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PIONEER F& 6MISSION TO JUPITER

https://ntrs.nasa.gov/search.jsp?R=19730012132 2020-04-08T13:34:48+00:00Z

Pioneer F and G Missions

Man's first reconnaissance ofthe giant planet Jupiter willbegin with the launch of twospacecraft, Pioneers F and G,in 1972 and 1973 on missionswhich are planned to last forseveral years.

These spacecraft are expected, to be the first to go beyond the

orbit of Mars, to pass throughthe Asteroid Belt and to use

•Jupiter's gravity to escape thesolar system. After a trip ofmore than a billion miles, eachcraft will spend about a weekswinging around Jupiter, with

maximum scientific return dur-ing closest approach, to withinabout 90,000 miles.

The bizarre and spectacularplanet Jupiter is potentially themost interesting in the solarsystem. Striped in yellow-orange and blue-gray like anenormous rubber ball, it has ahuge red "eye" in its southernhemisphere. Its mass is morethan twice that of all the otherplanets combined. Scientistsrecently have raised the possi-bility of life on the planet. Ithas 12 moons and, like a small

star, appears to have its owninternal heat source. Jupiterrotates at fantastic speed. Aspot on its equator travels at22,000 mph, compared to 1,000mph for a similar spot on Earth.Because of the planet's appar-ent semi-liquid character, thisrotation produces a large equa-torial bulge.

One goal of the Pioneer F andG missions is to develop tech-nology and experience for othermissions to the outer planets,planned for the late 1970s, andalso to assess hazards of deep

space, primarily penetration bya high-velocity rock fragmentin the Asteroid Belt, and pos-sibly crippling effects of Jupi-ter's radiation belts.

After the flight past Jupiter,scientific data from Pioneer Fwill be retrieved out to the limitof the spacecraft's communica-tion system, 1.5 billion or moremiles from the Sun.

Pioneer F will be launchedbetween February 27 andMarch 13, 1972, Pioneer G be-tween April 3 and 20, 1973.

The Pioneer Project is managed by the National Aeronautics and Space Administration's AmesResearch Center, Mountain View, California, for the Office of Space Science and Applications, NASAHeadquarters, Washington, D.C.

Spacecraft

©Pioneers F and G are iden-

tical spacecraft weighing about570 pounds apiece, including65 pounds of scientific instru-ments. Each will be capableof performing 13 scientific ex-periments, and photographingJupiter in better detail thanEarth-based telescopes.

MAJOR SUBSYSTEMS

RADIOISOTOPETHERMOELECTRICGENERATORS (2)

THRUSTERS

MEDIUM-GAINANTENNA

HIGH-GAIN ANTENNA

COMMANDDISTRIBUTION UNIT

STELLAR REFERENCEASSEMBLY

LOW-GAIN ANTENNA

TRAVELING WAVETUBES (2)

DIGITAL TELEMETRYUNIT

VPIONEER JUPITER SPACECRAFT

Navigation, Attitude Control, and PropulsionFor navigation, the Doppler

shift in frequency of the Pio-neer radio signals will be usedto calculate continuously thespeed, distance, and positionof the spacecraft. The Dopplershift is caused by motion ofthe spacecraft and is measuredby ground tracking.

Because the planes of the or-bits of the Earth and of Jupi-ter almost coincide, the mostefficient trajectories to Jupiterlie in the Earth's orbital plane(the ecliptic).

Pioneers F and G will be

positioned in the ecliptic planeby pointing their high-gain,narrow-beam dish antennascontinuously at the Earth. The

gyroscopic effect of a spin offive revolutions per minutewill stabilize them in this at-titude. The axes of spacecraft

EARTH WILL ORBIT SUN TWICE JUPITERCOMPLETES 1/6 REVOLUTION DURING MISSION

ATTITUDE CONTROL AND PROPULSION

EARTH ORBIT

SPACECRAFT TRAJECTORY

RADIO SIGNAL PATTERNFROM GOLDSTONE TRACKINGSTATION, CALIFORNIA

CHANGE IN SPIN-RATE VELOCITYTHRUSTERS

FIRE IN UNISON

CONSTANTEARTH-POINT

CHANGE IN a ATTITUDEATTITUDE 1 THRUSTERS

lf=» PULSE

CONSTANTEARTH-POINT

spin coincide with the axes ofthe radio beams of the space-craft high-gain antennas.

Earth-point of the space-craft high-gain antennas ismaintained by a conical scansystem on the spacecraft. Ituses the intensity pattern ofthe incoming radio signals tomeasure amount and directionof drift of the spin axes fromexact Earth-point. Drift is thenautomatically corrected.

