Mars Odyssey Detects Signs of Water

The Mars Odyssey (MO) spacecraft has made its first significant discovery: it has detected large deposits of hydrogen - possibly water - near the Red Planet's poles.

Reporting MO's preliminary observations, scientists said the first pass by the probe's neutron spectrometer had revealed evidence of the element in soil at high latitudes.

"It is big," Bill Feldman, of Los Alamos National Laboratory, said of the strength of the signal picked up by Odyssey.

The results indicate large amounts of hydrogen on the surface, a likely sign of water-ice. The observations "are precisely what you would expect for a very hydrogen-rich environment", Feldman said.

American space agency (Nasa) scientists said they were excited by the initial indications of hydrogen deposits, describing the readings sent back as clearer, more definite and much earlier than had been expected.

"We were expecting that it would take many orbits to determine the presence of hydrogen," said Stephen Saunders, a MO scientist. "But we saw it the very first time."

Scientists already know that water exists on Mars; it is frozen in the polar icecaps and exists as vapour in thin clouds.

There is also good evidence that water flowed on the planet's surface in the recent past, carving out deep channels and canyons.

Significant water-ice deposits easily accessible from the surface would make it much more likely that life existed at some stage on Mars.

The MO is currently tightening its orbit around the Red Planet for a mapping mission that will get underway in January. It will use a battery of instruments to survey the planet's surface.

As well as the neutron spectrometer, its gamma-ray spectrometer will chart the chemical composition of the surface. Its infrared camera will peer at areas on the night side of Mars.

"We think it will be a very exciting winter and spring," James Garvin, a Nasa scientist, told a meeting of the American Geophysical Union in San Francisco.

For a little more detail:

FROM SPACE.COM
The Mars Odyssey spacecraft has uncovered preliminary yet tantalizing evidence for water near the surface of Mars and away from the permanently frozen north polar ice cap.
Scientists already know there is water ice in the polar cap. But water ice near the surface in warmer regions of the planet would be a remarkable and long-sought finding that would have broad implications in the search for extraterrestrial life and for the possibility of human exploration of Mars.
The data, collected during tests of Odyssey's neutron spectrometer, show signs of hydrogen, which may or may not mean there is water. Hydrogen is one component of water but also exists alone and in other substances.
NASA researchers stressed that the findings are preliminary. They aren't sure exactly what the new data tell them, but they were optimistic enough to discuss the research this week at a meeting of the American Geophysical Union in San Francisco.

Just 3 feet down
The detection of hydrogen points to the possibility that there is water ice within 3 feet (1 meter) of the surface, said James Garvin, lead scientist for the Mars Exploration Program at NASA Headquarters in Washington, D.C.
"Is this a real science result? Maybe," Garvin told SPACE.com. "But whatever it is, it bodes very well for finding hydrogen in the upper few feet of Mars, and the most likely culprit is water ice."

Such ice might melt in summer months and would be reachable by robotic or human explorers. It might even support microbial life, as researchers have found on Earth that wherever there is water, there is life.

Bill Feldman, the principal investigator of Odyssey's neutron spectrometer and a researcher at Los Alamos National Lab, first revealed the findings Wednesday at the AGU meeting.
The quantity of hydrogen detected was so startling -- suggesting a huge concentration relative to what Feldman saw with a similar instrument on Lunar Prospector, which surveyed the Moon -- that researchers may task Odyssey to begin mapping crustal water ice during the first week January, Garvin said.
Science just beginning
Meanwhile, Odyssey isn't even supposed to be doing science yet. The craft, which arrived at Mars in September, is still in the middle of aerobraking, a procedure designed to slow it down and pull it into a permanent, stable orbit around Mars. The task won't be completed until at least mid-January.
But Garvin said a great story may be about to unfold.
The hydrogen detection was made during the first test of Odyssey's neutron spectrometer, a subsystem of a gamma ray spectrometer instrument.
The test pass covered an area from the equator to the north pole. The resolution of the observations were at 100 kilometers or more.
Garvin explained that the speculation of water ice is based on comparing observations over the permanent ice cap with observations farther south. Scientists know that the polar cap contains both water ice and carbon dioxide ice, commonly thought of as dry ice. The northern ice cap shrinks in summer to as little as 1,000 kilometers in diameter. In winter, it ranges as far south as 60 degrees latitude. Odyssey detected hydrogen farther south, at 55 degrees. The poles are at 90 degrees and zero represents the equator.
"This pass suggested that hydrogen was enriched in a high-latitude region extending from around 55 degrees North to near to the edge of the north polar cap, and that it was not enhanced over the north polar permanent cap," Garvin said. "This suggests, in a most preliminary sense, that if the hydrogen in the northern high latitudes is water, that there is ice in the upper meter or so of this region ... and that it is masked by a carbon dioxide frost cover on the permanent cap."
Garvin and others expect a flurry of findings from Odyssey early next year. The craft will also map Mars in visible and infrared light, and is expected to produce a picture a day beginning in February. But it is the search for water that will be Odyssey's top priority.
Just weeks ago, one top Odyssey scientist said the prospects for finding water near the surface of Mars represented a longshot.
All that seems to have changed now.
"We're not there yet, but getting close. So stay tuned," Garvin said. "We should be reporting on definitive water mapping by sometime in early February 2002. My bet is that we will see lots of new 'water stories' once Odyssey is mapping."

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