Return-path: X-Andrew-Authenticated-as: 7997;andrew.cmu.edu;Ted Anderson Received: from beak.andrew.cmu.edu via trymail for +dist+/afs/andrew.cmu.edu/usr11/tm2b/space/space.dl@andrew.cmu.edu (->+dist+/afs/andrew.cmu.edu/usr11/tm2b/space/space.dl) (->ota+space.digests) ID ; Sat, 1 Dec 1990 03:09:24 -0500 (EST) Message-ID: Precedence: junk Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Sat, 1 Dec 1990 03:08:49 -0500 (EST) Subject: SPACE Digest V12 #604 SPACE Digest Volume 12 : Issue 604 Today's Topics: Galileo Fact Sheet (long) Administrivia: Submissions to the SPACE Digest/sci.space should be mailed to space+@andrew.cmu.edu. Other mail, esp. [un]subscription notices, should be sent to space-request+@andrew.cmu.edu, or, if urgent, to tm2b+@andrew.cmu.edu ---------------------------------------------------------------------- Date: 29 Nov 90 17:57:45 GMT From: csus.edu!wuarchive!sdd.hp.com!elroy.jpl.nasa.gov!jato!mars.jpl.nasa.gov!baalke@ucdavis.ucdavis.edu (Ron Baalke) Subject: Galileo Fact Sheet (long) GALILEO FACT SHEET/PROJECT BACKGROUND November 29, 1990 SUMMARY Galileo is a NASA spacecraft mission to Jupiter, launched October 18, 1989, and designed to study the planet's atmosphere, satellites and surrounding magnetosphere. It was named for the Italian Renaissance scientist who discovered Jupiter's major moons in 1610 with the first astronomical telescope. This mission will be the first to make direct measurements from an instrumented probe within Jupiter's atmosphere, and the first to conduct long-term observations of the planet and its magnetosphere and satellites from orbit around Jupiter. It will be the first orbiter and atmospheric probe for any of the outer planets. The Jet Propulsion Laboratory designed and developed the Galileo Jupiter orbiter spacecraft and is operating the mission; NASA's Ames Research Center developed the atmospheric probe with Hughes Aircraft Company as prime contractor. The German government is a partner in the mission through its provision of the spacecraft propulsion subsystem, scientific instruments on both orbiter and probe, and ground operations support. In order to reach Jupiter, Galileo must pick up the necessary speed by flying past Venus and twice by the Earth, using the gravity-assist technique employed by Voyager to reach the planets Saturn, Uranus and Neptune. These gravity-assist encounters have provided the opportunity for Galileo to conduct brief scientific observations of Venus (closest approach February 10, 1990) and the Earth-Moon system (December 8, 1990 and 1992). Designed to measure and observe Jupiter's atmosphere, magnetosphere and satellites, Galileo's instruments can add to knowledge of the inner bodies, supplementing previous spacecraft data and complementing the Venus surface studies by the Magellan project. In addition, Galileo's flight through the asteroid belt provides opportunities for the first close-up observation of an asteroid. In late October 1991 it will encounter the asteroid Gaspra, and a second potential opportunity occurs in August 1993, with the asteroid Ida. In December 1995 the Galileo atmospheric probe will conduct a direct examination of Jupiter's atmosphere, while the larger part of the craft, the orbiter, begins a 22-month, 10-orbit tour of the major satellites and the magnetosphere, including long- term observations of Jupiter throughout this phase. The 2-1/2-ton (2,222-kilogram) Galileo orbiter spacecraft carries 10 scientific instruments; there are another six on the 750-pound (340-kilogram) probe. The spacecraft radio link to Earth and the probe-to-orbiter radio link serve as instruments for additional scientific investigations. Galileo communicates with its controllers and scientists through the Deep Space Network, using tracking stations in California, Spain and Australia. LAUNCH OPERATIONS The Galileo spacecraft was carried into Earth orbit on October 18, 1989, by Space Shuttle Atlantis, commanded by Donald E. Williams and piloted by Michael J. McCulley. Mission specialists Shannon W. Lucid, Ellen S. Baker and Franklin R. Chang-Diaz deployed Galileo and its IUS (Inertial Upper Stage) booster from the shuttle. The two- stage IUS solid rocket accelerated the spacecraft out of Earth orbit toward the planet Venus. The Galileo mission was previously designed for a direct flight of about 2-1/2 years to Jupiter. Changes in the launch system after the Challenger accident, including replacement of the Centaur upper-stage rocket with the IUS, precluded this direct flight. Trajectory engineers designed a new interplanetary flight path using gravity assists, once with Venus and twice with Earth, to build