Encyclopedia Astronautica
Galileo



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Galileo
Credit: NASA
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Galileo
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STS-34
STS-34 Galileo spacecraft / IUS deployment sequence in OV-104's payload bay
Credit: NASA
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STS-34
STS-34 Galileo spacecraft / inertial upper stage (IUS) deployment
Credit: NASA
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STS-34
Moon taken by Galileo after completing its first Earth Gravity Assist
Credit: NASA
American outer planets probe. One launch, 1989.10.18. The Galileo Jupiter orbiter was designed to perform in-depth studies of the giant planet's atmosphere, satellites, and surrounding magnetosphere.

The spacecraft's primary mission was the deployment of an atmospheric probe into Jupiter's atmosphere. During interplanetary cruise, 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, a series of mission extensions and software improvisations resulted in the original science objectives being vastly exceeded. Galileo also performed two asteroid flybys and obtained images of the far side of Jupiter when Comet Shoemaker-Levy impacted in July 1994.

Galileo was designed to perform in-depth studies of Jupiter's atmosphere, satellites, and surrounding magnetosphere. The mission was named in honor 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. Following deployment of the probe, the spacecraft went into orbit around Jupiter to continue its investigations.

At the beginning of Galileo's interplanetary cruise, the planned deployment of the high gain antenna failed on 11 April 1991. Subsequent attempts to release it also failed. This forced use of the the low gain antennas at an order-of-magnitude lower than planned data rate. Heroic efforts by JPL staff to develop workarounds resulted in virtually no loss of science data. During its flight to Jupiter, Galileo also performed the first and second asteroid flybys - Gaspra (October 1991) and Ida (August 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. The Galileo probe was released on 12 July 1995 and entered Jupiter's atmosphere on 7 December 1995. Problems with the tape recorder on 11 October 1995 also forced workarounds, but Galileo provided years of service in Jupiter orbit.

The orbiter was dual-spin stabilized. The spinning section (3 rpm) housed fields and particles instruments, antennas, propulsion system, computers, and most other support systems. The despun section provided fixed orientation for remote sensing instruments, star scanner, and gyros. The bipropellant propulsion system (HHM, NTO) from the Federal Republic of Germany used 12 x 10 N thrusters, 1 x 400 N main engine. S-band communications were through two omni low gain antennas (40 bps typical). The deployable 4.8 meter wire mesh high gain antenna failed to unfold and could not be used (planned downlink rate >100 kbps). Redundant flight computers with high level of fault protection kept Galileo operating throughout its extended mission.

The orbiter was powered by two radioisotope thermal generators (570 W BOL, 485 W EOL). An 11 meter deployable boom provided mounting for some science instruments. Orbiter Payload:

  • Near-Infrared Mapping Spectrometer (NIMS) - made multispectral images for atmosphere and surface chemical analysis
  • Ultraviolet Spectrometer (UVS) - studied gases
  • Solid-State Imager (SSI) - visible imaging with 800 x 800 array CCD
  • Photopolarimeter (PPR) - measured radiant and reflected energy
  • Magnetometers (MAG)
  • Dust Detection Experiment (DDE)
  • Plasma Investigation (PLS)
  • Energetic Particle Detector (EPD)
  • lasma Wave Investigation (PWS)
  • Radio Science Probe

The probe consisted of a deceleration module, comprising an aeroshell and aft cover, for reentry and thermal control. A 2.5 m parachute controled descent following deceleration module release. The descent module contained redundant L-band transmitters, an instrument package, and batteries. Downlink to the Orbiter was at 128 bps. Primary lithium-sulfur batteries (18 Ahr total) provided power during descent.

Probe Payload:

  • Atmosphere Structure Experiment - measured 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 - measured the difference, upward versus downward, in radiant energy flux at each altitude
  • Lightning and Energetic Particles - measured light and radio emissions associated with lightning and energetic particles in Jupiter's radiation belts
.

Financial/Operational:

Gross mass: 3,881 kg (8,556 lb).
Height: 6.15 m (20.17 ft).
First Launch: 1989.10.18.
Number: 1 .

