Mars Odyssey Orbiter, USA

The 2001 Mars Odyssey is an orbiter carrying three scientific instruments designed to make global observations of Mars to improve understanding of the planet's climate and geologic history, including the search for liquid water and evidence of past life. The mission will extend across a full Martian year, or 29 Earth months.

MARS ODYSSEY AND THE NASA PROGRAMME

2001 Mars Odyssey is part of NASA's Mars Exploration Program, a long-term effort of robotic exploration of the red planet. The opportunity to go to Mars comes around every 26 months, when the alignment of Earth and Mars in their orbits around the sun allows spacecraft to travel between the two planets with the least amount of energy. 2001 Mars Odyssey was launched on 7 April 2001 on the Delta II launch vehicle from Cape Canaveral, Florida and arrived at Mars on 24 October 2001 where it has entered into orbit around the planet. The spacecraft took until late January to settle into a final, circular mapping orbit 250 miles above the planet.

SPACECRAFT JOURNEY AND MISSION

After firing its main engine to slow itself enough to be captured by Mars' gravity, the orbiter began to circle the planet once every 25 hours. Over the next 76 days, the spacecraft gradually edged closer to Mars, using the friction of the atmosphere to lower its orbit (a technique called aerobraking) until it reached a two-hour science orbit. Without aerobraking, the spacecraft would need to carry much more fuel. The spacecraft will then begin its science mapping orbit for 917 Earth days, and will also serve as a communications relay for US and international landers arriving at Mars in 2003/2004.

Odyssey's primary science mission will take place January 2002 through July 2004. For the first time, the mission will map the amount and distribution of chemical elements and minerals that make up the Martian surface. The spacecraft will look especially for hydrogen, most likely in the form of water ice, in the shallow subsurface of Mars. It will also record the radiation environment in low Mars orbit to determine the radiation-related risk to any future human explorers who may one day go to Mars.

In other words, the mission has four main objectives. Objective one is to determine whether life ever arose on Mars. The second objective is to characterize the climate of Mars. Objective three is to characterize the geology of Mars. The final objective for the Mars Odyssey is to prepare for human exploration.

SPECTROMETER STUDIES OF MARS

The 2001 Mars Odyssey mission makes use of many innovative technologies, but the most important among them are the three primary instruments that will carry out science investigations once the spacecraft arrives at Mars. All three involve the use of spectrometers. The three primary instruments, in the form of spectrometers, carried by 2001 Mars Odyssey are THEMIS, GRS, and MARIE.

THEMIS (Thermal Emission Imaging System) is used for determining the distribution of minerals, particularly those that can only form in the presence of water. GRS (Gamma Ray Spectrometer) is used for determining the presence of 20 chemical elements on the surface of Mars, including hydrogen in the shallow subsurface (which acts as a proxy for determining the amount and distribution of possible water ice on the planet). MARIE (Mars Radiation Environment Experiment) is used for studying the radiation environment.

During and after its science mission, the Odyssey orbiter will also support other missions in the Mars Exploration Program. It will provide the communications relay for U.S. and international landers, including the next mission in NASA's Mars Program, the Mars Exploration Rovers, to be launched in 2003. Scientists and engineers will also use Odyssey data to identify potential landing sites for future Mars missions.

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