Pioneer Saturn Encounter Press Kit

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RELEASE NO: 79-108

CONTENTSGENERAL ELEASE ............................... 1-11ENCOUNTER PROFILE .................................. 12-26

Encounter Sequence ............................... 12Picture Sequences.....................21Saturn Picture Time Schedule (chart)................23Trajectory Selection ............................. 25Post-Saturn ...................................... 26

ENCOUNTER TIMELINE ................................. 27-30SATURN..............................................

32-39EARTH, JUPITER, SATURN COMPARISON TABLE ............ 40THE SATELLIES OF SATURN ............................ 41-44PIONEER SATURN SCIENCE..............................45SCIENTIFIC OBJECTIVES ..............................46-48THE EXPERIMENTS..................................... 49-53Magnetic Fields.......................................49Interplanetary Solar Wind, Bow Shock Waveand Magnetosphere ...............................49Radiation Belts and Cosmic Rays .................. 51Dust, Meteoroids and Interplanetary Dust ......... 53

CELESTIAL MECHANICS ................................ 54-57Atmosphere, Temperature, Moon, InterplanetaryHydrogen, Helium and Dust .......................54Pictures, Atmospheres and Moon Surfaces .......... 4Atmosphere, Ionosphere, Temperature .............. 57

ENCOUNTER OPERATIONS ...............................58TRACKING AND DATA RETRIEVAL ........................58-60THE SPACECRAFT .....................................60-63

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THE HELIOSPHERE ..................................... 64-67Solar Wind, Magnetic Field and Solar Cosmic Rays.. 65he Interstellar Gas..................................66Galactic Cosmic Rays .................................66

PIONEER EXPERIMENTERS ............................... 68-72THE ENCOUNTER TEAM .................................. 73-74PIONEER SATURN CONTRACTORS .......................... 75-77

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Firs Decade...Lunar NewsLanding Naticnal Aeronautics andab\AN,,L in~g Space Administration

r 1969-1979 Washington D C 20546AC 202 755-8370

/1.For Release

Nicholas PanagakosHeadquarters, Washington, D.C. IMMEDIATE(Phone: 202/755-3680)

Peter WallerAmes Research Center, Mountain View, Calif.(Phone: 415/965-5091)

RELEASE NO: 79-109

A BILLION MILES FROM EARTH, PIONEER SATURN MAKES LEFT TURN

Saturn-bound Pioneer 11 has been reoriented slightly in

space to permit a scientific instrument to begin measuring the

ringed planet.

Controllers at NASA's Ames Research Center in Mountain

View, Calif., fired Pioneer's two thrusters to tilt the spin

axis by 1.2 degrees. (The antenna, aligned with the spin axis,

is usually kept pointing toward Earth within half a degree to

maintain the maximum communications data rate.)

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The "left turn" made last Thursday permitted investigatorsto begin making measurements with the ultraviolet photometer,which searches for hydrogen, helium and other properties onSaturn, its rings and its moons.

Other instruments are being successively turned on as thespacecraft, now some 13 million kilometers (8 million miles)from the planet, accelerates toward it at 30,700 km/hr (19,200mph). Pioneer already is experiencing the tremendous gravityof the ringed planet. The huge, swirling gas ball will pullthe spacecraft toward it at an ever faster rate, until atclosest approach on Sept. 1, Pioneer will speed past Saturnat 114,000 km/hr (70,900 mph).

With Saturn still 16 million km (10 million mi.) away,Pioneer has returned 10 pictures of the planet, the first evertaken from a spacecraft. Because of the great distances, theseimages of the shaded side of Satirn's rings have been no largerthan a penny.

As the spacecraft continues moving closer to the planet,the images will grow larger and more clear. By Sinday, Aug. 26,they will begin to be better than any ever taken from Earth.In the closest pictures, Sept. 1, images of Saturn's cloud topsare expected to be 20 times better than Earth-based photos.

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Firsecade... NSA News4,mTLa;di,- National Aeronautics an dnd ing Space Administration

N 69-1979 Washington, D C 205461969197 AC 202 755-8370

For ReleaseMary FitzpatrickHeadquarters, Washington, D.C. IMMEDIATE(Phone: 202/755-8370)

RELEASE NO: 79-110

OLSTAD TO BE DEPUTY OF TECHNOLOGY OFFICE

Dr. Walter B. Olstad, Chief of the Space Systems Divisionat NASA's Langley Research Center, Hampton, Va., will becomeDeputy Associate Administrator of the Office of Aeronauticsand Space Technology, effective Oct. 1, at NASA Headquartersin Washington.