Since the spacecraft rotatecontinuously, thrusts to changetheir attitudes can occur at only

photopolarimeter will show theentire planet, while at closestapproach (to within one planetdiameter, 86,900 miles) the im-age will cover about 25 per centof the planet's surface. Thispicture will show the terminator(the line between sunlit anddark hemispheres), which isnever seen from the Earth.Scanning in strips 0.03° wide,the camera will complete a pic-ture in from 25 to 110 minutes.

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JupiterJupiter has a mass some 318

times that of the Earth. Twoof its 12 moons, Ganymedeand Callisto, are larger thanthe Earth's moon.

The atmosphere is madeup of hydrogen with minoramounts of methane and am-monia, prohably helium, andsome water. Temperatures inthe upper atmosphere may benear room temperature. Theseconditions could produce thebuilding blocks of life, or evenlife itself.

The surface is hidden by a

JUPITER'S VISIBLE SURFACE

NORTH POLAR REGIONNORTH NORTH NORTH TEMPERATE BELT

NORTH NORTH TEMPERATE ZONENORTH NORTH TEMPERATE BELT

NORTH TEMPERATE ZONENORTH TEMPERATE BELT

•** NORTH TROPICAL ZONE„ NORTH EQUATORIAL BELT„ EQUATORIAL ZONE„ EQUATORIAL BAND.- EQUATORIAL ZONE- NORTH COMPONENT OF SOUTH

EQUATORIAL BELT- SOUTH EQUATORIAL BELT- SOUTH COMPONENT Of SOUTH

EQUATORIAL BELTSOUTH TROPICAL ZONE

GREAT RED SPOTSOUTH TEMPERATE BELT

SOUTH TEMPERATE ZONESOUTH SOUTH TEMPERATE BELT

SOUTH SOUTH TEMPERATE ZONESOUTH POLAR REGION

dense layer of clouds whichform bright yellow-orange andslate blue bands (atmospherecurrents) around the planet.Jupiter has a huge "eye" or Red

Spot, 30,000 miles long and8,000 miles wide, which driftsvery slowly about the samelatitude, but floats more rap-idly in longitude.

Communications and Data Handling

one point on the circle of rota-tion. Sensors will fix upon eitherthe Sun or the star, Canopus, toprovide the reference for thesethrusts.

Mid-course trajectory cor-rections will be made by smallchanges in velocity of thespacecraft. Thrusters will turnthe Pioneers, aligning the spinaxes in the direction of thevelocity change. They will thenfire continuously to make thecourse change, and afterwardswill return spin axes and an-tennas to Earth-point.

Communication equipmentincludes the nine-foot alumi-num-honeycomb, high-gain,narrow-beam (3°) dish antennafor long distance communica-tion, plus a wider beam (32°)medium-gain antenna. Othercomponents are an omni-direc-tional antenna, two receivers,and two transmitters poweredby redundant traveling wavetubes.

At Jupiter, the spacecraftwill return to Earth 1024 databits per second (EPS). Thespacecraft can provide a coded

data stream for scientific andengineering data, at rates from16 to 2048 EPS. While trans-mitting, the spacecraft can, atthe same time, store up to49,152 data bits for later trans-mission.

Commands from Earth arerouted by the Command Dis-tribution Unit to any one of255 destinations on the space-craft. Up to five commands canbe stored for later execution.

Electric Power The PicturesAt Jupiter and beyond, so-

lar radiation is too weak toefficiently provide power from

THCRMOELECTRI\ FUEL 04!

REENTRY HEAT SHIELIi FUEL CAPSULE'

RADIOISOTOPE THERMOELECTRICGENERATOR

solar cells, so four radioiso-tope thermoelectric generators(RTG's) will be used. Twopairs of RTG's are mountedat the ends of two booms,120° apart. The RTG's.deviceswhich convert nuclear energyto electricity, provide 160 wattsof power at launch with poweroutput expected to be at least120 watts five years later. TheRTG's are fueled with Pluto-nium 238 dioxide, and their nu-clear energy (heat) is turnedinto electricity by 90 thermo-electric couples.

The photo polarimeter ex-periment will provide images ofJupiter.

The camera-like device willuse the spin of the Pioneersto scan the planet in narrowstrips in both red and bluelight. Investigators will thencombine these elements tomake composite pictures. Su-perimposition of the red andblue elements will provide two-color pictures of Jupiter.

