By Leonard David
Senior Space Writer
posted: 12:00 pm ET
12 January 2002

NASA's Mars Odyssey reached a major milestone Friday - the end of repeatedly dipping into the Martian atmosphere to slow down. The probe is now ready to begin its science mapping mission in late February.

Odyssey completed weeks of delicate "aerobraking" maneuvers -- skimming through the upper reaches of the Martian atmosphere -- 332 times since its arrival at Mars.

The craft was launched on April 7, 2001, crossing interplanetary space to reach Mars on October 23, 2001.

The closest point in Odyssey's orbit, called the periapsis, is now 125 miles (201 kilometers) above the surface of the Red Planet. The farthest point in the orbit, labeled the apoapsis, is at an altitude of 311 miles (500 kilometers).

Over the next few weeks, Odyssey's operators will refine the spacecraft's orbit until it reaches its final mapping altitude - a 249-mile (400-kilometer) circular orbit. During that time, the probe will be reconfigured to start the science mapping mission.

"The successful completion of the aerobraking phase is a major milestone for the project. Aerobraking is the most complex phase of the entire mission and the team came through it without a hitch," said David A. Spencer, Odyssey's mission manager at the Jet Propulsion Laboratory (JPL) in Pasadena, California.

JPL manages the 2001 Mars Odyssey mission for NASA's Office of Space Science in Washington, D.C.

The mission's major goal is to map the amount and distribution of chemical elements and minerals that make up the Martian surface. Odyssey will especially look for hydrogen, most likely in the form of water ice, in the shallow subsurface of Mars.

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