Olstad succeeds Dr. John M. Klineberg, who went to NASA'sLewis Research Center in Cleveland as Deputy Director on July 1.

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A native of Greenport, N.Y., o.stad received his bachelor

of science degree in mechanical engineering from Brown Univer-sity, Providence, R.I., in 1954; a master of science

degree in

aerospace engineering from Virginia Polytechnic Institute andState University in 1958; and his doctor of philosophy

degree

in applied mathematics from Harvard University in1966.

He began his NASA career inJune 1954 as an aeronautical

research engineer at Langley, first in the TransonicTunnels

Branch and then in the Reentry Physics Branch, Hewas named

Head, Gas Physics Section in 1966; Head, AdvancedEntry Analysis

Branch in 1969; and Chief, Space Systems Divisionin July 1975.

Olstad's fields of specialization were aerothermodynamics,

radiation heat transfer, applied mathematics, numericalanalysis

ar.d the management of research and development programs.He

has authored or co-authored more than 40 technicalpapers.

Associate editor for the Journal of Spacecraft andRockets,

he is a member of the American Institute of Aeronauticsand

Astronautics and serves with that group's TechnicalCommittee

on Space Systems.

He and his wife, the former Helen H. Thompson, arethe

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First -Decade ... [UI.5A Npa Lunar JSte k Lu anr i National Aeronautics and( `3 Landing Space Adrinistrationrs969-1979 Washingtor, DC 20546AC 202 755-8370

Nicholas PanagakosHeadqua~rters Washington, D.C. WEDNESDAY,Phone: 202/755-3680)August 22, 1979

Peter WailerAmes Research Center, Mountain View, Calif.Phone: 415/965-509l)RELEASE NO: 79-108

PIONEER O NCOUNTERSATURN NET 1

NASA's Pioneer ii spacecraft Will reach the giant ringedplanet Saturn on Sept. 1, after a six-year, three-billion..kilo-meter (two-billion..mile) journey across the solar system.Pioneer l3 will take the first closeup Pictures and makethe first close measurements of Saturn, its mysterious ringsand several of its 10 satellites, including the planet-sizedTitan.

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August 22,979

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-2-Sweeping through the most intense part of Saturn's mas-sive radiation'belts, Pioneer will come within 21,400 km(13,300 mi.) of the planet and as close as 1,900 km (1,200 mi.)to the Saturnian rings.

Closest approach will be at 2 p.m. EDT, Sept. 1.

The images returned by Pioneer 11 (also called PioneerSaturn) are expected to provide five to six times more detailof the planet than the best pictures taken from Earth.

Information returned by the spacecraft is expected tocontribute to a better understanding of the origin and evolu-tion of the Sun and planets. This, in turn, should providescientists with a greater knowledge of our own Earth.

Data obtained by Pioneer 11 will also be useful in plan-ning the encounters of Voyager 1 and < with the ringed planetin 1980 and 1981. The Voyagers are now Saturn--bound afterencounters with Jupiter in March and July respectively.

Saturn is the second largest planet in the solar system,only slightly smaller than Jupiter. It is an immense diffusebody whose volume is 815 times that of Earth, but whose massis only 95 times greater.

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-3-This Lakes Saturn the least dense planet in the solarsystem, lighter on the average than water. Like Jupiter,Saturn appears to be composed mainly of hydrogen and heliumand to behave in many ways like a liquid planet.

Appearing to the Earth observer as a bright yellowishstar of the first magnitude, Saturn is the sixth planet fromthe Sun, around which it revolves at an average distance of1.4 billion km (886 million mi.). It completes one orbitaround the Sun every 29 1/2 years. If the years are long,the days are short -- it rotates on its axis every 10 hours,14 minutes.

Difficult to observe in detail from Earth because of itsgreat distance, Saturn is known to have a banded structurewhich is probably due to cloud systems similar to those ofJupiter.

Saturn's most distinctive trademark is its elaborate ringsystem -- believed to consist of ice, ice-covered rocks or iceimbedded with rocks. The planet's rings are one of the greatspectacles of the solar system. Discovered by Galileo in 1610,the rings range outward about 77,000 km (48,000 mi.) fromSaturn's cloud tops. Total width of the three visible ringsis 64,800 km (40,300 mi.).

