Magellan (spacecraft)
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| Magellan (spacecraft) | |
|---|---|
| Name | Magellan |
| Mission type | Venus orbiter |
| Operator | NASA / Jet Propulsion Laboratory |
| COSPAR ID | 1989-033B |
| SATCAT | 19969 |
| Mission duration | 4 years, 5 months, 8 days |
| Spacecraft | Magellan |
| Manufacturer | Martin Marietta / Hughes Aircraft |
| Launch mass | 3,445 kilograms (7,595 lb) |
| Power | 1,029 watts |
| Launch date | May 4, 1989, 18:46:59 UTC |
| Launch rocket | Space Shuttle ''Atlantis'' / Inertial Upper Stage |
| Launch site | Kennedy Space Center LC-39B |
| Deployment date | May 5, 1989 |
| End of mission | October 13, 1994 |
| Decay date | October 13, 1994 |
| Orbit reference | Cytherocentric |
| Orbit periapsis | 294 kilometers (183 mi) |
| Orbit apoapsis | 8,463 kilometers (5,259 mi) |
| Orbit inclination | 85.5 degrees |
| Orbit period | 3.26 hours |
| Apsis | cytherean |
| Programme | Discovery Program |
| Previous mission | Lunar Prospector |
| Next mission | NEAR Shoemaker |
Magellan (spacecraft), also known as the Venus Radar Mapper, was a pioneering robotic space probe launched by NASA to map the surface of Venus using synthetic-aperture radar. It was the first interplanetary mission launched from the Space Shuttle and the first to use aerobraking as a primary technique for circularizing its orbit. The spacecraft's detailed radar imaging provided the first high-resolution global view of the planet's cloud-shrouded surface, revolutionizing our understanding of Venusian geology.
Mission overview
The primary objective of the Magellan (spacecraft) mission was to obtain high-resolution radar maps of Venus's surface, as optical observations are impossible due to the planet's permanent, thick cloud cover. Managed by NASA's Jet Propulsion Laboratory, the mission aimed to study surface features, geological processes, and the planet's gravitational field. The data was intended to provide insights comparable to the photographic coverage of Earth and Mars, filling a critical gap in planetary science. The mission was part of a renewed focus on Venus following the earlier successes of the Venera program and Pioneer Venus project.
Spacecraft design
The Magellan (spacecraft) bus was based on the legacy design of the Voyager program, utilizing spare parts from the Voyager 1, Voyager 2, Galileo, and Ulysses programs to reduce cost and development time. The main body was a 4.6-meter (15 ft) tall hexagonal structure, with a large 3.7-meter (12 ft) diameter high-gain antenna that served dual purposes for communications and radar imaging. Power was supplied by two square solar panels, and stabilization was maintained through a system of reaction wheels and thrusters. The spacecraft was built by Martin Marietta with the radar system supplied by Hughes Aircraft.
Scientific instruments
The spacecraft carried a single primary scientific instrument: a sophisticated synthetic-aperture radar (SAR). This system operated in three primary modes: imaging, altimetry, and radiometry. The radar would transmit signals at 2.385 GHz (S band) through the Venusian clouds, with the reflected echoes used to construct detailed images and topographic maps. A separate altimeter mode measured surface height, while a radiometer gauged the natural microwave emissions from the surface to estimate properties like dielectric constant and density.
Mission profile and timeline
Magellan (spacecraft) was launched on May 4, 1989, aboard the Space Shuttle Atlantis during the STS-30 mission. After deployment from the shuttle's cargo bay, an Inertial Upper Stage rocket propelled it on a 15-month trajectory to Venus. It entered orbit on August 10, 1990, and began its primary mapping cycle, which lasted 243 Earth days (one Venusian day). The mission was extended several times, allowing for more detailed mapping and gravitational studies. The mission concluded with a controlled descent into the Venusian atmosphere on October 13, 1994, for a final aerodynamics experiment.
Scientific discoveries
The radar maps revealed a world dominated by volcanism and tectonics, with over 85% of the surface covered by volcanic plains. It discovered vast coronae, pancake-like domes, and evidence of extensive lava flows. Notably, the data showed a relative lack of impact craters, indicating a geologically young surface, globally resurfaced around 500 million years ago. The mission found no evidence of plate tectonics as on Earth, but identified features like tesserae, which are highly deformed highland regions. It also mapped massive shield volcanoes like Maat Mons.
Legacy
Magellan (spacecraft) provided the first complete, high-resolution map of Venus, which remains the most detailed global dataset of the planet's surface. Its success demonstrated the effectiveness of synthetic-aperture radar for planetary exploration and validated aerobraking as a vital technique for future missions like the Mars Global Surveyor. The mission's vast data archive continues to be used by scientists and informed later Venus missions proposed by NASA, ESA, and Roscosmos. It solidified the Discovery Program's model for focused, cost-effective planetary science.
Category:NASA probes Category:Venus spacecraft Category:Spacecraft launched in 1989 Category:Discovery Program