up the speed to reach Jupiter, taking a total of just over 6 years. This is called the Venus- Earth-Earth-Gravity-Assist or VEEGA trajectory. EARTH TO JUPITER Galileo makes three planetary encounters in the course of its gravity-assisted flight to Jupiter. These provide opportunities for scientific observation and measurement of Venus and the Earth-Moon system. The mission also has a chance to fly close to one or two asteroids, bodies which have never before been observed close up, and to obtain data on other phenomena in interplanetary space. The instruments designed to observe Jupiter's atmosphere from afar can also improve our knowledge of the atmosphere of Venus; sensors designed for the study of Jupiter's moons can add to information about our own planet and its satellite. VENUS The planet Venus is approximately the size and density of the Earth, and it has a solid surface beneath a cloudy atmosphere, but it does not otherwise resemble our planet. The atmosphere is deep and dense; cloud tops are some 40 miles above the surface, where the atmospheric pressure is more than 90 times that on Earth and the temperature near 900 degrees Fahrenheit. The clouds are essentially opaque to visible light, and the surface can be observed only by radar from Earth or spacecraft or by a spacecraft hardy enough to land and survive on the surface. Many observations of these types have been made, but they have been of limited scope or resolution; NASA's Magellan mission, in orbit around Venus, is making a global high-resolution radar survey. Many features of the atmosphere remain unknown, including details of the motion of the upper regions, the form of deeper clouds, and the existence of lightning storms. The Galileo spacecraft approached Venus February 9, 1990 from the night side and passed across the sunlit hemisphere. Closest approach was about 10 p.m. PST, or about 1 a.m. EST February 10, at a distance of 10,000 miles (16,000 kilometers) above the cloudtops. For a day before and several days after closest approach Galileo scientists collected measurements of charged particles, dust and magnetism, infrared and ultraviolet spectral observations, data for infrared lower-atmosphere maps, and 81 camera images. Virtually all these data had to be tape-recorded on the spacecraft for playback in November 1990, because Galileo's capabilities are constrained during this early phase of flight. The spacecraft was originally designed to operate between Earth and Jupiter; at Jupiter, sunlight is 25 times weaker than at Earth and temperatures are much lower. The VEEGA mission has exposed the spacecraft to a hotter environment from Earth to Venus and back; spacecraft engineers devised a set of sunshades to protect the craft. For this system to work, the top of the spacecraft was pointed close to the Sun, with the main antenna furled (precluding high-rate communications) for protection from the Sun's rays, until well after the first Earth flyby in December 1990. Therefore, scientists had to wait until the spacecraft is close to Earth to receive the recorded Venus data, transmitted through a low-gain antenna. EARTH (FIRST PASS) Approaching Earth for the first time about 14 months after launch, the Galileo spacecraft will have the opportunity to measure the magnetic tail far above the dark side of Earth and parts of both the near and far sides of the Moon. After passing Earth, Galileo will observe its sunlit side. At this short range, scientific data can be transmitted at higher rates using only the spacecraft's low- gain antennas. The high-gain antenna is to be unfurled like an umbrella about 5 months after the first Earth encounter. FIRST ASTEROID: GASPRA Nine months after the Earth passage, Galileo will enter the asteroid belt, and 2 months after that it will perform the world's first asteroid encounter. Gaspra is believed to be a fairly representative main-belt asteroid, about 10 miles or 15 kilometers across, probably similar in composition to stony meteorites. The spacecraft will pass about 900 miles (1,600 kilometers) from Gaspra at a relative speed of about 18,000 miles per hour; scientists expect to collect several pictures of Gaspra, and measurements to indicate composition and physical properties. The exact flyby geometry has not yet been selected. EARTH (SECOND PASS) Thirteen months after the Gaspra encounter, the spacecraft will have completed its 2-year elliptical orbit around the Sun and will arrive back at Earth. It will need a much larger elliptical orbit (with a 6-year period) to reach as far as Jupiter, and the second flyby of Earth will pump the orbit up to that size. Passing about 185 