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The rings are very thin, with estimates of thicknessranging from several meters to as much as three kilometers(two miles). The rings are so thin that they are nearlyinvisible when viewed edge-on from Earth. Astronomers havedetermined from Earth that the orbiting ring particles arein part, and probably mostly, water ice. They may also con-tain metals, perhaps from the core of a broken-up moon. Thereis little rock. Most authorities think the particles rangefrom snowball-sized to automobile-sized pieces with a fewhaving a diameter of a mile or more.

The rings are believed to have originated either from thecapture of a "wandering moon", which was then torn apart bySaturn's gravity, or -- more likely -- as a result of gravi-tational forces that prevented formation of a close-in satel-lite from the original planetary nebula.

Until the recent discovery of thin rings around Jupiterand Uranus -- the two giant planets that flank Saturn -- theSaturnian ring system was believed to be unique.

The Saturn encounter is the second planetary surveillancetask for Pioneer 11. On Dec. 2, 1974, it skimmed within42,760 km (26,725 mi.) of Jupiter's cloud tops.

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-5-This close passage permitted the gravity and motion ofJupiter to act as a slingshot, increasing the spacecraft's

velocity and placing it on the trajectory which is now carry-ing it toward its close encounter with Saturn.

The trajectory from Jupiter to Saturn is about three timesas long as the first leg of Pioneer's outbound journey fromEarth to Jupiter. Pioneer's trajectory carried it high abovethe plane of the ecliptic in which solar system planets revolvearound the Sun, reaching a maximum height of about 160 millionkm (100 million mi.) in 1976.

As Pioneer approaches Saturn, its trajectory lies abovethe ring plane and, since the ring plane is tipped up relativeto the direction of the Sun, the plane is lighted from below.The view from Pioneer will therefore be of a ring plane lightedfrom the other side and this should permit optical measurementsof ring structure never before possible.

Picture resolution of Saturn will begin to exceed thatfrom Earth on Aug. 26 as the spacecraft approaches the planetat a distance of five million km (three million mi.). AfterAug. 30, Pioneer will be too close go Saturn to image the fullplanet with its rings.

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At about noon on Aug. 31, the last picture of Saturn'sfull disc, without the rings, will be made. Two hours beforeclosest approach to Saturn itself, Pioneer will make its mostdetailed picture, resolving cloud features 80-100 km (50-60mi.) in size.

A critical event will occur on the morning of Sept. 1,when Pioneer -- traveling at a speed of 85,000 km/hr (53,000mph) -- passes through the plane of Saturn's rings at a veryshallow angle (4.7 degrees) on its descent toward the planet.Planetary debris could be in the area. Even impact with asmall fragment could disable the spacecraft. Ring planepassage will take about 0.8 seconds.

As it rushes in toward the planet, Pioneer Saturn willapproach from the north and cross outside the edge of Saturn'souter ring at a distance of 34,600 km (21,500 mi.). It willthen skim in under the rings, from 2,000 to 10,000 km (1,200to 6,200 mi.) below them. At the point of closest approach,on the planet's night side, Pioneer will come within 21,400 km(13,300 mi.) of Saturn's banded cloud tops.

For an hour and 20 minutes, Pioneer will make the historicfirst passage under Saturn's rings, making closeup optical mea-surements to determine their structure and other first-timeobservations. -more-

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The spacecraft will be moving too fast for good ringpictures while beneath the rings.

When Pioneer makes its closest approach to Saturn's cloudtops, just before it passes behind the planet, it will betraveling 114,100 km/hr (71,900 mph). Closest approach willoccur at 12:34 p.m. EDT spacecraft time. Earth-received timeof spacecraft signals at NASA's Ames Research Center, MountainView, Calif., which manages the Pioneers, will be 2 p.m. EDT.Almost 1 1/2 hours are required for radio signals to cover theEarth-Saturn distance of 1.4 billion km (960 million mi.).The spacecraft will make another shallow-angle crossing ofSaturn's ring plane on its ascent away from the planet.

On Sept. 2, Pioneer will make its closest approach toTitan, Saturn's largest moon, taking pictures and making mea-surements of the satellite from 356,000 km (220,700 mi.) away.

