Latest Mission Could Be Rover's Last
NASA scientists eyeing a crater they
call "the candy store" have sent the Mars rover Opportunity to the
very edge -- literally. The rover's front wheels Wednesday rolled
over the lip of a crater called Endurance, onto a 25-percent grade.
It's the kind of slope that could trip up Opportunity and send it
crashing to the bottom of the abyss. Even if it makes it safely
down that steep incline, there are questions about whether
Opportunity can make it back out again.
But the risk might just be worth it. The "candy store" contains
an outcropping of rock older than anything the rovers have seen to
date. At the bottom of the crater, up to 23 feet below the edge,
there's an outcropping that could allow scientists at the Jet
Propulsion Lab in Pasadena (CA) see millions of years in the face
of the exposed rock.
"If you want to learn about history, there are worse places to
get stuck than in a library," said Firouz Naderi, Mars Exploration
Rover Program Manager.
Opportunity was lured into the pit after finding deposits of
salt -- perhaps sea salt -- on the rim of the Endurance crater. The
rock at the bottom could show evidence of a warmer, wetter climate
on Mars. You know, the kind of climate conducive to life.
"But we don't even know yet what that rock is like down there,"
said Chief Mission Scientist Steve Squyres. "We hope it will tell
us a story of a planet that's mostly made of basalt, but we don't
know whether the bedrock in the crater is volcanic or sedimentary
-- and if it's sedimentary, then it could be evidence that old, old
water was there, too."
On the other side of Mars, Opportunity's twin, Spirit, is also
on the hunt for important clues about the presence of water. In a
recently dug trench, Spirit made a rather amazing discovery.
Chemical analysis of the material it scooped up showed enriched
deposits of magnesium sulfate.
Epsom salt. "It's not the story that we expected. It's not the
one that we initially went hunting for," said Squyres.
Spirit's Alpha Particle X-ray Spectrometer (APXS) detected
concentrations of magnesium sulfate as high as 15 percent of the
total sample. That's high.
"If you went and you tasted it, you would taste the salt,"
Squyres said.
Spirit is now just about 100 yards from the Columbia Hills,
where Squyres expects to find even more evidence that water once
covered at least parts of a planet now more barren than the
harshest desert on Earth.
As for Opportunity's trip into the Endurance crater, experts
give it a 50-50 chance of ever coming out again. But some at JPL
are a lot more confident.
"In addition to being robots, the Mars rovers are interplanetary
all-terrain vehicles. And this week, we're going to prove it one
more time on Mars at Meridiani," said rover mobility engineer Randy
Lindemann.
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