer detail,'We.. target.: .... preset name\ :;.. . ' discovered that Mars is not uniform. Instantly the computer that had ''''.Acenturyago, as the first large , The early'flybys ( in 1964 guided the spacecraft. on its journeyI telescOpes were trained on Mars, and Mariners 6 and .7 in 1969) had. , 1 sent a message to Earth that said opservers saw that the planet had a. . produced. photos Of a heavily cratered essentially: "I am here. I am down / reddi 'h surface, wte polar caps, an surface'that looked as dead and static safely:I am beginning my work." Earth aim() phere,"cloudS, and changing as the surface oTthe Moon. But the was more than 321 million kilometers pane ns of light and dark that might photograph and maps obtained frorn, '(200 million miles) awayand even at. be v getation on its surface, It seemed1,- in 1971, as it orbited Mars

the incredibly fast speeddf, light . to bel an Earthlikp planet on which life for about a. year, showed that the (300,000-kilometers per second), it coulexist, and some astronomers planet is4actually a tw&part world. was almost 20 minutes later, 5:12 claimed to see long lines of canals ,The sOutheM half of. MarsIch the A.M., PaCifiC Daylight Time, before the :Made by intelligent beings.' Fiction first Mariner sp acecraft had loed. at, Lander's Message'reached the Viking !writers, therefore, needed little seems mUctlike the surface of the encOuragement to populate Mars with Moon: ancient, inactive, and still

a wide variety of creatures: '' 'heavily cratered by an intense . philosophical canal builderS,Thathery meteorite bombafdment thattrnay have , Figure 1..Mars at CloseRange. Tiny Martian pebbles appear in sharp detail in mOl i sters who invaded'Earth, and a occurred during-the planet's earliest this first picture ever taken on the surface var ety,o1 humanoids with humap traits years.. of Mars:iEven alter being transmitted for of good and evil: . 1 . . The northern half of Mars is more 320 kilometers (200 Von miles), The , methddically . EaAhlike: younger appearing, - , the picture is So clear that.ttre observer removed the basis for much of this geolopically'active, and perhaps still , seems to stand on Marsteside the Viking kind of romance about Mars. No ,,.. changing. In this part of Mars the

1 Lander. One ofthekander's footpads canals could be. seen at close range, Mariner 9 pictures showed huge . (lower Wit) rests firmly on a surface made and the appearance was explained volcanoes, great of ,and of fine soll'and scatte,ed rocks. Large rock as optical illusions that had affected... cracks and fractures in the crust. Mask (Opperecenter) shows triangular faces that . art ly.ast onomers. The Martian-'e: 4surPliSing and most exciting to may have been cut bywind-driven.sand. . Another rock ts dptted'with atmosphere roved too thin to breathe, scientists, were.huge canyonS and aftd there vi/aVery littlewater. These. small dark.pits that Possibly.Were' form d . \ by gas escaping from once-mOlten.lava ',discoveries only iFicreas4'd our The pictiire,was taken iv/Ma camera tha about the real nature of.Mars . scanned the cenevertically, line by line, from left.toright, Completing the picture botit 5 minutes. a _ winding, braided Channels that, elsewfierer are basic question's that distances, there is no possibility of seemed to Kaye been' scoured by we continue to ask'as we explore direct intervention if anythirig..goes floods of running Water, although nd other planets.The scorched. an, wrong. Once the computer on-the liquid water can be e on the wat rless Moon has yielded no' ce. Viking spacecraft was given the prder surface of Mars. t On Earth, the records of the to land, the landing went ahead' Bythe early 1974, Mar had been origin of life have been erased by the automatically, and the people on Earth rdeognized as an.9in-betwetn" world,4 d elopMent and'activities of later could only wait and hope. partly like the Earth,:partly.like. the pl t arid animait'life forms. On Mars; Considering these diffidulties, it was Moon, yet unique in.rnany, Ways./ where the environnpent,for life is not surprising that Viking 1 was . neither as harshfaS, the Moon's nor as actually the fourth attempt to land a ,generous as-ith&Eerth's we might find, spacecraft op the. surface of Mars. Viking to Seek AnsWers preserved, the answers to how life Two Soviet/spacecraft, Mars -2 (197 dame into ,being. We might eien find and (1973), apparently The Viking mission4c.)uld make a life itself,/ answering one of ojir oldest crashe hile attempting to landA more thorough study,to answer some' speculations: Whether Viking detected third viet spacecraft, Mars-3 (1'971) of the questions raised by Mariner V a humanoid or invisible microbe, the soft- nded safely but stopped For example, how old are the huro discovery of4any Martian life would put-, o erating after less than 20 secOnds volcanoes that Mariner 9, had us forever in a nom tionship.to the, n the surface. discovered on Mars? It was clear that universe around us. The Viking,missiqh had two unique

Mars,like the Earth and Moon '4 , and kmportant features designed to ° showedevidenceof internal hat and make the landing successful. First, the volcanic activity. But the Moorrhas The Viking Spacecraft landing area was to' be carefully been dead and quiet for more than 3 photographed and inspected while the billion years, since the last floodS of The Viking Mission to Mdrs thus spacecraft stayed in orbit around laVepoured across its surface to form combined two major goals: to study Mars. In addition, the actual landing the lunar "seas." The Earth; on the the atmosphere and geology of the could be postponed until, an . other hand, has been active for the entire piano, and to analyze its soil acceptable site was found. Viking .1 same length of time and active and'seardh for life in two specific spent a month circling Mars while the today. If the volcanoes of Mars are locations. Each of the two Vikings cameras in the Orbiter portion . old, then Mars may be a d4ad'world launched .toward Mars in 1975-wee-a'. photographed possible landing sites in like the Moon. If the volcanoes are doublespaCeship. One part,.the great detail and transmitted the yoong (and to geologists, a few Orbiter, would circle Mars photographs back to Earth yvhere hundred million years is "young"), the( continuously, photographing tie scientists examined them for rough Mars.may still be an active planet like surfaceof Mars,and.analyzing its grdund, boulders;:and other possible

the. Earth. . ? atmosphere from hungjeds of hazardi The winding channels Carved across kilometers.above the planet. The other The Viking photographs were the Martian surface are anOther ,half, the Lander, would go down to the sharper and more detailed than mystery revealed by Mariner 9. If these surface of Mars, carrying a battery of anything obtained during the earlier channels were cut, by flood waters, instruments to probe directly around Mariner missions. Landing Sites that then where has all the water gone? Is the landing, site. Once down, the had been considered safe.because Mars .now,in an ice age like those that Lander would never leave. The'Viiings they seemed smooth and level in the once chilled the Earth? Was Mars' would not return to Earth with a load,of Mariner9 pictures suddenly displayed water now rozen away underground, Martian rocks and soil. Instead they. waiting for alight Warming to bring it. would radio back to Earth their Figure 2. A Viking Robot Ready for Mars. . rushing forth ag in?' The further study discoveries about the atmosphere_ . of Mars might show us how the Earth' . A full-size working model of the Viking ; chemistry, quakes, soil, and, perhapS, Lander sits on a simulated Martian surface had started its.long historyf vdThaniC the life of Maps. , at the-NASA Jet Propulsion Laboratory. activity. and we might eveearn how The landing Of Viking 'Lori, the This spacperaft, about 1.5 meters (5 feet) climatic charges and ice ages begin surface of Mars was a complicated across and about 0.5 meters (1.5 feet) and end. - and ambitious undertaking, more high, weighs about 890 kilograms (1 ton), Moreover, where there are heat and diffidult in some ways than landing The soil sample collecting afmrstretche liquid water, there may be life. "How astronauts on the Moon. Engineers; atipcit 3 meters (10 feet) to the lower right: did life start?" and "1sthere life knew that, at the moment of landing,. The cameras are the vertical cylinders, each with a vertical black slit. The disk, , Aslars.and Earth would be.so far apart top.rear, is the S-band high -gain radio that commun ations betWeen,the antenna that transmits to Earth ihe camera Viking and'its Earth-bound hurhan pictures and scientific data. Equipment cOntrollets would take about 20 and instruments are identified in the minUtes.for a one-way trip. At sucfi accompanying diagram ,}*;%A'Li

:.:;7711q1,s. .44.:4444 ..."_t ',-"ete14-:/;,,'-k el e41 .1 4s g* 41114'44t4

...4U t 4!} yl :a' . , i.kk%

-t* ."*;

1 ,;.,*; .": L 4 v'

is. C7 ."-" , P' r. n4. '7 = - `

-t '':-;.'-i - . . , 1. .- -1...... -,.....' `sc." r" I' .-.k..* - . : :' . a ' .a" stal A t#t4t'.''; A ,k t _ t c , SS. t..r.:r e 1

. S-band high-gain Radio&tope thermoelectric ' antenna (Lander to generator coolant lines (Nonfunctioning in .DSN direct ) Propulsion fill and: landed configu'ratiOnl Magnifying N2fmakeup lines

Radar altimeter '.Radioisotope thermoelectric ., electronics number I enerator wind cover 171 (( Camera (2r .k.leeeoaology sensors Seistnometer a. Radioisotope thermoelectric rneratorpower source Metecirology (under cover)12) boom assembly

Ultrahigh requency w anten (relay) Magbet a d camera test arget .-sv. 1,-` Temperature sensor .fc '4. r ' 2.. el :1"1..4".4 A.,. , .1_*.k Leg 2 %.4i.x-';"..1.:11:r' '.AO engine (4) Z's..4 ;,:t1. and low gain -.1S. ;/.:.!, antenna Gas chromatograph mass Terminal descent spectrometer brocessor propellarit tank (2) View ' processor mirroc(2) ((' Terrznal descent landing (underside of X ray fhiorescence F urlable boom Lander structure) experiMcnt funnel