Titan is the largest known planetary satellite in thesolar system, larger than Mercury. It appears to be wrappedin opaque orange smog and has a methane-containing atmospherewhich may be as dense as Earth's at the surface, and is fardenser than Mars'. Titan's hydrocarbon atmosphere is thoughtto be very similar to the primordial atmosphere of Earth andmay well have produced organic molecules, the building blocksof life.

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-8-Like Jupiter, Saturn has white, yellow and yellow-brownbanded cloud belts which appear to be the tops of planet-circling atmospheric streams, driven by the ringed planet'sfast, 10-hour spin and by an internal heat source.

Pioneer 11 is expected to return approximately 150 pic-tures of Saturn, with the first transmission scheduled forAug. 20 at a distance of about one million km (634,000 mi.)from the planet.

About two-thirds of the 150 images expected by projectscientists at the Ames Center will show more detail than ispossible through observations made from Earth. These highresolution photographs will be received at Ames from Aug. 26until Sept. 8. The smallest object visible will be about 95 km(50 mi.) in diameter.

Travel time for spacecraft data being transmitted back toEarth at the speed of light will be 86 minutes, as comparedwith 52 minutes required for Voyager 2 data to reach Earth fromJupiter in July 1979.

After passing the planet, Pioneer Saturn will head out ofthe solar system, traveling in roughly the same direction thatthe solar system does with respect to the local stars in ourgalaxy.-more-

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-9-A sister spacecraft, Pioneer 10, flew past Jupiter forthe first time in history in December 1973, and is now on itsway out of the solar system, the first manmade object to do so.Pioneer lO's solar system exit path is almost opposite toPioneer Saturn's, and it has already reached the orbit of Uranus.

On the outside chance that the Pioneers may be capturedby an intelligent species during their nearly endless travelsamong the stars, each carries a plaque with a message aboutEarth.

Spacecraft operations during evcounter will be complicatedby the two-hour, 52-minute roundtrip communications time andthe need to send roughly 10,000 commands to the spacecraft inthe two weeks centered on closest approach, most commandsgoing to the spacecraft imaging system. Operations strategyis to set most systems in one standard mode throughout theencounter.

Pioneer Saturn weighs 260 kilograms (570 pounds) and isspin-stabilized, giving its instruments a full circle scan 7.8times a minute. It uses nuclear sources for electric powerbecause sunlight at Jupiter and beyond is too weak for anefficient solar-powered system.

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Pioneer's 2.75-meter (9-foot) dish antenna looks back atEarth throughout the mission -- adjusting its view by changesin spacecraft attitude as the spacecraft and home planet movein their orbits around the Sun.

Pioneer carries a 30-kg (65-lb.) scientific payload of 11operating instruments. Two other experiments use the space-craft and its radio signal as their instruments.

At Saturn, Pioneer's instruments are expected to:* Determine whether the planet has a magnetic field andbelts of high-energy charged particles, and the effects ofthe rings on such belts.* Provide a temperature and density profile from the

planet's cloud tops to its core.* Determine the presence of an internal heat source;how much heat Saturn is radiating; and effects of this heaton internal and atmospheric circulation.* Determine the masses of Saturn's two outer rings.Are the rings made mostly of ice, or perhaps metals?* Determine the existence and character of the hypo-thesized outer "E-ring," which could double total ring width,and pose a hazard to Pioneer, the two Voyagers and other

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* Measure light intensity and polarization from themysterious ninth moon, Iapetus, which is six times as brighton its leading hemisphere as its trailing one; first findingsof mass and density of the moon, Rhea; and confirm and improvethese measurements for Titan.

* Characterize Titan's atmospheric aerosols (smog), itsatmosphere structure and temperature, and take its picture.

* Measure Saturn's hydrogen/helium ratio (its two mainconstituents) and determine atmospheric structure, layeringand heat distribution, both horizontally and vertically.

* Study structure, temperature and flow of the atmosphere'sbelt and zone system, and obtain data related to atmospherecomposition.

* Make at least 50 closeup color pictures of Saturn, itsrings and cloud tops.

The Pioneer 10 and 11 projects are managed by Ames. Thetwo spacecraft were built by TRW Systems, Redondo Beach, Calif.

(END OF GENERAL RELEASE. BACKGROUND INFORMATION FOLLOWS.)

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(Note: All times in the Background Information sectionof the press kit are Pacific Daylight Time -- PDT.)