More... - Chronology...


Associated Countries
See also
  • Shuttle The manned reusable space system which was designed to slash the cost of space transport and replace all expendable launch vehicles. It did neither, but did keep NASA in the manned space flight business for 30 years. More...

Associated Launch Vehicles
  • Shuttle American winged orbital launch vehicle. The manned reusable space system which was designed to slash the cost of space transport and replace all expendable launch vehicles. It did neither, but did keep NASA in the manned space flight business for 30 years. Redesign of the shuttle with reliability in mind after the Challenger disaster reduced maximum payload to low earth orbit from 27,850 kg to 24,400 kg. More...

Associated Manufacturers and Agencies
  • JPL American agency;manufacturer of rockets, spacecraft, and rocket engines. Jet Propulsion Laboratory, Pasadena, USA. More...
  • NASA American agency overseeing development of rockets and spacecraft. National Aeronautics and Space Administration, USA, USA. More...

Bibliography
  • McDowell, Jonathan, Jonathan's Space Home Page (launch records), Harvard University, 1997-present. Web Address when accessed: here.
  • JPL Mission and Spacecraft Library, Jet Propulsion Laboratory, 1997. Web Address when accessed: here.
  • McDowell, Jonathan, Launch Log, October 1998. Web Address when accessed: here.
  • NASA Report, Galileo Jupiter Arrival Press Kit, Web Address when accessed: here.
  • NASA Report, The Jupiter Millennium Mission Press Kit, Web Address when accessed: here.
  • NASA Report, Galileo End of Mission Press Kit, Web Address when accessed: here.
  • NASA Report, Galileo Mission to Jupiter Factsheet, Web Address when accessed: here.
  • NASA Report, Millennium Flyby Travel Guide, Web Address when accessed: here.
  • NASA Report, The Galileo Mission To Jupiter and It's Moons, Web Address when accessed: here.
  • NASA Report, Project Galileo: surviving Io, meeting Cassini, Web Address when accessed: here.

Associated Launch Sites
  • Cape Canaveral America's largest launch center, used for all manned launches. Today only six of the 40 launch complexes built here remain in use. Located at or near Cape Canaveral are the Kennedy Space Center on Merritt Island, used by NASA for Saturn V and Space Shuttle launches; Patrick AFB on Cape Canaveral itself, operated the US Department of Defense and handling most other launches; the commercial Spaceport Florida; the air-launched launch vehicle and missile Drop Zone off Mayport, Florida, located at 29.00 N 79.00 W, and an offshore submarine-launched ballistic missile launch area. All of these take advantage of the extensive down-range tracking facilities that once extended from the Cape, through the Caribbean, South Atlantic, and to South Africa and the Indian Ocean. More...
  • Cape Canaveral LC39B Shuttle, Saturn V, Saturn I launch complex. LC39A and LC39B, part of the Kennedy Space Center, were built on Merritt Island (north/northwest of the Cape) to support the Saturn V/Apollo lunar landing program in 1963-1966. The sites were modified in the last half of the 1970s to support the manned Space Shuttle program. More...

Galileo Chronology


1989 October 18 - . 16:53 GMT - . Launch Site: Cape Canaveral. Launch Complex: Cape Canaveral LC39B. LV Family: Shuttle. Launch Vehicle: Shuttle. LV Configuration: Space Shuttle STS-34R.
  • Galileo - . Payload: Atlantis F5 / Galileo [IUS]. Mass: 3,881 kg (8,556 lb). Nation: USA. Agency: NASA; JPL. Class: Outer planets. Type: Outer planets probe. Spacecraft: Galileo. USAF Sat Cat: 20298 . COSPAR: 1989-084B. Deployed from STS-34 18 October 1989; entered Jupiter orbit 7 December 1995 and conducted investigations of Jupiter's moons, atmosphere, and magnetosphere. Although the antenna failed to deploy, NASA developed workarounds and the spacecraft cruised the Jovian system for eight years. Its propellant then depleted, it was maneuvered to enter the Jovian atmosphere on September 21, 2003, at 18:57 GMT. Entry was at 48.2 km/s from an orbit with a periapsis 9700 km below the 1-bar atmospheric layer. The spacecraft continued transmitting at least until it passed behind the limb of Jupiter at 1850:54 GMT, at which point it was 9283 km above the 1-bar level, surprising Galileo veterans who feared it might enter safemode due to the high radiation environment. On its farewell dive, it had crossed the orbit of Callisto at around 1100 on September 20, the orbit of Ganymede at around 0500 on September 21, Europa's orbit at about 1145, Io's orbit at about 1500, Amalthea's orbit at 1756, and the orbits of Adrastea and Metis at 1825. Galileo was destroyed to prevent the possibility that its orbit would eventually be perturbed in such a way that it would crash on and biologically contaminate Europa, which was considered a possible place to search for life. Light travel time from Jupiter to Earth was 52 min 20 sec at the time of impact, and the final signal reached Earth at 1943:14 GMT.

