Mars Odyssey launched from Cape Canaveral on April 7, 2001, and arrived at Mars about 200 days later on October 24. Upon arrival, the spacecraft's main engine fired in order to decelerate, which allowed it to be captured into orbit around Mars. Odyssey then spent about 76 days aerobraking, using aerodynamic drag from the upper reaches of the Martian atmosphere to gradually slow down and reduce and circularize its orbit. By planning to use the atmosphere of Mars to slow the spacecraft in its orbit rather than firing its engine or thrusters, Odyssey did not need an additional 200 kilograms (440 lb) of propellant on board. This reduction in spacecraft weight allowed the mission to be launched on a Delta II 7925 launch vehicle, rather than a larger, more expensive launcher.
Mars Odyssey launched from Cape Canaveral on April 7, 2001, and arrived at Mars about 200 days later on October 24. Upon arrival, the spacecraft's main engine fired in order to decelerate, which allowed it to be captured into orbit around Mars. Odyssey then spent about 76 days aerobraking, using aerodynamic drag from the upper reaches of the Martian atmosphere to gradually slow down and reduce and circula.rize its orbit. By planning to use the atmosphere of Mars to slow the spacecraft in its orbit rather than firing its engine or thrusters, Odyssey did not need an additional 200 kilograms (440 lb) of propellant on board This reduction in spacecraft weight allowed the mission to be launched on a Delta II 7925 launch vehicle, rather than a larger, more expensive launcher.