miles (300 kilometers) above the surface, 25 miles above the altitude at which it was deployed from the Space Shuttle more than 3 years before, Galileo will use Earth's gravity to change its flight direction and pick up about 8,000 miles per hour. Each gravity-assist flyby requires several rocket- thrusting sessions, using Galileo's onboard propulsion module, to refine the flight path. (Asteroid encounters may require similar maneuvers to obtain the best observing conditions.) Passing the Earth for the last time, the spacecraft's scientific equipment can make observations of the planet, both for comparison with Venus and Jupiter and to aid in Earth studies. It can also observe the north polar regions of our Moon, for comparison with Jupiter's satellites and to obtain new data on lunar regions never explored before. SECOND ASTEROID POSSIBILITY Nine months later, Galileo could have a second asteroid-observing opportunity, if this were determined to be the best use of spacecraft propellant reserves. Ida is about 20 miles or 30 kilometers across; like Gaspra, it is believed to represent the majority of main-belt asteroids in composition, though there are believed to be differences between the two. Relative velocity for this flyby would be nearly 28,000 miles per hour. Approaching Jupiter Some 2-1/2 years after leaving Earth for the third time and 5 months before reaching Jupiter, Galileo's probe must separate from the orbiter which has been carrying it since before launch. The spacecraft precisely adjusts its trajectory to establish the atmospheric probe's 5-month free flight to Jupiter, and then turns to orient the probe so that it will enter the atmosphere in the correct attitude. Finally, it spins up to 10 rpm and releases the spin-stabilized probe. Several days later the Galileo orbiter readjusts its trajectory to aim for its own Jupiter encounter. AT JUPITER Early in December 1995 the Galileo orbiter and probe will approach Jupiter separately. They will have travelled about 2-1/2 billion miles (4 billion kilometers) in a complex multiple looping path for more than 6 years. For the last 60 days of the approach, the orbiter carries out a comprehensive program of observations of Jupiter and measurements of its environment in space. The probe will enter the atmosphere to make direct measurements. The orbiter will fly close by Io, receive the probe signals for relay to Earth and go into orbit around Jupiter, all in a period of about 7 hours. While the probe is still approaching Jupiter, the orbiter will have its first two satellite encounters. After passing within 20,000 miles (33,000 kilometers) of Europa, it will fly about 600 miles (1,000 kilometers) above Io's volcano-torn surface, about 1/20 the closest flyby altitude of Voyager in 1979. A few hours later, the probe will enter the upper atmosphere, about 6 degrees north of Jupiter's equator, at more than 100,000 miles per hour or about 47 kilometers per second, and slow by aerodynamic braking for about 2 minutes before deploying its parachute and dropping its heat shields. Then it will float down about 125 miles or 200 kilometers through the clouds, passing from a pressure of 1/10 that on Earth's surface to about 25 Earth atmospheres in 75 minutes. The probe batteries are not expected to last beyond this point, and the radio-communications link will be terminated. About 133,000 miles (214,000 kilometers) above, the orbiter will receive, store and transmit the probe's science data. Next, the orbiter must thrust with its main engine to go into orbit around Jupiter. This orbit, the first of 10 planned, will have a period of about 8 months. Additional maneuvers and the first Ganymede close flyby in July 1996 will shorten the orbit, and each time the orbiter returns to the inner zone of satellites it will make a gravity-assist close pass over one of them to change its orbit while making close observations. These satellite encounters will be at altitudes as close as 125 miles (200 kilometers) above the surfaces of the moons, typically about 100 times closer than the Voyagers' satellite flybys. Throughout the 22-month orbital phase, Galileo will continue observing the planet and the satellites and gathering data on the magnetospheric environment. SCIENTIFIC ACTIVITIES Galileo's scientific experiments are being carried out by more than 100 scientists from six nations. These are supported by dedicated instruments and the radio subsystems on the Galileo orbiter and probe. NASA has appointed 13 interdisciplinary scientists whose studies reach across more than one Galileo instrument data set. The experiments and principal scientists are listed