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ZL2VAL > ROVERS 20.03.04 10:27l 116 Lines 5504 Bytes #999 (0) @ WW
BID : 410671ZL2VAL
Read: GUEST
Subj: More evidence of water
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Sent: 040320/0808Z @:ZL2AB.#46.NZL.OC #:37804 [New Plymouth] FBB7.00g
From: ZL2VAL@ZL2AB.#46.NZL.OC
To : ROVERS@WW
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 Mössbauer 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 life.
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 http://marsrovers.jpl.nasa.gov
and from Cornell University, Ithaca, N.Y., at http://athena.cornell.edu
=========================
73 de Alan, (Sysop ZL2AB).
AX25:ZL2VAL@ZL2AB.#46.NZL.OC
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Message timed: 21:04 on 2004-Mar-20 (NZT)
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Points to ponder
~~~~~~~~~~~~~~~~
Marriage
~~~~~~~~
You know the honeymoon is pretty much over when you start to go out with
the boys on Wednesday nights, and so does she.
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