[meteorite-list] Mars Rovers: On The Roll To New Targets

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu, 28 Dec 2006 10:01:46 -0800 (PST)
Message-ID: <200612281801.KAA05937_at_zagami.jpl.nasa.gov>

http://space.com/missionlaunches/061228_rovers_update.html

Mars Rovers: On The Roll To New Targets
By Leonard David
space.com
28 December 2006

NASA's Opportunity and Spirit Mars rovers are on the prowl. Science
teams are plotting out new escapades for the twin robots - new
destinations certain to reveal more secrets from the red planet.

Within Meridiani Planum, the Opportunity rover is relaying great
pictures of Victoria Crater and its walls, said Steve Squyres,
lead scientist of the Mars Exploration Rover (MER) project from Cornell
University in Ithaca, New York.

So far, the story at Victoria is surprisingly similar to what rover
scientists saw at Endurance Crater, a feature they closely studied for
months back in 2004.

Squyres told SPACE.com that the rover's Panoramic Camera (Pancam)
is telling Mars researchers that the rocks in the crater are mostly
"fossilized dunes" - with layering that preserves clear evidence of
ancient transport by wind.

Opportunity's Mini-Thermal Emission Spectrometer (Mini-TES)
has revealed that this material is sulfate-rich all the way down,
Squyres said. Mini-TES characterizes the martian terrain by using
thermal infrared spectroscopy.

"So the picture we got back at Endurance, with a sulfate-rich dune field
and lots of acidic groundwater, seems to apply here as well - several
kilometers to the south," Squyres added. "This was a big, long-lived
dune field and there was lots of water here."

Into Victoria Crater

What rover scientists may learn when Opportunity steers down inside the
crater is anybody's guess. But first finding a driveway into Victoria is
high on the priority list.

"So far we have found two safe entry routes into Victoria. Those are
Duck Bay and Bottomless Bay. We have not yet confirmed that either is a
safe exit route, but they both have potential," Squyres advised.

Opportunity is continuing with its scenic tour of the rim of Victoria
Crater, said William Farrand, a research scientist at the Space Science
Institute in Boulder, Colorado. He is also a member of the MER science team.

"We have been getting some spectacular panoramas of the promontories and
inner rim of Victoria. We are also in the process of building up images
for a fabulous stereo model of the crater," Farrand told SPACE.com.

It is still a bit early, Farrand said, for rover science team members to
assess the totality of the geologic story contained in the walls of
Victoria. Doing so calls for detailed inspection of the stratigraphy of
the walls - an assessment of strata, or layers.

"We are really taking a methodical approach to mapping out the
stratigraphy exposed in the walls of the crater. Once we've gotten
further around I think we will have a better understanding of what that
stratigraphy is telling us," he said.

Spirit: back to Home Plate

On the other side of Mars at Gusev Crater scientists are preparing to
steer the Spirit Mars rover back to a region called "Home Plate" - a still
baffling formation near the Columbia Hills.

At the moment, Spirit has been busy looking at a target tagged
"Esperanza" - the first "vesicular" basalt that has undergone detailed
scrutiny.

Vesicular basalts form when dissolved gas in a lava comes out of
solution, "like bubbles in soda," Squyres tutored, creating little
Swiss-cheese-like voids within the rock.

"We've seen lots of vesicular basalts at Gusev, particularly around Home
Plate, and this is our first chance to really find out what they are
made of and how they may or may not be related to Home Plate," Squyres
explained.

Target-rich environment

Squyres said that Spirit is likely to stay in the vicinity of Home Plate
for a long time.

>From overhead, NASA's Mars Reconnaissance Orbiter has used its High
Resolution Imaging Science Experiment (HiRISE) camera to sharp-shoot the
site that Spirit is now appraising.

"The recent HiRISE image of the Spirit site has shown us that there are
many more scientifically interesting targets around Home Plate than we
realized. Some of these features are difficult to spot from ground
level," Squyres pointed out.

The powerful HiRISE camera has found things that Mars rover scientists
hadn't realized were there before. "So, having found our way with much
difficulty to such a target-rich environment, we're going to work it for
all it's worth."

New field season

Spirit packed up winter camp and started out on a new field season over
the past couple of weeks, said Larry Crumpler, a MER science team member
based at the New Mexico Museum of Natural History and Science in
Albuquerque.

"It was a very long winter," Crumpler said, "but the Sun is getting high
enough now that Spirit can survive with no tilt," a parking position
used to glean more solar energy to keep the rover healthy.

Spirit has scrambled off the ledge it has been sitting on since last
April. The rover has started a new field season on Mars - even as winds
starting to pick up and dust in the air started going up, Crumpler
noted, "just like a spring day in New Mexico."

"Hopefully, we will have a solar panel cleaning event somewhere in the
future. That will make the power situation better even as the atmosphere
becomes dustier and the Sun's rays are dimmed," Crumpler added.

Wheel drag

Spirit is limping a bit. The rover's front right wheel is not working.
So the robot is dragging it, using its five other wheels to move about.

"It makes approaches for studies of targets with the instruments tricky,
requiring a crab-like motion to put targets within the instrument work
space," Crumpler told SPACE.com. "So the first drives are tentative and
very carefully considered for their value in learning anew how to drive
on Mars."

Driving Spirit onward, the plan is to make it back to the edge of Home
Plate. Spirit will then pick up where it left off last martian fall, and
continue a drive clockwise around the south edge of Home Plate, Crumpler
said.

Another goal of the traverse around the margin will be to see if there
are any indicators of Home Plate's geologic origin - be it volcanic or
just a product of wind action.

"Although it is clear that the materials that make up the outcrops are
volcanic, it is not clear whether the deposition was volcanic in
origin - air fall or ballistic - or whether it was just blown into a low
spot by normal wind processes," Crumpler explained.

This is probably the first place where real field geology has come to
the fore, Crumpler points out. "Chemical analysis of the rocks can tell
us many things, but it can't tell you in every case how the rocks got
where they are...that's the job of field geology," he said.

Beyond Home Plate

"We should begin exploring the unseen southern margin of Home Plate in
the New Year," noted Jim Rice, a science team member of the Mars
Exploration Rover Project at Arizona State University in Tempe.

"I am personally looking forward to seeing new cross sectional views of
the layered rock outcrops along the southern margins of Home Plate,"
Rice said. "How long we will stay at Home Plate is unknown...it sort of
depends on what we find there. This is the nature of exploration."

After Home Plate, Rice is voting for study of features nicknamed "von
Braun" and "Goddard", after the two great rocket pioneers.

'These are very high priority targets in my opinion," Rice told
SPACE.com. "Von Braun looks like some of the classic layered buttes and
mesas one would see here in Arizona. Goddard could be either an impact
crater or volcanic vent. The only way to know is to go."

How these two features fit into the overall, complex story of the
Columbia Hills is yet to be determined, Rice said.

Enter the Promised Land

Rice said he's longing for a look at another big target labeled the
"Promised Land", a region he first pointed out and named some three
years ago shortly after Spirit landed in January 2004.

The origin of this material is unknown and this region would in effect
constitute a new landing site, Rice suggested.

But the start of the Promised Land is about 3,000 feet (800 meters) away.

That's a long haul given Spirit's mobility issues: its balky right front
wheel. "But we should at least try. It would be a shame if we only see
it from afar. We will not know what possible geologic treasures the
Promised Land holds until we enter its domain," Rice concluded.
Received on Thu 28 Dec 2006 01:01:46 PM PST