[Mars-discuss] Fwd: NASA Spacecraft Detects Buried Glaciers on Mars

[Thomas Coffee]

"Altogether, these glaciers almost certainly represent the largest
reservoir of water ice on Mars that is not in the polar caps," said
John W. Holt of the University of Texas at Austin, who is lead author
of the report. "Just one of the features we examined is three times
larger than the city of Los Angeles and up to one-half-mile thick. And
there are many more. In addition to their scientific value, they could
be a source of water to support future exploration of Mars."

Now if we can just land astronauts near the edge of a Martian cliff.

- Thomas


---------- Forwarded message ----------
From: NASA Jet Propulsion Laboratory <info at jpl.nasa.gov>
Date: Thu, Nov 20, 2008 at 3:44 PM
Subject: NASA Spacecraft Detects Buried Glaciers on Mars
To: Thomas Coffee <tcoffee at mit.edu>






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News Release: 2008-220                                        November 20, 2008

NASA Spacecraft Detects Buried Glaciers on Mars

PASADENA, Calif. – NASA's Mars Reconnaissance Orbiter has revealed
vast Martian glaciers of water ice under protective blankets of rocky
debris at much lower latitudes than any ice previously identified on
the Red Planet.

Scientists analyzed data from the spacecraft's ground-penetrating
radar and report in the Nov. 21 issue of the journal Science that
buried glaciers extend for dozens of miles from edges of mountains or
cliffs. A layer of rocky debris blanketing the ice may have preserved
the underground glaciers as remnants from an ice sheet that covered
middle latitudes during a past ice age. This discovery is similar to
massive ice glaciers that have been detected under rocky coverings in
Antarctica.

"Altogether, these glaciers almost certainly represent the largest
reservoir of water ice on Mars that is not in the polar caps," said
John W. Holt of the University of Texas at Austin, who is lead author
of the report. "Just one of the features we examined is three times
larger than the city of Los Angeles and up to one-half-mile thick. And
there are many more. In addition to their scientific value, they could
be a source of water to support future exploration of Mars."

Scientists have been puzzled by what are known as aprons – gently
sloping areas containing rocky deposits at the bases of taller
geographical features – since NASA's Viking orbiters first observed
them on the Martian surface in the 1970s. One theory has been that the
aprons are flows of rocky debris lubricated by a small amount of ice.
Now, the shallow radar instrument on the Mars Reconnaissance Orbiter
has provided scientists an answer to this Martian puzzle.

"These results are the smoking gun pointing to the presence of large
amounts of water ice at these latitudes," said Ali Safaeinili, a
shallow-radar instruments team member with NASA's Jet Propulsion
Laboratory, Pasadena, Calif.

Radar echoes received by the spacecraft indicated radio waves pass
through the aprons and reflect off a deeper surface below without
significant loss in strength. That is expected if the apron areas are
composed of thick ice under a relatively thin covering. The radar does
not detect reflections from the interior of these deposits as would
occur if they contained significant rock debris. The apparent velocity
of radio waves passing through the apron is consistent with a
composition of water ice.

Scientists developed the shallow radar instrument for the orbiter to
examine these mid-latitude geographical features and layered deposits
at the Martian poles. The Italian Space Agency provided the
instrument.

"We developed the instrument so it could operate on this kind of
terrain," said Roberto Seu, leader of the instrument science team at
the University of Rome La Sapienza in Italy. "It is now a priority to
observe other examples of these aprons to determine whether they are
also ice."

Holt and 11 co-authors report the buried glaciers lie in the Hellas
Basin region of Mars' southern hemisphere. The radar also has detected
similar-appearing aprons extending from cliffs in the northern
hemisphere.

"There's an even larger volume of water ice in the northern deposits,"
said JPL geologist Jeffrey J. Plaut, who will be publishing results
about these deposits in the American Geophysical Union's Geophysical
Research Letters. "The fact these features are in the same latitude
bands, about 35 to 60 degrees in both hemispheres, points to a
climate-driven mechanism for explaining how they got there."

The rocky debris blanket topping the glaciers apparently has protected
the ice from vaporizing, which would happen if it were exposed to the
atmosphere at these latitudes.

 "A key question is, how did the ice get there in the first place?"
said James W. Head of Brown University, Providence, R.I. "The tilt of
Mars' spin axis sometimes gets much greater than it is now. Climate
modeling tells us ice sheets could cover mid-latitude regions of Mars
during those high-tilt periods. The buried glaciers make sense as
preserved fragments from an ice age millions of years ago. On Earth,
such buried glacial ice in Antarctica preserves the record of traces
of ancient organisms and past climate history."

JPL manages the Mars Reconnaissance Orbiter for NASA's Science Mission
Directorate in Washington. For more about the Mars Reconnaissance
Orbiter, visit: http://www.nasa.gov/mro

                                                   -end-


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______________________________________

Thomas Coffee
Massachusetts Institute of Technology
Department of Aeronautics & Astronautics
Space Systems Laboratory
617.549.5492
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