Voyager Fact Sheet

8/8/2019 Voyager Fact Sheet

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(NASA-News-fielease-77-11U) VCYS.GEB(National aeronautics and SpaceAdministration) 1** pN77-79000 Unclas00/15 35962


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NOTE TO EDITORS; This fact sheet outlines the missionand basic scientific rationale for Voyager. It is sug-gested that it be retained in your files for futurereference.

For Further Information:


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VOYAGER

The National Aeronautics and Space Administration willlaunch two Voyager spacecraft in late summer 1977 for an ex-tensive reconnaissance of the outer planets.Riding atop a Titan Centaur rocket, the Voyagers willbe launched from Kennedy Space Center, Fla., on a decade-long odyssey that could take them to as many as 15 majorheavenly bodies.These include giant Jupiter and ringed Saturn andseveral moons of both planets, probably Uranus and possiblyNeptune.The information returned by the spacecraft is expectedto shed new light on the origin and early history of thesolar system and our own planet Earth.

Voyager Next Step to Study Outer PlanetsNASA has already sent spacecraft to Venus, Mercury, Jupiter

and Mars. Project Voyager is the next step in the United Statesprogram of systematic planetary exploration in which the solarsystem is used as a natural laboratory.


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Outer Planets Have Many SatellitesJupiter and Saturn are drastically different from theterrestrial planets, appearing to be composed primarily ofhydrogen and helium. Jupiter is larger than all the otherplanets in the solar system combined. Jupiter has 13 or 14known satellites (the recently discovered 14th has not yetbeen confirmed). Jupiter orbits the Sun more than five timesfarther away than Earth. One Jovian year equals about 12Earth years. Jupiter's day is about 10 hours long.Saturn orbits the Sun almost 10 times as far away asEarth, completing one orbit every 30 Earth years. A day onSaturn is also about 10 hours long. Telescopic observationsof Saturn's rings are dazzling. The widest visiblering has an outer radius of 137,000 kilometers (85,000 miles).Saturn has more than 10 satellites, including the largest,Titan, which has an atmospheric density comparable to thatof Earth.

Trajectories, Speeds DifferPlans call for the first launched Voyager to fly a slowertrajectory, allowing the second spacecraft launched about12 days later to overtake it and reach Jupiter about fourmonths earlier. Jupiter's gravity will slingshot the Voyagerstoward the ringed planet Saturn, with the two spacecraftreaching Saturn about nine months apart.Photography of Jupiter will begin in December 1978, 80


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Planets1 Moons to Get Close LookShortly before closest approach to Jupiter on March 5,1979 Voyager 1 will fly about 415,000 km (258,000 mi.) fromAmalthea, giving scientists their first close look at theinnermost of Jupiter's satellites. Closest approach to Jupiterwill be 3.9 radii (Rj) from the surface of the planet (about280,000 km or 110,000 mi.). Jupiter will occult the Sun and

Earth, as seen by instruments on the spacecraft, allowingscientists to make precise measurements of the structure andcomposition of its atmosphere.After passing Jupiter, the first Voyager will examine allfour of the big Galilean satellites: lo from 22,000 km (14,000mi.), Europa from 733,000 km (455,000 mi.) and Ganymede andCallisto from about 120,000 km (74,000 mi.). Observations ofJupiter will continue for about a month after closest approach,until early April 1979.The second Voyager will begin its observatory phase abouttwo weeks later, again 80 days before closest approach. Itwill observe four satellites during the inbound leg: Callistofrom 220,000 km (136,000 mi.), Ganymede from 55,000 km (34,000mi.), Europa from 201,000 km (125,000 mi.) and Amalthea from550,000 km (342,000 mi.).

Encounters ScheduledClosest approach to Jupiter will occur July 10, 1979.The spacecraft, following a more distant path than its pre-


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V O Y A G E R A P P R O A C H , T O S A T U R N


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The Voyager spacecraft each weigh 810 kilograms (1,785pounds). The scientific instruments weigh a total of 105 kg(231 Ib.) for each spacecraft. The new Voyager spacecraftdiffer from past planetary Mariner spacecraft, due primarilyto the environment into which they will venture and the greatdistance across which they must communicate with Earth. Sincethe outer planets receive only a small fraction of the sunlightthat strikes Earth and Mars, the Voyagers cannot depend onsolar energy but must use nuclear power radioisotope thermo-electric generators. Another obvious difference is the largeantenna: the antenna on the Voyager spacecraft is 3.7 meters(12 feet) in diameter.Onboard Instruments Listed

