viking fact sheet may 1972

8/8/2019 Viking Fact Sheet May 1972

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TABLE OF CONTENTS

VIKING......... .........................................1-9Martian Life....................................... 2-3Previous Mars Missions ............................ 3-4Viking Launch.............. . .... 4-5Journey Through Space ....................... 5Tracking.......................................... 6Injection into Mars Orbit and Lan ding............ 6-7Landing........................................... 7-8Orbiter........................................... 8-9

VIKING INVESTIGATIONS .................................. 9-16The Search for Life............................... 9-10Photosynthetic Analysis......................... 9Metabolic Analysis ............................... 10Respiration ..................................... 10Molecular Analysis................................ 10-11Inorganic Chemistry ...... 11-12Ima ingyse .2.-9ging System~........... ...................... 1Lander Camera..................................... 12-13Entry Science ...................................... 13-14Water Detection .................................... 14Thermal Mapping................................... 14R'adIio Sclence. ... 16Weather Station on Mars .................... ..... 15Physical and Seismic Characteristics....... 16

COMMUNICATIONS......................................... 16-17MANAGEMENT RESPONSIBILITIES ........................... 17VIKING SCIENCE TEAMS.................................... 18-21VIKING QUESTIONS AND ANSWERS ........................... 22-27

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VIXIM

The National Aeronautics and Space Administration isscheduled to launch two spacecraft to Mars in 1975 to orbitthe planet and sort-land on the surface to significantlyadvance knowledge of the planet with emphasis on determiningIf lire once existed, is present, or might develop.Called Viking, the two spacecraft will travel some700 million kilometers (#40 million miles) through space onnearly a year's Journey to arrive when the planet is about330 million kilometers (206 million miles) from Earth on the

other side of the Sun. Each 3,400-kilogram (7,500-pound)spacecraft will be launched from the Eastern Test Range,Florida, aboard a Titan III/Centaur launch vehicle during a30-day launch period between mid-August and aid-September.

The program will stat between $750 and $830 million,with the launch vehicles costing an additional $66 million.Once in Mars orbit the spacecraft will separate intotwo parts, an orbiter and a lander. Together they willconduct scientific studies of the Martian atmosphere andsurface. While the orbiter performs visual (television),thermal, and water-vapor mapping, the lander will conductanalyses or the Martian soil and atmosphere.The lander's science instruments will collect data fortransmission to Earth, direct or via the orbiter, includingpanoramic, stereo color pictures of its immediate surroundings; 4molecular and organic analyses of the soil; and atmospheric,meteorological, magnetic, and seismic characteristics. Itwill also make measurements of the atmosphere as it descendsto the surface.The lander capsules will be heat-sterilized berorelaunch to comply with international planetary quarantinerequirements and to prevent false Indications in the life-detection experiments. Under international agreements theU.S. has pledged not to land an unsterilized spacecraft onthe planet until at least the year 2018.

Why Viking?There are many scientific and philosophical reasons forgoing to Mars, landing on the surface, and searching for lifeor lack thereof.

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We are witnessing profound changes in the planet Earth,due largely to interactive processes between evolvinm.life,including the dominant life form, man, and the evolvingplanet. The Earth's equilibrium is being altered by its lifeform and rapid changes are taking place which are poorly ornot at all understood and whose consequences cannot yet bepredicted.It is of crucial importance to study the nature of other; planets, presumed to have originated at about the same timeand by the same general processes. In this context, th epresence of life is of iere importance than any othermeasurement; in fact, finding that Mars is without life couldbe of equal importance. The study of a planet which has

evolved in the absence of life would provide us with a yard-stick with which to determine, for example, how the atmosphereof the Earth has been influenced by the advent of biologicalprocesses, Comparative planetology will be of great value inunderstanding the troubled Earth, and in formulating measuresto protect our own environment.On the other hand, if life is found on Mars, no matterhow primitive or simple, man will have one more tool forunderstanding the origin of life and will be that much closerto understanding his own place and role in the universe. Atthis time man can only speculate about such profound questionsas his uniqueness in the universe. He can only guess aboutthe beginning of life and the relationship of the origin andevolution of life to the origin and evolution of a planet.More data points are needed.Viking, then, is the beginning of a long process of studyand understanding -- a key step in determining where man fits,how he can best make use of his home planet, and perhaps aglimpse into his future in the solar system and beyond.

Martian LifeThe question of Martian life has been debated for

centuries; however, there is no conclusive way to determineits presence except by a direct search on the surface.Viking will be NASA 's first mission to do that.

