[meteorite-list] Mars Rover Finds 'Puddles' On The Planet's Surface

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Fri, 8 Jun 2007 13:08:27 -0700 (PDT)
Message-ID: <200706082008.NAA19167_at_zagami.jpl.nasa.gov>

http://space.newscientist.com/article/dn12026-mars-rover-finds-puddles-on-the-planets-surface.htm

Mars rover finds "puddles" on the planet's surface
David Chandler
New Scientist
08 June 2007

A new analysis of pictures taken by the exploration rover Opportunity
reveals what appear to be small ponds of liquid water on the surface of
Mars.

The report identifies specific spots that appear to have contained
liquid water two years ago, when Opportunity was exploring a crater
called Endurance. It is a highly controversial claim, as many scientists
believe that liquid water cannot exist on the surface of Mars today
because of the planet's thin atmosphere.

If confirmed, the existence of such ponds would significantly boost the
odds that living organisms could survive on or near the surface of Mars,
says physicist Ron Levin, the report's lead author, who works in
advanced image processing at the aerospace company Lockheed Martin in
Arizona.

Along with fellow Lockheed engineer Daniel Lyddy, Levin used images from
the Jet Propulsion Laboratory's website. The resulting stereoscopic
reconstructions, made from paired images from the Opportunity rover's
twin cameras, show bluish features that look perfectly flat. The
surfaces are so smooth that the computer could not find any surface
details within those areas to match up between the two images.

The imaging shows that the areas occupy the lowest parts of the terrain.
They also appear transparent: some features, which Levin says may be
submerged rocks or pebbles, can be seen below the plane of the smooth
surface.

Smooth surface

The smoothness and transparency of the features could suggest either
water or very clear ice, Levin says.

"The surface is incredibly smooth, and the edges are in a plane and all
at the same altitude," he says. "If they were ice or some other
material, they'd show wear and tear over the surface, there would be
rubble or sand or something."

His report was presented at a conference of the Institute of Electrical
and Electronics Engineers, and will be published later this year in the
institute's proceedings.

No signs of liquid water have been observed directly from cameras on the
surface before. Reports last year pointed to the existence of gullies on
crater walls where water appears to have flowed in the last few years,
as shown in images taken from orbit, but those are short-lived flows,
which are thought to have frozen over almost immediately.

Speedy evaporation?

Levin and other reasearchers, including JPL's Michael Hecht, have
published calculations showing the possibility of "micro-environments"
where water could linger, but the idea remains controversial.

"The temperatures get plenty warm enough, but the Mars atmosphere is
essentially a vacuum," says Phil Christensen of Arizona State
University, developer of the Mars rovers' mini-Thermal Emission
Spectrometers. That means any water or ice exposed on the surface
evaporates or sublimes away almost instantly, he says.

But, he adds, "it is theoretically possible to get liquid water within
soil, or under other very special conditions". The question is just how
special those conditions need to be, and whether they ever really are
found on Mars today.

If there were absolutely no wind, says Christensen, you might build up a
stagnant layer of vapour above a liquid surface, preventing it from
evaporating too fast. "The problem is, there are winds on Mars... In the
real world, I think it's virtually impossible," he told New Scientist.

Simple test

Levin disagrees. He says his analysis shows that there can be wind-free
environments at certain times of day in certain protected locations. He
thinks that could apply to these small depressions inside the sheltered
bowl of Endurance crater, at midday in the Martian summer.

He adds that highly briny water, as is probably found on Mars, could be
stable even at much lower temperatures.

Although the rover is now miles away from this site, Levin proposes a
simple test that would prove the presence of liquid if similar features
are found: use the rover's drill on the surface of the flat area. If it
is ice, or any solid material, the drill will leave unmistakable
markings, but if it is liquid there should be no trace of the drill's
activity.

Levin's father Gilbert was principal investigator of an experiment on
the Viking Mars lander, which found evidence for life on the planet,
although negative results from a separate test for organic materials led
most scientists to doubt the evidence for biology.

Journal reference: R. L. Levin and Daniel Lyddy, Investigation of
possible liquid water ponds on the Martian surface (2007 IEEE Aerospace
Applications Conference Proceedings, paper #1376, to be published in
IEEE Xplore <http://ieeexplore.ieee.org/>)
Received on Fri 08 Jun 2007 04:08:27 PM PDT