at the end of this fact sheet. SPACECRAFT The Galileo mission and systems were designed to investigate three broad aspects of the Jupiter system: the planet's atmosphere, the satellites and the magnetosphere. The spacecraft was constructed in three segments, which help focus on these areas: the atmospheric probe; a non-spinning section of the orbiter carrying cameras and other remote sensors; and the spinning main section of the orbiter spacecraft which includes the fields and particles instruments, designed to sense and measure the environment directly as the spacecraft flies through it. The spinning section also carries the main communications antenna, the propulsion module, flight computers and most support systems. Atmospheric Probe The probe weighs about 750 pounds (340 kilograms), and includes a deceleration module to slow and protect the descent module, which carries out the scientific mission. The deceleration module consists of an aeroshell and an aft cover, designed to block the heat generated by slowing from the probe's arrival speed of about 100,000 miles per hour to subsonic speed in less than 2 minutes. After the aft cover is released, the descent module deploys its 8-foot (2.5-meter) parachute and drops the aeroshell; its radio-relay transmitter and all six of its instruments go to work (two instruments started storing data on the way in). Each operating at 128 bits per second, the dual L-band transmitters send nearly identical streams of scientific data to the orbiter. Probe electronics are powered by batteries with an estimated capacity of about 18 amp-hours on arrival at Jupiter. Probe instruments include an atmospheric structure instrument group measuring temperature, pressure and deceleration; a neutral mass spectrometer and a helium- abundance interferometer supporting atmospheric composition studies; a nephelometer for cloud location and cloud-particle observations; a net-flux radiometer measuring the difference, upward versus downward, in radiant energy flux at each altitude; and a lightning/radio-emission instrument with an energetic-particle detector, measuring electromagnetic waves (light and radio-frequency) associated with lightning and energetic particles in Jupiter's radiation belts. Galileo Orbiter The orbiter, in addition to supporting the probe activities, will support all the scientific investigations of Jupiter's satellites and magnetosphere, and remote observation of the giant planet itself, including those carried out on the way to Jupiter. The orbiter weighs about 4,900 pounds (2,222 kilograms), including about 2,035 pounds or 925 kilograms of rocket propellant. This is used in almost 30 relatively small maneuvers during the long gravity-assisted flight to Jupiter, three large thrust maneuvers including the one that puts the craft into its Jupiter orbit, and the 30 or so trim maneuvers planned for the satellite tour phase. The propulsion module consists of 12 10-newton thrusters, a single 400-newton engine, and the fuel, oxidizer, and pressurizing-gas tanks, tubing, valves and control equipment. (A thrust of 10 newtons would support a weight of about 1 kilogram or 2.2 pounds at Earth's surface.) The propulsion system was developed and built by Messerschmitt-Bolkow-Blohm (MBB) and provided by the Federal Republic of Germany as a partner in Project Galileo. The orbiter's maximum communications rate is 134 kilobits per second (the equivalent of about one black-and- white image per minute); there are other data rates, down to 10 bits per second, for transmitting engineering data when the Earth-spacecraft geometry makes communication difficult. The Galileo spacecraft acquires and transmits a total of 1,418 engineering measurements (temperatures, voltages, computer states and counts, and the like). The spacecraft transmitters operate at S-band and X-band (2,295 and 8,415 megahertz) frequencies. The high-gain antenna is a 16-foot (4.8-meter) umbrella-like reflector unfurled after the first Earth flyby. Two low-gain antennas (one pointed forward and one aft, both mounted on the spinning section) are provided to support communications duri9g the Earth-Venus-Earth leg of the flight and whenever the main antenna is not deployed and pointed at Earth. The despun section of the orbiter carries a radio relay antenna for receiving the probe's data transmissions. Because the time delay in radio signals from Earth to Jupiter and back is more than 1 hour, the Galileo spacecraft was designed to operate from programs sent to it in advance and stored in spacecraft memory. A single master sequence program can cover from weeks to months of quiet operations between