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- Feb 9, 1999
Pictures of Mars released today by NASA show areas of hydrogen, in blue, which could indicate the presence of ice on the planet.
March 2, 2002
Spacecraft Sends Its First Images of Mars
By JOHN NOBLE WILFORD
Eleven months after its departure from Earth and four months after its arrival at Mars, the Mars Odyssey spacecraft has finally settled into its working orbit and started sending back pictures and other scientific observations of the planet.
The National Aeronautics and Space Administration yesterday made public the mission's first mapping pictures and other data, including evidence of significant amounts of frozen water on and under the Martian surface.
"The signal we've been getting loud and clear is that there is a lot of ice on Mars," William Boynton, a planetary scientist at the University of Arizona, said at a news briefing at the Jet Propulsion Laboratory in Pasadena, Calif., where the mission is managed.
The findings are based on measurements showing the presence of large amounts of hydrogen, especially in a broad region from the planet's south pole to 60 degrees south latitude. Mission scientists said the hydrogen most likely indicated the presence of water ice. The extent of water ice at the north pole cannot be determined, the scientists said, because the northern hemisphere is just coming out of winter and the polar region is obscured by deep layers of frozen carbon dioxide.
The detection of a hydrogen-enriched surface was made by three gamma-ray spectrographic instruments. When cosmic rays strike the planet's surface, they set off reactions that produce distinctive gamma rays that are in effect signatures of the chemical elements in the soil.
In a statement, James Garvin, chief scientist of the Mars exploration program at NASA, said the preliminary assessment of the gamma- ray results indicated the likely presence of hydrogen in the upper few feet of the Martian surface. Scientists for more than two decades have speculated that Mars was not always such a cold, arid place and could have great stores of water bound in polar ice caps and permafrost.
"Further analysis and another month or so of mapping will permit more quantitative assessment of these observations and allow for a refined interpretation," Dr. Garvin said.
Scientists estimated that at most water probably accounts for just a small percentage of the mass of the Martian surface, but is spread over vast stretches of the landscape and extends at least as deep as three feet. Water is considered an indispensable ingredient of life, and its presence on Mars is of increasing interest to scientists who suspect that life once existed on the planet.
The main objectives of the $300 million mission are not only to search for near-surface deposits of water, but also to map the mineral composition of the surface and examine radiation hazards that human explorers would face at Mars. The spacecraft is operating in a circular orbit 200 miles above the planet.
The fact that the spacecraft got there at all and is sending data is a source of no little relief to NASA officials and scientists. At the last opportunity, in 1999, the agency suffered a double failure when an orbiter and a lander each crashed on approach to Mars. That forced the cancellation of a landing mission for this year and led to new management of the Mars Odyssey mission.
Roger Gibbs, Odyssey's deputy project manager, said, "We have a very well-operating spacecraft, and the results have exceeded our expectations."
The only serious problem, engineers said, is that the instrument for detecting radiation on and around Mars stopped communicating and had to be turned off last August. In measurements on the way, however, the instrument indicated that the daily dose of radiation astronauts would experience on such a journey would be more than twice the dose endured by astronauts in the International Space Station in Earth's orbit.
R. Stephen Saunders, the chief project scientist, said "we've not run out of things to try" to restore the radiation-detection instrument to full operation.
The spacecraft's camera system, designed for mapping the planet's surface mineralogy and looking for more clues to its complex geologic history, is taking pictures in visible and infrared light. The infrared instrument has produced detailed temperature maps of the Mars surface by day and night. Some of the infrared images, scientist said, are 30 times sharper than anything previously available.
Copyright 2002 The New York Times Company