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Within our present knowledge of the solar system, Marsremains one of the most likely spots for the formation ofextraterrestrial life. But it has been beyond thecapabilities of our three previous fly-by missions andrecent Mariner 9 orbiting mission to resolve this question.The recent Russian missions have also left the issueunresolved.Is Earth truly a unique life-supporting planet in thei -nse totality of creation? There is growing evidence tothe contrary. In studying the anras with telescopes overthe past several centuries, oan has been able to veroy thatthe basic chemical elements of wich Earth is composed are

found throughout the universe. In Just the last century ithas been proved that the ratio of these elements in our ownsolar system is consistent with the overall ratio generallyobserved throughout the universe.In other words, we appear to be residing on a minorplanet in a rather ordinary solar system in a galaxy of noparticular note among the billions of billions of'other solarsystems in our galaxy and beyond.Radio astronomers have detected simple organic compoundsin interstellar space. Recent detection of complex organiccompounds in meteorites that impacted Earth has increased

our confidence that life could evolve on neighboring bodies.And we know from laboratory tests that certain terrestrialmicroorganisms can survive under Martian conditions.The hostile environment on Mars leads most biologiststo believe that any Martian life would be microscopic, likesimple bacteria. Because there are many strange adaptationsof Earth life to unusual conditions, such as microbes in thenear boiling springs of Yellowstone National Park, scientiststhink that, if life exists on Mars, it will have speciallyadapted to presenc conditions there.

Previous Mars MissionsThe Mariner Mars flights have supplied most of theMartian data which permits us to plan and design the Vikingmission. These data include atmosphere composition, atmosphericstructure, surface elevations, atmosphere and surface tempera-turs, topography, figure of the planet, and ephemerisinformation.

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Mariners have also supplied much experience in conductingan orbital mission, inserting a spacecraft into planetaryorbit, and processing large quantities of digital data. Thedesign or the Viking orbiter in based on the Mariner space-craft, with many of the subsystem being nearly identical.The Mariner flights bave provided the logical incrementalsteps in the exploration of Mars which had to precede Viking,just as Viking is a necessary prelude to eventual sampleretrn, by automated roving vehicles and possible mannedmissions t-oMars.

Viking LaunchThe precise launch period was selected to provide aminimum-energy tlrjectory from Earth to Mars. Opportunitiesto make such flights occur at approximately 25-month intervals.In separate launches spaced at least 10 days apart, twoTitan/Centaur launch vehicles will lift off from cape KennmtY,each placing the Centaur upper stage and the Viking spacecraftinto a 184-kilometer (115-mile) parking orbit. After coastingabout 30 minutes, the Centaur wiii re-ignite to send the

spacecraft on its journey to Mars.The Titan.bootWr is a two-stage liquid-fueled r0c1et,with two additional large, solid-propellant rocket$ strappedonto the booster, and is a member of the Titan family usedon NASA's manned Gemini progrep. The Centaur is a lAquidoxgqn and liquid fiyrogen, high-energy upper stage used onunmanned Surveyor rflght to the Moon and Mariner flightsto Mars.At liftoff the solid rockets provide 9.61 million newtons(2.16 million pounds) of thrust. When the solids burn out,the first stage of the Titan booster ignites, and the second

stage ignites as the first stage shuts down. The Centaurignites on second stage shutdown to inject the spacecraft intoorbit. Then after up to a 30-minute coast a~gnuni the Earthinto position for restart, the Centaur re-ignites to propelViking on its Mars trajectory, Once this maneuver is completedthe spacecraft separates from the Centaur which subsequentlyis deflected away from the flight path to prevent its impacton the surface of Mars.

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-5-Shortly after separating from the Centaur, the orbiterportion of the combined orbiter-lander spacecraft orientsand stabilizes the spacecraft by using the SUn and a verybright star in the southern sky, Canopus, for celestialreference.

Journey Through SpaceThe Viking may have to make several trajectory flightpath corrections during its Journey. These corrections willbe based on nayigation information acquired from Earth-based

tracking of the spacecraft. Thus by firing its orbit-insertion engine several times in a predetermined directionthe spacecraft's trajectory will be altered to insureinterception of Mars.Power is produced by solar panels which open up afterinjection into orbit to span more than 10 meters (33 feet)tip to tip. Batteries supplement the solar panels and areused when the panels are shaded from the Sun or when peakpower is demanded. In turn, the batteries are charged bythe solar panels. Small attitude control jets on the edgesof the orbiter's four solia panels keep the spacecraftstabilized and oriented.The orbiter will furnish electric power to the landeruntil they separate at the planet. The lander has a set ofrechargeable batteries which will be charged during Marssgrface operstigns by two radioisotope thermoelectricg9nfraotares (Mo) being provided by the Atomic EnergyCommission (A$C). The RTOg convert heat produced by anuclear source into electricity, making the landersindependent of solar energy.-Information concerning flight performance is transmittedto Earth throughout the flight. An onboard orbiter computercontrols all spacecraft operationa and supplies commands fortrajectory corrections in addition to controlling the orbiter'sscientific equipmnt while in orbit. At the same time groundcontrollers will be monitoring all phases of the mission viathe worldwide tracking facilities.

