Glaciers Hide Beneath Protective Rubble
Extensive radar mapping of the middle-latitude region of
northern Mars shows that thick masses of buried ice are quite
common beneath protective coverings of rubble.
The ability of NASA's Mars Reconnaissance Orbiter to continue
charting the locations of these hidden glaciers and ice-filled
valleys -- first confirmed by radar two years ago -- adds clues
about how these deposits may have been left as remnants when
regional ice sheets retreated.
The subsurface ice deposits extend for hundreds of kilometers,
or miles, in the rugged region called Deuteronilus Mensae, about
halfway from the equator to the Martian north pole. Jeffrey Plaut
of NASA's Jet Propulsion Laboratory, Pasadena, CA, and colleagues
prepared a map of the region's confirmed ice for presentation at
this week's 41st Lunar and Planetary Science Conference near
Houston.
The Shallow Radar instrument on the orbiter has obtained more
than 250 observations of the study area, which is about the size of
California.
"We have mapped the whole area with a high density of coverage,"
Plaut said. "These are not isolated features. In this area, the
radar is detecting thick subsurface ice in many locations." The
common locations are around the bases of mesas and scarps, and
confined within valleys or craters.
NASA Image
Plaut said, "The hypothesis is the whole area was covered with
an ice sheet during a different climate period, and when the
climate dried out, these deposits remained only where they had been
covered by a layer of debris protecting the ice from the
atmosphere."
The researchers plan to continue the mapping. These buried
masses of ice are a significant fraction of the known non-polar ice
on Mars. The ice could contain a record of environmental conditions
at the time of its deposition and flow, making the ice masses an
intriguing possible target for a future mission with digging
capability.
The Shallow Radar instrument was provided by the Italian Space
Agency, and its operations are led by the InfoCom Department,
University of Rome "La Sapienza." Thales Alenia Space Italia, in
Rome, is the Italian Space Agency's prime contractor for the radar
instrument. Astro Aerospace of Carpinteria, CA, a business unit of
Los Angeles-based Northrop Grumman Corp., developed the
instrument's antenna as a subcontractor to Thales Alenia Space
Italia.