Leg 3 Terminal descent engine 13) 6 lir-- Collector head

Radar altimeter antenna /18 nozzle crinfigurat ) Magnets qty

ra.diri.u. 1. ttar, Z. PtZ-1.;;It.1. . _

t . A Viking's -Eye View ; ,'

deep gullies, scattered craters, and . 'spacecraft was sterilizfikl by heating it The safelanding of Viking 1 rugged outcrops of.rock-Lno place to to temperatures .abovthe ,boiling 4. immediately established orie basic fact 'land:a spacecraft which had only 22 point of water. Each nde,.k,and all of about Mart: the planet's surface is-

centimeters (8 V2,inches) of ground its.1 million separatearts, had to . strong enough to supporctheavy . clearance. While the photographs survive a number Of jor,caises:lhe mactine. The Lander rest firmly on were being scanned, the large radio sterilization,beating, t6d shock and . a rolling plain strewn with rocks; and telescopes at Arecibo, Puerto Rico, vibration Of l8uncha'one-year,,400- the cameras.on the Lander began and Stone, California, bounced mirliiftn mi,le,trip.thrciuh interplanetary allst immediately to transmit back to 's radar waves off Mars, using the radara... S. space the passage:through Ma'rs' Earth the first views of the Martian I. reflections to measure-the roughness ,. atmosphere, and the landing on its landscape. , of the planet's surface in different Surface. No wondednele were , ,,Viking's cameras stood abOut-1,6 1 regions. First one landing. site was heartfelt ctieers from the scientists and meters (5 feet) above the grounds and i rejected, and4heri another. Finally, a engineers when:Viking 1's first pictures their view of Mars was mud:\ likewhat

new site was located, photographed,!-.began to appear! . . aPerson standing in the same place scanned 14ith radar, and found The Lander-s,are so We'll.designed woulsee. The two cameras could be . ,:,acceptable, and Viking) destended that it is often poSsible to.fix'them ope fed independently to provide to a perfect landing ina level rolling -whelthings do wrong. When the pan 'auras covering almoSt a full region called the Plain's of Chryse, A sampling arm on Viking 1 got stuck, a circlearound the 'Lander. they could little More than .a month later, after a carefully-planned series-of commands .'. be (*rated together to prodtoe- similar thorough check of a more from Earth freed it, and the cameras :;.sterqo piatures.frommhich the shape ...:northTrn region of Mars, the . then showed that asmall pin which of this surroundings surface could..be Lander made an equally flawless had caused the trouble had fallen free accurately measured (Figure 4). Most. landing on the Plains of Utopia. Two to the ground. Later, when the arm of the pictures were black-and-white, Landers.sit on the surface of Mars, -stuck this timetin an 'extended but different detectors inside the

while two Orbiters 'Circle overhead, .. ;position, a different series of Cameras were sometimes used to photographing the planet and relaying commands brought it safely back into Provide pictures thateproduced the --( , back toEarth the news,of what the ! the spacecraft. Each of thes'e "repairs" actual hues of the Martian surface. LanderS find. was a-carefully-planned operation. .. ',The first pictures 'showed firm soil The Landers on the surface of Mars . Each set of commands was first tested andscattered rocks imrnediately , are far more complex than any . i on a. duplicate Viking Laiidersitting on beneath the Lander. As the cameras . automatic spacecraft launched before.\a simulated Martian surface at .the looked.out to the horizon, they Even if the Landers had neVer,left \ NASA Jet Propulsion Laboratory, and photographed agently 'rolling, red Earth, their design and construction .- 'athe cameras on the real .Viking were - landscaPe ;Oat could almost have

would still be an impressive . used to check the ,progress of the ,' , been a/desert scene in the Arfiecan technological achievement. Each "repairs'. at everystep. .Southwest, The reddish .gray soil was landir looks like a cluttered six-Sided With the minor troubles correeted,.' -'-'-clotted.v,vilh rocks o all sizes. The s,. Worl2berich with three legs (Figure 2) the Landers even. took on new tasks .Colbrs of the rocksaried from dark'.. but it cdntains the equivalent of two . that had not been planned before the gray to light gray tolightly reddish power stations, two'computer centers, landing. After digging up samples of (Figure). Some rocks up in a TV studio, a weather, station, an .exposed soil, the Lander's.sampling. great detail, and many wereWeefilled with earthquake detector, two cheMical arm was used to push large rocks,, ...bubbles. These rocks lodked like the

_ . laboratories (one for organic and ore aside 'and to collect samples Of the lavasyoduced by erupting gis-rich. for inorganic' analyses),,three separate protected soil beneath them (Figure 3). volcanoes.on Earth, and scientists incubators fOr any Martian life, .a scoop 1.i think that the bedrock on Which both and backhoe"for digging trenches and s Vikings, have landed is made up of

collecting Soitsarnples, afid mpiature a ancient Martian lava flows. . railroad'ocart or delivering the samplet.!., The Vikihg cameras also saw wind-f to the laboratories and incubators. produced features that:havelamiliar Equipment that would normally fill _counterparts' in Earth's deserts.

.. several buildings trd been designed Although the atmosphereof Mars', i. .in.rniniature to fit On a spacecraft less thin, its winds are still strong enough I 1than.3.meters (10 feet) across, to blow dust and fine sand across.th ,Furthermore, to avoid contaminating surface_There are dunes of light- ; Mars with Earthly bacteria,.the entire colored sand, and detailed pictures 6f .. .. s the dunes revealed finer ripples within se them (Figure 6). There' are places where the wind apparently scoured out the line soil, revealing flat masses of . Oi

.'

-111111111111.1111EN

a!" a 7Figuree3.,Mr. Badger" Gets a Nudge. Controlled by scientists back on Earth, the sampling arm on the Viking 2 Lander '4 reaches'ut to push aside a large PorouS.: rock anto collect a 'sample of the Ilk. e protecteMartian soil beneath iC.Becaug7 of its shpe, the rock was informally . '' .. christend "Mr. Badger" after a character in Kennth Grahame's book,.The Wind in. , the Willws. The Martian.'Ar. Badger" is about,,2centimeters (10 inches) Icing and weighsseveral pouQds. 1 Figure.Mars In 3-0 These two images / of theame scene, one taken by each earneron the Viking .1 Lander, qan be combied, by: using a pocket viewerinto,a`pingle3-dimensional view that sows the rolling Martian terrain and the shpes of the numerous boulders: (Whelooking at the images with a stereo viewe, concentrate on a small objectlike - a roc..Move.the viewer around until the two' iages of the rock comestogether. Thenou should' see the landscape in 3-d,) 1'

, ;ea. 'V- "' t'"?..'4L'ff,,";4":;4 . , "162,t". "

4 tr 't.

Figure 5. A. Summer Day's Work on . Mars. Traces of human' exploration already ,show on the red surface ofMars,,Two trenchel dug.by the soil sampling arm of the Viking '1 Lander appear asthort black Smudges (left); and the soil near the bottom of the picture that appears' racked and pitted was disturbed by the rocket tir exhaust blaSt a& touchdown and by the 1. impact of the footpads,. The soil sampling'. arnrand scoop is at right center: arm Vower left) holds a brush for cleaning off imagnels. Light and dark rocks.can be seen. The dark-rock to the right of the trenches is abbut 25 centimeters (10 inches). across: The apparent hdrizon is about 100 meters (330 feet) away and may be the rim of a small irrteact crater. Boulders 1 and 2 meters -(3 ghd fr feet) across are visible_40he distance.

Figure 6. Early Morning on aMartian Desert..The variety of the Martian surface is captured in this panorama by the Viking 1 Lande.4. The view covers a horizontal angle ofabout .100 degrees: about one quarter Of a circle. Martian northeast is at the left, southeast at the right. The newly- risen Sun is just above the center of the picture. Shapeof the small sand dunes (center and left) indicate that the winds that formed them blew from upper left' tawarctiowecright Large boulder (left), named "Big Joe," measures 1 by 3 meters (3 by 10 feet /and is only 8 meters (25 feet) from the Lander. The vertical white

object (center) is the Viking boom that, .. holds the weather-measuring instruments.

.4110 4. ,. lob -AI., ., .....!-. .""444.0ier

-4-7-1421-111" ;. fnurerAt -arbtaz- ,

I.j -.:A ,. _ - *.ra a, .. P/INft qkit ' - h... c- s-- 4111rel;,/, 414: -;;;-151.414,#1:: -114 4; . lit10. 1.-- ' 44- .. . -. "4E gelb iih 7. - ... 11, It .....a... 44 l','' - .:...... ,,:.. dile ...... , ...... ,- t N"

a, , t A

it I

,41464." 41141,10?

t *G. '1,41$ 4. "*Zit

a

1'

'44

Figure 7. "Caution! Viking at Work!" More thanqoo million kilometers (200 miliion.miles) from Earth, an .historic and .exciting expavating7ob produced this tiny ;. trench in4he sulactof Mars. The trench; sg66Ped'otit by the sample col/ecVn arm :4:iglidikak 4 of the Viking 1 Lander. is about 8 . 'VW %Ole 4, centimeters .(3 inches) wide. The shape Of the trench indicateS (*.the Martian soil is 4e.1141%, (ine- grained and about as cohesive.as wet 4. drit-- bedch sand on Earth.*The steep 14;, "*- uncollapsed walls, at the far end Of the vviits.10-7kL; trench; and the clods of soil piled up at the 44. near enCi show how well the Martian soil _ALArt&it--.34,06 .sticks together. 7

-7 a-

,,.7

FSH . The'.Winds'of Mars

grayish.Oedrock. At ther places .. as firm as good farming soil on Earth. For the iirSt time we can now.' streakS'of :dust have been-deposited The soil of Mars sticks together in Measure and record the weather on over and behindboulde. When. about the same,way,too: smaller another world...UnliKe-the airless.Moon, Viking 1:fiftt landed:. some of theSe particles ;clump together into larger .--IvTars'has'an'atmosph.ere,Windsti and