ENCOUNTER PROFILE

Encounter SequenceThe two-month Pioneer 11 encounter period, Aug. 2 toOct. 1, will proceed as follows:* Beginning Aug. 2, the spacecraft, 1.5 billion km (932

million mi.) from Earth, will be tracked via 64-m (210-ft.)dish antennas in Spain and Australia for about 10 hours a day.Pioneer will be 25 million km (15 million mi.) from Saturn,traveling toward it at 30,600 km/hr (19,000 mph) relative tothe planet.

* On Aug. 6, when tracking time increases to 18 hours aday and the station at Goldstone, Calif., joins the team oftracking stations, Pioneer will be 1.5 million km (939 millionmi.) from Earth. With 20 million km (12 million mi.) left toreach Saturn, all science instruments will be undergoing checksin preparation for the encounter. As the spacecraft movestoward Saturn at 31,000 km/hr (19,200 mph), the imaging photo-polarimeter begins taking polarimetry measurements of Saturn.

* The ultraviolet photometry instrument will begin fourdays of Saturn observations on Aug. 16. On the 17th, withPioneer 1.53 billion km (949 million mi.) from Earth, trackingstations begin 24-hour tracking of the spacecraft, as it travelstoward Saturn at 31,300 km/hr (19,400 mph). At this point,Pioneer will be 12.7 million km (8 million mi.) from Saturn.

* Encounter activity intensifies on Aug. 20, when theimaging photopolarimeter begins taking images of Saturn.These first pictures are not expected to show much detailsince the spacecraft will still be 10.2 million km (6.3million mi.) from the planet. During the encounter, Pioneerwill transmit more than 100 images of Saturn, its rings andthe planet-sized moon Titan.

* On Aug. 24, photopolarimetry measurements will be madeof the Saturnian moon Iapetus.

* On Aug. 25, with Pioneer 1.55 billion km (959 millionmi.) from Earth, two-station tracking will begin, doubling therate of data transmission and substantially improving imagequality. At this point, 5 million km (3 million mi.) fromSaturn, picture resoluLion will begin to be better than anythingobtained from Earth-based telescopes.

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Most of the images of the rings obtained during themission will show the rings lighted from the other side,thusproviding optical measurements not obtainable from Earth.* On Aug. 27, hurtling toward Saturn at 33,100 km/hr(20,500 mph), Pioneer will pass Phoebe, the moon farthestfrom Saturn, at a distance of 9,453,000 km (5,860,860 mi.).Scientists estimate Pioneer could cross the bow shock ofSaturn on Aug. 27. (The location of the bow shock at Jupiterwas found to be very variable and dependent on solar windintensity.)* On the 28th, Pioneer will make the first ultravioletphotometer measurements of Saturn's large moon Titan, as wellas added photopolarimetry measurements of Iapetus, Saturn'smysterious ninth moon, which is six times brighter on one sidethan the other. Iapetus will be encountered at a distance of1,039,000 km (644,180 mi.) as Pioneer flies by at 33,500 km/hr(20,800 mph). At that time, Pioneer will be 3.3 million km(2 million mi.) from Saturn. More light measurements (photo-polarimetry) will be made of the satellite on Aug. 29. Alsoon that day, ultraviolet photometry measurements will be madeof the three moons, Hyperion, Tethys and Dione.* Pioneer will continue moving closer to Saturn, sendingback full-disc pictures of she planet and its rings untilAug. 30, when the spacecraft will be 2 million km (1.3 million

mi.) from Saturn, too close to take images of the planet andrings together. The last full-planet picture of the inboundjourney will be taken from 1 million km (700,000 mi.) away onAug. 31 at about 1:55 a.m. PDT and probably will be the bestfull-planet view.* In the early morning hours of Aug. 31, Pioneer 11 willpass the eighth Saturnian satellite, Hyperion (diameter 224 kmor 140 mi.) at a distance of 674,000 km (417,880 mi.), as thespacecraft speeds toward Saturn at 37,800 km/hr (23,400 mph).At this point, Pioneer will be too close to the planet to getfull-disc views. Photopolarimetry measurements will be madeof Hyperion on Aug. 30 and 31 and of Rhea on the 31st. Ultra-violet photometer measurements of Rhea will be made on Aug. 30.On the 31st, the instrument will measure light from five satel-lites: Titan, Rhea, Dione, Tethys and Enceladus. Ultravioletmeasurements of Saturn's rings also will be made on Aug. 31.Ten hours before closest approach on Sept. 1, the photometerwill begin 14 hours of measurements of Saturn's ultravioletlight.* Two hours before closest approach, the imaging photo-polarimeter will take its most detailed pictures, showing cloudfeatures as small as 80-100 km (50-60 mi.) in size.