At 350,000 miles from Jupi-ter, a complete scan by the

MODEL OF JUPITER INTERIOR

CLOUD TOPS

AMMONIA CRYSTALSAMMONIA DROPLETS

UPPER I AMMONIA VAPORATMOSPHERE | ICE CRYSTALS

WATER DROPLETSWATER VAPOR

LIQUID AND/OR SOLID HYDROGEN

METALLIC HYDROGEN

INTERNAL ENERGYSOURCE GRAVITATIONAL

OR RADIOACTIVE

ROCKY SILICATESMETALLIC ELEMENTS

The planet periodicallyemits huge surges of radionoise. It has a magnetic fieldestimated to be 20 times asstrong as the Earth's, and ra-

diation belts estimated to bea million times more intensethan Earth's.

Jupiter appears to radiatethree times as much energy as

it absorbs from the Sun, sug-gesting that it may have inte-rior processes similar to thoseof the Sun.

Composition of the giantplanet is believed to be at leastthree quarters hydrogen. Earthbased studies have not yetshown whether the "surface" issolid hydrogen, or slush, or liq-uid hydrogen. Pioneers F and Gwill examine the sunlit side asthey approach, and the darkside as they pass behind theplanet. The dark side cannot beseen from the Earth.

AsteroidsPIONEER PASSAGE THROUGHJUPITER'S MAGNETIC HELDAND RADIATION BELTS

MAGNETICAXIS

CHARGED PARTICLESFROM THE SUN TRAPPEDIN JUPITER'S MAGNETIC FIELD

SPACECRAFT TRAJECTORYAND PATH ACROSSJUPITER'S SURFACE

Both Pioneer spacecraft willspend from six months to ayear passing through the aster-oid belt which circles the Sunbetween the orbits of Mars andJupiter.

There may be as many as50,000 asteroids ranging in sizefrom one mile in diameter tothe 480-mile-diameter Ceres.In addition, there are manyhundreds of thousands of stillsmaller asteroids and probablymillions of fragments. In total,there is estimated to be enoughasteroidal material to form a

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small planet.In the center of the Belt, pro-

jectile-like asteroidal materialhas an estimated average speedof about 30,000 mph. Whilesize distribution of asteroidalmaterial is not known, a col-lision between the spacecraftand even very small asteroidsis probably unlikely. Analysessuggest that Pioneer F will ap-proach no closer than threemillion miles to any knownasteroid.

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MARS

BOUNDARY OF HELIOSPHERE

EARTH

SOLAR MAGNETIC FIELD

SOLAR COSMIC RAYSrURANUS

PLUTO I \ SOLAR WIND

GALACTICCOSMIC RAYS

PIONEER ESCAPETRAJECTORY

AST JUPITERBELT

INTERSTELLARGAS

NEPTUNE

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LaunchThe Pioneers will be launched

by Atlas-Centaur launch vehi-cles mounted with TE-M-364-4solid-fuel third stages. TheTE-M-364-4 has a thrust of14,800 pounds.

An Atlas-Centaur vehicle fora Pioneer mission is about 130feet high and 10 feet in diam-eter. The booster is the AtlasSLV-3C which has an overallthrust of 413,400 pounds. Theupper stage is the 30-foot, Cen-taur vehicle with a thrust of30,000 pounds.

Launch will be from Cape

LAUNCH VEHICLE

Kennedy, on a direct ascenttrajectory. At third stage cut-off, the Pioneers will have avelocity of about 32,400 miles-

per-hour, believed the fastest aman-made object has ever trav-eled in space.

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Mission Events and Operations

EARTH ATENCOUNTER

ASTEROID BELT JUPITERORBIT

RADIO SIGNAL45 MINUTES EARTH-JUPITER

45 MINUTES JUPITER-EARTH

JUPITER ATENCOUNTER

PIONEER HELIOCENTRICTRAJECTORY: ESCAPEFROM SOLAR SYSTEM

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The flights to Jupiter willtake from 630 to 795 days, withthe shorter trip times resultingfrom launches during the ear-lier days of the 15-day launchwindows.

Mission events include: lift-off, passage through the Earth'sshadow, acquisition of thespacecraft by the Deep SpaceNetwork (DSN) and first orien-tation to point the spacecraftantenna toward the Earth.

V Experiments will be turnedon one at a time, starting anhour after launch. After four

hours, the spacecraft, travelingat half-a-million miles per day,will have passed out of theEarth's magnetosphere into in_-terplanetary space.