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TrackingThe Deep Space Network (DSN) supporting Viking willconsist of two networks each with three stations having26-aeter (85-foot) antennas and one network of three stat1 '-mwith 64-meter (210-foot) antennas. The 64-aeter stationswill be located in California, Australia, and Spain. TheCalifornia station is now in operation and the other twowill be completed in 1973. During most or the Viking inter-planetary flight, the spacecraft will be in contact with oneof the stations. During orbital operations at Mars, therewill be continuous tracking of the spacecraft by one of thelarger DSN stations.In addition to tracking the precise path of the space-craft, this system processes three kinds of data: engineeringtelemetry, science, and commands for signals to the space-ecraft to initiate or change programmed operations.Communication with Viking will take longer and longeras the spacecraft gets farther away from Earth. When itreaches Mars sending a message one way will take 20 minutes.This means a roundtrip minimum of 40 minutes will pass beforea command from Earth can be received by the spacecraft inresponse to its initial transmission. For this reason,automation is essential. Operations that cannot be interrupted,such as the soft landing, will be performed completelyautomatically by an onboard preprogrammed computer.

Injection into Mars Orbit and LandingAs the spacecraft nears the planet (each spacecraftarrives at a different time), it is maneuvered into the properattitude for being placed in orbit. The engine will be firedfor nearly an hour to place the combined orbiter and landerin a highly elliptical orbit of 1,500 kilometer (930 miles)by 33,000 kilometers (20,500 miles) which has a period ofapproximately 24 hours to match Mars' period of rotationThe spacecraft will be tracked for at least 10 days afterachieving orbit to get detailed information necessary toachieve a precise landing as well as check out preselectedlanding sites. Mission controllers will have a total of 50days, if necessary, to further study the planet to confirmoptimum landing sites.

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The lander is prepared fo r separation after confirmationor a landing site based on observational data from Mariner 9 ias well as Viking observations. An ideal candidate landingarea would be relatively low, wars, wet, safe, and interesting.Landing

The Viking lander instruments, weighing about 67 kilograms(147 pounds), are divided into two areas of investigations,those used during the atmospheric entry phase prior to landingand those used on the Martian surface. Entry data will provideinfore 6tonn the upp r ataosphere on concentratiokondmcomposition and on the pressure, temperature, and density ofthe lower atmosphere.

When a landing area is determined, the lander's power isturned on, and the lander within its aeroshell separates fromthe orbiter. The aeroshell shields the lander against theintense heat generated as It decelerates during the highspeed entry through the thin atmosphere.During descent and landing, the lander maintainscoeaunication with the orbiter, which serves as a relaystation between the lander and Earth.A parachute is deployed to further decelerate the landerat about 6,000 mters (20,000 feet) above the surface.Shortly thereafter, the aeroshell is jettisoned. The para-chute is Jettisoned about 1.6 kilometers (' mile) above thesurface, and the terminal propulsion system begins firingits three engines. This is a rocket subsystem similar tothat used by the Su. veyor lunar landers.The engines, firing 5 to 10 minutes, slow the lander fora sort landing and shut down just as the foot pads touch the Vsurface.As soon as the lander is on the surface all its systemsnot necessary for science operations are shut down to conservepower. Its computer immediately determines the lander'sattitude on the surface to provide information necessary foraligning the S-band transmitting/receiving antenna to Earth.

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8-Scientific data and monitoring information are

immediately relayed to Earth via the orbiter. At the sametime, the two 35-watt nuclear-fueled generators arerecharging the lander's batteries so operations can becontinued fo r at least 90 days.The landed instruments consist of a gas chromatograph/mass spectrometer for detecting organic molecular buildingblocks or life in the soil; a biology instrument capable of :

performing three dirrerent life detection experiments; threemeteorology sensors; a seismometer; an X-ray fluorescencespectrometer for inorganic chemical analysis or surfacematerial, which in still under review; two raceimile egraeps;and magnete, plus a supporting device to collect soil samplesand measure surface properties. All this instrumentationwill help answer important questions which can only beresolved by placing instruments on the Martian surface.

