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Status: Active.
Gross mass: 231,000 kg (509,000 lb).
Height: 39.00 m (127.00 ft).
Diameter: 2.44 m (8.00 ft).
Thrust: 4,000.00 kN (899,200 lbf).
Apogee: 400,000 km (240,000 mi).
First Launch: 1998.01.10.
Last Launch: 2006.11.17.
Number: 20 .
The 2001 Mars Odyssey probe entered Mars orbit on October 24, 2001. The orbit insertion burn with the main 640 N bipropellant N2O4/hydrazine engine began at 0218 GMT lasted 20 min 19 sec. Mass of the spacecraft was then 456 kg, including 79 kg of fuel left. Initial orbit was was 272 x 26818 km x 93.42 deg with periapsis near the Martian north pole. 76 days of aerobraking began on October 26 to slowly circularise the orbit to its 400 km altitude, 2 hour period sun synchronous operational orbit. The solar panels reached 180 deg C as Odyssey skimmed through upper atmosphere of Mars on each orbit.
After reaching the operational orbit, the probe was to conduct a 917 day mapping program. It was to also serve as a communications relay for American and international landers expected to arrive in 2003/2004. In the Martian orbit, it was to map the distribution of elements and minerals on the surface, the distribution of hydrogen (embedded in water ice) and the radiation environment. The second was to assess the likelyhood of past or present life, and the third was to assess the radiation hazard to manned missions. The three major instruments on board were THEMIS (Thermal Emission Imaging System at the visible and infrared light) for the distribution, at 100 meter resolution, of minerals that form only in the presence of water, GRS (Gamma Ray Spectrometer) for determining hydrogen and other elements, and MARIE (presumably, MArs RadIation Environment) for determining the radiation hazard. THEMIS was to also enable site selection for a future manned landing. THEMIS was expected to provide 15,000 images, each covering 20 x 20 km. GRS carried two neutron monitors also. The gamma rays and neutrons come out of the surface in distinct, element-specific energies, released by cosmic ray bombardment.