planetary and satellite encounters. During busy encounter operations, one program covers only a few days or less. These sequences operate through flight software installed in spacecraft computers in various subsystems and scientific instruments. In the command and data subsystem, there are about 35,000 lines of code, including 7,000 lines of automatic fault protection software, which operates to put the spacecraft in a safe state if an untoward event such as an onboard computer glitch were to occur. The articulation and attitude control flight software has about 37,000 lines of code, including 5,500 lines devoted to fault protection. Electrical power is provided to Galileo's equipment by two radioisotope thermoelectric generators. Heat produced by natural radioactive decay of plutonium is converted to approximately 500 watts of electricity (570 watts at launch, 485 at the end of the mission) to operate the orbiter equipment for its 8-year baseline mission. This is the same type of power source used by the Voyager and Pioneer Jupiter spacecraft in their outer-planet missions. Most spacecraft are stabilized in flight either by spinning around a major axis, or by maintaining a fixed orientation in space, referenced to the Sun and another star. Galileo represents a combination of these techniques, and is the first dual-spin planetary spacecraft. A spinning section rotates at 3 rpm, and a "despun" section is counter-rotated to provide a fixed orientation for cameras and other remote sensors. A star scanner on the spinning side is used to determine orientation and spin rate; gyros are used for turns and instrument pointing. Instruments which measure fields and particles, together with the main antenna, the power supply, the propulsion module, most of the computers and control electronics, are mounted on the spinning section. The instruments include magnetometer sensors mounted on a 36- foot (11-meter) boom to escape interference from the spacecraft; a plasma instrument detecting low-energy charged particles and a plasma-wave detector to study waves generated by the particles; a high-energy particle detector; and a detector of cosmic and Jovian dust. It also carries the Heavy Ion Counter, an engineering experiment added to assess the potentially dangerous charged-particle environments the spaceraft flies through, and an added Extreme Ultraviolet detector associated with the UV spectrometer on the scan platform. The despun section carries instruments and other equipment whose operation depends on a steady pointing capability. The instruments include the camera system; the near-infrared mapping spectrometer to make multispectral images for atmosphere and surface chemical analysis; the ultraviolet spectrometer to study gases; and the photopolarimeter-radiometer to measure radiant and reflected energy. The camera system is expected to obtain images of Jupiter's satellites at resolutions from 20 to 1,000 times better than Voyager's best. This section also carries a dish antenna to track the probe in Jupiter's atmosphere to pick up its signals for relay to Earth. GROUND SYSTEMS Galileo communicates with Earth via NASA's Deep Space Network (DSN), which has a complex of large antennas with receivers and transmitters located in the California desert, in Australia and in Spain, linked to a network control center at JPL in Pasadena, California. The spacecraft receives commands, sends science and engineering data, and is tracked by doppler and ranging measurements through this network. The German Space Operations Center and tracking station at Weilheim will also support Galileo cruise science activities beginning in September 1991. At JPL, mission controllers including about 275 scientists, engineers and technicians supported the mission at launch; nearly 400 will support Jupiter operations. Their responsibilities include commanding the spacecraft, interpreting the engineering and scientific data it sends in order to understand how it is performing and responding, and analyzing navigation data obtained by the Deep Space Network. The controllers use a set of complex computer programs to help them control the spacecraft and interpret the data. As indicated above, the Galileo spacecraft carries out its complex operations, including maneuvers, scientific observations and communications, in response to stored sequences which are sent up to the orbiter periodically through the Deep Space Network in the form of command loads. Designing these sequences is a complex process balancing the desire to make certain scientific observations with the need to safeguard the spacecraft and mission. The sequence design