The cameras will give the 66 principal scientistsparticipating in Viking a vastly improved view, in both colorand stereo, of the Martian topography and surface structure.Of even greater interest to biologists interested in theevolution of life will, be the results obtained from theorganic and inorganic analyses of the Martian soil, and thethree life-detection experiments.Lander instruments will also determine the temporalvariations of atmospheric temperature and pressure, and windvelocity and direction; seismological characteristics of theplanet; the atmospheric composition and its variation; andthe magnetic and physical nature of the surface.

Orbiter

While experiments are proceeding on the surface, theViking orbiters will be passing overhead, observing thelanding site so that local measurements made by the landersmay be correlated with overall surface effects. Typicalconditions to be searched for by th e orbiters include thebuildup of dust store#, variations in temperature andhumidity, and the passage of the seasonal wave of darkening.

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The Viking orbiters each carry about 65 kilograms (14pounds) of instruments consisting of two high-resolutiontelevision camerez, an infrared spectrometer and an infraredradiometer. These instruments will be employed to surveylanding sites both before and after lander deployment inorder to provide data on surface temperature, atmosphericwater concentration, the presence of clouds and dust stormsand their movement, the topography and color of the terrain,and other information to describe the broader aspects of thelanding site and its relationship to the overall planetcharacteristics. These data will then be integrated withthe lander data to make possible a better understanding orwhat is happening on the surface.VIKING INVESTIGATIONS

The Search for Life

Scientists believe that, if life exists on Mars, mostprobably it is in the form of microorganisms. To search forevidence of their existence in the surface samples, threedifferent Investigations will be performed. The biologyinstrument will examine three different soil samples, whichwill also be analyzed by the molecular analysis instrumentfor organic content.

Photosynthetic Analysis - Photosynthesis is the processof foring organic compounds, suih as carbohydrates, bycombining basic compounds like carbon dioxide, water, andsalUt8, using the Sun as a source of energy. It is a basicfife-sustaining process; plant life on Earth consumes carbondioxide during photosynthesis.In the Viking experiment a soil sample is inoculated withcarbon dioxide gas that has been labeled with a radioactivetracer. The soil and gas are then allowed to incubate insimulated Martian sunlight fo r a period of time- Later, all

remaining gas is flushed out of the chamber and the sampleis heated to 6000 C (about 11000 F). The heating willliberate any of the labeled carbon dioxide incorporated intoorganic molecules in a photosynthesis process, and theliberated gas can then be measured. A substantial quantity oflabeled gas would indicate that a photosynthetic process hadtaken place, which would be strong evidence of the presence ofliving plant-like organisms.- more -


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-atabolicna is It is possible that the organismssuetarnlnte y obtaining nourishment from organic materialsrather than through photosynthesis. Therefore, an analylsisvory similar to the hotouynthesie reaction analysis has beenplanned, which will feed" organic compounds containingr dioactirly labeld earbon to seaol mample--sugar, as anexa plo. If organis v irlnhe sample, and they can consumethe food oftered to them, they will discard--as waste--radioactive carbon gases that can be measured. A sharp risein the production or such metabolic gases would be strongevidence that life is present.

ResDiration - As metabolism takes place. the compositionof the gaseous environment is in a state of continuous change.For this analysis, which is closely related to the metabolicconversion analysis already described, the sample Is wet witha growth medium.A sample of the Martian atmosphere is pumped into thechamber headspace above the sample and monitored. Changesin the composition of the gases will again be evidence ofthe existence of lire as a result of cellular respiration.In the event of positive results from one or more ofthese experiments, a control sample will be prepared tofurther verify the evidence. A co-on sample is first heatsterilized to ensure that all living organisms are destroyed

before analysis is made. Then, if the result is changed,scientists c&n be relatively certain that the originalevidence was due to the existence or living organisms.Molecular Analysis

This investigation will perform a chemical analysis ofthe Martian atmosphere and soil. The chemistry is importantin all scientific aspects of understanding the planet, butparticularly so for biology. All life we know is organic(made of things like sugars, fats, proteins).The composition of the atmosphere is important inunderstanding the overa'l chemistry ot the planet And inhelping to trace back the history of its formation.

