Mars - 2001 Mars Odyssey

In 1895 Percival Lowell said "If Mars be capable of supporting life, there must be water upon his surface; for to all forms of life water is as vital a matter as air. To all organisms water is absolutely essential. On the question FIGURE 7.2 The Sojourner rover "Sojourner Rover," in NASA Facts: Mars Pathfinder, National Aeronautics and Space Administration, Jet Propulsion Laboratory, California Institute of Technology, May 1999, http://www.jpl.nasa.gov/news/fact_sheets.cfm (accessed January 14, 2004)of habitablility, therefore, it becomes all-important to know whether there be water on Mars."

A century later this same issue drove NASA to conduct its most extensive program of missions to the Red Planet, the Mars Exploration Program. This is a long-term program in which robotic explorers are used to investigate Mars in support of four science objectives:

• Determining whether life ever existed on Mars
• Characterizing the climate of Mars
• Characterizing the geology of Mars
• Preparing for future human exploration of Mars

The overall motto of the Mars Exploration Program is "Follow the Water." In other words, the mission scientists hope that discovery of liquid water on Mars will lead them to any microscopic life forms that exist on the planet or were ever present.

The 2001 Mars Odyssey mission falls under NASA's Mars Exploration Program. The mission was named after the hit 1968 movie 2001: A Space Odyssey, based on a short story by science fiction author Arthur C. Clarke.

On April 7, 2001, Odyssey was launched toward Mars atop a Delta II rocket. The spacecraft reached Mars six months later. To conserve fuel Odyssey was placed in Martian orbit via aerobraking. The spacecraft skimmed against the upper edge of the Martian atmosphere hundreds of times over a three-month period to slow itself down.

In February 2002 Odyssey reached its final orbit and began mapping the planet's surface. The mission was intended to last for at least one Mars year. In early January 2004 Odyssey completed one Mars year in service. As of 2006 the spacecraft was still operational and functioning well nearly 275 million miles from Earth.

A schematic of the spacecraft is shown in Figure 7.3. It includes three scientific instruments: a thermal imaging system, a gamma ray spectrometer, and the Mars Radiation Environment Experiment (MARIE).

The thermal imaging system collects surface images in the infrared portion of the electromagnetic spectrum. Everything that has a temperature greater than absolute zero emits infrared radiation. Scientists use Odyssey's images to identify and map minerals in the surface soils and rocks. This work is being coordinated with the mineral mapping being performed by the Mars Global Surveyor.

Odyssey's gamma ray spectrometer can detect the presence of various chemical elements on the planet's surface. This is particularly useful for finding water ice buried beneath the surface and for detecting salty minerals. Odyssey data indicate the presence of large amounts of water ice just beneath the surface in the polar regions. The MARIE instrument collects radiation data that will be useful to planning any future Mars expeditions by humans.

Odyssey's telecommunications system is performing a dual role. It transmits to NASA data collected by the spacecraft itself and also data collected by other NASA spacecraft conducting Mars missions.