'piles of fed 'du'st were-being eroded ' ;clods, and the walls of shalloW -.weather-patterris. . and bloWn away by the sUmmer.: trenches:remain straight and shoW Mars' atmosphere is:thinner-and.-

breezes that .swirled arbUbd the little tendency to collaOse.: . colder than Earth's, and 'scientists, Lander: Seen from the surface, the two were eager to study its weather Sometimg the Viking cameras Viking landing sues have their patterns'in the hope of finding g-enerel turned away frorrythe- landscape to differences. The Plains of Utopia, principles that Would help us better .study in cfetail.the giechahical :- where Viking 2 landed, are more\ underStand the weather of. our own properties of the graind on which the rolling than the Plains of Chryse where .planet. The Viking: cameras,Often, Lander rests. The cameras- carefully. Viking 1sits. The Viking.1 site (Chryse) looked above the_horizon to photOgraphe'd the/Streaks. produced in .apparently haS a larger variety of rock p.hotogrjaph the sky, and a battery of the soil by the rocket engines when types, while the rocks at theNiking:2 instruments recorded Winds, Viking landed. Later, as the-soil was locality (Utopia) are more uniforrh,.. baromet.Mc , and the chemical trenchecyand probed and shaken to ,generally vesicular (bubtie-richand composition of the

collect Samples, the cameras recorded more abundant. There is bedr (Figure 9). . . the appearance of marks, trenches, exposed at the Chryse site,. and none Viking's first view of the sky and clods of soil, on the-surface visible at Utopia. produced amajor surprise. Although (Figure 7). By studying these pictures, There are rippled sand dunes at the many scientists had expected that the scientists back on Earth were able to Chryse locatibn, and none at UtoPia. Martian sky would-13e blue like that of . determine that the MartianSoil is about The boulders at the Chryse site Earth, the Viking pictures' showed commonly haie.flat, polished faces, instead that it has a creamy-pinkish apparently produced by wirid--iblown -hue (rigure.10).:Tne explanatiOn is '

sand. . that the Martian' atmosphere contains a The Utopia site c.Viking 2) shoWs an- great al of line:suspended red dust. unexplained pattern of shallow troughs , . that connect to form polygonal patterns. One of these troughs runs right past the Vikir:j 2 Lander (Figure 8

Figure 8. A Crowd of Martian Rocks. Like a throng of curious onlookers, thousands of rocks and boulders surround the Viking 2 Lander as it rests on Mars' Plains of Utopia. The field of rock and soil extends to the horizon about 3 kilometers (2 miles) away. (The honzonactually level, 'apt3ears tilted beca2se the spacecralbis resting on the surface at a slight angle`io th-er horizontal.) Mapy of the rocks display small pits and.holes that may be bubbles formed when the rocks were molten lava. The rock tnthe lower right corner is about 25. centimeters (10 inches) across, and the large rock in the center is about 60 centimeters (2 feet) long. The small sandy A trough' that winds across the picture 'rem upper left to lower right is part of -an A_ unexplained network of su.chhannels or d. depressions that form strange polygonal surface patterns in the Utopia region.

12 13 Figure 9. "And Now, the Weather for Mars.",The first interplanetary weather reports Come from a small white instrument box (upper right) mounted on . . . the end of a long boom that holds the box about 1.3 meters (4 feet) above the, Martian suiface. The boom holds the box out of range of most wind disturbance's caused by the body of the Viking Lander. Instruments in the box measure the-wind , velocity, wind direction,. temperature, and atmospheric pressure. In the backgiound are sand dunes forrried by strong Martian winds. The parallel bands in the sky are not real; they were 'produced by the computer processingof the picture.

Figure 10. A Red Sky for a Red tenet.. The red surface of Mars lends clor to the Martian sky.in this view fro e Viking 1 Lander. Fine red dust from the soil is carried into the atmosphere, giving the sky a. pinkish hue instead of the blue color expected by scientists. Light and dark. boulders are strewn on the surface in the foreground, and light-gray ledges of be ock appear through the soil in the mid le distance. The horizon, about 100 met s (330 feet) away, may be the rimof an i act crater. This color picture was made y combining three separate picture, each taken through'adifferent color filter. The colors were matched by comparing similar pictures taken of colored objects on the Viking Lander itself.

13. 14 AlthougH the individual dust particles and broadcast to Earth on the first high in tfte atmosphere or swirl around \ tiny, perhaps only 0.001 millimeter day, remained: almost unchanged from the high slopes of Martian volcanoes (1/,2 ,000 inch) across, there is day to day: (Figure 11). In small valleys,. apparently enoughof this dust in the "Light winds from:the' East in the late atmospheric water freezes out during air to give the whote.,esky a reddish tint, afternoon, changing to light winds from the Martian night and then vaporizes Earth's sky is generally not so dusty.. the Southeast after midnight. Maximum again'when the sun rises, forming

Only after large volcanio,*Uptione or winds were 1# Miles per hour. . local patches of white fog thaanish sandstorms .do'we see asreddening of .Temperature ranged from minus 122° quickly in the relative warmt' of the terrestrial sunsets that produces ,Fahrenheit just after dawn to minus 22° Martian day (Figure 12). something like the color of the Martian Fahrenheit in midafternoon. Totally.unlike the Eart however,. sky. Atmospheric pressure 7.70 millibars." was the steady declinin atmospheric. The sky of Mars grew even dustier (On Earth the same day,.July 21, pressure recorded bthe Viking several months after the Vikings 1976, the lowest temperature recorded instruments. Dunn he ,Lander's first landed, and the spacecraft carefully was minus 100 degrees Fahrenheit at Month on Mars, t atmospheric recorded the change. the Soviet Vostok Research. Station in preseure droprf d by about 5 percent. Astronomers have known for years the Antarctic, and the highest (On. Earth, su a large drop. in that huge duststorms often come temperature was plus 117° F at pressure:is'ually found only in the swirling out of the southern part of Tirnimoun, Algeria. The eye of a m tor hurricane.) Scientists Mars, covering the whole planet and recorded a'highof 109°. F. at Needles,.. think thate 'carbon dioxide (CO2) shutting off the surface from the view California and a low of -37°..F. at Point Which kes up most of Mars' of Earth-based telescopes. Such a Barrow, Alaska.) atrnos ere was freezing out as solid stdrth*.hrouded Mars in 1971 as Some of the .similarities between CO2 .r '!dry ice") on the cold southern Mariner 9 arrived in orbit, and the Mars' weather and. Earth's were ,polr cap, .which was then in the spacecraft was-able- to proyide a surprising, because the atmosphere m dle of the Martian winter. The photographic record of:the'storm's of Mars is less than a hundredth as king lender's thus seemable, from

subsidence and the gradual, dense as Earth's.' Nevertheless, on . o points.On the surface, to detect appearance of the Martian surface both planets,' the atmospheric the slow grciwth.of an entire polar cap through the/ clouds.cit-dust. These dust' temperWure reached its peak at about thousands of kilometers away, a feat storms usually develop.as P.M. lace' time. The daily thatwould be iMposeible in the reaches the point in its orbit that is temperature variatioris recorded by complex water-rich atmosphere of closest to the'Sun, and in the Spring.of Viking showed the same pattern as Earth. 1977,. these clouds arose again and records from.a terrestrial desert While one group of scientists spread over the Martian surface.- High "control" site at China Lake, California, followed the changes in Mars' weather, above the sTorrns, the Viking Orbiter although the temperatures in the two an entirely.different group was busy

cameras phOtographed the shapes of places differed by more than 83° C. analyZing the chemical composition of . the dust clouds.and followed.their (150° F.): Furthermore, the changing the atmosphere itself. The gases in a progress. With these data, scientists patterns of wind direction over the flat planet's atmosphere can come from are learning more about Martian winds Plains of Chryse on Mars were many different sources. Some gases and about the nature of the dust that duplicated by the.winds blowing over'. may have been trapped from the they carry. the equally flat Great Plains of the original solar nebula when the planet After Viking landed, the Martian midwestern United States. formed.. Others may have been. weather was clear, cold, uniform,.and Martian weather includes -two other released by heat and chemical repetitious. The weather report, features familiar to terrestrial weather recorded by the Viking instruments watchersclouds and log. The air of . Mars contains only about 1/1000 as much water.as Earth's atmosphere, . but even this small amount can condense out, forming Clouds that ride_,

110

15 . . . . Flgure.11. W Ian VolcanVo'werts Abpve the Cloudi. In this Viking .1 .'Orbiter photographtaken from 8,000 kiloineters '(5,000 miles) away. clouds .cover the lower slopes of-Mars' largest volcand, (Mount.Olympus), making it look tike a satellite piCtbre of a, terrestrial hurricane.. The huge mass of the volcano is 600

. kilorneters (375 Miles) across, and the, cliffs that mark its edge.can.be seen inthe upper right corner. The symmitstands 24 kilometers (15 miles) above Me Martian' surface, and the summit crater, visible above the clouds, is 80 kilometers (50 miles) across. The clouds in the upper left. show a striking pattern of waves and ripples. Nearpy dark Circle is a k photographic flaw. 40..

16 1.5 c

',, 5.

