Spacecraft finds evidence of water on Mars
WASHINGTON (AP) – Evidence of vast deposits of water frozen under the rocky soil of Mars suggests a source of drinking water and rocket fuel for explorers and boosts the possibility that life once existed on the Red Planet. Scientists using instruments on NASA’s Mars Odyssey spacecraft have found strong signals that ice – perhaps enough to twice fill Lake Michigan – lies just beneath the red surface of Mars.
“The subsurface ice detected by Odyssey instruments represents only the tip of an iceberg frozen underground,” Jim Bell, an astronomer at Cornell University in Ithaca, N.Y., and author of a report in the journal Science. Two other papers giving details of the Odyssey probes of Mars also will appear in the journal next Friday.
In a study led by William Boynton of the University of Arizona, researchers reported that a gamma ray spectrometer detected a high concentration of hydrogen in the top three feet of Mars in large areas around the planet’s poles.
“This is the best direct evidence we have of subsurface water ice on Mars,” Boynton said in a statement. “We were hopeful that we could find evidence of ice, but what we found is much more ice than we ever expected.”
Planetary experts have long believed Mars once had lakes, ponds and rivers and was more Earthlike. The water disappeared early in the planet’s history, and researchers have been puzzled about where the water went. Now, the new studies suggest the water filtered into the soil and became trapped as ice.
Odyssey’s instruments detect the signature of water in the soil by measuring the reaction of cosmic rays as they strike the Martian surface. Cosmic rays are highly energetic particles, and when they collide with atoms, they send other particles, such as neutrons, flying off in all directions. These neutrons, in turn, strike hydrogen atoms, gamma rays are emitted, and the neutrons are slowed.
Thus, by measuring the gamma rays and the velocity of neutrons, the instruments collect a signature for the presence of hydrogen. And most scientists believe the most likely source of this hydrogen is frozen water, which comprises two atoms of hydrogen and one of oxygen.
“The signal Odyssey has detected is a very strong signal, which is easy to reconcile as ice,” said Bell. “It is not a certainty, but it is very compelling evidence” for the presence of water ice.
Earlier studies had found evidence for the presence of water on Mars. The polar ice caps change seasonally, as if ice were melting; water vapor was detected in the planet’s atmosphere, and the Mars surface is shaped with flood plains, gullies and channels similar to those formed by water on Earth.
The new evidence supports the notion of a great deal of water on Mars, Bell said, and this could make it easier to explore the Red Planet.
“If there is a resource there waiting for future explorers, that is less that we will have to bring from Earth,” he said. “It makes the whole process a lot easier.”
Frozen water could be thawed for drinking. Also, water could be split into its chemical components, hydrogen and oxygen. The oxygen could be used for breathing and the two chemicals can be recombined to make rocket propellant.
The presence of vast quantities of water also boosts the possibility that life – probably microbes – once existed on the Red Planet and possibly could still be there deep underground in pockets of liquid water.
“This doesn’t prove that there was or wasn’t life on Mars, but we know that water is a key requirement for life as we know it,” said Bell. “This is a piece of evidence in support of the hypothesis” that Mars was once more Earthlike, with bodies of water and, perhaps, some forms of life.
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