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Both the atmospheric and soil analysis consist ordetecting and identifying specific olecules by using adevice called a gas chromatograph-v*s spectrometer. Forthe atmospheric analysis the method is simply to "sniff" theMartian atmosphere with the aasipectroueter The detectis sensitive to one part per 10 million, and will detect anychemical whose molecular weight is less than two hundred.Seasonal variation in atmospheric composition may stronglyinfluence or be evidence of biological activity as mightunusual isotope ratios or compounds in unstable equilibriumwith the environment.The soil analysis Is more complex. The instrumentcontains several tiny ovens; each can receive a soil samplefrom the soil processor. The oVrs are heated to 5000 C(about 9000 7) During heating the organic compounds arevaporized and analyzed. If Mors has not evolved a livingsystem, the organic analysis might help to explain and toprovide knowlsfge or pre-biological organic chemical evolution.A high yield of organic material would support a positiveactive biology result or, in the absence of a positive activebiology finding, suggest the possible presence of organismswhich did not respond to the conditions in the biologyinstrument; a high yield of organic material in the absenceof a positive result for active biology could be indicativeof earlier biological activity.

Inormanic ChemnotryThis investigation which is still under review wouldperform an elemental analysis of the Martian soil. Theelemental composition would identify rm ktxP9! existing onthe planot and is important in determining the degree ofdifferentiation that has occurred on the planot. Theinorganic composition and character of the surface is ofinterest to the biologists as well as toLtQchabslts and

planetologists.The analysis would be performed by an X-ray fluorescencespectrometer. The instrucont consists of two radioisotopeX-ray sources which bombard the surface material inducingX-ray fluorosconce, and two thin-window proportional counterswhich detect and differentiate the spectrum of the inducedfluorescence The instrument is capable of quantativeaullyois for most major, minor, and some trace elements witha sensitivity range of 0.02 percent to 2.0 percont dependingupon the element.-more-


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The sample to be analyzed would be obtained by the surfacesampler and delivered to the instrument by the soil processorand be a part of the same sample examined for organic contentand liviizg organisms.

t Imaging System

Viking will extend our knowledge of Mars by examiningunique sites at a higher resolution than previously obtained.The Viking visual imaging system on the orbiter will obtainpictures at a resolution of about 50 meters (165 feet) perTV line at an orbiter altitude of 1,500 kilometers (930 miles)permitting one to distinguish objects about twice the size of afootball field.

The orbiter system consists of two identical cameras.Each camera is composed of a telpocope, filterb, TV tube, andappropriate electronics.Prior to initiation of the landing sequence, the orbitercameras will aid in certification of the preselected landingsites or, if ecessary, in he identification of suitablealternatives. After landing, the lander "ground truth"otzervations will be available to verify and extend theinterpretation of orbiter camera pictures for a more detailedunderstanding of the physical and chemical character of thesurface in areas other than the landing sites. Valuable datais also expected relative to variable features such as clouds,dust storms, and seasonal albedo changes.Picture 1 is taken by camera 1 and stored in the taperecord*es. Picture 2 is then taken by camera 2 and, whileit s being put in the tape recorder, camera 1 is preparedfor taking picture 3 by erasing the previous picture from the

TV tube. This process is repeated until the requiredpictures are acquired.Lander Camera

on the Viking lander, two facsimile cameras willsubstitute for man's eyes. They can b* directeo to look atthe area on the ground nearby, or perform a 360 panoramicscan of the entire landscape around the lander.

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-13-The cameras will take pictures in high quality black-and-white, in color and in the near inrrared. rgion. Picturestaken by the two cameras can also be combined to yieldstereoscopic views or the areas.The pictures will convey a great deal of informationabout the geological character of the surface of Mars, andcould identify any higher form or life that may exist. Cloudsand dust storms may be seen. The cameras will help inseleoting the places where the surface sampler Is to dig forsoil specimens to be analyzed by the other instrumentscPictures or th e digging itself will provide information on thephysical properties or the soil.The facsimile camera operates by using a small mirrorwhich scans a vertical line and projects the image lightintensity slowly onto a small detector. After that line isscanned, the camera is turned a fraction of a degree andanother vertical line is scanned. This process is repeatedmany times to build up an image from the many scan lines.The detector is a small photocell that converts the light inthe picture image to an electronic signal which is then trana-mitted to Earth. The picture is obtained by reversing theprocess, converting the electronic signal to a light which isscanned over a film to prepare a negative for making thephotograph.