S;'

f A V

4

Jr,

tts

16 17 . .. reactions-aeep inside the planet. Still Earth's atmosphere: The. remainder is than the chemical composition alone 5

others may .beproducedby-the . pitrogen.(23.perbent) oxygen (0..1-0.4 would suggest. Th6 ratio of heavy to transformation' (de*) of radioactive percent); and/argon (1-2 percent). The light carbon atoms (carbon-13 to elerberits in the planers rocks. The discovery Of nitrogen was exciting . carborr!.12) is 118,9-,Irid the ratio of. 'chemistry of ariatrinbSphere thus because thi.element is an essential * heavy to light oxygen .atoms (oxygen-; ....prbvided unique information about a :* corponen of the.Proteiftmolecules 18.to.oxygbn-16) is.1/500. These - planet's origin; its history, and the whiOh for living thingS. The small. values are identical lo those measured chemical composition of its rocks. ,..amount o free oxygen is Surprising, - in our ownLatqlosphere,l-lbwever, the

Edrth's atmosphere is compos'ed . butthislement can be, formed in.. element nitrogen is different. The ratio almost entirely.Of two gases: nitrogen manyw ys, and its presence dbes not of. heavy to light nitrogen (nitrogen-15-.

and oxygen. Scientists believe thaLthe . prove'at there is or has been plant to. nitrogen -14) is 1/156 on Mars, while. nitrogen (78 percent of our u life. on. Mars. the value on Earth is 1/271. . . . atmosphere) .came out of the interior of M, e precise analyses have The carbon and oxygen ratios the Earthbillions of years ago, while detected traces of the r4re inert gases demonstrate a basip.similarity between the oxygen (21 percent) has been krypton and xenon in the Martian air. . Mars and Earth, despite the chemical . . produced gradually by the plant life Th se two gases make up only about differences tin their atmospheres. One that has existed for billions of years. A 1 art per million of the Earth's explanation is that both Mars and mall amount of the inert gas argon d Mosphere, and scientists have not Earth formed from similar parts of the . 0.9 percent) has,been formed by the et been able to measure precisely the solar nebula which had the same . ecay of radioactive potassium atoms my amounts present in the air of Mars. lotope ratios. However, the isotope ratios of in the Earth'scrust. . Viking instruments also measured The composition of the K./tertian the ratios of different isotopes in:the nitrogen provide evidence for different atmosphOle was measured in two.. -Martiantmosphere. (Isotopes are two histories of thiS element on the two. pladesat high altitudes as the atoms of he same chemical element planets. If.theoriginal nitrogen ratio on Lander descended, and on the that have different atomic weights, for Mars had been the same as on the sr- .surface, The composition was the, example tirdniurn235 and urenium- Earth, then the light atom.(nitrogen14) same in both .places, showing that the 238.) Isotope ratios of elernents in the- must have gradually escaped from the . Martian winds keep the atmosphere as atmospheres and rocks of other . atmosphere of Mars, possibly because well-Mixed as Earth's. planets are important because they. Mars' gravity is not as strong as .The.pressure of Rars' atmosphere is prdvide information that Cannot be Earth's. only' aboyt 1/125 that of Earth't and its obtained from chemical analyses . From these atmospheric data, chemical composition is totally alone. Isotope measurements can scientists have calculated that the different. Most of Mars'. atmosphere, indicate the temperature at. which ancient atmosphere of Mars, before (95 percent) is carbon dioxide,. a gas ',rocksrmed; if two different planetsi WhiCh makes: up only 0.03 percent of haysimilar isotope ratios; then they md.y have formed from the, same part Zof the original solar nebula., I... The isotope ratios measured, by the Viking Lander show that the atmosphere of Mars is more Earthlike

.

Figure 12. Foggy* ming in a Martian . Valley. White pia hes of early-mornirig fog and mist fil rugged network of Martian canyo and spill ocitonto the surrounding. . fU rust- colored plateau. The clouds are. probably formed by water vapor that has frozen ou of the.air during the previous Martian nit, In the sunlight, the water vaporizesgain, becoming briefly visible as mist before being absorbed into the dry atmosphere. This part of gars,' called LabyrinthUsNoctis (The Labyrinth nf the Night), was photographed- at dawn byriia Viking '1 Orpiter; the view covers an area about 100' kilometerS (62 miles) on a side. The color picture was made by superimposing three separate black-and- white images taken through colOr, filters.

17 %.- IfiL the nitrogilli was lost, might have been about 5 per cent of the soil is four or five times as dense.as it is magnetic material and that it is an now. This early atmosphere also might oxide like (Fe,0,,), the hsave contained enough Water to form mineral that forms terrestrial ,a layer several meters deep ever the lodestones. This result makes Mars pholesurfaceof the planet. Herd was. seetri rather Earthlike, the lunar soil, by 'another irrliCation that the winding contrast, has only about:1 per cent of channelsfon Mars actually had been magnetic material, and it is all metallic carved by water, althoughthe iron. . . atmospheric analyses could not tell us' More precise measurements of the where this water had vanished. soil were made with an instrument that bombarded a soil sample.with X-rays and then measured the secondary X- The Chemistry of Mars rays given off by the atoms in the . Martian soil. ,'Whild the atmosphere of.. Mars was The composition of the Martian sail, .'giving up its secrets, other scientists as determined by the.borribardment . with. other ir)struments began to test expecirnent, is approximately the same. the solid matter of the planet, to see at WOlanding. sites,. even though the what could be deciphered frOm the two sites are about 5000 kilometers -rockaryd'windblown dust around the (3100 miles) apart.

._spacecraft. . The 'chemical elements detected, ," On the eighth day'of Viking is and their amounts (in weight percent), Figure 13. The Aricient Crust of Mars. residence bn Mars, a long arm are (Si) 21, iron (Fe) 13, Mars shows a battered and heavily- reached out from the spacetraft, and aluminum (Al.)'8, (Mg) 5,, cratered Moon-like surface in,this picture a small scoori at the end of the arm (Ca).4,.(S) 3, , taken from the Viking./ Orbiter from ' began to dig a small trench in the (CI) 0.7, (Ti) 0.5, and 18,000 kilometers (11,200 miles) away. loose soil about two meters away from potassiurri (K) less than 0.25. The, flat circular plain at top left is Argyre, a large impact basin about 800. kilometers Where the Lander stood (Figure 7). Scientists calcblate that, to balance Continually guided by a omputer (500 miles) in diameter and located in the these elements, oxygen (0) make8 up - southern part of Mars. This.. basin, aboard the Lander, the a carefully another 42 per cent of the soil, leaving surrounded by a rugged Wide of pushed the scoop througthe trench about 8 percent.made up of elements mountains, may have been,fortned by a .and then retreated slowlyaC'k to the (e.g., , hydrogen) that cannot huge meteorite impact billion ..of Lander, bringing-with it the firstAample be.dptected by this method. ago; Smaller, younger craters cover the of Martian soil eve.to'be analyzed. This compositiqn corresponds Martian surface outside tObasin. The air Within the Lander, the soil samp'e Aas approximately to that pf a terrestrial, or is clear and.cloudless oaveArgyre, but the brightness of the distant Martian horizon . sieved automatically, divided, and sent t.lunar lava, but there are some on its wayfor several different.yinds of "striking differences. The. Martian soil . (top tight)suggests,thry clouds are present there. The parelletwhite speaks analysis, - ;,. contains less aluminum than a above the horizOn arp.61sr;:cfoudra'yers, One test'of the soil did not require a terrestrial basalt and4less, titanium than perhaps cot-lipase° of frozen CO, these chemical laboratory, Several magnets . a lunar basalt. , clouds are aboiit 25 to 30 klorrieters (15 were mounted on.the scoop, nand The unusually large amounfof to 20milea) above the surface of Mars. another magnet had been placed on detected, confirms the long-held theory

'the outside Of the Lander, These . '.that the red dust of Mars is a red iron Figure 14. A View Down a Volcano's magnets trappedand held magnetic 14 oxide similar to terrestrial.rust. The red Throat. From 6,000 kilometers (3,700 particles in the'Soil and windbloWn color and the small amount (about 5 miles) up, the bamerasiof the Viking 1' dust. By simply examining:these per gent) of; magnetic material sagest Orbiter'provide- a vertical view of Arsia magnets.with the Viking cameras now Monsone oI Mars'ars Iaresgt volcanoes.o canoes. Thee ..... volcano reaches about19 kildmeters (12 6 and then, the amount of magnetic miles) abcivp. the surrounding Martiar7 ! .. material in the.Martian soil could be terrain, more than twice as high as 'Earth's I. measured. Early results, suggest that Mount Everest. fhe crcular central area in its summit is about 120 kilometers (75 miles) across. Around this. summit crater, the slopes of the volcano are covered with lava flows that produce distinctive braided patterns seen clearly Eet the bottom of the pictbre. At leftand right, small craters and ' canyOns cut into the main Gene of the volcano; these features may be the sources of vast amounts of lava that spilled out to flood the surrounding plains. ;; rof

'4;

4

rT.i

20 19

+ if 1

1 . , . . that the iron must be p1resent in two or knowwhatlife looks,like?"4 wa"not .002 to the confined 'atmosphere More distinct mineralst only. one of 'possible to build, ori one smalll above the soil§ample. The .sample

which 47rnagnetic. 1 , ,"spacecraft, enough instruments to,.. was then illuminated with simutated /.the,.-The chemic61analyses indicate that detect all the, possible forms of life that.Martian sunlight. If .any-Martian life- Martian soft cannot Oe made of . scientists could imagine tb exist 'on ',forms conVerted the C0_ into organic . fresh. basalt la"v'a alone. The presence ;Mars. Before buildihg tf-1instruments,- compounds, the compounds coUld. be .of Water.(perha0.as.much..asi, per. tllescientisSs had to make soMe detected by theiadioac,trvity. cer-it)1,n the.§oil.,..the large..imourit of: '-ciecisions.about what the jnstrurrients ...Living terrestrial orgapiSms give off

iron, arittthe unusually large.ambunt of should look for. .. .. gaseS`. Plants give off oxygen, animals sulfur, all indicate that the soil is a. .The. Viking experiMents were. .7. give off carbon dioxide, and both. mixture of original.basalt lava with designed,. around two assum-ptiona?.4, exhale-.watet..A second, ex.periment on Other compOunds that have fOrrnethas First; it assumed that Martian life; each Lpnder, the gas exchange- -'the rock -has been.changed or. would be like Earth life,, which" is based . experiment was designed to detect

