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Galileo
Galileo -

Credit: NASA. 22,296 bytes. 272 x 362 pixels.



Class: Planetary. Type: Outer Planets. Nation: United States. Agency: NASA, JPL. Manufacturer: JPL, NASA Ames Research Center.

Galileo was designed to perform in-depth studies of Jupiter's atmosphere, satellites, and surrounding magnetosphere. The mission was named in honour of Galileo Galilei, the Italian Renaissance scientist who discovered Jupiter's major moons in 1610. The spacecraft's primary mission was the deployment of an atmospheric probe into Jupiter's atmosphere (Dec.7, 1995). Following deployment, the vehicle went into orbit around Jupiter to continue its investigations. During its interplanetary cruise, the planned deployment of Galileo's high gain antenna failed, forcing use of the its low gain antennas at much lower than planned data rates. Despite the failure, it is believed approximately 70% of the original science objectives will be achieved. During its flight to Jupiter, Galileo also performed the 1st and 2nd asteroid flybys - Gaspra (Oct.1991) and Ida (Aug.1993). Galileo was also the only vehicle in a position to obtain images of the far side of Jupiter when more than 20 fragments of Comet Shoemaker-Levy plunged into Jupiter's atmosphere in July 1994.

Spacecraft: Orbiter: Dual-spin stabilised. Spinning section (3 rpm) houses fields and particles instruments, antennas, propulsion system, computers, most other support systems. Despun section provides fixed orientation for remote sensing instruments, star scanner, gyros. Bipropellant propulsion system (HHM, NTO) from Federal Republic of Germany uses 12 10N thrusters, 1 400N main engine. S-band communications through 2 omni LGAs (40 bps typical), deployable 4.8 meter wire mesh HGA failed to deploy (planned downlink rate >100 kbps). Redundant flight computers with high level of fault protection. Powered by 2 RTGs (570W BOL, 485W EOL).11 meter deployable boom for some science instruments. Probe: Deceleration module, consisting of aeroshell and aft cover, to slow initial descent and provide thermal control.2.5 m parachute controls descent following deceleration module release. Descent module contains redundant L-band transmitters, instrument package, batteries. Downlink to Orbiter at 128 bps. Primary lithium-sulphur batteries (18 Ahr total) provide power during descent. Payload: Orbiter: Near-Infrared Mapping Spectrometer (NIMS) - makes multispectral images for atmosphere and surface chemical analysis, Ultraviolet Spectrometer (UVS) - studies gases, Solid-State Imager (SSI) - visible imaging with 800 x 800 array CCD, Photopolarimeter (PPR) - measures radiant and reflected energy, Magnetometers (MAG), Dust Detection Experiment (DDE), Plasma Investigation (PLS), Energetic Particle Detector (EPD), Plasma Wave Investigation (PWS), Radio Science Probe: Atmosphere Structure Experiment - measures temperature, pressure and deceleration, Probe Mass Spectrometer - atmospheric composition studies, Helium Abundance Detector - atmospheric composition studies, Probe Nephelometer - cloud location and cloud-particle observations, Net Flux Radiometer - measures the difference, upward versus downward, in radiant energy flux at each altitude, Lightning and Energetic Particles - measures light and radio emissions associated with lightning and energetic particles in Jupiter's radiation belts.
Financial/Operational:
Antenna release failed on 1991.04.11 and subsequent attempts to release it failed, reducing data return rate by an order of magnitude. Probe was released on 1995.07.12 and entered Jupiter's atmosphere on 1995.12.07. Problems with tape recorder on 1995.10.11 forced workarounds.



STS-34STS-34 - STS-34 Galileo spacecraft / IUS deployment sequence in OV-104's payload bay

Credit: NASA. 43,050 bytes. 488 x 474 pixels.


Specification

Design Life: 8 years . Total Length: 6.2 m. Total Mass: 3,881 kg.


Galileo Chronology


18 October 1989 Galileo Launch Site: Cape Canaveral . Launch Vehicle: Shuttle. Mass: 3,881 kg.

Deployed from STS-34 10/18/89; entered Jupiter orbit 12/7/95; investigations of Jupiter's moons, atmosphere, magnetosphere; antenna failed to deploy. Spacecraft engaged in research and exploration of the upper atmosphere or outer space (US Cat B).


11 April 1991 Galileo antenna relese fails

Subsequent attempts to release it failed, reducing data return rate by an order of magnitude.


01 October 1991 Galileo passes by asteroid Gaspra

Galileo returned the first images of an asteroid.



STS-34STS-34 - STS-34 Galileo spacecraft / inertial upper stage (IUS) deployment

Credit: NASA. 5,381 bytes. 298 x 257 pixels.


01 August 1993 Galileo passes by asteroid Ida

This was the second flyby of an asteroid.


01 July 1994 Comet Shoemaker-Levy crashes into Jupiter

Galileo was also the only vehicle in a position to obtain images of the far side of Jupiter when more than 20 fragments of Comet Shoemaker-Levy plunged into Jupiter's atmosphere.


12 July 1995 Galileo probe released

It entered Jupiter's atmosphere on 1995.12.07.


11 October 1995 Problems with Galileo tape recorder

Problem forced workarounds and reduced data return.


07 December 1995 Galileo Probe entered Jupiter's atmosphere

Bibliography:



STS-34STS-34 - Moon taken by Galileo after completing its first Earth Gravity Assist

Credit: NASA. 27,946 bytes. 471 x 455 pixels.



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Last update 12 March 2001.
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