1990 February 9 - .
  • Galileo, Venus Flyby - . Nation: USA. Spacecraft: Galileo.

1990 December 8 - .
  • Galileo, first Earth Flyby - . Nation: USA. Spacecraft: Galileo.

1991 April 11 - .
  • Galileo antenna relese fails - . Nation: USA. Spacecraft: Galileo. Summary: Subsequent attempts to release it failed, reducing data return rate by an order of magnitude..

1991 October - .
  • Galileo passes by asteroid Gaspra - . Nation: USA. Spacecraft: Galileo. Summary: Galileo returned the first images of an asteroid..

1991 October 29 - .
  • Galileo, Asteroid Gaspra Flyby - . Nation: USA. Spacecraft: Galileo.

1992 July 8 - .
  • Comet Shoemaker-Levy 9 Near-Jupiter Flyby (0.0008 AU), Comet Breakup - . Spacecraft: Galileo.

1992 December 8 - .
  • Galileo, second Earth Flyby - . Nation: USA. Spacecraft: Galileo.

1993 August - .
  • Galileo passes by asteroid Ida - . Nation: USA. Spacecraft: Galileo. Summary: This was the second flyby of an asteroid..

1993 August 28 - .
  • Galileo Flyby of Asteroid Ida & Dactyl - . Nation: USA. Spacecraft: Galileo.

1994 July - .
  • Comet Shoemaker-Levy crashes into Jupiter - . Nation: USA. Spacecraft: Galileo. Summary: 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..

1994 July 16 - .
  • Comet Shoemaker-Levy 9 Impacts on Jupiter - . Spacecraft: Galileo.

1995 July 12 - .
  • Galileo probe released - . Nation: USA. Spacecraft: Galileo. Summary: It entered Jupiter's atmosphere on 1995.12.07..

1995 October 11 - .
  • Problems with Galileo tape recorder - . Nation: USA. Spacecraft: Galileo. Summary: Problem forced workarounds and reduced data return..