. "weathered" by contact with.the- oh the element c;arbon-and.Thrives by this.kindofactivity:Nutrients apdi ' almo§phere of Mars..The soil could be° .transforming carbon CompOunds. . water,were added tth thatOil, and the

a.mixture of ironsrichclay minerals a\-id second, the example.of.Earth snowS7. cherniCal cOmposition'of the gas . .other. compbunds.atqh as iron that where there are large. ilia forms .above the'Soil.was Icontinuously hydroxide:and magnesiUm . (like human. bengs r-4: elephants), ...analyzed. for changes that might The soil of Mars is much more 7 there are.also...sInall ones (like rndicate biological activity. .,.similarto Earth's soil than to the soil of .bacteria). and thatAhe small ones are A third experiment on each Lander 'the.Moon: The lunar. soil, as-We.have far- more abundant, with ))sands or. was based on the fact that terrestrial learned from thesamples returned by millions of them in every gram of.soit an.imals"(including humans) consume the missions, is waterless, . '-To hava.the best pos'sible. chance.of "organic compounds and give-off unweathered.; and formed by the. detacting life, an instrument should carbon dioxide. The labeled 'release continuous bombardment of large and took for the most 'abundant kind of life.... experiment added. a variety of radio-. .' 'small meteorites.. Mat,tian.soil seems If a Martian v,ersion of Viking.were sent activIsnutrients to the Soil. then waited. almost terrestrial; it.vontaips water, it to Earth to look. for life,it might' easily. to see'if any radiOaCtiVe00_(derived. seems to be weathered; and it is land in e'place where there Were from consumption of this "fOod') would continually blownabout and neither elephants hor humans, but it be given off... redistributed by. the Wind. would be very unlikely to land in a SeVeral soil samples were place wherathere Were no bIcteriain ...- processed by all three instruments on o . . the soli. .. each Lander: The results? Puzzling. ' The Viking instruments were Three Chances, for Life 4 There is definitely some fOrrh of activity designed, therefore, to detect carbon in the Martian soil, but jt is not yet A major goal of the Viking missions. based Martian microbes or similar clear whether this activity is caused by Was to determine whether the soil of 'Creatures living in the soil. t he three Martian life or by some unusual Mars was dead like the soil ofthe labbfatoties in ech Lander were chemical charactedstic of the soil - Moon or, teeming.with microscopic life essentially incub rs, designed to itself. warm and nourishikany life, living or Viking has given us some chemical like the soilsof Earth: Soil samples .. brought into the Lander weredivided dormant, in the MViansoikand to information about th'e.artian soil, but . . ° and sent to three separate biological detect. with sensitive instruments the laboratories to be tested in different' chemical products of the organisms' ways for the presence of life, activity. One characteristic of terrestrial Searching fOr raises a : . ba,p(c problem, best summed up as: organisms .suchas plants is that they \How do you look for life if you don't transform,cAon dio'xide (CO2).in the surrdunding .air into the .organic compounds which make.Up their roots, branch0s, and leaves. Accordingly, One Viking biological experiment, designated carbon assimilation (or7 pyrolytic release) added radioactive

..20 .t..7

..,"r".",

, ,4q

. Figure 15.LandslidesFillMartian' "GrandTanyon". ThilYiking,1. Orbiter pture, taken fro.rp a r,angeof 2,000; kdometers (1,240,miles)-shows'a srfisl sergment'of the ( "Mariner ,Vglley7, a huge gaSh,that.runs east-west

1'10ralmOst-a-,00trkifermateri-1(3;000-rbiles) . . :..,akftV the equatorial region of Mars. ,This - :part of thetanyon is more than50 , 'kilometer's (30-milet) across and 2. N .kilometers (1.3 miles), deep. 'The aprons of\.: . cfebris on the canion floor shOiv how the cany,dn.wideris as its walls collapse and

.produce ithrpense landslides. The large . apron-in the center has'oVerridden.and partly coyered.ep older landslide '1609sit .to the left: The lines in.the deposits indicate the direction in whichthe material flowed after breaking away. from the canyon.ivalfs. White streaks in the middle of the cinyon are features produced by winds blowing along the length of the canyon. Upper walls of the canyon provide a cross...sectional view through the different rock layers that cover this part of Mars; hard, resistant rocks (lava flows) at the top overlie less durable rubble (wind-blown dust or volcanic ash) toelow. Dark circle.near.center is

photographic flaW. .

. ,' . ,Figure 16. The Vanished Rivers of Mars.

Cameras'n the Viking,1 Orbiter . photographed this r719 of wandering channels that cut across the terrain west of the Viking 1.landing site. The surface slopes downward,._ dropping about 3 kiloMeters (2 miles) in elevation from left to right. Flood waters once poured across this region frornoleft to right, cutting thrOugha high ridge (right)Jo:pourout into the plains to the east. Older craters-were cut, filled, and eroded by this flood, Younger craters,. formed after the flood, show sharp outlines. The late of these torrents.is unknown; the water.maY now be frozen, as ice in the polar caps or as permhfrost in the Meier, soil. Row8 of dark circles are photographic flaws.

21 **If.tiV?P' . . - ) we still do not know, enough about its.: 'cixygen-and carbOn-(ich materials that definite.an&Wers about thachemicals, nature'to predict wlrat reactions will; originally had' been produced.in the the-minerals, and, perhaps, any life occur when:paterarid nutrients are soil by.fultra,violet forms in the red. soil of Mars. . added to it in Viking:ps biological -Finally, the labeled releage laboratories. The Martian soil may experiment showed d.reOid:release of contain many unusual and unexpected radioactive c02 that at first seemed to-. From Mars to Einstein ...chemidals;.posSibly Rirmed- by-tha be.caused.by biological.activity. But .1 repeated blasts of Ultraviolet radiation, . the release quiCkili.sloWed down, Late in Noverfiber,,,1976, Mars -from .the-Sun -that Penetratethethin :suggesting_that some..chemicat in the passed behind thetun, and - . atrftbsphere of Marsand blanket the soil was beivigrapidly used up, comitunicatiOns between Earth and surface of the..planet:Earth'S soils are lhereas a biolbgical reaction. should. Viking were cut off until Mid- not affected in thisway;,. because the ave continued as,the organisms brew December,.when Mars. appeared can . Sun's ultraviolet light is 'absorbed by and multiplied. . the other side of the. Sun, As Mars .,. our denser atmosphere, and the :.; 1 One problem with a biological .paSsed.behind the Sun, the Viking 'chemistry Of Martian soil could verY. Interpretation of these reactions is that spacecraft carried out major- well be unpredictably different kohl' analyses of Martian soil by another experirnent ki.study, not Mars;' but the. the.,soils of our own planet. Even If Viking instrument have detVcte'd none basic nature of the universe itself: Martian soil is completely tifelesS; itis of the organic' carbon molecules that The spaCeCraft signals from Mars posSible that somareactions with the make-uri living things.' It is hard to: made it possible for scientists on Earth added .water and nutrients are 7' understand how these chemical to carry out the most accurate test imitating biologic41'activity. . reactions could be caused by Earthlike ever performed of Einsteih's Theory of Because of 'these uncertainties, microbes that leave'no other trace, scientists are being cautious in:their living or dead, in the Martian soil.. interpretations of the biological At themoment, we knoW that there 'experiments, even though, many of the are reactive ,irig6edients in the soil of results resemble those froM tests Mars, but it will take more experiments. made an terrestrial soils rich in living and more examination of the Viking Figure 17. Islands in the Str4ra The' organisms. data before we know just what they raised rims of these Martian craters seem The carbon assimilation 'experiment are.'Asthis work goes on, the to have acted as banierSs.tO floods of "' shoWed that.a small of CO2 separate Viking experiments. support Water that poured across the sur /ace of had been converted into carbon and reinforce each other, each one Mars in the past. The upstream (lower left). compounds, but this conversion could providing data to help interpret the sides of alIcthe craters seem eroded,vith streamlined islarid8 left on-the doWhStreani have been accomplished by some results of another. The .chemical (upper right) sideyA curiously shaped' reducing agent in the soil,./suct-as 'analyses of the soil, ',made by X-ray ejecta deposit still .p reservea rct u n d the metallic iron: .methods,_ are used 16:help interpret the uppermost crater may have been above In the gaSexchange experiment, p6z2ting results of the biological the level of the floods. This spectacular both oxygen and CO2 were given off' exPeriF9ents. The instrument that has scenery, photographed by the Viking 1" when water.!.kaS added to the s011y' looked in vain for orgianic.carbon Orbiter from 1600 kilometers'(1000 'miles) Howevtr,4s-ieactions could have molecules .has also..0asured the above Mars, is located nee the Viking 1 been causqd*,the decoMposition of amount of sucl-r ino?ganic gases as landing site on the Plains of Chryse., (Small: . dark rings in the picture were caused by a water and, sulfur, clioxideln-the soil. flaW in the camera.) . When these data-are combined and 4 , , evaluated, wamay.'haVe some more Figure 18. The Source of the Flood1,This `Strange Martian valley; more than 50 kilometers across, shows a striking change from a chaotic, hilly floor at its head (right). to a narrower and more streamlined shape (left). One explanation is that water, frozen below the Martian surface, suddenly melted and ran out, causing the ground lo . '.ct a 4. collapse and producing a short -lived torrent that eroded the downstream part of the valley. Such "collapsed terraih" is common in this pect.of Mars; numerous and small impact craters can also be 'seen.seen. A smaller valley, possibly'produced ' by a'smalier flood, is visible near the. large'. ,impact crater' at the top of the picture. This7. picture was taken:by the Viking 1 Orbiter/ frpm a distance of 2300kiloMeters (1900 ., 23. niles)., (The small dark rings in.the picture are caused.by a flaw in the camera.) / .

