[meteorite-list] Mars Rover Finds Mineral Possibly Linked to Water

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu Apr 22 10:32:11 2004
Message-ID: <200401301655.IAA09655_at_zagami.jpl.nasa.gov>

http://www.nytimes.com/2004/01/30/science/space/30CND-MARS.html

Mars Rover Finds Mineral Possibly Linked to Water
By KENNETH CHANG
New York Times
January 30, 2004

PASADENA, Calif. - The Mars rover Opportunity has discovered the
iron oxide - a possible sign of water from Mars' ancient past - that was the
original motivation for sending it to a broad plain near the planet's
equator.

On Earth, the iron oxide, known as gray hematite, usually forms in the
presence of water, either hot springs or the bottom of a lake or sea,
although it can also form out of oxygen-rich lava without water.

>From orbit, the Mars Odyssey spacecraft had spotted the color signature of a
hematite deposit the size of Oklahoma in the plain, known as Meridiani
Planum. Opportunity landed last Sunday in a particularly flat section in the
western half of Meridiani Planum.

The deployment of Opportunity continues so smoothly that for the second day
in a row, mission controllers moved up by a day the time when Opportunity
will drive off its landing platform.

For the trip to Mars, the rover was folded up to fit within a triangular
pyramid. After landing, the pyramid opened like flower petals, forming a
platform. For the past several days, controllers extended the rover's
wheels, turned on instruments and tested equipment. If preparations continue
without hitches, Opportunity will drive about 10 feet straight off the front
of the lander early Saturday morning, its seventh day on Mars.

By contrast, Opportunity's twin rover, Spirit, which landed on the opposite
side of Mars three weeks before Opportunity, did not start its drive until
its 12th day.

With Spirit, air bags used to cushion the landing blocked the forward exit
ramp - a piece of reinforced fabric - so controllers swiveled it by 120
degrees to take a different ramp. Opportunity has no such obstacles.

"This is a cake walk by comparison," said Kevin Burke, the lead engineer for
handling the lander exits. "Realistically it's pretty benign."

Early this morning, engineers rehearsed the roll-off with a mock-up at a
test laboratory at NASA's Jet Propulsion Laboratory, which is running the
two rover missions.

To ease the exit, controllers have pushed the back "petal" down, pitching
the rover forward at an angle of 12 degrees. In the test, the engineers have
put the mock-up in a similar pose. It looks like a swimmer about to jump off
a diving board.

At 5:17 a.m. Pacific time, the mock-up rover rolled off the mock-up lander
without incident, to a round of applause from the onlookers, the 546th and
final such test.

"It was more a show-and-tell" to curious scientists and engineers, Mr. Burke
said. "In this case, it's the simplest of tests."

>From its stationary perch on the lander, Opportunity has already taken a
360-degree photographic panorama of its surreal, largely barren
surroundings.

By luck, it ended up in a shallow, 20-yard-wide crater with exposed bedrock,
which scientists hope will tell the geological history of Meridiani Planum.
The bedrock contains thin layers, which could be layers of sediment carried
by ancient flows of water. The layers could also be volcanic ash from
successive eruptions or wind-blown sediments.

Today scientists got their first look at data from an instrument that looks
at infrared light radiated from the rocks and soil. The mix of infrared
wavelengths identifies certain minerals.

Hematite has the same composition as rust - two parts iron, three parts
oxygen - but when the atoms are stacked into crystals the size of sand
grains or larger, the mineral is gray, not red.

As had been expected by the scientists, the dark pebbles and gravel on the
surface contain hematite. But the fine reddish soil beneath the gravel did
not show any signs of hematite, nor did the exposed bedrock. This raises a
new hematite question.

"This is what is in the back of my mind: Where did it come from?" said Dr.
Wendy M. Calvin, a professor of geology at the University of Nevada at Reno
and a member of the science team.

In places where the rover had bounced on landing, the pebbles vanish,
leaving sharp imprints of the air bags in the reddish soil. The hematite
disappeared, too.

"We don't see it in smushed areas," she said. "I don't know what happened to
it."

If the gravel had just been pushed under the surface, as some of the
scientists believe, then the hematite should still be evident, she said.

The alternate hypothesis is that the impacts pulverized the particles into
tiny dust particles, too small to radiate the telltale hematite color
signature.

When Opportunity rolls off the lander, it will stick instruments at the end
of a mechanical arm into the soil, which should be better able to identify
the minerals there.
Received on Fri 30 Jan 2004 11:55:24 AM PST