Magellan Credit - NASA Media Gallery

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.

Design Life: 4 years. Typical orbit: Venus orbit. Length: 6.40 m (20.90 ft). Span: 9.20 m (30.10 ft). Mass: 3,444 kg (7,592 lb). Associated Launch Vehicle: Shuttle.

• 1989 May 4 - Magellan - Launch Site: Cape Canaveral. Launch Vehicle: Shuttle. Mass: 3,444 kg (7,592 lb).

  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 -

• 1994 October 12 - Magellan Burnup in Venus' Atmosphere -

• NASA Report, The Magellan Venus Explorer's Guide, . Accessed at: http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19900019276_1990019276.pdf. -right click to download pdfs!

• NASA Report, Revealing the face of Venus: Magellan, . Accessed at: http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930017328_1993017328.pdf. -right click to download pdfs!

• NASA Report, The Face of Venus: The Magellan Radar-Mapping Mission, . Accessed at: http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19960023593_1996031327.pdf. -right click to download pdfs!

• Krebs, Gunter, Gunter's Space Page, University of Frankfurt, 1996. Accessed at: http://www.skyrocket.de/space.

• NASA Report, Magellan: The Unveiling of Venus, . Accessed at: http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19890015048_1989015048.pdf. -right click to download pdfs!

• JPL Mission and Spacecraft Library, Jet Propulsion Laboratory, 1997. Accessed at: http://msl.jpl.nasa.gov/home.html.

• McDowell, Jonathan, Jonathan's Space Home Page, Harvard University, 1997-present. Jonathan McDowell's complete on-line listing of all objects orbited and over 20,000 rocket launches Accessed at: http://www.planet4589.org/jsr.html.

• USAF Satellite Database, USAF Institute of Technology, 1995. Accessed at: ftp://archive.afit.af.mil/pub/space/.

• NASA Report, Magellan Mission to Venus, . Accessed at: http://www.jpl.nasa.gov/news/fact_sheets/mgn.pdf. -right click to download pdfs!

• National Space Science Center Planetary Page, As of 19 February 1999.. Accessed at: http://nssdc.gsfc.nasa.gov/planetary/planetary_home.html.