22 2 4

,E4 J im General Relativity. The theory, wrrch . Landers will operate for a year or two, explains'gravitation and the 'sending back photographs and other relatilbrishibs between space and time, informatibrt from Mars. Each:Lander.. predicts that light waves (or, radio -. has a long.liied nuclear pOwer saurce, waves) will be slowed down as they and each Orbiter gets electricity fr-dm. pass close to a large and massive large solar cell arrays backed up by Object like the..Surt.Precise ..... tWo nickel-cadmium.batteries_ rheastirerneni.of the delay in radio . Scientists are eager to use the transmission from the Viking - Lander instruments to follow the spacecraft as Mars went behind the . weathgr patterns at Ohryse and Utopia Sun would test. whether the General through the Martian fall and 'winter, Relativity. Theory was correct or ..and into the.spring whenthe time.of whether some competing theory was a.. planet-wide dust storms is thQughi..to, better explanation of how.our 'universe .4: begin. A complete weather redorci:o.f.:,.. works..6 the .Martian ygeciihichis two Earth...-. ".'.On the day of the experiment, .. years Fong, would be a unique. November 25,. 1976, Mars was about document that could.lead td better ,32.1- million kilometers (200 millron understanding theWeather and chrrtiale miles).frorriEarth, and the radio on Earth and other worlds.' signals took about 42 minutes to make GeolOgistS are also eager for a long the round-trip. But the timing and period-of Viking date The Viking-- signalling devices Used in. Viking Landers carry to detect. cwmunications are accurate that ":' so that scientists can the transmission time could be determinewhether Mars .is active like. . measured to one ten - millionth --" the Earth or dead andOiet likethe , Figure 19. Spla.t? The crater , 18 (0.0000001) of a second, With such Melon. Unfortunately, the instrument on . kilometers (11 miles) in.diameter, looks accuracy, it was not dfficult to . VilVig 1 did not operate. .. . entirely .different from the numerous craters determine that the radio signals from Since Viking 2 landedlri.September, that cover the MoOn and Mercury". The

Mars had been delayed by a full two .1976,. its sensitive seismometehas . high ceniral peak inside this Crater, and ten- thousandths (0.0002) of .a been steadily recording the tiny the scalloped blanket of ejected material second.exactly 'he delay predicted vibrations caused by.the wind and the around it. Make ,Yuty look like a large-Scale_ by.the,Theory oferieral Relativity. mechanical-devices on the spacecraft. version ofcrater forMed...by throwing a a' This Viking reltivity. experiment was -F(distinctive."event" in early pebble into thick mud: One possible explanation foi this resemblance is that also the most accurate measurement November, 1976, may have been a . * large quantities of frozen water beneath. of distance ever made: the 321- million- quake.with a Richter magnitude of 6.4, the Martian surface were instantaneously kilometer Earth -Mars distance was i fully as large as the major San melted by the heat produced by a large determined with.apaccuracy.of about Fernando earthquake that struck the meteorite impact. As a result, huge "Mud

1.5 meters (5 feet)! 1 LOSAngelesareain 1971. avalanches," made of water and- broken Overhead,' the two Orbiters continue rock, poured out of.-the crater to form the' to takepictures of the surfade of Mars - curiously-shaped blanket around it. This at Next? and to measure the amount of water view was taken by the Viking 1' Orbiter . vapor in the Martian air and the . . from a range of 1897.kilometers (1165 miles). (Yuty is named for a village la, Although most of the Viking terripekitures-of the Martian surface. . . Honduras.) 'excitement was concentrated in the Even before the Landers touched., . first ,fewmonths after-the , it is' down, the Orbiters had provided new Figure VI Cracks In:the Martian Crust? likely that the Viking Orbiters and high-resolution photographs of the This part of Mars, .west of the Argyre major features of Mars: circular basins is cut by numerous parallel t and.mountains (Figure 13), huge fraatued (faults) that run for hundred's of . volcanoes (Figure 14), great canyons' ,kilometers through- circulaf.craters and flat and 'landslides (Figure 15), mazes of Warns alike. The dominant set of fractures ( co IDleft runs from lower left to upperPP s.

right, but Othei fractures run in other . direction's (see lower.right)..The fractures may be the surface.effects.of.Slow mbvemjnts in the interior .of the pknet. The srriall fan- shaped channels (top center) may been cut by running' water at some .time in the past. The light- colore.d region (top right) is Part of a froSt

deposit associated with Mars' polar . cap. ".."- 7.`.7 .

a

\, .winding, water-cut channels (Figures beneath the polar ice.is comprised of 16, 17, and 18), and craters with.... . layer upon layer of what may be

curiously scalloped deposits around windblown. dust.- Here under the polar . ' thern.(Figure: 19). Large areas of Mars cap maybe. preserved the records of are covered with strange patterns of the changing climates of Mars during. fractures and joints in the bedrock thousands Cr millions of years in the (Figure 20),and with unexplained past.'SOrne individual layers, as much polygonal marking's that resemble,"on as 50 meters thick and covering ' a large scale,, the permafrost or hundreds of square'kilometers; m.ay. ",patterned groUnd" of Earth's Arctic have been deposited by huge .."

regions. . 'sandstorms farmore violent than any On 'September 30; 1976, the orbit of observed on Mars. today.; the Viking 2 Orbiter was shifted so that When the Orbiters finish their task, . the spacecraft cbuld swing over the much of Mars will ,be photographed, War regions of Mars, This.maneuVer mapped, and studied,,in great detail, made it possible to 'study in detail the and future missions to Mars. will be Figiare 21. The Land of the (Martian) Midnight Sun. The north polar region of mystehous white polar caps that .were planned with better maps then many Mars is displayed by the camera of the.' one of the firSt features of Mars to be. terrestrial explorers hAVe had. Viking 2 Orbiter as. the spacecraft passed been thrOugh Earth-based telescopes:,.; .The Vikings also explored other over the Martian Arctic for the first time in. The Orbiter found that the amount of worlds near Mars. In February, 1977, October, 1976. Broad regions of white ice water in the atmosphere varies greatly; the Viking 1 Orbiter made two close are broken by.darker slopes and.valleys it is almost.zero near.the south (winter) approaches to Phollos, one of the two cut into,layered rocks that underlie the polar cap,. then increases .dfamatically Moons that circle Mars. From as icecap itself, Individual rock layers appear, as one moves northward into the . close as 120 kilometers (75 miles) as curved parallel lines that follow the ' contours of the slopes and valleys. northern (summer) hemisphere of- away, the Viking cameras . Measurements of 'the surface temperature, Mars. Over the north polar cap itself, photographed the irregular, cratered made by instruments carriedon the . theatOospheriOyvater content 1, surface of in such detail that Orbiter, indicate that the ice is frozen decreases and. the 'instruments tiny craters and mounds .a few meters water, not frozen carbon dioXide. Top to indiCate that .the SUrface temperatures acroSscan be seen in the. pictures bottom of the picture is abobt360 are about 760° c.(-'96° F.). (igures 23 and 24). Many scientists kilometers (225 miles). The Martian north Coldas these.temperatures are, think that .Rhobos, which is only 20 pole is about 300 kilometers (170, miles) they are.above thefreezing point of kilometers (1.2 miles) in diameter, is an beyond the top of theOcture. (Just like CO2 in the Martian atmosphere, and asteroid that was captured by Mars at the Earth's Arctic regions in summer, this . stientists'are nowsure that the part of Mars also'has.a "midnight sun"or Some time in the past. If they are right, total daylightbecause the inclination of permanent polar caps on Mars are the Viking cameras have given. us our Mars' axis and the length of the Martian .made of waterke instead of frozen .firSt close look at what we wilt find day are almost identical to Earth's. CO '2 ("dry ice'').. The polar caps thus when we venture beyond Mars into the contain; a large. reservoir Of the watec. millions (*tiny bodies that occupylhe Figure 22. A Valley that oats into the . that,mact-haye cut the channets-on Asteroid Belt itself.. Past. Walls of a deep valley, eroded in the irf an ancient and warmer time. Even as the Viking data continue to Martian north polar Cap, display the The Cover Of. ice, is not .continuous, flood in, there are active disdussions layered deposits of rock or windblown and ttie nOrifiern.polar cap. is cut .dust that Underlie the polar ice itself., Individual layers' as little'as 50 meters (165 steep-sided. ice .trge varlecrs..(flu'r..6 feet), thick can be,detected, even though 21).HighrnagnifitatforiPictut'es 'of. the theipictureas taken from,about 2200 valley, walls (Figure .22) revealed to ktrneters (1370 miles)away. The different surprised scientists thatfthebedrodk." layers may record many past changes in ti the Martian climate, by the same . -. . mechanisms That produce the changing ice ages on the Earth. Dark smudges on. the icesurface may be recent deposits pi windblown dust. This closeup vieiv,'teken _ in Martian mid - summer (October, 1976) by the 'Viking 2 Orbiter, shows. an area of the polar cap about 60 by 30 kilometers'(37' by 18 miles): Water ice (white) covers a

high, level plateau, and the steep wall. of . the valley (Op) drops about 500 meters (1650 feet) from the ice layer to the bottomIrpis color picture was made by . combining black-and-white piCtures taken through three different color filters..

about follow-up missions to Mars that shock of a hard landing. In this way a can now.beplanned on the. basis of.. network of instruments.could be what we have already learned. For all placed, on Mars to give us global that Viking haS done, it is only a coverage of the planet's chemistry, beginning; what we have learned from Marsquakes, and weather. the robots on Mars is still not much More ambitious, but entirely within .more than we had leaMed from the our abilities, is a more complex robot . robots (Surveyor spacecraft) that we that would land on Mars, collect sent to the Moon before the first samples of rocks and soil, and return, astronauts landed there. We know that them to Earth, where they could .be the surface of Mars will support the studied directly with the resources of, weightof machines and humans. We all of Earth's laboraories. Only in this have the first rough chemical analyses way can we make the thousand -of the soil. We have taken pictures of necessary analyses that are too the airface and dug-trenches in it. complex to be made by machines on ;And we can now:make excellent maps the surface of Mars Only with such of the planet and pick the sites for returned samples can we determine future landings. . . with.confidence the ages of the rocks, To send astronauts to Mars would the minerals that compose them, their be a major uridertaking. Not only co-iplete chemical composition, and would a manned mission require the weathering they have undergone. Figure3. A Battered Moon of Mars. extensive technological developments, With instruments that are now Even tincraters in the surface of Mars' but fliere are serious medical availablp;:te could finally establish innermos moon, Phobos, are captured in problems involved in keeping the crew beyond dot whether such returned this photograph taken by the Viking 1 Orbiter caMeras on February 18, 1977. To physiCally fit during a two -year trip.in samples contain any Martian life. With . zero gravity. the experience of a decadeiirrspace,' take this pioture, the. spacecraft came as ' For the near future 'at least, and with the knowledge gaiOd from close as 480 kilometers (300 miles) to the tiny moon, Ahotagraphing features as machines must do our exploring for sampling the Moon, we car:Collect, small as 20 meters (65 feet) across.. us. One possibility would be a robot preserye, and analyze suchsamples Phobos is elliptical in shape; the top-to- "rover" that would land on Mars and from the surface of Mars whenever we bottOm. diameter'is 19 kilometers (12