1995 December 7 - .
  • Galileo, Jupiter Orbit Insertion - . Nation: USA. Spacecraft: Galileo.

1995 December 7 - .
  • Galileo Probe entered Jupiter's atmosphere - . Nation: USA. Spacecraft: Galileo.

1996 June 27 - .
  • Galileo, Ganymede 1 Flyby - . Nation: USA. Spacecraft: Galileo.

1996 September 6 - .
  • Galileo, Ganymede 2 Encounter - . Nation: USA. Spacecraft: Galileo.

1996 November 4 - .
  • Galileo, Callisto 3 Flyby - . Nation: USA. Spacecraft: Galileo.

1997 February 20 - .
  • Galileo, Europa 6 Flyby - . Nation: USA. Spacecraft: Galileo.

1997 June 25 - .
  • Galileo, Callisto 9 Encounter - . Nation: USA. Spacecraft: Galileo.

1998 February 10 - .
  • Galileo, Europa 13 Flyby - . Nation: USA. Spacecraft: Galileo.

1998 March 29 - .
  • Galileo, Europa 14 Flyby - . Nation: USA. Spacecraft: Galileo.

1998 May 31 - .
  • Galileo, Europa 15 Flyby - . Nation: USA. Spacecraft: Galileo.

1998 July 21 - .
  • Galileo, Europa 16 Flyby - . Nation: USA. Spacecraft: Galileo.

1998 September 26 - .
  • Galileo, Europa 17 Flyby - . Nation: USA. Spacecraft: Galileo.

1998 November 22 - .
  • Galileo, Europa 18 Flyby - . Nation: USA. Spacecraft: Galileo.

1999 February 1 - .
  • Galileo, Europa 19 Flyby - . Nation: USA. Spacecraft: Galileo.

1999 May 5 - .
  • Galileo, Callisto 20 Flyby - . Nation: USA. Spacecraft: Galileo.

1999 June 30 - .
  • Galileo, Callisto 21 Encounter - . Nation: USA. Spacecraft: Galileo.

1999 August 14 - .
  • Galileo, Callisto 22 Flyby - . Nation: USA. Spacecraft: Galileo.

1999 November 26 - .
  • Galileo Io 25 Flyby - . Nation: USA. Spacecraft: Galileo.

2000 January 3 - .
  • Galileo, Europa 26 Flyby - . Nation: USA. Spacecraft: Galileo.

2000 February 22 - .
  • Galileo, Io 27 Flyby - . Nation: USA. Spacecraft: Galileo.

2000 May 20 - .
  • Galileo, Ganymede 28 Flyby - . Nation: USA. Spacecraft: Galileo.

2000 December 28 - .
  • Galileo, Ganymede 29 Flyby - . Nation: USA. Spacecraft: Galileo.

2001 May 25 - .
  • Galileo, Callisto 30 Flyby - . Nation: USA. Spacecraft: Galileo.

2001 August 6 - .
  • Galileo, Io 31 Flyby - . Nation: USA. Spacecraft: Galileo.

2002 January 17 - .
  • Galileo, Io 33 Flyby - . Nation: USA. Spacecraft: Galileo.

2002 July 9 - .
  • Galileo, Enters Solar Conjunction - . Nation: USA. Spacecraft: Galileo.

2002 July 28 - .
  • Galileo, Exits Solar Conjunction - . Nation: USA. Spacecraft: Galileo.

2002 November 5 - .
  • Galileo, Amalthea 34 Flyby - . Nation: USA. Spacecraft: Galileo.

2003 August 11 - .
  • Galileo Enters Solar Conjunction - . Nation: USA. Spacecraft: Galileo.

2003 September 1 - .
  • Galileo Exits Solar Conjunction - . Nation: USA. Spacecraft: Galileo.

2003 September 21 - .
  • Galileo ends mission and is commaned to burn up in Jupiter's atmosphere. - . Nation: USA. Spacecraft: Galileo. USAF Sat Cat: 20298 . Although the antenna failed to deploy, NASA developed workarounds and the spacecraft cruised the Jovian system for eight years. Its propellant then depleted, it was maneuvered to enter the Jovian atmosphere on September 21, 2003, at 18:57 GMT. Entry was at 48.2 km/s from an orbit with a periapsis 9700 km below the 1-bar atmospheric layer. The spacecraft continued transmitting at least until it passed behind the limb of Jupiter at 1850:54 GMT, at which point it was 9283 km above the 1-bar level, surprising Galileo veterans who feared it might enter safemode due to the high radiation environment. On its farewell dive, it had crossed the orbit of Callisto at around 1100 on September 20, the orbit of Ganymede at around 0500 on September 21, Europa's orbit at about 1145, Io's orbit at about 1500, Amalthea's orbit at 1756, and the orbits of Adrastea and Metis at 1825. Galileo was destroyed to prevent the possibility that its orbit would eventually be perturbed in such a way that it would crash on and biologically contaminate Europa, which was considered a possible place to search for life. Light travel time from Jupiter to Earth was 52 min 20 sec at the time of impact, and the final signal reached Earth at 1943:14 GMT.

2003 September 21 - .
  • Galileo, Jupiter Impact - . Nation: USA. Spacecraft: Galileo.

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