Encyclopedia Astronautica
Magellan



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Magellan
Credit: NASA
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STS-30
STS-30 Magellan spacecraft & IUS deployment from Atlantis' payload bay (PLB)
Credit: NASA
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STS-30
STS-30 Magellan spacecraft & IUS deployment from Atlantis' payload bay (PLB)
Credit: NASA
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STS-30
IUS with Magellan spacecraft drifts into space after STS-30 deployment
Credit: NASA
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STS-30
Magellan radar image compared to high resolution Earth-based image of Venus
Credit: NASA
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STS-30
Global view of Venus from Magellan, Pioneer, and Venera data
Credit: NASA
American Venus probe. One launch, 1989.05.04. The primary objectives of the Magellan mission were to map the surface of Venus with a synthetic aperture radar (SAR) and to determine the topographic relief of the planet.

At the completion of radar mapping 98% of the surface was imaged at resolutions better than 100 m, and many areas were imaged multiple times. Additional studies included measurements of surface altitude using radar altimetry and measurements of the planet's gravitational field using precision radio tracking. The mission was divided up into "cycles", each cycle lasted 243 days (the time necessary for Venus to rotate once under the Magellan orbit - i.e. the time necessary for Magellan to "see" the entire surface once.)

The Magellan mission scientific objectives were to study land forms and tectonics, impact processes, erosion, deposition, chemical processes, and model the interior of Venus. A total of 4225 usable SAR imaging orbits were obtained. Each orbit typically covered an area 20 km wide by 17,000 km long, at a resolution of 75 m/pixel. This raw SAR data was processed into image strips called full-resolution basic image data records (F-BIDRs). Adjacent F-BIDRs were then assembled into full-resolution mosaiced image data records (F-MIDRs). These images were then compressed once (by a factor of 3), twice (9), or 3 times (27), to give C1-, C2-, and C3-MIDRs.

The spacecraft was 3-axis stabilized using 3 reaction wheels. A 3.7 m diameter high gain antenna was used for both telecommunications and radar. Attitude sensors included 2 cruise sun sensors, 1 star scanner, and 2 inertial reference units. The power system included a 12.5 m2 solar array (1029 W EOL) and NiCd batteries (2 x 30 AHr). The hydrazine propulsion system had 0.9 N and 445 N thrusters. X-band (20 W) and S-Band (5 W) communications were provided with downlink rates of 268.8 or 115 kbps. Uplink rates were 31.25 and 62.5 bps.

A single radar instrument operated simultaneously as a Synthetic Aperture Radar (SAR), altimeter, and radiometer. Radar frequency was 2.385 GHz, with 325 W peak power and 25 km swath width (variable). Altimeter resolution was 30 m. Radiometer accuracy was 2 deg C. SAR resolution was 150 m (range and azimuth). An X- and S- band radio subsystem precisely tracked the spacecraft's orbit to make measurements of the gravity field.

Original name of the project was the Venus Orbiting Imaging Radar. Hughes supplied the radar mapper, and Martin the satellite.

Gross mass: 3,444 kg (7,592 lb).
Height: 6.40 m (20.90 ft).
Span: 9.20 m (30.10 ft).
First Launch: 1989.05.04.
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...
  • Martin American manufacturer of rockets, spacecraft, and rocket engines. Martin Marietta Astronautics Group (1956), Denver, CO, 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.
  • National Space Science Center Planetary Page, As of 19 February 1999.. Web Address when accessed: here.
  • NASA Report, Magellan Mission to Venus, Web Address when accessed: here.
  • NASA Report, Magellan: The Unveiling of Venus, Web Address when accessed: here.
  • NASA Report, The Face of Venus: The Magellan Radar-Mapping Mission, Web Address when accessed: here.
  • NASA Report, Revealing the face of Venus: Magellan, Web Address when accessed: here.
  • NASA Report, The Magellan Venus Explorer's Guide, 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...

Magellan Chronology


1989 May 4 - . 18:47 GMT - . Launch Site: Cape Canaveral. Launch Complex: Cape Canaveral LC39B. LV Family: Shuttle. Launch Vehicle: Shuttle. LV Configuration: Space Shuttle STS-30R.
  • Magellan - . Payload: Atlantis F4 / Magellan [IUS]. Mass: 3,444 kg (7,592 lb). Nation: USA. Agency: NASA; JPL. Class: Venus. Type: Venus probe. Spacecraft: Magellan. Decay Date: 1994-10-12 . USAF Sat Cat: 19969 . COSPAR: 1989-033B. SAR radar imaging of the Venusian surface, gravitational field mapping. The Magellan spacecraft was deployed from shuttle STS-30 on May 5, 1989, arrived at Venus on August 10, 1990 and was inserted into a near-polar elliptical orbit with a periapsis altitude of 294 km at 9.5 deg. N. The primary objectives of the Magellan mission were to map the surface of Venus with a synthetic aperture radar (SAR) and to determine the topographic relief of the planet. At the completion of radar mapping 98% of the surface was imaged at resolutions better than 100 m, and many areas were imaged multiple times. The mission was divided up into 'cycles', each cycle lasted 243 days (the time necessary for Venus to rotate once under the Magellan orbit - i.e. the time necessary for Magellan to 'see' the entire surface once.) The mission proceeded as follows: 10 Aug 1990 - Venus orbit insertion and spacecraft checkout;15 Sep 1990 - Cycle 1: Radar mapping (left-looking); 15 May 1991 - Cycle 2: Radar mapping (right-looking); 15 Jan 1992 - Cycle 3: Radar mapping (left-looking); 14 Sep 1992 - Cycle 4: Gravity data acquisition; 24 May 1993 - Aerobraking to circular orbit; 3 Aug 1993 - Cycle 5: Gravity data acquisition; 30 Aug 1994 - Windmill experiment; 12 Oct 1994 - Loss of radio signal; 13 Oct 1994 - Loss of spacecraft. A total of 4225 usable SAR imaging orbits was obtained by Magellan. Magellan showed an Earth-sized planet with no evidence of Earth-like plate tectonics. At least 85% of the surface is covered with volcanic flows, the remainder by highly deformed mountain belts. Even with the high surface temperature (475 C) and high atmospheric pressure (92 bars), the complete lack of water makes erosion a negligibly slow process, and surface features can persist for hundreds of millions of years. Some surface modification in the form of wind streaks was observed. Over 80% of Venus lies within 1 km of the mean radius of 6051.84 km. The mean surface age is estimated to be about 500 million years. A major unanswered question concerns whether the entire surface was covered in a series of large events 500 million years ago, or if it has been covered slowly over time. The gravity field of Venus is highly correlated with the surface topography, which indicates the mechanism of topographic support is unlike the Earth, and may be controlled by processes deep in the interior. Details of the global tectonics on Venus were still unresolved.

1990 August 10 - .
  • Magellan, Venus Orbit Insertion - . Nation: USA. Spacecraft: Magellan.

1994 October 12 - .
  • Magellan Burnup in Venus' Atmosphere - . Nation: USA. Spacecraft: Magellan.

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