then drive across its surface, making choose. rriiles), but diaeters' in.other directions . chemical and biological analyses as it The Vikings have become- a bridge are 21 kilomet rs (13 miles) and 27 went. Another .possible mission would into the future. When the Landers have .kilometers (17iles). Because of its involve a new kind of Orbiter around sent their last data back to Earth, they irregular shape nd ancient, cratered Mars, one that would carry instruments will remain like monuments drithe surface; scientistthink that Phobos may be an asteroid Met was captured by Mars, to measure the chemical composition . surface of Mars, waiting silently_until possibly billions of,years agn. A large ,, of Mars'. surface, just as instruments new machines, and finally human crater at the loweriqght is named Hall after carried, on the Apollo spacecraft beings, come to stand beside them. . the' AMerican astronomer who. discovered ' mapped the chemistry of nearly one- (Figure 25.) the two moons of Mars. in 1877. The quarter of the Moon. From this Orbiter, ragged appearancet the right side is probes could be dropped to the produced by shadOw on the unlit parts of surface, carrying instruments Phobos' irregular sulfa e especially designed to. survive the Figure 24. A Moon .Abo tto Break? -11,prallel lines of fractures nd craters extend acrpss the whole Wade of Mars' inner. moon Phobos.. 8ome\scientists '4P think. that the whole moon'i gradually breaking up from the impact of large ,meterorites and from the tida forces produced during its rotationsround Mars. the future, Phobos may Oisin egrate completely into small fra.gments, forming a ring around Mars like the familia rings of Saturn,or the similar rings recently around the distant planetranus This picture was taken by the Viking 1. Orbiter as it passed within 300 'kilo ters (200 miles) of Phobos on Ma The pictu're Op the right i e original. data; the left-hand ure is the compur- processed v

28'

L 4

,0;

30 r. Figure 25. A Viking Sees a Sunset on a New. World. The Sun has set on Mars, but a lingering twilightbrings a reddish glow to.the Martian surface (left) and to the top of theVikingi Lander (lower right). The light of the Sun is scattered by red dust in the atmosphere, coloring the surface and/ producing a reddish color in the sky where the. Sup has set. Near the.Sun, the picture is overexposed, and that part of the sky appears white (upper right). The colored rings around the white spot are not real; they are produced during the computer . processing of the camera's pictures. A human eye. looking at. the same scene, would see a black night sky, grading uniformly into a reddish glow where the Sun has set.

Figure 26. "Mars, this is Viking . Viking, this is Mars." An apparent welcoming committee of lave-like .Martian rocks is framed by the radio antenna (top) and,other instruments on the Viking 2 . Lander. .The pink color of the sky is produced bj? fine red dust carried by the Martian winds. The AmeriCan flag (left) and several color calibration charts helped scientists determine the - actual color of the

Martian sky and landscape from the . pictures returned by Viking's cameras.

31 ..,

Appendix Suggestions for Further Reading

The Planet Mars;

Avener,. M.M., and.R.D. Mac Elroy our,knowledgfabout Mars in the pre- Mutch, T.A., R.E. Arvidson,J 11976), On the Habitability of. Mars, Mariner and pre-Viking Years. Still a Head !IL; K.L. Jones, and R.S. . NASA Special Publication SP -414, useful source'of information about the Saunders119.76), The Geology 'f

. U.S. Government Printing Office,.105 general characteristics of ,Mars and 'Mars,. Princeton, N.J., Princetd. p., price $5.26. A long4ange the history of study of planet. University.Press, 400 p., price .35.00. consideration of whether life can kgraduate-level textbook on t e - survive on Mars and of how we might Hartmann, W.H., and O. Raper Surface features,. geological bring life includirfg.ourSelves ... to (1974), The New Mars: cthe Discoveries pritesses, and rock formatio s of -the planet to change its present of Mariner 9, NASA Special Publication Mars as deterMined from sp cecraft . environment into something more SP -337, U.S. Government Printing observations. (There is a.brif

Earth like. ' . Office, 179 p., price $8.75. A appendix containing' earlyiking beautifully illustrated textbook that' -.results.) The book provide a detailed Bradbury,. R., A.G. Clarke, B., 'combines theeearly discoveries. about scientific summary of oururrent Murray, C. , and W. Sullivan Mars with the findings of Mariner 9's knowledge about Mars. It also

(1973),: Mars and the Mind of Man, . close -up, pictures. Carefully selected provides good comparis hs of how New York,Harper and Row, 143 p., photographs highlight separate the same geological for es. price $7.95: A collection of essays chapters that describe different, volcanoes, wind, and.vvater about Mars, in which five scientists features. of Marss. Photographs operate indifferentways on the Earth,

and writers discuss their feelings compare similar views of Mars and Moon, and Mars. / . ' abOutMars and what might .be found Earth. Veverka,' J. (1977)/"Phcrb there. as Maririer 9 went into orbit ," Scientific American,' Vol. 236, around theoplanet in 1971. The book Mars as Viewed. by Mariner 9 No. 2, February; 1977, pp. 30-37.. A also presents some later reaqtions of (1974), NASA Special Publication.SP- descrintioh-of the two tiny moons of the same people to the disceries 329, U.S. Government Printing Office, Mars, revealed in close-up made by the spacecraft. 225 p., price $8.15, A detailed !..picture photographs taken by the Mariner and book" of Mars as seen'through the Viking spacecraft. The moons may be Carr, M: (1976), "The VolcOoes of cameras of Mariner 9, thiS document captured asteroids. They give us an Mars," Scientific Americati, Vof. 234, Contains several .hundred captioned ,indication of what million ?of other No:1, January, 1976, pp. '32-43. A illustrations of the craters, volcanoes, small bodies in the solar system may detailed discussion of the huge canyons, dunes, clouds, and icecaps' be like. volcanoes discovered on Mars \in 1971 that make Mars a complex and. by the Mariner. 9 spacecraft: thir size fascinating..planet, partly like Earthand and appearance, their differenc s from partly like the-Moon. Viking Results terrestrial volcanoes, their ages,1\and what they tell about the history end Hoyt, W.G..(1976), Lowe/Land Mars, "Mars: Our First Close Look," internal. structure of Mars. -Tucson, University of Arizona Press,' National Geographic, Vol. 151, No. 1, 376 p., price $13.95 hardbound, $8.50 January, 1977, pp. 2-31. Handsomely

. Slasstone, S. (1968), The Book, of paperback. A detailed and scholarly illustrated presentatio. n of Viking results Mars, NASA Special, Publication SP- biography of the astronomer percival for the general reader. Scientific 179, U.S. Government PrintinT0fiice, and his involvement, in the results are combined with beautiful 315 p.,. price $5.25.. A thorough controversy over the existence of color panoraMas of the surface of compilation, now somewhat dated, of intelligent life on Mars. For people, Mars. interested in the history of.astrohomy an'd the study of Mars in the early-'20th Century.

'3 3 32 Experiments. and Activitiqs Young, R. S. (1976) "Viking on 1. Geography and Mission letting the inflated balloon expel air. in rMarg-the First. Months,",NASA Report Planning. the direction that the block is moving to. Educators, Vol. 4, No. 4, December,' (i.e:, "downhill"). Show that this' The following are the Martian arrangement slows the block down, 1976, pp. 1 -5. To obtain write. and of Iodations Educational Programs Division/FE, just as ' mentors sloWed that were considered as possible National Aeronautics and Space down the Viking' Landers. Turn the landing sites,for the Viking spaCecralt: Administration, Washington, D.C. block around so that the balloon 20546. . expels air in the "uphill" direction as 22° N. 48° W. (Viking 1 landed tf-Le block slides down the plane. Two technical summaries of the , near here.) Calculate the amount of velocity Viking scientific results are: 20° N. 108° E. added.tO (or subtracted from) the 44° N. 10° W. block by the action of the balloon in

Young, R.S. (1976), 'Viking on Mars: 46° N. 110° W each. use. . A Preliminary, Survey," American 46° N. 150° E. (Viking 2 landed Scientist, Vol. 64, No. 6, November- near herel, 3. Life Detection 7° S. 43° W. December, 1976, pp.-920-627. Carry out simple versions of the . 5° S. 5° W. Viking life detection experiments by .1' Viking 1:. Early ,Results, (1976), If MASA (the Martian Aeronautics making chemical tests for the'

NASA Special, Publication SP-408, and Space Administration) .sent presence of life.in terrestrial soils. An . U.S. Government printing Office,.67 p., spacecraft toland at the same apparatus to deteCt carbon dioxide price $2.00. latitudes and longitudes on Earth, (CO2) or water (H2O) given off by where would each one land? What organisms in the. soils can be. made by Technical articles on all aspects of hazards would be encoUnteredTWhat . connecting two bottles with a U-tube., Viking science, written by the scientists would happen to the spacecraftWhai Place a sample of organic-rich soil in themselves, have appeared in the would the spacecraft see?.WouldUI one'bottle. (Use commercial peat if no followingissues of the magazine detect water? life? intelligence? suitable soil is availaPlej 'Science, published by the American If you were working for MASA, what To detect CO2, place a limewater ASsociation for the Advarldernent of sites would you pick for a landing on solution in the other bottle. The end of Science: Earth? Why? For each site, identify the the U-tube should be placed about 10: 27 August 1976, Vol. 193, No. 4255, hazards that your t pacecraft lander mm (1/2 inch) above the surface'Of the pp. 759-815. would have to survive. What would.you limewater. Any CO2 given off will"readt 1 October 1976, Vol. 194, No 4260, expect to find? Find some pictures of with trig limewater to produce arcloutly pp. 57-105. the Earth frprn space to examine-for or milky appearance. (Try using a f 17 December 19760 VOL 194, No. interesting locations. photographic light-meter to measure 4271, pp. 1274-1353. 2. Demonstrate the retrorocket principle by attaching a balloon to a wooden block and sliding the block .down an inclined plane. Determine the velocity-from the length of the plane and the time it takes the block to slide down. it. Repeat the same experiment, how rapidly the limewater turns 5. Stereo Photography . the soil, e.g., scraping the magnet .cloudy.) DemOnstrate .how, three-dimensional through the soil, pouring the soil over Although water in the soil may not .;stereo pictures, like those produced the magnet:or spreadint out the soil be prodUcet1 by organisms, its by the Viking cameras, are rinde and in.a thin layer andpassing the magnet

presence indicates the possibility of . used. Take one picture of a scene ova it. First wrap the magnet in paper life. Water given off the soil can be (e.g., a classroom); move the camera or plastic film srthat you can easily observed by using a commercial 2-3 feet sideways, and take another remove the magnetic material that.