process itself is supported by software programs, for example, which display to the scientist maps of the instrument coverage on the surface of a satellite for a given spacecraft orientation and trajectory. Notwithstanding these aids, a typical 3-day satellite encounter will take efforts spread over many months to design, check and recheck. The controllers also use software designed to check the command sequence further against flight rules and constraints. The spacecraft regularly reports its status and health through an extensive set of engineering measurements. Interpreting these data into trends and averting or working around equipment failures is a major task for the Galileo flight team. Conclusions from this activity become an important input, along with scientific plans, to the sequence design process. This too is supported by computer programs written and used in the mission support area. Navigation is the process of estimating, from radio range and doppler measurements, the position and velocity of the spacecraft to predict its flight path and to design course-correcting maneuvers. These calculations must be done with computer support. The Galileo mission, with its complex gravity-assist flight to Jupiter and 10 gravity-assist satellite encounters in the Jovian system, is extremely dependent on consistently accurate navigation. In addition to the programs which directly operate the spacecraft and are periodically transmitted to it, the mission operations team uses software amounting to 650,000 lines of programming code in the sequence design process; 1,615,000 lines in the telemetry interpretation; and 550,000 lines of code in navigation. These all had to be written, checked, tested, used in mission simulations and, in many cases, revised before the mission could begin. Science investigators are located variously at JPL or at their home laboratories, linked by computer communications. From either location, they are involved in developing the sequences affecting their experiments and, in some cases, helping to change preplanned sequences to follow up on unexpected discoveries with second looks. JUPITER'S SYSTEM Jupiter is the largest and fastest-spinning planet in the solar system. Its radius is more than 11 times Earth's, and its mass is 318 times that of our planet. It is made mostly of light elements, principally hydrogen and helium. Its atmosphere and clouds are deep and dense, and a significant amount of energy is emitted from its interior. The earliest Earth-based telescopic observations showed bands and spots in Jupiter's atmosphere; one storm system, the Red Spot, has been seen to persist over 3 centuries. Atmospheric forms and dynamics were observed in increasing detail with the Pioneer and Voyager flyby spacecraft, and Earth-based infrared astronomers have recently studied the nature and vertical dynamics of deeper clouds. Sixteen satellites are known. The four largest, discovered by the Italian scientist Galileo in 1610, are about the size of small planets. The innermost of these, Io, has active sulfurous volcanoes, discovered by Voyager 1 and further observed by Voyager 2 and Earth-based infrared astronomy. Io and Europa are about the size and density of Earth's moon (3-4 times the density of water) and probably mostly rocky inside. Ganymede and Callisto, further out from Jupiter, are the size of Mercury but less than twice as dense as water; their interiors are probably about half-and-half ice and rock, with mostly ice or frost surfaces. Of the others, eight (probably captured asteroids) orbit irregularly far from the planet, and four (three discovered by the Voyager mission in 1979) are close to the planet. Voyager also discovered a thin ring system at Jupiter in 1979. Jupiter has the strongest planetary magnetic field known; the resulting magnetosphere is a huge teardrop-shaped, plasma-filled cavity in the solar wind pointing away from the Sun. The inner part of the magnetic field is doughnut- shaped, but farther out it flattens into a disk. The magnetic poles are offset and tilted relative to Jupiter's axis of rotation, so the field appears to wobble around with Jupiter's rotation (just under 10 hours), sweeping up and down across the inner satellites and making waves throughout the magnetosphere. MANAGEMENT The Galileo Project is managed for NASA's Office of Space Science and Applications by the Jet Propulsion Laboratory, a division of the California Institute of Technology. This responsibility includes designing, building, testing, operating and tracking Galileo. William J. O'Neil is project manager, Torrence V. Johnson is project scientist, Clayne M. Yeates