tntra ScienceAs the lander enters the atmosphere and descends to theMartian surface, there will be an opportunity to learn aboutthe structure of the atmosphere and about its chemicalcomposition.Atmospheric chemical composition will be measured atshort Intervals during the lndoer aerosholj's descent toidentify changes in composition at 4iIterent altitudes. Thisinvestigation will show the proportions of gases such as

carbon dioxide, rdtogoen, ogan, Mgognd of M.lee suchas ions and lelootrons Pressure, temperature, ano nsityvariations with altitude will be masured during the descentat low altitude, to determine the atmosphere's verticalmtructur

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To accomplish these investigations, pressure and tempera-ture sensors are mounted in the aeroshell, with additionalpressure, temperature and accelerometer sensors mounted inthe lander so that data can be collected all the way to th esurface after the aeroshell has separated. A magnetic sectormass spectrometer is used to determine the composition anddensity of the atmosphere Another instrument, a retardingpotential analyzer, has the special task of determining th econcentration of ions and electrons in the Martian atmosphere.Water Detection

The Mare atmospheric water detector on the Viking orbiterwill be able to detect water in the Mars atmosphere. Theinstrument can detect very small amounts of water vapor witha high resolution.The water detector is an infrared spectrometer whichoperates on the following principle: If water vapor is inthe atmosphere, it will absorb a particular part of theinfrared light that is produced by the Sun in much the samemanner that the ozone in our atmosphere absorbs the ultra-violet light, or the same manner in which a yellow filterabsorbs all colors except yellow. The infrared spectrometercan determine that the particular part of the infrared light

has been absorbed and how much has been absorbed. This inturn tells the scientists that there is water vapor in theatmosphere and how much.Thermal Mapp4ing

The intensity of the infrared energy that is radiated bythe Mars surface is an indicator of the surface temperature.The infrared thermal mapper on the Viking orbiter can measurethe radiated energy and therefore provide scientists with thedata necessary to determine the surface temperature of Mars.Similar measurements were made by Mariners 6 and 7 and 9;however, these measurements cover only a small portion ofMars by covering narrow strips of the surface. The Vikingthermal mapper will cover large continuous areas at a betterresolution than previously obtained. Thermal mapping datawill contribute significantly to the selection of landingsites and provide a temperature map of much of the planet atvarious times, both day and night. In addition, scientistsmight be able to locate features such as volcanoes, using thetemperature information provided.

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Radio ScienceThe radio communications system can be used as ascientific instrument to obtain more than Just the datatransmitted over it. The alterations of the radio signalscaused by the planet and its atmosphere can be interpreted byscientists to understand more about the planet and itsimmediate environment.As the radio beacon passes through the atmosphere thesignal is changed to characterize the atmosphere.The radio system--including the radar--will be used formeasuring the gravitational field of Mars, determining theaxis of rotation, measuring the surface properties, andperforming certain relativity experiments. It will also beused to determine the location of the lander on the ground.A special radio link, the X-band, is very useful forstudying charged particles, the ions and electrons. This isparticularly so for measurements of the ionosphere of Mars.It will also be used when Mars and the Earth are lined upwith the Sun to do some solar corona experiments.The radio data will be received by the three large 64-meter (210 foot) antennas of the Deep Space Network, and the

large antenna in England, at Jodrell Bank, will also receivesignals to do an experiment in long-based interferometry.

Weather Station on Mars

Weather has been important in influencing the thermalhistory and the geological character of Mars. The meteorologi-cal conditions also affect any life that may exist on theplanet. Like Earth's, the dynamic weather conditions on Marsundergo cyclic changes both daily as well as seasonally.Periodic measurements will be made of the atmospherictemperature, pressure, and the wind speed and direction forthe duration of the mission.

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Physical and Seismic Characto',rlstioGeological measurements will be made of the physical andmagnetic properties of the surface and of the internal seismicactivity. Scientists do not know the level of uAron withinMars, but will reco'd for periods long *nough to establishwbether it is a vorn active planet or not. The interpretationof the formation or Mars could be greatly enhanced ir thisdata were available.iA sensitive miniaturized seismomstor is mounted insidethe lander. The soeirao background and the lAeger events, such

as Mars quakes or meteoroid impacts are measured with v 3-axisdevice carable of detecting ground motion transmitted throughthe lander legs. The instrument uses a rapid data mode duringspecial seismic events to obtain much more data during thoseperiods.The magnetic properties of the planet are measured bysmall but powerful magnets which will be mounted on the landersoil sampler. These magnets will come into contact with thesurface during soil sample acquisition, then will be maneuveredin sight of the Viking cameras. Pictures of clinging particleswill be evidence of magnetic material in the toil.The cameras wil. also photograph the footprints of thelander and the trough made by the sampler to enable scientiststo study the cohesive properties of the soil, its porosity,hardness, yartiole size, etc. Such olservations will helpthem to deduce information about the physical properties ofthe planet's surface.

