>>Date: Tue, 28 May 2002 13:00:27 -0400 (EDT)
>>Subject: ODYSSEY FINDS WATER ICE IN ABUNDANCE UNDER MARS' SURFACE
>>Headquarters, Washington May 28, 2002
>>Jet Propulsion Laboratory, Pasadena, Calif.
>>University of Arizona, Tucson, Ariz.
>>ODYSSEY FINDS WATER ICE IN ABUNDANCE UNDER MARS' SURFACE
>> Using instruments on NASA's 2001 Mars Odyssey
>>spacecraft, surprised scientists have found enormous
>>quantities of buried treasure lying just under the surface of
>>Mars-enough water ice to fill Lake Michigan twice over. And
>>that may just be the tip of the iceberg.
>>"This is really amazing. This is the best direct evidence we
>>have of subsurface water ice on Mars. We were hopeful that we
>>could find evidence of ice, but what we have found is much
>>more ice than we ever expected," said William Boynton,
>>principal investigator for Odyssey's gamma ray spectrometer
>>suite at the University of Arizona, Tucson.
>>Scientists used Odyssey's gamma ray spectrometer instrument
>>suite to detect hydrogen, which indicated the presence of
>>water ice in the upper meter (three feet) of soil in a large
>>region surrounding the planet's south pole. "It may be better
>>to characterize this layer as dirty ice rather than as dirt
>>containing ice," added Boynton. The detection of hydrogen is
>>based both on the intensity of gamma rays emitted by
>>hydrogen, and by the intensity of neutrons that are affected
>>by hydrogen. The spacecraft's high-energy neutron detector
>>and the neutron spectrometer observed the neutron intensity.
>>The amount of hydrogen detected indicates 20 to 50 percent
>>ice by mass in the lower layer. Because rock has a greater
>>density than ice, this amount is more than 50 percent water
>>ice by volume. This means that if one heated a full bucket of
>>this ice-rich polar soil it would result in more than half a
>>bucket of water.
>>The gamma ray spectrometer suite is unique in that it senses
>>the composition below the surface to a depth as great as one
>>meter. By combining the different type of data from the
>>instrument, the team has concluded the hydrogen is not
>>distributed uniformly over the upper meter but is much more
>>concentrated in a lower layer beneath the top-most surface.
>>The team also found that the hydrogen-rich regions are
>>located in areas that are known to be very cold and where ice
>>should be stable. This relationship between high hydrogen
>>content with regions of predicted ice stability led the team
>>to conclude that the hydrogen is, in fact, in the form of
>>ice. The ice-rich layer is about 60 centimeters (two feet)
>>beneath the surface at 60 degrees south latitude, and gets to
>>within about 30 centimeters (one foot) of the surface at 75
>>degrees south latitude.
>>"Mars has surprised us again. The early results from the
>>gamma ray spectrometer team are better than we ever
>>expected," said R. Stephen Saunders, Odyssey's project
>>scientist at NASA's Jet Propulsion Laboratory (JPL),
>>Pasadena, Calif. "In a few months, as we get into Martian
>>summer in the northern hemisphere, it will be exciting to see
>>what lies beneath the cover of carbon dioxide dry-ice as it
>>"The signature of buried hydrogen seen in the south polar
>>area is also seen in the north, but not in the areas close to
>>the pole. This is because the seasonal carbon dioxide (dry
>>ice) frost covers the polar areas in winter. As northern
>>spring approaches, the latest neutron data indicate that the
>>frost is receding, revealing hydrogen-rich soil below," said
>>William Feldman, principal investigator for the neutron
>>spectrometer at Los Alamos National Laboratories, New Mexico.
>>"We have suspected for some time that Mars once had large
>>amounts of water near the surface. The big questions we are
>>trying to answer are, 'where did all that water go?' and
>>'what are the implications for life?' Measuring and mapping
>>the icy soils in the polar regions of Mars as the Odyssey
>>team has done is an important piece of this puzzle, but we
>>need to continue searching, perhaps much deeper underground,
>>for what happened to the rest of the water we think Mars once
>>had," said Jim Garvin, Mars Program Scientist, NASA
>>Another new result from the neutron data is that large areas
>>of Mars at low to middle latitudes contain slightly enhanced
>>amounts of hydrogen, equivalent to several percent water by
>>mass. Interpretation of this finding is ongoing, but the
>>team's preliminary hypothesis is that this relatively small
>>amount of hydrogen is more likely to be chemically bound to
>>the minerals in the soil, than to be in the form of water
>>JPL manages the 2001 Mars Odyssey mission for NASA's Office
>>of Space Science, Washington. Investigators at Arizona State
>>University, Tempe, the University of Arizona, Tucson, and
>>NASA's Johnson Space Center, Houston, operate the science
>>instruments. The gamma-ray spectrometer was provided by the
>>University of Arizona in collaboration with the Russian
>>Aviation and Space Agency, which provided the high-energy
>>neutron detector, and the Los Alamos National Laboratories,
>>New Mexico, which provided the neutron spectrometer. Lockheed
>>Martin Astronautics, Denver, developed and built the orbiter.
>>Mission operations are conducted jointly from Lockheed Martin
>>and from JPL, a division of the California Institute of
>>Technology in Pasadena.
>>Additional information about the 2001 Mars Odyssey and the
>>gamma-ray spectrometer is available at /is available on the
>>Internet at: http://mars.jpl.nasa.gov/odyssey/ and
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Dale K. Stalnaker
NASA/Glenn Research Center
Power & Propulsion Office
PHONE: (216) 433-5399
FAX: (216) 433-2995
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