Fifteen years ago, the Mars Odyssey orbiter launched from Cape Canaveral Air Force Station in Florida. At 11:02 a.m. on April 7, 2001, Odyssey began a 200-day journey to the red planet which was followed by a three-month long, fuel-saving aerobraking phase which used Mars' thin upper atmosphere to slow the spacecraft and adjust the size and shape of its orbit.

The official name “2001 Mars Odyssey” was selected as a tribute to science fiction author Arthur C. Clarke and his novel "2001: A Space Odyssey."

The mission and its three primary instruments immediately went to work on objectives which support the four science goals of NASA’s Mars exploration program: determine whether life ever arose on Mars, characterize the climate of Mars, characterize the geology of Mars and prepare for human exploration.

The THEMIS (Thermal Emission Imaging System) instrument is used to determine the distribution of minerals, particularly those that can only form in the presence of water; GRS (Gamma Ray Spectrometer) determines 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). These instruments worked together to globally map the amount and distribution of many chemical elements and minerals that make up the Martian surface. Hydrogen distribution maps led scientists to discover vast amounts of water/ice in the polar regions buried just beneath the surface.

MARIE (Mars Radiation Environment Experiment) studies 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.

The orbiter has also provided a communications relay for missions on the surface of Mars. It supported communications with the Mars Phoenix Lander as well as both Mars Exploration rovers, "Spirit" and "Opportunity," transmitting over 95 percent of the data from the rovers to Earth. Imaging from Odyssey was used to select the landing site for the Curiosity rover and continues to serve that same data relay function for Curiosity along with the Mars Reconnoissance Orbiter, which arrived in 2006. (The European Space Agency's Mars Express orbiter may also be used when other data paths are not available.)

Odyssey set the longevity record for a Mars mission in December 2010, and it continues to pile on the years.

"The spacecraft is remarkably healthy, and we have enough fuel to last for several more years,” said Odyssey Project Manager David Lehman of NASA's Jet Propulsion Laboratory in Pasadena, Calif. “In addition to the quality of this spacecraft, the careful way it is operated has been crucial to how it has stayed so productive so long.”

The 16 Earth years that Odyssey has been at work equate to about six Martian years. It has observed seasonal patterns that repeat each year and other seasonal events, such as large dust storms, which differ significantly from year to year.

Over the years, mission planners have been able to adjust the spacecraft orbit to observe early morning light on the surface of Mars and to study morning clouds and fogs and compare ground temperatures in the morning to temperatures of the same sites in the afternoon and pre-dawn.

Tony Rice is a volunteer in the NASA/JPL Solar System Ambassador program and software engineer at Cisco Systems. You can follow him on twitter @rtphokie.