drying agent, like."Indicaiting Drierite" picture of the same scene. Examine adheres to it. : or cobalt chloride paper, instead of the two pictures with a stereoscope, Examine.the collected material with limewater. The drying material can be moving them until.the picture is seen a hand lens or a low-power.

placed either in theU-tubeor in the . in three dimensions. Make sketches microscope.: How much white second bottle,' Water can be detected and maps of the scene, indicating nonmagnetic sand was collected with by weighing the drying material 'or by . objects that are high and low, near the dark magnetic'material? noting the change in color. ana far. A print-making color-camera Prepare a soil sample that contains In experiMenting:Oith heating the is convenient,. but any camera can be a known weight of magnetic material. soil, low heat should increase organic used. Try various collection methods and activity and should cause a faster. If you use a color camera, you can, weigh the amount of 'magnetic material evolution of CO, or H.O. Too.much demonstrate how the Viking cameras collected in each way. Calculate the- heat will kill theorganisms arid stop produce color pictures by combining efficiency of each method, i.e., the; gas. production. In addition, test a photographs taken through different weight. collected divided by the'Weight "control sample" that has been cdIOr filters. Experiment by placing_ Originally present. Discuss why. some sterilized by heating the soil bottle in colored filters.(of glass or plastic) in collection methods do not approach

.boilingmater, and observe the front of the camera lens before you 100 percent efficiency. . difference in behavior. take the picture. Wratten gelatin filters. Make Up several soilsamples with are best: number 47B (blue); 29 (red), varying amounts of magnetic material,

4. Wind Erosion . 61 (green). Colored acetate can also --e:g., I, 5, 10, and 25 percent, Process Experiment with making wind- be used; it is cheaper, but it. will distort each sample with the most efficient produced landforms by blowing an the image somewhat. Take.each collection method, and weigh the . electridfan (or hair dryer) over a large . picture in a,stereo-pair through : amount.of magnetic material collected. shalloW box filled with loose sand. different colored filter's, then "combine" Calculate the total amount of Magnetic. Vary the force of thewind,,,the the colors'by viewing the *stereo -pair material present, knowing that: distance or the fan from. the sand, and with the stereoscope. Which pair of (amount present) = amount collected) the angle at which the wind strikes the color filters produces-the best match /.(effibiency):.Repeatthe experiment a few times. How reprbdticible ,are your surface. Try 'to duplicate-the sand . with the colors in theoriginal scene? dunes and ripples seen in Viking Are two colors adeduate,to make a. results? How accurate are. they? pictures Cif the Martian surface. good match?, Substitute a different magnetic Place rocks on thesarid surface, Material (iron.metal filings for and try to duplicate other features 6. Magnetic Material in 'the magnetite or vice versa) and repeat . seen on Mars: wind-scour under rocks, Soil . 'the experiments. Does the efficiency of the collecting methods change? Why? :trails of sand on the downwind side of . Make a synthetic "Martian spir.by.. rocks, and sand deposits on-top of i mixing .about 5 percent of magnetic .. " rocks. How can these,features be material. (crushed magnetite; Fe0, or 7: Mechanidal Properties of used. to deterrhihe the wind direction? iron metal filings) with clean white the Soil Reverse the direction.of the wind, and sand. Using a large bar or horseshoe Study how the mechanical See how much wind force is needed to magnet, try various methods of properties of different` soils affect the change these wind features so that .collecting this magnetic material from appearende of trenches dug in them. they indicate the new wind direction-. -1. Make a series of soil samples by. Do wind features on Mars necessarily, mixing loose sand with varying indicate the present wind amounts of fine clay or chalk powder. direction?Try making and studying 3- dimensional stereo photographs Of your artificial wind features. (See Experiment #5.)

S 4'

Experiment on mixtures that contain . Maunder to demonstrate the eye's zero percent.dlay,(pure sand),, 25 tendency to produce imaginary lines to percent, 50 percent, and 100 percent 'connect objects that are entirely clay (pure. clay): separate but poorly seen.) . Make trenches by sticking a ruler into the soil and.pulling it through the,, soil sample.. Note the appearance of 9. Mars in Fact and Fiction. each trench, and describe what people have often Corlimented -that happens to theWalls after the trench is science- fiction literature often predicts' formed. What percenqlge of Clay is future 'facts and developments: (Jules needed to.form a Steep-walled trench Verne's From the Earth to the Moon, and 20,000 Leagues Under the Sea like those in the Viking pictUres? are often cited as examples.) Pour a esample of each soil onto a flat. Science- fiction has been written 'surface from a height of a few about Marsfor more than three centirtieters Note how the piles differ quarters of a century}. A partial list of in. smoothness,, in slope; and in the books, all available in paperback, is: number and size of clumps formed by the soil. H.G. Wells, The War of the Worlds Is there anydifference in behavior (1898). - between the. soil that has 25 percent Edgar Rice Burroughs, A Princess of clay and the soil that is pure clay? Mars (1912). Examine the Viking pictures of the C.S. Lewi,s, Out of .the Silent Planet trendies dug in Martian soil. boes the (1944). Mirtian .soil behave like loosasand?. Robert A. Heinlein, :Red Planet -Which soil sample best duplicates the (1949):. behavior of the Martian soil? Ray Bradbury, The Martian Study the effect of water by ChropiclesA1950). sprinkling a.little water on the surface Arthur C. Clarke, Sands of Marst of the soil sample before digging the 41952).: trench. Through whiCh soil does the What conditiOns of temperatlk 4 water move fastest? How does the atmosphere; and cliMate did the water affect the shape of the trench in Various authOrs attribute to Mars? What

each soil? . kinds of Martians lived in these,` conditions? tw did Earth people. 8. The "Canal" Illusion adjuSt to Ma., and Mirtianslo Earth? On a white sheet of paper abOUt 2 Did the authors' view of Martian feetby 3 feet in size, draw.a random conditions change as we learned more arrangement of dots, circles, ovals, about Mars? How accurately did the straight lines, wavy lines and irregular. authors predict the Yeal,nature of Mars smudges. Make sure that the diagram as we have determinedif from Viking is a completely random, pattern: Hang and other.spacecraft?,r the. paper at the ftont of the classr0bm How would you Write;arCaccurate" so that it is, well -lit, and have the science- fiction novel based on the '..students draw what they see. view of Mars reveale.d:-by Viking/ What Compare the drawings by students kinds'of ''Martians". could exist? What whb,are closest to the diagram 'with protection would humans need on the thbse by students who are further ' surface of Mars? What haZards Would away. WhiCh Ones 'reproduce the humanS on Mars.face.from natural pattern, best? How many in which' processes or from "MartianS"? group draw straight lines where none are present in.the picture? (ThiS eideriment was first perforMed many year's ago by the astronomer

35 - 7:- Suggested Vieiving

A series of four filMS produced by A Odestion of Life":, NASA discUss the planet Mars and the 41-1Q 270CQLOR;-728 'A MINS. Viking life detection experiments. The The film ISa composite version of three films, produced before the Viking 15-minute films: Life? (HQ 261), Mars: landings on Mars, may be borrOwed Is There Life? (HQ 263) and Mars and from NASA Regional Film Libraries Beyond (HQ 264). A definition of life without rental charge. and general conditions necessary to . . . sustain life are discussed. Viewers are ntroduced to the possible past history HQ 2611:OLOR-141/2 MINS. of Mars as well as its present surface General characteristics of,life are first topography and its capacity to support described with non-life similarities life as we know. it. Major emphasis is ...ngted. A number of adaptations are placed on the Viking life detection inplUded to show how life has adapted experiments includirig-the three to Eartlh conditions, and hoW certain, 'biology experiments and the organic individuals cawithstanq analysis instrument. Consideratiortis environmental insults. In conclusion, given tOthe potential significance of the habitat of Mars is described with discovering life elseitere in the the question raised,as to the possibility urtiverse. of life existing there.

MarsIS There Life? HQ 263C,OLOR-14 1/2 MINS, Students are introduced to the possible-

. path history of Mars, as well as its present surface topographyfrOm volcanoes, ice caps, stream, beds, impact ciaters,canyoriaand wind- groded surfaces. The Viking !ander and its biology experiments are disci:1.0ed in relationship to the search for life oh Mats: in conclusion, Studentsare asked to consider life forms that might' be able to Survive on Mars, and the potential significan-c.e of their gis ove7y.

Mars and. Beyohd. HQ 264COLOR-14 1/2 MINS. This filmIracei the Vikingmission to Mars 'to specifically explore the biochemical evidence of life. Elementary chemical Components of life (as we,know it) are introduted;.. these are related to the organic analysjsinstrurnent on board the Viking lander. The instrument is described by design and operationS; TI-Orog ram concluclesWith therkiiential significande.otlpiochernical findings how they may relate to past, present and future Martian life.

31 36 *US. GOVERNMENT rharatriC OFFICE:19770-247-915'