Ground computers will con-stantly refine calculations ofthe spacecraft trajectory. Con-trollers will correct the trajec-tory at four days and again at30 days, to precisely target thespacecraft for its encounterwith Jupiter hundreds of dayslater.

Attitude changes to sharpenEarth-pointing of the space-

craft will be made every twoor three days early in the mis-sion and every week thereafter.

After 180 days or more, thePioneers will begin passagethrough the asteroid belt. Con-trollers will prepare emergencyprocedures for possible impactby asteroid fragments.

For the week-long Jupiterfly-by, they will develop a de-tailed sequence of events. Com-mands must be precisely timedwith the spacecraft's positionrelative to the planet. Opera-tions will be complicated by the

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round trip communication timeof 90 minutes due to limitationsof light speed.

Hazards at planet encounter

include possible crippling dam-age from Jupiter's radiationbelts.

The Pioneers are unique

among U.S. interplanetaryspacecraft in being controlledalmost entirely from the groundrather than by automatic, on-board systems. Controllers willbe on duty 24 hours a day. Dur-ing cruise, they will send around20 commands per day, and, atencounter with Jupiter, hun-dreds of commands. Responsesto malfunctions must be imme-diate.

These direct-control featuresof the Pioneers make them rel-atively low cost and adaptablefor many missions.

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Data Return, Command, and Tracking

NASA's Deep Space Network(DSN), operated by the JetPropulsion Laboratory, willtrack and receive data fromthe Pioneers. For early partsof the mission, tracking will beby the DSN's 85-foot (26-me-ter) antennas. Where high ratesof data return are required,the powerful global net of 210-foot (64-meter) antennas of theDSN will take over. At Jupiterdistance, the 85's can receive128 bits per second (EPS), whilethe larger 210-foot dishes canhear 1024 EPS. The 210's will

be able to retrieve spacecraftdata out to about 1.5 billionmiles from the Sun.

Mission Control will be atCape Kennedy for the launch,and at the DSN's Space FlightOperations Facility (SFOF),Pasadena, California, immedi-ately after launch and duringJupiter fly-by. During cruise,both before and after planetencounter, control will moveto the Pioneer Mission Analy-sis Area, Ames Research Cen-

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ter, Mountain View, California.

Incoming telemetry datafrom the spacecraft will be re-ceived at the DSN stations,and immediately formatted forhigh-speed transmission to the

SFOF computers. These com-puters will check for criticalchanges and provide data foranalysis by specialists on thespacecraft, on the experiments,and on ground systems. Theiranalyses will be used immedi-

DE6P SPACE NETWORK

ately for spacecraft control. Alldata will also be transmittedto the Ames Research Centerfor detailed operational andengineering analysis and dis-tribution to individual experi-menters. Outgoing commandswill be verified by the MissionControl computers and thensent to individual DSN sta-tions for transmission to thespacecraft. The same compu-ters will confirm spacecraft re-sponse to commands as theyprocess incoming telemetrydata.

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The Experiments-What They TellMagnetic Fields

Magnetometer — will mapthe interplanetary magneticfield beyond the orbit of Mars,Jupiter's magnetic fields, andthe modulation of Jupiter'smagnetic fields by its innermoons.

The Interplanetary SolarWind and the Heliosphere

Plasma Analyzer—will mapthe density and mechanisms of

the solar wind (ions and elec-trons flowing out from theSun) beyond the orbit of Mars;will determine solar wind in-teractions with Jupiter, includ-ing the planet's bow shockwave; and will look for theboundary at which the solarwind and solar atmosphere(the heliosphere) end and in-terstellar space begins.

Cosmic Rays, Jupiter'sRadiation Belts and RadioSignals

Charged Particle Instru-ment, Cosmic Ray Tele-scope — These two experi-ments will map beyond the or-bit of Mars the density, speed,direction, and mechanisms ofcosmic rays (atomic nuclei)coming from the Sun and Gal-axy. These instruments candistinguish whether the parti-cles are nuclei of one or moreof the ten lightest elements(helium, carbon, oxygen, etc.)and which one. They also willobserve the interaction ofcharged particles (protons and

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electrons) with Jupiter andwithin Jupiter 's radiationbelts.

Jupiter's Charged Particles

Geiger Tube Telescope,Trapped Radiation Detec-tor — These two experimentswill attempt to learn the con-tents and mechanisms of Jupi-ter's radiation belts by mea-suring the intensities, energies,and distribution of energeticelectrons and protons in the

belts, and will study Jupiter'shuge, periodic radio signals.

