Monday, September 3, 2007

2001 Mars Odyssey


The only launch during the 2001 launch window was of NASA's 2001 Mars Odyssey (hereafter referred to as Odyssey). Odyssey was launched on April 7, 2001 aboard a Delta II rocket, and reached Mars on October 24, 2001. The spacecraft is still functional and is, among operating spacecraft, the current longest running mission at 2,141 days (as I write this).

Odyssey was originally named Mars Surveyor 2001 Orbiter and was intended to have a companion spacecraft, Mars Surveyor 2001 Lander. The Lander's mission, however, was canceled in May 2000 following the failures of Mars Climate Orbiter and Mars Polar Lander in late 1999. Subsequently, the name 2001 Mars Odyssey was selected for the orbiter as a specific tribute to the vision of space exploration shown in the works of Arthur C. Clarke, including the novel and movie, 2001: A Space Odyssey.

Odyssey's mission is to use spectrometers and imagers to hunt for evidence of past or present water and volcanic activity on Mars. To do this, Odyssey takes high spatial and spectral resolution images of Martian surface mineralogy and images of surface morphology using its Thermal Emission Imaging System (THEMIS). Odyssey also looks for shallow, subsurface hydrogen (as a sign of the presence of water) and is making a global map of elemental composition using a Gamma Ray Spectrometer (GRS). Another instrument, the Mars Radiation Environment Experiment (MARIE), was used to measure the radiation environment of Mars. That instrument was in use for about 18 months before failing. One other instrument aboard Odyssey is a High Energy Neutron Detector (HEND), provided by Russia.

The initial mission was concluded in August 2004. NASA has approved an extended mission through September 2008 to allow observation of year-to-year differences in phenomena like polar ice, clouds and dust storms. Odyssey also acts as a relay for communications between the Mars Explorations Rovers and Earth. About 85 percent of images and other data from NASA's twin Mars rovers, Spirit and Opportunity, have reached Earth via communications relay by Odyssey, which receives transmissions from both rovers daily. The orbiter helped analyze potential landing sites for the rovers and is doing the same for Mars Phoenix, scheduled to land on Mars in 2008.

Odyssey is also unique in that the mission has its own theme music, "Mythodea," by the Greek composer Vangelis.

Above are two images of Odyssey: the first is an enlarged photograph of Odyssey taken by the Mars Orbiter Camera aboard NASA's Mars Global Surveyor; the second is an annotated computer drawing of Odyssey at the same angle as it appears in the actual image. At the time the photo was taken, the two spacecraft were about 90 km (56 miles) apart. The camera's successful imaging of Odyssey and of the European Space Agency's Mars Express in April 2005 produced the first pictures of any spacecraft orbiting Mars ever taken by another spacecraft orbiting Mars.

Odyssey and Mars Global Surveyor are both in nearly circular, near-polar orbits. Odyssey is in an orbit slightly higher than that of Global Surveyor in order to avoid the possibility of a collision. However, the two spacecraft occasionally come as close together as 15 km (9 miles).

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