[meteorite-list] Newly Supercharged Rovers Racing to New Destinations

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu Apr 22 10:31:15 2004
Message-ID: <200404211642.JAA02942_at_zagami.jpl.nasa.gov>

Newly supercharged rovers racing to new destinations

[Image]
The Opportunity rover's navigation camera provides a
view of the jumbled bedrock lining the rim of Fram
Crater in Mars' Meridiani Planum.

By James Oberg
NBC News space analyst
Special to MSNBC
April 21, 2004

HOUSTON - When you've proven the existence of a salty lake on Mars, what
do you do for an encore? NASA's newly supercharged rovers may be racing
toward an answer. "I think some of the best stuff may still be ahead," the
program's chief scientist said Tuesday.

Steven Squyres spoke to MSNBC.com just after his team had
seen the first images of Fram Crater, the first crater the Opportunity rover has
looked at it in detail since it left Eagle Crater, its interplanetary hole-in-one
landing spot on Mars. It was Eagle Crater's perfectly-preserved sediments that
yielded the evidence of a Martian shore.

Fram Crater, on the other hand, is not so neat.

"Fram is really busted up," Squyres said excitedly. "It's really scrambled,
disrupted stuff, with ejecta blocks lying around." He speculated that whatever
object had hit the Martian surface to form Fram Crater had been going at a much
higher speed than the one that hit to form Eagle Crater.

Squyres and his team are also excited by the rovers' newly pumped-up speed.
Just two months ago, it was cause for celebration when the Spirit rover traveled
nearly 70 feet, or 21 meters, in a day -- shattering by more than three times the
record set by the Pathfinder mission in 1997. With the new navigation software
installed, Opportunity recently performed a one-day drive of 155 yards, or 142
meters.

"Release-9 is fantastic," Squyres exulted; "We are loving it, especially the
mobility."

This new speed is what is enabling the rovers to reach exciting new regions to
explore.

Mini-tornadoes and a long trek for Spirit Spirit has just arrived at a crater
dubbed "Missoula." While not as rocky as the Bonneville Crater that Spirit
explored earlier, it's interesting enough to keep the
rover busy for a few days.

Along with taking images of the rocks thrown out by this eons-old meteorite
impact, Spirit's cameras are scanning the skies to do "dust devil fishing":
seeking time-lapse images of Martian mini-tornadoes. When captured by
cameras on probes orbiting Mars, these mini-tornadoes show up as tall, thin
white clouds, casting a shadow and leaving a dark trace on the ground as they
move. In Spirit's cameras, nothing has shown up so far but the odds are that
persistence will pay off.

In a few days, Spirit will head for the hills - the "Columbia Hills" that were
named in honor of the shuttle crew lost last year. "We'll proceed at a good
purposeful pace so as to arrive when we still have plenty of rover [lifetime]
left," Squyres said.

As the hills grow closer, the science team will look for specific features.
"First is bedrock outcrops," Squyres said, adding that photos from space show
that a lot of material was eroded out of the area by massive floods. The hills
probably are remnants of that erosion and could show distinctive signs of the
process, and what the region looked like before the floods.

"We'll be looking for any kinds of layering," Squyres said, "and other than
that, any things that look different " we'll see what Mars gives us."

There could be landslides, dead geysers, evaporite beds, towering cliffs showing
cross-sections of a billion years of Martian geology, even cave mouths into the
hills. Spirit will probably spend the rest of its life wandering these hills.

Opportunity hopes to dive deeper
Halfway around the planet, Opportunity is exploring the sand dunes of the
Meridiani Plains. After the rover finishes with Fram Crater, it will head
toward Endurance Crater, a trip of about a week.

"At Eagle Crater, we saw the upper 30-40 cm of the last chapter of what may
be a long and pretty complicated book," Squyres said. "It showed us the last
dying gasps of a body of water - shallow, salty, evaporating away." But what
about earlier chapters in this book?

"My hope is at Endurance we'll see deeper down and find evidence of
sedimentation in deep water," he continued. The rover's instruments should
be able to determine this by measuring less salt and more mud in the layers.

Clues from images of the crater made by orbiting spacecraft have led Squyres
and his team to suspect that at Endurance, layers are exposed not just at
the top, but "farther down the walls" of the crater as well.

Once Opportunity sends back images from Endurance, the mission
scientists will have some decisions to make. "We'll make a very detailed
model of the crater," Squyres said, "and then we sit down and think real
hard about what to do."

"It may be we can get in," he said, "and it may be we can get in but can't
get out. Even in that case, if the scientists decide that they can get
access to the rest of the "book of Mars," they may take the plunge.

If Endurance doesn't mark the end for Opportunity, the rover may press on to
other regions of interest. Squyres described "etched terrain" to the south where
surface coloration suggests changing rock types.

"There are two ways to get deeper down," he explained. "You can find a
hole, or you can find rock layers where the surface is tilted slightly to
form a very gently sloping surface." On such structures - and the "etched
terrain" could be one -- the rover could reach lower and lower layers
simply by moving downhill across the surface.

'Every last drop of science'
Scientists at the Jet Propulsion Laboratory in California, where the rovers
are controlled, have made it clear that the vehicles could break down
suddenly at any moment. The main threat is the severe thermal swings of the
day-night temperature cycles. A critical power feed or computer chip could
just snap, and the rover would be dead.

However, the prime limiting factor on vehicle lifetime was originally thought
to be a gradual decay of electrical power generation from the solar arrays, as
Martian dust built up on their surfaces. But while there has been "some
degradation," Squyres said, "it is flattening out." One possibility, others
have speculated, is that the rovers' bumpy progress is shaking some of the
dust loose.

"We're finding ways to streamline our operations to make this mission
sustainable," Squyres said, voicing a hope that the rovers could survive for a
long, long time -- and not kill their ground control teams through overwork,
either.

"Our job is to wring every last drop of science out of these rovers," Squyres
said. And with the new regions about to be explored, that science harvest will
continue.
Received on Wed 21 Apr 2004 12:42:30 PM PDT