Mars Rover Finding Suggests Once Habitable Environment
By KENNETH CHANG
Published: December 12, 2007
SAN FRANCISCO - The lame wheel on the NASA Mars rover Spirit has proven an
invaluable science tool, turning up evidence of a once habitable
environment, scientists said Monday.
Meanwhile, images from the Mars Reconnaissance Orbiter have largely
unraveled the mystery of geological patterns called "spiders" that appear
each spring around the south pole.
The scientists reported their findings here at a meeting of the American
Geophysical Union.
The right front wheel of Spirit stopped turning in March 2006. Since then,
the rover has been driving backwards, dragging the lame wheel along. This
May, scientists noticed a bright spot in the trail of overturned dirt.
They turned Spirit around for a closer look, finding high levels of silica,
the main ingredient of window glass. They then aimed the rover at a nearby
rock, wanting to break it apart to determine if the silica was just a
surface coating, or if the rock was silica all the way through.
The target rock survived Spirit's charge, but a neighboring rock cracked
open. The interior of that rock, which the scientists informally named
"Innocent Bystander," turned out to be rich in silica.
On Earth, such high concentrations of silica can form in only two places: a
hot spring, where the silica is dissolved away and deposited elsewhere, or a
fumarole, an environment, often near a volcano, where acidic steam rises
through cracks. The acids dissolve other minerals, leaving mostly silica. On
Earth, both environments teem with life.
Spirit's twin, Opportunity, which has been exploring a spot on the other
side of Mars, has found evidence of an environment once steeped in acidic
groundwater. The silica discovery is the first time that Spirit has seen
signs of widespread water in its surroundings, a 90-mile-wide impact crater
known as Gusev Crater.
Gusev was chosen as a landing site, because, at least from orbit, it looks
as if it were once a lake with what appears to be river channels flowing
away from it. However, until now, the rocks that Spirit has examined have
largely been volcanic basalt with little hint of water.
"This shows us a side of Mars we haven't seen before, and my guess is that
it's more common than we had thought," said Steven W. Squyres, the project
scientist for the rovers. "Whichever of those conditions produced it, this
concentration of silica is probably the most significant discovery by Spirit
for revealing a habitable niche that existed on Mars in the past."
With the length of days shortening in Mars now, Spirit is currently hurrying
to a sloping winter resting spot where it can tilt its solar panels toward
the Sun. A global dust storm over the summer left a layer of dust on the
rover's solar panels, and mission managers expect that the panels will be
operating at only 30 percent efficiency. By contrast, the panels operated at
70 percent efficiency during Spirit's first Martian winter and 50 percent
during the second winter
"It's going to be a lot more difficult for Spirit," said John Callas, the
project manager for the rovers.
To conserve energy, some of Spirit's heaters may have to be turned off,
letting the electronics chill.
Opportunity is in much better shape. Closer to the equator, it receives much
more sunlight, and its panels have been regularly cleaned by gusts of wind.
From far above the surface, the Mars Reconnaissance Orbiter has been taking
a closer look at radial patterns of "spider" gullies, as well as bright and
dark fan-like features that appear in the Martian landscape each spring.
Scientists first spotted the gullies several years ago in images taken by
the Mars Global Surveyor. With the much higher resolution of Reconnaissance
Orbiter, scientists saw for the first time that the gullies were wider at
the center of the pattern. Another instrument allowed them to map the images
onto the Martian topography; the centers of the spiders were at the top of
the small hills. Those two bits of information indicated that the gullies
were carved by something flowing uphill - and that pointed to carbon
dioxide.
At a news conference on Tuesday, Candice Hansen, deputy principal
investigator for the orbiter's high-resolution camera, said it now appeared
that a layer of translucent carbon dioxide ice, perhaps half a yard thick,
formed over the south polar terrain during the winter months.
In the spring, sunlight warms the ground, vaporizing carbon dioxide at the
base of the ice layer. The gas flows uphill, carving channels in the
underlying soil. At weak points in the ice, the gas erupts in small geysers.
The release of pressure causes the carbon dioxide gas to freeze solid and
fall as white snow - the white parts of the fan-like patterns. Dust blown
out with the carbon dioxide falls on the ground to form the dark parts of
the fans.
"It is unlike anything on Earth," Dr. Hansen said, though similar patterns
have been seen on the Neptunian moon of Triton.
http://www.nytimes.com/2007/12/12/science/space/12mars.html?ref=us
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| User: "Werewolfy" |
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| Title: Re: 'Spiders' On Mars ... |
12 Dec 2007 04:48:41 AM |
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On 12 Dec, 04:40, "Docrodile" <swampth...@hellsbayou.net> wrote:
"It is unlike anything on Earth," Dr. Hansen said, though similar
patterns have been seen on the Neptunian moon of Triton."
He's wrong...it's just like on Earth. They leave certain tell-tale
signs of their presence. It's the spiders again, real ones. I didn't
know they had colonised Triton as well, their spread is happening at a
faster rate than I thought.
The horrible things adapt so well to any environment. There'll be webs
in space soon.
Ugh
Werewolfy
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| User: "Docrodile" |
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| Title: Re: 'Spiders' On Mars ... |
12 Dec 2007 02:03:44 PM |
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"Werewolfy" <Werewolfy1@yahoo.co.uk> wrote in message
news:4dc1ff51-9811-417f-8958-65e3e3f46c38@n20g2000hsh.googlegroups.com...
On 12 Dec, 04:40, "Docrodile" <swampth...@hellsbayou.net> wrote:
"It is unlike anything on Earth," Dr. Hansen said, though similar
patterns have been seen on the Neptunian moon of Triton."
He's wrong...it's just like on Earth. They leave certain tell-tale
signs of their presence. It's the spiders again, real ones. I didn't
know they had colonised Triton as well, their spread is happening at a
faster rate than I thought.
The horrible things adapt so well to any environment. There'll be webs
in space soon.
Ugh
Werewolfy
I find a Black and Decker Dustbuster rechargeable vacuum a formidable weapon
against the invading arachnids !! With the crevice tool engaged, I've sucked
'em up from hard to reach spaces. It is then necessary to take a piece of
tape and seal off the end until they expire. Sometimes, I delight in
watching their horrid lil' bodies spin rapidly around the *cyclonic suction*
see-thru chamber!! After a couple of minutes of that sadistic enjoyment,
they're either too worn out to crawl or have gone to Cobweb Heaven (or
Hell).
Doc :))~
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