Press Release

Evidence of icy region and recent climate change observed on Mars

By SpaceRef Editor
July 25, 2001
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IMAGE CAPTION: [Larger version] A high-resolution image of Mars’ surface, left, shows an
ice-rich layer that appears to be flowing downhill. The
newly observed terrain is a mixture of water ice and dust
and was formed in the past 100,000 years, much more
recently than previously thought.

PROVIDENCE, R.I. — New images of the surface of Mars
provide the first direct evidence that the climate of
Mars changed during the last 100,000 years, much
more recently than the hundreds of millions of years
scientists had previously thought, according to Brown
University geologist John Mustard. The high-
resolution images show evidence of water ice closer to
the equator than had previously been observed.

Mustard, with graduate student Christopher Cooper and
undergraduate Moses Rifkin, wrote about the findings in
the July 26 issue of Nature.

The images were recorded by the Mars Orbiter Camera
aboard NASA’s unmanned Mars Global Surveyor. They show a
unique surface terrain of pits and hummocks that appears
to have been soil once impregnated by water ice. The ice
has since evaporated, leaving a five-meter thick mantle
of porous terrain that is being broken up by wind and
other factors.

“Where the mantle is still intact, you could conceive
of water ice not far below the surface,” Mustard
said. “Where it’s broken into pits and hummocks, the
water is gone.”

The geologically young terrain was observed in two bands
north and south of the equator at 30 to 60 degrees
latitude. The location is significant because
it shows that ice in the soil was once present as close
to the equator as 30 degrees and as recently as 100,000
years, while previous observations had shown that ice had
been present in the polar regions. Due to climate change,
it now appears the icy region moved from the planet’s
poles to nearer its equator, and has now retreated to the
poles, the most recent of probably many such cycles,
Mustard said.

“While we have always thought the climate of Mars has
changed over time, this is direct evidence for change.
And that change fits with the theory of periodic climate
change, similar to the change that causes the ice ages on
Earth,” Mustard said.

“Maybe we don’t have to go to the poles to find water
ice. It’s easier for a spacecraft to survive at the
equator,” Mustard said.

The work was supported by grants from NASA.

SpaceRef staff editor.