Original run date: October 25, 2001

Odyssey's success cheers NASA

PASADENA, Calif. - NASA declared its Mars Odyssey spacecraft healthy Wednesday after a flawless entry into orbit that broke a succession of failed missions to the red planet and set the stage for a series of controlled dips into the atmosphere.

The satellite arrived within a half-mile of the targeted point Tuesday night, a feat mission officials likened to hitting a bull's-eye after a six-month, 286 million-mile journey from Earth.

"All eyes were on navigation for this one, so I am glad we could deliver," lead navigator Bob Mase said at the National Aeronautics and Space Administration's Jet Propulsion Laboratory.

Arriving in Mars orbit was the most critical step in the $297 million mission; coaxing the spacecraft into a much tighter orbit is the next.

During the next three months and 400 spins around Mars, Odyssey will make sporadic dips into the martian atmosphere in a process called aerobraking. The technique, scheduled to begin Friday, will gradually reshape the probe's orbit.

"During aerobraking, we're literally surfing the waves of the martian atmosphere," said David Spencer, the mission's manager at the JPL.

Mars' gravity captured Odyssey in a large elliptical orbit in which the spacecraft takes 18 1/2 hours to completely circle the planet.

Aerobraking largely eliminates the need to use an engine firing to draw Odyssey into a closer orbit around Mars, but it requires around-the-clock attention from the mission team.

"It's a way to save propellant, but what you use is people," said Steve Jolly, the mission's risk manager at Lockheed Martin Astronautics, the Denver-area company that built the spacecraft.

The spacecraft should settle into its final mapping orbit by late January, when it will zip around Mars every two hours at an altitude of 250 miles.

Arrival at Mars has been perilous for previous missions: Just one-quarter of all satellites launched to the planet have successfully gone into orbit.

Mars Observer disappeared as it neared the planet in 1993, probably due to a fuel system explosion. In 1999, a mix-up between English and metric units put the Climate Orbiter too close to Mars, causing it to burn up in the atmosphere. NASA's Polar Lander vanished three months later, probably due to a software error sending it crashing to the planet's surface. Mission officials said Odyssey's success erased the stigma of those failures.

Original run date: October 24, 2001

Odyssey in Mars orbit

Chris Richards / Staff
William Boynton and Christopher Shinohara toast with champagne moments after the Mars Odyssey spacecraft made contact.

Success of difficult maneuver brings cheers at UA laboratory

With the future of Mars exploration hinging on its fate, a NASA spacecraft safely emerged from the dark side of the Red Planet Tuesday night and phoned home.

The mood at an open house at the UA's Lunar and Planetary Laboratory went from jittery to jubilant as NASA's Mars Odyssey spacecraft performed a difficult maneuver to curve and slow into Mars orbit.

Three Mars missions have been lost since 1993, two of them at the same critical juncture Odyssey met at 7:26 p.m. Tucson time.

Odyssey will map the chemical and mineralogical makeup of the planet, scouting sites for future missions that ultimately could lead to human exploration of Mars. Two of the three instruments aboard Odyssey were designed and built by Arizona scientists.

The spacecraft fired its main engine, then disappeared behind Mars where no contact with mission control was possible until it transmitted a radio signal back to NASA at 7:54 p.m.

A crowd of more than 120 people at the UA's Kuiper Space Sciences Building watching NASA television on a big screen saw officials at the Jet Propulsion Laboratory in Pasadena, Calif., suddenly smile and embrace, and began a raucous celebration of their own in the third-floor atrium.

"Folks, we're on our way," said William Boynton, a University of Arizona cosmochemist and team leader for the gamma ray spectrometer instrument aboard Odyssey.

After two consecutive failures, NASA needs Odyssey to meet expectations to keep its Mars program on course, said Michael Drake, director of the Lunar and Planetary Laboratory and chairman of NASA's Solar System Exploration Subcommittee.

"It was extraordinarily important that we go into orbit successfully tonight," Drake said. "It wouldn't have meant we won't go to Mars, but if it had failed, it would certainly have caused a significant re-evaluation and delay in the program."

Boynton said he was nervous but confident that errors that doomed previous missions would not be repeated. "This time, I knew a lot more people were looking over people's shoulders," he said.

The spacecraft still needs to perform a series of "aerobraking" procedures to ease it into its science orbit, but the orbit-entry maneuver performed Tuesday is "the most stressful point" of any planetary mission, Boynton said.

"Everybody thinks going into orbit is easy, but getting into the atmosphere just deep enough to slow a spacecraft but not so deep as to rip it apart is anything but easy," Drake said.

"Now, it's relatively straightforward, as straightforward as anything in space can be."

Boynton and a team of 30 at the UA built the gamma ray spectrometer, which will map the composition of Mars for the presence of 20 chemical elements.

The spectrometer, made up of a gamma ray sensor and two neutron detectors, will look for salt crystals from dried-up oceans and hydrogen from water that may yet exist on the surface and up to 2 meters below.

The other Arizona instrument, THEMIS, is composed of a camera and a thermal imager built by Philip Christenson of Arizona State University. THEMIS will identify minerals on the Martian surface.

The third instrument, designed by scientists at NASA's Johnson Space Center, will measure how much dangerous radiation there is on Mars, so NASA can protect astronauts who will someday visit the planet. That instrument, MARIE, has yet to show a pulse, and has been turned off indefinitely, said Heather Enos, senior project coordinator for the spectrometer team.

That gives new irony to the moni-ker of "Arizona Orbiter" that LPL's Drake half-jokingly suggested for Odyssey.

"This is pretty much a pure Arizona activity, and it speaks credibly to how capable Arizona scholars are when it comes to Mars exploration," Drake said. "I think it's a real tribute to people here and at ASU."

Both THEMIS and the gamma ray spectrometer have been tested during Odyssey's 285 million-mile journey to Mars that began in April. Both are operating optimally, Enos said.

The neutron detectors of Boynton's instrument will be switched on as Odyssey slows down into smaller and smaller elliptical orbits.

"We could be getting data from those as early as 9 a.m. (today)," said Chris Shinohara, project manager for the spectrometer team.

The real science will begin in February, when the craft settles into a circular orbit about 260 miles from the planet.

If the rest of Odyssey's missions mirror last night's orbit entry, Boynton will get data back from the Red Planet after two failed attempts.

His first gamma ray spectrometer reached the planet on Mars Observer, which vanished as it was about to enter orbit in 1993. Observer probably blew up when it pressurized its propellant tanks just before it fired its main engine, said geologist David Kring, director of the UA's Space Imagery Center.

Six years later, Mars Climate Orbiter zeroed in on the planet too hard and essentially burned up in the atmosphere, Kring said.

Boynton's second crack at Mars came that same year, with a set of miniature ovens that would have cooked Martian soil aboard Mars Polar Lander, which never called home to signal its arrival. Kring said the prevailing opinion is that when Polar Lander's parachutes opened, the jolt told the craft to turn off the retrorockets that slowed its descent, causing the craft to crash onto the surface.

Odyssey has a special significance in identifying ideal landing sites for future missions, Enos said. High concentrations of hydrogen, signaling the presence of water or ice, would make excellent landing spots, she said.

* Contact Thomas Stauffer at 573-4197 or at stauffer@azstarnet.com.

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