Odyssey enters orbit around Red Planet

PASADENA, Calif. -- NASA's 2001 Mars Odyssey spacecraft appeared to successfully enter orbit late Tuesday around the Red Planet, where the space agency suffered back-to-back failures on its previous two tries.

Engineers and scientists at NASA's Jet Propulsion Laboratory received preliminary indication shortly before 8 p.m. that a programmed engine firing had slowed the spacecraft and allowed Mars to capture it into an egg-shaped orbit.

Mission control at NASA's Jet Propulsion Laboratory erupted in cheers.

Odyssey dove over Mars' north pole and dipped behind the planet after the burn began, leaving mission team members waiting anxiously. About 20 minutes later the probe reappeared and transmitted a signal to Earth across 93 million miles of space.

The Mars Odyssey, which reached Mars after a six-month, 286 million-mile journey from Earth, is the first mission to the planet since two NASA failures in 1999. For the space agency, the project represented a shot at redemption.

"It's great. It's wonderful. We're back at Mars," said Daniel McCleese, chief scientist of the JPL Mars program. "The orbit looks even better than the predictions. It's really good."

A spacecraft's transition from interplanetary cruising to arrival has proved to be one of the most challenging phases in the exploration of Mars.

In 1993, contact with NASA's Mars Observer was lost as the satellite neared Mars, probably after a fuel-system explosion. Six years later, a mix-up between English and metric units in calculating trajectory put the Climate Orbiter too close to Mars, causing it to burn up in the atmosphere. The Polar Lander vanished three months later, probably because a software error caused it to plunge to the surface.

Low success rate

The back-to-back losses in 1999 underscored the difficulty of getting to Mars: Fewer than one-third of the 30 missions launched to the planet by the United States and other countries since 1960 have succeeded.

Despite the recent failures, NASA has continued to explore Mars from orbit via the Global Surveyor, which arrived in 1997 and has transmitted thousands of highly detailed images of the Martian surface and dust storms in its atmosphere.

Odyssey was equipped with two instruments to map the distribution of minerals and search for water across the dusty surface of Mars. Liquid water is considered a necessary element for life; finding reservoirs could help determine whether life ever existed on the Red Planet.