COMMUNICATIONS

Both the ore4, wr and the lander are capable of communica-ting with Ferb.e The lander system is limited, by power andthermal constraints, to tranu..Assion periods of veral hoursdaily. The orbiter system can transmit at high data ratescontinuous y and can also be used as a relay station for datatransmitted from the lander. Both the lander and the orbiterhave data storage systems which collect data at rates higherthan the transmission rates to Earth, and both can be commandedover these communicative systems from the Earth.

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Three kinds of cowtunications systems will be used. S-band microwave links are used to transmit information, receivecommands from Earth, and to m asure velocity and distance.UHF links are used to relay information from the lander tothe orbiter. Finally, as a special techniq e for science use,there is an X-band link from the orbiter to Earth.The S-band systems using broad and narrow beam antennas,one used as both the orbiter and lander. The narrow beam,high-data-rate antennas must be carefully oriented towardEarth. To accomplish this, the antennas are steerable. Dueto the planet's rotation, the antenna on the lander must bemoved continuously during each transmission period. The fixedbroed beam, low-data-rate antennas are used to receive signals

from Earth.The lander-to-orbiter communication link is an ultra-high-frequency (UHF) system that is used fo r rapid, high-volume transmission. The orbiter records this data and thenplays it back to Earth over its S-band system. The X-bandsystem on the orbiter is used fo r science only. The orbiter/lander UHF system begins operating when tne lander separatesfrom the orbiter, Wad continues ope"ating through the descentand landing. The relay link will be activated again each daywhen the orbiter passes over the lander.

MANAGEMEWT RESPONSIBILITTESViking management responsibilities are under the overalldirection af the Office of Planetary Programs, office of Space ;Science, NASA Headquarters. Langley Research Center, Hamoton,Va., exercises overall project management and is responsiblefor the lander portion of Viking. The Jet PropulsionLaboratory, Pasadena, California, iE responsible for theorbiter and the Deep Space Network. Lewis Research Center,Cleveland, Ohio, is responsible for the Titan/Centaur launchvehicle and integration of the spaceoraf* to the launchvehicle. Kennedy Space Center will be In charge of launchoperations.Major contractors are the Martin Marietta Corporation,Denver, which Is responsible for the lander and systems inte-gration and builds the Titan III booster.General Dynamics/Convair, San Diego, California, buildsthe upperstage Centaur.

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VIKING SCIENCE TEAMSTeams of scientists were selected by the NationalAeronautics and Space Administration to direct the Vikingscientific investigations. To Oulfill this responsibility,these scientists in'-iract with project engineers who areresponsible for hardoare design, test and fabrication offlight hardware.Scientists and engineers working together determinedetails of the investigations and instruments; the compromisesthat must be madF because of weight, power, or data constraints;and the ultimate flexibility of experiments.Each science team has a loader who is also a member ofthe Science Steering Group that d-velops the scientific policiesand contributes to the overall coordination of Viking sciencerequirements.Science Steering Group0. A. Soffen, Chairman, Langley Research CenterR. S. Young, Vice Chairman, NASA Headq'artersA. T. Young, Secretary, Langley Research CenterW. w Bender, Martin Marietta0. - Snyder, Jet Propulsion LaboratoryAli Science Team Leaders or Principal InvestigatorsOrbiter ImagingM. H. Carr, U. S. Geological SurveyW. A. faum, Lowell Observatory0. A. Briggs, Bellcomm.H. Masuroky, U.S.G.S.D. U. Wise, U. of MassachusettsWater Vapor N~appln.,C. B. Farmer, JPLD. D. LaPorte, JPL

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-19-BiologyH. P. Klein, Ausu Research CenterN. R. Horowitz, CaltechW. Vishniac, U. of RochesterG. V. Levin, Biospherios, Inc.J. Lederborg, Stanford U.A. Rich, MITV. I. Oyams, AMn Research CenterMolecular AnalysisK. Biemonn, MITD. M. Anderson, U. S. Army ColdRegions Res. Ing. Lab.L. S. Orgel, Salk InstituteJ. Oro, U. o0 HoustonT. Owen, State U. or New Yorkat Stoney Brook0. P. Shulman, JPLH. C. Urey, U. or California atSan DiegoA. 0. C. Nier, U. of MinnesotaThermlMapnH. H. Kietfer, U.C,L,A.S. C. Chape, Ant.a BarbaraResearch Corp.;G. Munch, CaltechE. D. Miner, JEL0. Neugebauer, CaltechLander ImagingT. A. Mutch, Brown U.A. B. Binder, IIT Research InstituteF. 0. Huck, Langley Reenarch Cent-rE. C. Levinthal, Stanford U.E. C. Morris, U.S.G.S.C. Riagan, Cornoll U.A. T. Young, JPL

