Updated at 2:31 p.m. ET.
The Mars
Exploration Rover (MER) "Opportunity" will perform a risky descent
into the red planet's giant Victoria Crater early next month.
The
announcement was delivered during a NASA teleconference today, and came after
months of debate about whether or not to proceed. Officials said the decision
has been difficult to make because some scientists think the crater may become
the aging rover's final resting
place.
Alan Stern,
NASA's associate administrator of the Science Mission Directorate in Washington, gave the go-ahead during the conference.
"We've
made a decision to authorize the rover to descend down into Victoria
Crater," he said, noting that the move is not without risks--if it
goes inside the large hole in Mars' crust, it may malfunction or not be able to
climb out. "But the science could occupy us not just for days or weeks,
but for months. This is why I've authorized the rover to go into the
crater."
Risky
maneuver
Opportunity is
currently perched on "Duck
Bay," an alcove on the rim of the crater from which it will descend.
Scientists have deemed the site the gentlest entry point to the 800-meter-wide
(2,600-foot-wide) crater.
The rover is
set to make its descent early next month. "Perhaps the 7th or 9th of
July," said John Callas, MER project manager at NASA's Jet Propulsion
Laboratory in Pasadena, California. He noted that the team will first see if
the rover can make the trip with a short "toe-dip" into Duck Bay.
"We chose our
entry point solely on the basis of safety," said Steve Squyres, principal
scientist of the Mars Exploration Rover team at Cornell University in Ithaca, New York. Squyres explained that moving the rover only a few feet down the slope and
backing it out should reveal any unpleasant surprises such as slips or slides.
In addition to
slippery terrain, the Mars scientists fully accept the risk of wheel failure or
other malfunction once in the crater. "We believe we can get in and explore and
get out safely, but if we were to have a wheel failure on Opportunity that
would make getting out very problematic," Squyres said.
Crater of
knowledge
During the
descent into Victoria Crater, however, the scientists expect to stay busy.
"It's much
farther away from our previous craters than any place we've been," Squyres said.
"And this thing is a hell of a lot deeper than any other crater we've looked at
so far. This provides us access to a much longer span of Mars' geologic
history."
But perhaps
the most important aspect of the crater, Squyres said, is that it's extremely old--possibly
billions of years. Instead of a fresh impact with chaotic jumbles of rock, the
crater has eroded to its current form and has exposed a clean spread of intact bedrock.
The rover
team's first objective with Opportunity is to scope out a bright band of rock in un upper portion of the crater.
"It's
different from everything else around it," Squyres said. "This is the layer
that was in contact with the Martian surface at the time of impact, so it may
have preserved information about ... the ancient Martian environment."
Long
journey
The rovers
Spirit and Opportunity have been exploring
the Red Planet since January of 2004 and were expected to last just 90 days on
the dusty surface. Defying the odds, they have both been in operation for more
than 12 times their expected mission length--but not without event.
Spirit's right
front wheel stopped moving in March of 2006, but has since proven an effective
soil-digging instrument. In May of this year, it turned up a powdery white
substance discovered to be 90 percent pure silica. Scientists think its
presence beneath the surface is indicative of a watery past on Mars.
In addition to looking out for mechanical troubles,
team members are closely watching a massive dust storm to the south of Opportunity.
"We are tracking this thing daily," Squyres said. "It's a risk to us, just as driving it down into a
crater is a risk to us. The dust levels are among the highest we've seen so far."
Assuming a safe journey and good weather, Squyres thinks Opportunity will make exciting discoveries while in the
crater, as well as when it leaves to investigate the cobble-strewn plains in
the area.
"We've
blown by a bunch of these stones in a hurry to get to crater," he said, and
have looked at "only a handful" of them. From meteorites to debris rocketed
from distant impact sites, Squyres said investigating the rock-strewn plains
will be Opportunity's next big mission.
"Nature has
delivered to us, in the form of these cobbles, exotic rocks from places we
can't sample," he said. In addition, the team hopes to look for more evidence
of surface water, which they think they discovered around Erebus crater.
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