Each Voyager will use 10 instruments and the spacecraftradio to study.the planets, their satellites, the rings ofSaturn, the magnetospheres surrounding the planets and inter-planetary space.In addition to wide-angle and narrow-angle televisioncameras, the Voyagers carry cosmic-ray detectors, infraredspectrometers and radiometers, low-energy charged-particledetectors, magnetometers, photopolarimeters, planetary radio-astronomy instruments, plasma and plasma wave experimentsand ultraviolet spectrometers.The television cameras are expected to provide scientistswith the best pictures of Jupiter and Saturn ever obtained and


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lo, Europa, Ganymede and Callisto Jupiter's Galileansatellites and Titan qualify as objects for close studyin their own right. They range from larger than the planetMercury down to the size of Earth's Moon; Titan is the onlysatellite in the solar system known to have an appreciableatmosphere.The Voyager trajectories make use of the favorable outer

planet alignment identified during proposed Grand Tour missionstudies to achieve flybys of both Jupiter and Saturn. Themost favorable opportunity for a close approach to Jupiterwith relatively short flight times to Saturn (less than fouryears) is the 1977 launch window.The mission also builds on information gathered aboutJupiter by the Pioneer 10 and 11 spacecraft particularlyabout Jupiter's magnetosphere.

Uranus Flyby OptionalNASA officials have an option to send the second Voyagerspacecraft on to the planet Uranus, with encounter occurringin January 1986. The Uranus option will be exercised only ifprimary Saturn science objectives have been met by the firstspacecraft and the operating health of the second warrantssuch an undertaking. There is also a possibility because

of the alignment of the outer planets that the secondspacecraft could be targeted to continue on to Neptune afterits encounter with Saturn.


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ExperimentImaging Science

Infrared InterferometerSpectrometer

Ultraviolet Spectrometer

Photopolarimeter

Plasma

Energy Charged Particles

Principal InvestigatorTeam Leader, Bradford SmithUniversity of Arizona,Tucson

Rudolf HanelGoddard Space FlightCenter

A. Lyle BroadfootKitt Peak NationalObservatory

Charles LillieUniversity of Colorado

Herbert Bridge ~Massachusetts Instituteof Technology

S. M. KrimigisJohns Hopkins AppliedPhysics Laboratory

Instruments and FunctionsTwo TV cameras with 1,500mm, f/8.5and 200mm, f/2 optics, multiplefilters, variable shutter speedsand scan rates. Wide-angle fieldof view, 56 x 55 millirad (about3 degrees square). On scan plat-form.Spectrometer-radiometer measuringtemperatures and molecular gascompositions, with narrow, 1/4-degree field of view, producingmeasurements every 48 seconds; onscan platform.Grating spectrometer measuring ion,atomic, and small-molecular gasabundances; spectral range 400-1600 angstroms; on scan platform.Telescope with variable apertures;filters, polarization analyzers andProof Test Model (PTM) detector; onscan platform.Dual plasma detectors, one alignedtoward Earth/Sun and one perpen-dicular, with detection ranges from4v to 6kv.Dual rotating solid-state detectorsets, covering various ranges from10 kev to more than 30 Mev/nucleon.

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ExperimentCosmic Ray

Magnetometer

Planetary RadioAstronomy

Plasma

Principal InvestigatorF. VogtCalifornia Institute ofTechnology

Norman NessGoddard Space Flight Center

James WarwickUniversity of Colorado

Frederick L. ScarfTRW Systems Group

Radio Science Team Leader, Von R., shlemanStanford University

Instruments and FunctionsHigh-energy, low-energy and'electron telescope systems usingarrays of solid-state detectors,several ranges from 0.15 to 500Mev/nucleon.Two low-field triaxial fluxgatemagnetometers located roughly 10m(33 ft.) from spacecraft on boom,two high-field (20 gauss) instru-ments mounted on spacecraft.Two 10-m (33-ft.) whip antennas andtwo-band receiver (20.4-1300 kHz,2.3-40.5 MHz), detecting planetaryradio emissions and bursts andsolar/stellar bursts.Uses 10-m (33-ft.) planetary radioastronomy antennas with stepfrequency detector and waveformanalyzer to measure plasma waves,thermal plasma density profile atJupiter and Saturn, satellite/magnetosphere interactions, wave/particle interactions.Uses spacecraft S-band/X-bandlinks during planet, satelliteand Saturn ring occultations toperceive changes in refractivityand absorption; celestial mechanicsinformation calculated fromtracking data.

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Voyager Fact Sheet