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Seoismowtr'P L. Anderson, CaltechR. L. Kovach, Stanford U.F. Press, MIT4 ?. TOkOZ, MITG0 Sutton, U. of Hawaii

MoteorologyS. L. Hses, Florida State U.N. Henry, Langley Research CenterC. B. LeOvY, U. of WashingtonJ. A. Ryab, McDonnell DouglasP. Kuettner, ESSA

Entry;A. 0. C Nier, U. or MinnesotaM. B. McElroy, HarvardA. Sieff, Ae Research centerN. WASpencr,OGoddard Space Flight CenterW. B. Hanson, U. or Texas

Physical propertiemR. W Sho-.rhill, BoeingR. P. Scott, Ca'techH. J. Moore, U.S.O.SR. 3. Hutton, TRW

Magnetic PropertiesR. B. Har~rsves, Princeton U.

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RadioW. H. Michael, Langley Research CenterD. L. Cain, JPLJ. O. Tavies, U. or Manchester England0. PJeldbo, JPLM. D. Grossi, Raytheon Co.O. s. Levy, JPL1. I Shapiro, MI1G. L. Tyler, Stanford U.

Inorganic ChemistryP. Toulmin, III, U.S.a.S.B. C. Clark, Martin Marietta Co.A. K. Baird, Pomona CollegeH. J. Rose, U.S.G.S.Science Team Leaders or Principsl Investigators arenamed rirst under each group.

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VIXIN QUESTIONS AND ANSWERS1. WhY go to Mars?

There are many reasons, including scientific, philo-sophioal, technical and national prestige considerations.However, the main purpose is to characterize the planet inas much detail as possible, including the possibility ofresolving the question of life on Mars.2. Why should we know more about other planets?

By comparing other planets with Earth we will be ableto better understand the rapid changes here and possiblyforecast future changes which are noo only poorly or notat all understood.For example, knowledge of other planets' atmospheresshould help us better understand our own pollution-threatenedatmosphere. Dust storms on Mars supply data on future effectsof smoke ar1 particulate pollution in Earth's atmosphere. Andstudy of storms on Mars, whose weather-making mechanism isrelatively simple because of that planet's lack of oceans, cancontribute to an understanding of Earth's weather, and thus toweather Prediction and possibly future weather control.

3. What difference does it make should life be discoveredon Mars?Kan will have more tools fo r understanding the origin andnature of life and will be that much closer to understandinghis own place and role in the universe.

4. What is Viking?Viking is a spacecraft consisting of an orbiter and alander, weighing 3,400 kilograms (7,500 pounds), measuring9.8 meters (32 feet) in width and 4.9 meters (16 feet) inheight. The spacecraft will be launched from Cape Kennedy,Pla., aboard a Titan III/Centaur rocket.

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5 Now big are the orbiters and landers separately?The orbiter measures 9.8 meters (32 feet) across and3.3 meters (10.8 feet) top to bottom. It weighs 2,360kilograms (5,200 pounds). The lander, which rests on threelogs meaures 2.7 moters (9 feet) across and 2.1 meters(7 feet) top to bottom. It weighs 1,050 kilograms (2,300pounds).

6 When will Viking be l ianched?The two Viking spacecraft will be launched separatelyduring a 30-day period, but not within 10 days of eachother, between mid-August and aid-September in 1975.

7. How far will they travel?They will travel some 700 million kilometers (44o millionmiles) through space on nearly a year's journey to arrivewhen the planet is about 320 million kilometers (206 millionmiles) from Earth on the other side of the Sun.

8. How much will the Viking mission -ost?Between $750 and $830 million, not including the launchvehicle. The Titan/Centaurs cost $66 million.

9. What will Viking do when it gets to Mars?The orbiter spacocraft will go into )rbit and willremain in orbit while the lander will separate and land onthe surface anytime within 50 days of arrival, via parachuteand retro-rocket. Together they will conduct scientificstudies of the Martian atmosphere and surface.

10. What will be the orbits of the orbiters?The crbit insertion retro-rockets will be fired fornearly an hour to place each Viking into a highly ellipticalorbit of 1,500 kilometers (930 miles) by 33,000 kilometers(20,500 miles).

viking fact sheet may 1972

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