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.References: 4, 552, 554.

The improved 3-stage Proton launch vehicle, with a new digital flight control system and enhanced first stage engines, delivered its payload section to a suborbital trajectory at 0356 GMT. The Briz-M upper stage then fired to enter a 200 km parking orbit. It appears that only two more burns were used to reach geostationary orbit: one at around 0440 GMT to enter a 200 x 35800 km GTO, after which the Briz-M toroidal drop tank was jettisoned, and one at around 1000 GMT, to circularize the orbit at geostationary altitude. Briz-M reportedly separated from its payload at 1031 GMT. Ekran was expected to reach its 99 deg E final location on around April 24. As of 5 September 2001 located at 99.27 deg E drifting at 0.009 deg E per day. As of 2007 Mar 11 located at 99.30E drifting at 0.005W degrees per day.References: 4, 552, 554.

• Bay 1-2: Orbiter Docking System, External Airlock, 3 EMU spacesuits - 2160 kg including 360 kg for the 3 suits
• Bay 3 Starboard: Adapter Beam with DCSU switching unit - 180kg
• Bay 5: Spacelab Pallet with Canadarm-2 SSRMS (Space Station Remote Manipulator System, 1800 kg mass), LDA, and 56 kg UHF antenna - 3256 kg
• Bay 6 Port: Adapter Beam with IMAX Camera - 238 kg
• Bay 8-12: Rafaello Module (MPLM-2) with MPLM racks and 3400 kg cargo - 7500 kg
• Sill: Canadarm RMS 303 - 410 kg

On 23 April the SSRMS station manipulator was unberthed from the SLP Spacelab pallet at 1114 GMT and latched on to the PDGF fixture on the Destiny ISS module at 1416 GMT. This was followed at 1458 GMT with the MPLM-2 Raffaello module being moved from Endeavour's payload bay by the Shuttle's RMS and berthed to the nadir port on the ISS Unity module at 1600 GMT. Over the next few days, the cargo racks on the MPLM were transferred to Destiny. Raffaello was then unberthed from Unity at 2003 GMT on April 27 and reberthed in the rear of Endeavour's bay for return to earth at 2059 GMT.

Undocking of Endeavour was delayed by a series of computer problems at the Station. Failures in the Station's command and control computers left only one of the three computers operating.

They were all restarted by April 29, and the Shuttle RMS grappled the Spacelab pallet at 2044 GMT . The station's Canadarm-2 released it at 2106 GMT, and the RMS berthed the pallet back in the Shuttle cargo bay. Endeavour undocked from the Station at 1734 GMT on April 29. The weather in Florida was bad at the planned May 1 landing time, so Endeavour landed in California. The deorbit burn was at 1502 GMT on May 1, with landing at 1610:42 GMT on runway 22 at Edwards. Endeavour returned to the Kennedy Space Center atop a Boeing 747 SCA aircraft on May 9.References: 4, 296.