[meteorite-list] NASA Plots Mars Rover's Next Moves

[Ron Baalke]

http://www.msnbc.msn.com/id/8119808/

NASA plots Mars rover's next moves

After freeing Opportunity, team plans for safer driving

By Alan Boyle
MSNBC
June 6, 2005

Like any car driver who has weathered a close call, the engineers
steering NASA's Opportunity rover on the Martian surface are already
sticking to safer driving techniques now that the six-wheeled robot has
broken free from a sand dune.

On Saturday, the science team reported that Opportunity
had popped out of the trench it had dug itself into more than a month
earlier.

"After a nerve-wracking month of hard work, the rover team is both
elated and relieved to finally see our wheels sitting on top of the sand
instead of half-buried in it," Jeffrey Biesadecki, a rover mobility
engineer at NASA's Jet Propulsion Laboratory in Pasadena, Calif., said
in a news release.

Team members gathered at a Sunday barbecue to celebrate the
breakthrough, and were back in their offices on Monday to plot out the
next moves.

The two top tasks are to study the characteristics of the troublesome
sand drift in Meridiani Planum and to develop safety-conscious
procedures for the road ahead, said Jim Erickson, rover project manager.

"In the event that we get into these kinds of drifts, we want to be able
to drive reliably," he told MSNBC.com Monday.

Planning Opportunity's itinerary

Opportunity will probably circle around - "gingerly," Erickson said - 
and take a close look at the dune where it got stuck, using its
camera-equipped robotic arm as well as its thermal imager, which
apparently is back in working order after some earlier glitches.

The mission team wants to figure out whether the rover became mired
because of the composition and the height of the dust in the dune, or
because it sank into crust that was thinner than usual, or because "the
topography just had a particular shape that gave us trouble driving on
it," Erickson said.

"We're probably not going to go very far. ... It depends on how paranoid
we are about approaching back to the area we just left," he said.

Planners are also considering a new type of zigzag driving to get across
the dune field, Erickson said. Opportunity would drive a short distance
in one direction, turn slightly to the right, verify that it won't get
stuck, then drive another short distance, turn to the left, and repeat.

"It'll take a lot longer to drive large distances," Erickson said. "With
this technique, we'll never break the 220-meter [single-day] record for
distance, but we don't want to."

The rover's next destination is a bright patch of ground to the south,
nicknamed Erebus Highway. Erickson and other rover team members hope
that the "highway" is a stretch of rocky material leading to a wide
crater also called Erebus.

"We're much more comfortable about driving on rocks," he said.

500-day mission

Erickson noted that Opportunity is approaching its 500th Martian day of
operations - and Spirit, its twin on the other side of the Red Planet,
already has passed the 500-day mark. Not bad, considering that the
rovers' "warranty period" ran out after 90 days.

The rover team has worked around glitches with a stuck heater and a
flaky steering motor actuator on Opportunity, as well as a balky drive
motor and a worn-down rock drill on Spirit. "So far we've always gotten
in and gotten out," Erickson said.

While the rover team was considering Opportunity's next moves, Spirit
was keeping busy investigating the geology of the Columbia Hills in
Gusev Crater. Cornell astronomer Steve Squyres, the principal
investigator for the rover missions, reported on Saturday that Spirit
had come across a nearby rock worthy of further investigation, nicknamed
Backstay.

"It's a loose rock, not bedrock, so it may be a piece of impact ejecta
from someplace far away," Squyres said in his mission update.

Even though the rovers already have sent back far more scientific data
than expected, the scientists and engineers at JPL are greedy for more -
and that's why the rover team worked through weekends and holidays to
get Opportunity moving again, Erickson said.

The original twin-rover mission cost $820 million, and mission
extensions have been budgeted at roughly $2.5 million per month. In
April, NASA gave the go-ahead for extensions to continue -
as far ahead as September 2006.

"We paid to get this vehicle to Mars," Erickson observed. "At some point
we will wear it out, and that's a good thing. Our goal in life is to
wear it out. But bad things happen on Mars. ... The dust storm season is
upon us, where you just might run out of time. Every day is precious."