Asteroids, Meteoroids,Interplanetary Dust, andCelestial Mechanics

Asteroid-Meteoroid Detec-tor — consists of four opticaltelescopes which can detect as-teroids and meteoroids as smallas 1/100,000th gram by mea-suring sunlight reflected fromthem. The instrument can mea-sure particle concentrations,

size, velocities, and direction.This will begin the first surveyof meteoroid and cometarymatter, and its source, beyondthe orbit of Mars.

Meteoroid Detector — con-sists of 216 penetration cellsattached to the spacecraft ex-terior. The cells measure im-pacts of particles from 1/100millionth to l/trillionth of agram to gain information onconcentrations of interplane-tary particles.

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MAGNETOMETERCOSMIC RAY TELESCOPEINFRARED RADIOMETERCHARGED PARTICLE INSTRUMENTTRAPPED RADIATION DETECTORULTRAVIOLET PHOTOMETERGEIGER TUBE TELESCOPEIMAGING PHOTOPOLARIMETERPLASMA ANALYZERMETEOROID DETECTOR SENSOR PANELS

)ID-METEOROID DETECTOR SENSOR

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Celestial Mechanics — Ex-perimenters will use precisionDoppler tracking of the Pioneerradio signals to improve calcu-lations on: the mass of Jupiter,character of the Jovian gravityfield, mass of Jupiter's 12moons, Earth's orbit, and othersolar system data.

Interplanetary Hydrogen,Helium, and Dust;The Heliosphere; Jupiter'sAtmosphere,Temperatures,Auroras, and Moons

Ultraviolet Photometer —will determine the density ofneutral hydrogen in interplan-etary space, will attempt tofind the limits of the helio-sphere by measurements ofhydrogen distribution, willmeasure the hydrogen-heliumratio in Jupiter's upper andlower atmospheres, will lookfor Jovian auroral activitynear both poles, and for phe-nomena resulting from pas-sages of the moon, lo. Mea-surements of light in the farultraviolet given off by hydro-

gen and helium will providedata to study these phenom-ena.

Infrared Radiometer—willmeasure infrared radiation tofind Jupiter's emissions ofthermal energy, and its tem-perature distribution. Thesedata will help tell how muchinternal energy Jupiter radi-ates, temperature of the darkhemisphere, location of hot orcold spots in the outer atmos-phere, whether there is a polarice cap of frozen methane, and

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the hydrogen-helium ratio inthe atmosphere.

Occultation Experiment —will measure effects of Jupiter'satmosphere on the Pioneerradio signals as the spacecraftdisappears behind the planetand reappears again. Thesechanges will show the refrac-tive index of the planet's at-mosphere, add to knowledge ofits hydrogen-helium ratio, andshow electron density in theionosphere.

Imaging Photopolarimeter—will measure intensities andpolarization of visible light. Itsmeasurements of reflected light(zodiacal light) will be used tocalculate the amount, distribu-tion, and origin (from asteroidsand comets) of interplanetarydust. At Jupiter, experimenterswill use the data to attempt tofind the structure and compo-sition of the Jovian clouds andatmosphere, data on the plan-et's thermal balance, and toretrieve close-up pictures. Theinstrument also will attempt to

collect data on Jupiter's little-known moons.

JUPITER MOONS

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t Team

1ATOMIC ENERGY

COMMISSIONSpace Nuclear Systems Division

D. S. GabrielSpace Nuclear Systems Office

G.A.NewhyIsotope Power Systems Project

Branch — H. JaffeSNAP-19/Pioneer Project

1

Teledyne Isotopes

NASA HEADQUARTERS PROGRAM MANAGEMENTOSSA— Dr.J.E.Naugle

Planetary Programs — R. S. KraemerPioneer Programs Manager — F. D. Kochendorfer

1

NASA-AMES RESEARCH CENTER (ARC)PROJECT MANAGEMENT

Director — Dr. Hans MarkDirector of Development — J. V. Foster

Pioneer Project OfficeProject Manager— C. E Hall

Project StaffManagement Control — J. R. SpahrMission Analysis & Launch Coordination — R. U. Hofstetter

Project Support

Reliability & Quality Assurance— J. R. MulkemR. O. Convertino

Magnetics — E. J. lufer

1EXPERIMENTS

SYSTEM

(ARC)

Manager — J. E. Lepetich

1

Time ZeroCorporation

Santa Barbara

Research Center

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1 1 1SPACECRAFT

SYSTEM

(ARC)

Manager — R. W. Holtzclaw

MISSIONOPERATIONS

SYSTEM

(ARC)