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* The most critical and dangerous event of the missionill occur at 9:05 a.m. PDT Sept. 1, when Pioneer flies throughhe plane of Saturn's rings at a very shallow angle (4.7 degrees)n its descent toward the planet. Some Planetary debris islmost certainly present in Saturn s ring plane, outside theisible rings. An impact with a fragment could destroy thepacecraft. For an hour and 20 minutes, 1.55 billion km (963illion Mi.) away from Earth, Pioneer 11 will make the historicirst flight under Saturn's rings, making closeup optical mea-urements to determine their structure. (Pictures during theing flight will be of Saturn, not of the rings.)* At 10:30 a.m. PDT, Sept. 1, Pioneer also will make itslosest approach to Saturn's fifth moons, Dione, inside Dione'srbit, 291,000 km (180,500 mi.) away. About 20 minutes later,t will pass the second moon,Mimasat 103,400 km (64,100 mi.).* At 11:05 a.m. PDT, Pioneer will reach its closestpproach to Saturn's cloud tops at 21,400 km (13,300 mi.) justefore it passes behind the planet. The spacecraft will beraveling at 114,100 km/hr ;70,900 mph).

* One-and-a-half minute; after closest approach, Pioneerill pass behind Saturn and be out of radio contact with Earthor 78 minutes. After Pioneer emerges, it will continue toly under the sunlic side of Saturn's rings for about 10 minutes.t 12:50 a.m. PDT, Pioneer will make its closest approach tohe fourth moon*Tethysat 331,700 km (205,700 mi.). Fiveinutes later, the spacecraft will make another shallow-anglerossing of Saturn's ring plane on its ascent away from thelanet. As it recrosses the ring plane, it will come closesto the third moon Enceladus at 225,200 km (139,600 mi.). Anour after the ascent crossing of the ring plane, Pioneer againill have a view of the rings lighted from below.* At 5:00 p.m. PDT, Pioneer will make its closest approacho the sixth moonRheaat a distance of 341,900 km (212,000 mi.).Three hours later, from about 420,000 km (260,000 mi.) away,ioneer will again get a full view of the planet plus its rings.ioneer will be moving away from the planet at about 54,000m/hr (332700 mph).* On Sept. 2, at 12:30 p.m. PDT, Pioneer will make itslosest approach to planet-sized Titan, Saturn's seventh moon,t a distance of 356,000 km (220,700 mi.). Pioneer will photo-raph and make other measurements of the 5,800-km (3,600-mi.)-iameter moon, the largest known satellite in the solar system.his moon dominates Saturn's satellite family both in diameternd mass, exerting a measurable gravitational force on theodies in that system.

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By Sept. 3, when Pioneer has moved 1.4 million km(900,000 mi.) away from Saturn, tentative infrared and ultra-iolet measurements are expected to become available. Byept. 6, an infrared map of Saturn may be available, as wells early calculations of the masses of the rings and of Rheand Titan. Picture resolution will be better than Earth-basedimaging through midnight, Sept. 7.Picture Sequences

Plans call for the imaging photopolarimeter to make about55 images between Aug. 20 and Sep'. 8. However, the instru-ent has been in space for six years, and it is possible thathe total number of images could be fewer than predicted.All of the images will not be available for distribution.Scientists hope to process for immediate distribution up tohree or four images each day during the encounter period.Between Aug. 20 and midnight Aug. 25, plans call for themaging photopolarimeter to take 49 images of Saturn. Theistance from the spacecraft to the planet will decrease from0.2 million km (6.3 million mi.) to 6.1 million km (3.8 mil-ion mi.).Between Aug. 26 and Sept. 8, 106 images are planned, theseaving better resolution than Earth-based photographs. Proces-ing of the best images for distribution purposes will beginug. 27. A maximum of seven images are planned on Aug. 26 andnother seven for Aug. 27. By Aug. 28, some images should bevailable for distribution.

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Documents

Pioneer Saturn Encounter Press Kit