[meteorite-list] Mineral in Mars 'Berries' Adds to Water Story

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu Apr 22 10:32:51 2004
Message-ID: <200403190146.RAA01759_at_zagami.jpl.nasa.gov>


Guy Webster (818) 354-5011
Jet Propulsion Laboratory, Pasadena, Calif.

Dwayne Brown (202) 358-1726
NASA Headquarters, Washington, D.C.

News Release: 2004-088 March 18, 2004

Mineral in Mars 'Berries' Adds to Water Story

A major ingredient in small mineral spheres analyzed by
NASA's Mars Exploration Rover Opportunity furthers
understanding of past water at Opportunity's landing
site and points to a way of determining whether the vast
plains surrounding the site also have a wet history.

The spherules, fancifully called blueberries although
they are only the size of BBs and more gray than blue,
lie embedded in outcrop rocks and scattered over some
areas of soil inside the small crater where Opportunity
has been working since it landed nearly two months ago.

Individual spherules are too small to analyze with the
composition-reading tools on the rover. In the past week,
those tools were used to examine a group of berries that
had accumulated close together in a slight depression
atop a rock called "Berry Bowl." The rover's Moessbauer
spectrometer, which identifies iron-bearing minerals,
found a big difference between the batch of spherules and
a "berry-free" area of the underlying rock.

"This is the fingerprint of hematite, so we conclude that
the major iron-bearing mineral in the berries is hematite,"
said Daniel Rodionov, a rover science team collaborator
from the University of Mainz, Germany. On Earth, hematite
with the crystalline grain size indicated in the spherules
usually forms in a wet environment.

Scientists had previously deduced that the martian spherules
are concretions that grew inside water-soaked deposits.
Evidence such as interlocking spherules and random
distribution within rocks weighs against alternate
possibilities for their origin. Discovering hematite in
the rocks strengthens this conclusion. It also adds
information that the water in the rocks when the spherules
were forming carried iron, said Dr. Andrew Knoll, a science
team member from Harvard University, Cambridge, Mass.

"The question is whether this will be part of a still
larger story," Knoll said at a press briefing today at
NASA's Jet Propulsion Laboratory, Pasadena, Calif.
Spherules below the outcrop in the crater apparently
weathered out of the outcrop, but Opportunity has also
observed plentiful spherules and concentrations of hematite
above the outcrop, perhaps weathered out of a higher
layer of once-wet deposits. The surrounding plains bear
exposed hematite identified from orbit in an area the
size of Oklahoma -- the main reason this Meridiani Planum
region of Mars was selected as Opportunity's landing site.

"Perhaps the whole floor of Meridiani Planum has a residual
layer of blueberries," Knoll suggested. "If that's true,
one might guess that a much larger volume of outcrop once
existed and was stripped away by erosion through time."

Opportunity will spend a few more days in its small crater
completing a survey of soil sites there, said Bethany
Ehlmann, a science team collaborator from Washington
University, St. Louis. One goal of the survey is to
assess distribution of the spherules farther from the
outcrop. After that, Opportunity will drive out of its
crater and head for a much larger crater with a thicker
outcrop about 750 meters (half a mile) away.

Halfway around Mars, NASA's other Mars Exploration Rover,
Spirit, has been exploring the rim of the crater nicknamed
"Bonneville," which it reached last week. A new color
panorama shows "a spectacular view of drift materials on
the floor" and other features, said Dr. John Grant, science
team member from the National Air and Space Museum in
Washington. Controllers used Spirit's wheels to scuff away
the crusted surface of a wind drift on the rim for
comparison with drift material inside the crater.

A faint feature at the horizon of the new panorama is the
wall of Gusev Crater, about 80 kilometers (50 miles) away,
said JPL's Dr. Albert Haldemann, deputy project scientist.
The wall rises about 2.5 kilometers (1.6 miles) above
Spirit's current location roughly in the middle of Gusev
Crater. It had not been seen in earlier Spirit images
because of dust, but the air has been clearing and
visibility improving, Haldemann said.

Controllers have decided not to send Spirit into Bonneville
crater. "We didn't see anything compelling enough to take
the risk to go down in there," said JPL's Dr. Mark Adler,
mission manager. Instead, after a few more days exploring
the rim, Spirit will head toward hills to the east
informally named "Columbia Hills," which might have
exposures of layers from below or above the region's
current surface.

The main task for both rovers is to explore the areas
around their landing sites for evidence in rocks and
soils about whether those areas ever had environments
that were watery and possibly suitable for sustaining

JPL, a division of the California Institute of Technology
in Pasadena, manages the Mars Exploration Rover project
for NASA's Office of Space Science, Washington, D.C.
Images and additional information about the project are
available from JPL at


and from Cornell University, Ithaca, N.Y., at

http://athena.cornell.edu/ .

Received on Thu 18 Mar 2004 08:46:25 PM PST

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