is science and mission design manager, Neal E. Ausman Jr. is mission director, and Matthew R. Landano is deputy mission director. The Federal Republic of Germany has furnished the orbiter's retro- propulsion module and some of the instruments and is participating in the scientific investigations. The radioisotope thermoelectric generators were designed and built by the General Electric Company for the U.S. Department of Energy. NASA's Ames Research Center, Moffett Field, California, is responsible for the atmosphere probe, which was built by Hughes Aircraft Company, El Segundo, California. At Ames, the probe manager is Benny Chin and the probe scientist is Richard E. Young. GALILEO MISSION EVENTS Launch: STS-34 Atlantis and IUS October 18, 1989 First trajectory-change maneuver November 9-11, 1989 Venus flyby (about 10,000 mi altitude) February 10, 1990 Venus data playback November 19-21, 1990 Earth 1 flyby (about 590 mi) December 8, 1990 Asteroid Gaspra flyby (about 900 mi) October 29, 1991 Earth 2 flyby (about 200 mi) December 8, 1992 Asteroid Ida flyby August 28, 1993 Probe release July 1995 Jupiter arrival (includes December 7, 1995 Io flyby at about 600 mi, Probe entry and relay, Jupiter orbit insertion) Orbital tour of Galilean satellites Dec '95-Oct '97 Europa, Ganymede, Callisto First Ganymede encounter July 1996 SPACECRAFT CHARACTERISTICS Orbiter Probe Mass, lb (kg) 4,890 (2,222 kg) 750 (340 kg) Usable propellant, lb (kg) 2,035 (925) -- Height (in-flight) 20.5 feet (6.15 m) 34 in. (86cm) Inflight span (exc. mag boom) 30 feet (9.2 m) -- Instrument payload 12 experiments 6 experiments Payload mass, lb (kg) 260 (118) 66 (30) Electric power RTGs, 570-480 watts Lithium-sulfur Battery, 730 w-h GALILEO SCIENTIFIC ESPERIMENTS Experiment/Instrument Principal Investigator Objectives PROBE Atmospheric Structure, Alvin Seiff, NASA Ames RC, Temperature, pressure, density, molecular weight profiles Neutral Mass Spectrometer, Hasso Niemann, NASA Goddard SFC, Chemical composition, helium abundance; Ulf von Zahn, Bonn University, FRG, Helium/hydrogen ratio Nephelometer, Boris Ragent, NASA Ames RC, Clouds, solid/liquid particles Net Flux Radiometer, L. A. Sromovsky, Univ. of Wisconsin, Thermal/solar energy profiles; Lightning/energetic particles, Louis Lanzerotti, Bell Laboratories, Detect lightning, measure energetic particles ORBITER (DESPUN) Solid-State Imaging Camera, Michael Belton, NOAO, (Team Leader) Galilean satellites at 1-km resolution or better, other bodies correspondingly Near-Infrared Mapping Spectrometer, Robert Carlson, JPL, Surface/atmospheric composition, thermal mapping Ultraviolet Spectrometer (includes extreme UV sensor on spun section), Charles Hord, Univ. of Colorado, Atmospheric gases, aerosols, etc. Photopolarimeter Radiometer, James Hansen, Goddard Institute for Space Studies, Atmospheric particles, thermal/reflected radiation ORBITER (SPINNING) Magnetometer, Margaret Kivelson, UCLA, Strength and fluctuations of magnetic fields; Energetic Particles, Donald Williams, Johns Hopkins APL, Electrons, protons, heavy ions in atmosphere; Plasma, Louis Frank, Univ. of Iowa, Composition, energy, distribution of ions; Plasma Wave, Donald Gurnett, Univ. of Iowa, Electromagnetic waves and wave-particle interactions; Dust, Eberhard Grun, Max Planck Inst. fur Kernphysik, Mass, velocity, charge of submicron particles Radio Science: Celestial Mechanics, John Anderson, JPL, (Team Leader), Masses and motions of bodies from spacecraft tracking Radio Science: Propagation, H. Taylor Howard, Stanford Univ., Satellite radii, atmospheric structure, from radio propagation Engineering Experiment: Heavy Ion Counter, Edward Stone, Caltech, Spacecraft charged-particle environment INTERDISCIPLINARY INVESTIGATORS Fraser P. Fanale, University of Hawaii Peter Gierasch, Cornell University Donald M. Hunten, University of Arizona Andrew P. Ingersoll, California Institute of Technology David Morrison, University of Hawaii Michael McElroy, Harvard University Glenn S. Orton, NASA Jet Propulsion Laboratory Toby Owen, State University of New York James B. Pollack, NASA Ames Research Center Christopher T. Russell, University of California at Los Angeles Carl Sagan, Cornell University Gerald Schubert, University of California at Los Angeles James Van Allen, University of Iowa ___ _____ ___ /_ /| /____/ \ /_ /| | | | | __ \ /| | | | Ron Baalke | baalke@mars.jpl.nasa.gov ___| | | | |__) |/ | | |___ Jet Propulsion Lab | baalke@jems.jpl.nasa.gov /___| | | | ___/ | |/__ /| M/S 301-355 | |_____|/ |_|/ |_____|/ Pasadena, CA 91109 | ------------------------------ End of SPACE Digest V12 #604 *******************