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ZL2VAL > SPIRIT 09.01.04 13:44l 149 Lines 6375 Bytes #999 (0) @ WW
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Subj: Mars rover may head for the hills
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Sent: 040109/1035Z @:ZL2AB.#46.NZL.OC #:33006 [New Plymouth] FBB7.00g $:33006_Z
From: ZL2VAL@ZL2AB.#46.NZL.OC
To : SPIRIT@WW
Scientists discuss where to visit first
By Chris Kridler
FLORIDA TODAY
Jan 8, 2004
PASADENA, Calif. -- The Mars rover is about the tallest thing in its
neighborhood, but it's eyeing some not-so-distant hills.
Scientists looking at vivid pictures of the landscape taken by
Spirit are considering climbing those hills, a thought that thrills
the people who are going to drive the rover.
"That's a dream come true for me," said Frank Hartman, a rover
driver. "The first thing I asked the mechanical engineering guys is,
I said, 'Can we drive up them?' And they said, 'Yeah, we can.'
Whether we're going to do that or not, I don't know."
The hills, which appear to be more than a mile away from the rover,
are just one tempting target for the scientists. Every
high-resolution picture that comes back from Mars fuels their debate
about where to go first.
"It's passionate, and right now we are kids in a candy store," said
project scientist Joy Crisp at NASA's Jet Propulsion Laboratory. "So
we are changing our minds quite a bit."
Several people have compared the debate to herding cats. The targets
are all over the place, and so far, every direction around the rover
holds something mysterious, deputy project scientist Albert
Haldemann said.
The science team is giving the drivers preliminary targets so they
can start thinking about how to get there. The drivers are really
planners who uplink an entire sequence of commands for the rover to
execute during the Martian day.
Hartman said the driver-planners use the two-eyed pictures taken by
the stereo cameras -- high-resolution color images and
low-resolution navigation images -- to judge distances and rock
heights.
"Just like your brain takes the images from your two eyes and
figures out three-dimensionally, we can get the computer to do that
as well," he said.
The computer is much more accurate than the human eye, since it can
take into account a camera's focal length, field of view and known
distortions to understand distances.
"We have a three-dimensional representation of that terrain that we
can sort of spin around and look at from every angle," Hartman said.
The good news so far is that the nearby territory, which NASA named
Columbia Memorial Station, is very drivable, he said. It appears the
rover, which has six hard wheels, can drive over just about everything.
If a rock is about 8 inches high or taller, Spirit would have to
drive around it.
Some people at the Jet Propulsion Laboratory have called the terrain
a "racetrack."
"Looks more like a Baja race to me, but it's good driving terrain,"
Hartman said.
The rover's first step off the lander may be the slowest. "It's
clear we want to stop and drop," said Ray Arvidson, a geologist from
Washington University in St. Louis who is deputy principal
investigator for the project.
Stop and drop means stopping right off the lander, stretching the
robot arm and wiggling its fingers -- that is, trying out the
instruments on the end of the arm on the closest soil and possibly
rock.
Once the rover rolls off, possibly next week, that process could
take three days, Haldemann said.
Then the scientists, equipped with more images and infrared data
that could help identify minerals in the rocks, will choose where to
go next.
"We see the picture, and there will be anywhere from two to three to
five people standing in front of the picture and just throwing out
ideas, and then a little bit of banter and argument back and forth,"
Haldemann said, "and maybe we'll even name a rock or two."
A chairman is given the task of moderating the debate of hundreds of
scientists and making a final decision, if necessary. They generally
reach a consensus, Crisp said, and the process worked well on the
Pathfinder-Sojourner mission seven years ago.
Each Martian night, the scientists pick a new target or decide to
make a new measurement. The instrument team figures out what to tell
the tools. The engineering team adds commands, and the drivers plot
a route. The mission managers give the plan an OK. Then the rover
gets its marching orders for the day.
"It's 19 hours to do all of that," Haldemann said. "It's a challenge."
"My guess is, the more data they get down, the more arguments
they're going to have," driver Hartman said. "When we were just
looking at that first nav-cam panorama, it was fairly low
resolution, so the feature that sort of leapt out at everybody was
that Sleepy Hollow."
Sleepy Hollow, to the north of the south-facing rover, might be an
impact crater. Craters are tantalizing because impacts on the
surface tend to kick up older rocks.
Spirit is looking at rocks at its landing site, the middle of
100-mile-wide Gusev Crater, to see if they formed in water. If the
minerals suggest a history of water, they will support the
hypothesis that Gusev Crater -- which has many craters inside it --
was once an ancient lake.
Twin rover Opportunity, when it lands in just over two weeks, will
look for similar evidence on the other side of the planet.
While craters are appealing, so are the hills.
"The hills potentially have clean exposures of bedrock," Haldemann
said. They could reveal ancient lake sediments or even volcanic rock
that might help fill in Gusev's history.
"It's to get at something fresher," Haldemann said. But that's only
the scientific perspective.
"I'm sure the engineers have the ambition just to climb the highest
hill on Mars that we can climb with our rover," he said with a laugh.
==============================
73 de Alan
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Points to ponder
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What happens if you get scared half to death twice?
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