2001 Mars Odyssey

2001 Mars Odyssey is a robotic spacecraft orbiting the planet Mars. The project was developed by NASA, and contracted out to Lockheed Martin, with an expected cost for the entire mission of US$297 million. Its mission is to use spectrometers and electronic imagers to detect evidence of past or present water and volcanic activity on Mars. It is hoped that the data Odyssey obtains will help answer the question of whether life has ever existed on Mars. It also acts as a relay for communications between the Mars Exploration Rovers, Mars Science Laboratory, and the Phoenix lander to Earth. The mission was named as a tribute to Arthur C. Clarke, evoking the name of 2001: A Space Odyssey.

Odyssey was launched April 7, 2001 on a Delta II rocket from Cape Canaveral Air Force Station, and reached Mars orbit on October 24, 2001, at 2:30 a.m. UTC (October 23, 7:30 p.m. PDT, 10:30 p.m. EDT). The spacecraft's main engine fired in order to brake the spacecraft's speed, which allowed it to be captured into orbit around Mars. Odyssey used a technique called "aerobraking" that gradually brought the spacecraft closer to Mars with each orbit. By using the atmosphere of Mars to slow down the spacecraft in its orbit, rather than firing its engine or thrusters, Odyssey was able to save more than 200 kilograms (440 lb) of propellant. Aerobraking ended in January, and Odyssey began its science mapping mission on February 19, 2002.

By December 15, 2010 it broke the record for longest serving spacecraft at Mars, with 3,340 days of operation, claiming the title from NASA's Mars Global Surveyor. It currently holds the record for the longest-surviving continually active spacecraft in orbit around a planet other than Earth at 11 years, 1 month and 1 day.