Manager — R. R. Nunamaker

TRACKINGAND DATA SYSTEM

Jet PropulsionLaboratory

(JPL)Manager — Dr. N. A. RenzettiPioneer Deep Space Network

Manager — A. J. Siegmeth

LAUNCH VEHICLESYSTEM

Lewis Research CenterNASA-(LeRC)

Manager — D. J. SchramoTracking and Data System —R. A. Flage

1 1

PRIMECONTRACTOR

TRW Systems Group

Project Manager. PioneerProject— B. J. O'Brien

Assistant Project Manager forIntegration and Test —

W. E Shrehan

Bendix FieldEngineeringCorporation

GSFC

IMcDonnell-

UNMANNEDLAUNCH

OPERATIONSKennedy Space CenterDirector — J. NeilonProject Representative —J. Johnson

1General Dynamics

General DynamicsConvair Division

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Experiments and Experimenters

Instrument

1. Imaging Photo Polarimeter

2. Helium Vector Magnetometer

3. Plasma Analyzer

4. Charged Particle Instrument

5. Geiger-Tube Telescope

6. Cosmic Ray Telescope

7. Trapped Radiation Detector

8. Ultraviolet Photometer

Principal InvestigatorDr. Thomas GehrelsUniversity of ArizonaDr. Edward J. SmithJet Propulsion LaboratoryDr. John H. WolfeNASA-Ames Research CenterDr. John A. SimpsonUniversity of Chicago

Dr. James A. Van AllenUniversity of IowaDr. Frank B. McDonaldNASA-Goddard Space Flight Center

Dr. R. Walker FilliusUniversity of California at San Diego

Dr. Darrell L. JudgeUniversity of Southern California

I

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,

Instrument

9. Infrared Radiometer

10. Asteroid-Meteoroid Detector

11. Meteoroid Detector

12. The spacecraft radio trans-mitter used for S-Bandoccultation experiment

13. The spacecraft and theDeep Space Network Dopplerradar used for celestialmechanics experiment

Principal InvestigatorDr. Guido MunchCalifornia Institute of Technology

Dr. Robert K. SobermanGeneral Electric Company

William H. KinardNASA-Langley Research Center

Dr. Arvydas J. KlioreJet Propulsion Laboratory

Dr. John D. AndersonJet Propulsion Laboratory

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Pioneer Accomplishments

Pioneers 6 to 9 continue to op-erate in solar orbit, and some oftheir accomplishments are:

1. The most precise determinationso far of characteristics of thesolar atmosphere (the helios-phere).

2. Determination of solar cosmicray and solar wind flow pat-terns, and magnetic and electricfield mechanisms in the solaratmosphere.

3. Longest-lived operational inter-planetary spacecraft (Pioneer6, launched December 16, 1965).

4. Pioneers 6 to 9, by the end of1971, had achieved 230 months ofday-to-day tracking and dataacquisition. Almost 20 billion

data bits had been received, pro-cessed, analyzed, and reportedto the scientific community. Atotal of 26,000 commands hadbeen transmitted to these fourspacecraft.

8. First occultations by solar discof man-made signal source (Pio-neers 6 to 9).

9. First lunar occultation using aninterplanetary spacecraft (Pio-neer 7).

5. First use of telecommunicationscharacteristics for spacecraftorientation.

6. First gathering of space weatherdata for operational use.

7. First spacecraft to use convolu-tional coding/sequential decod-ing (Pioneer 9).

10. First simultaneous receipt oftwo spacecraft signals using asingle ground antenna (Pio-neers 6 and 7).

11. First particles and fields investi-gations of radial and spiral char-acteristics of solar wind and so-lar cosmic rays (Pioneers 6 and7).

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12. Most distant intelligible telem-etry data from Earth, and mostdistant use of command func-tions, 170 million miles (Pio-neer 6).

13. First spacecraft to define char-acter of Earth's magnetic tail(Pioneers 6 and 7).

14. First spacecraft to use linearlypolarized S-band antenna andtherefore only spacecraft able toconduct Faraday rotation expe-riments during solar occultation(Pioneers 6 and 9).

15. First spacecraft equipped witha telecommunications range-adaptive telemetry system.

16. First major spacecraft systemdesigned, developed, and deliv-ered on a fixed-price incentive-fee contract.

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-•

The Pioneer spacecraft havea record of reliability and per-formance which makes themcandidates for future deepspace missions.

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National Aeronautics and Space AdministrationAmes Research CenterMoffett Field, California 94035

GPO 791-263