[meteorite-list] Mars Rover to Seek Safe Winter Haven

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu Feb 16 17:13:14 2006
Message-ID: <200602162211.k1GMBVG04088_at_zagami.jpl.nasa.gov>


Mars rover to seek safe winter haven
Kimm Groshong
New Scientist
16 February 2006

While Spirit busily studies a finely layered outcrop dubbed Home Plate,
mission planners say the rover's daily power supply is steadily
dropping. And with the Martian winter looming and dust accumulating on
Spirit's solar arrays, the team is preparing to drive Spirit to a safe

The Martian winter does not officially begin until August, but Byron
Jones, rover mission manager at NASA's Jet Propulsion Laboratory (JPL)
in Pasadena, California, US, says the team would like to get Spirit
situated on a slope called McCool Hill, with its solar arrays tilted
northward, in plenty of time.

That tilt maximises the sunlight falling on the arrays and worked well
for the rovers during their first Martian winter, which peaked in
September 2004.

Wednesday was Spirit's 754th Martian day (sol) in operation - a sol is
24 hours and 40 minutes. The team estimates it will take about 40 sols
for Spirit to trek from Home Plate to McCool Hill and they want to
arrive by their 800th sol.

"We're steadily approaching a point where if we don't reach a northern
facing slope, we won't be as productive as we'd like," Jones told New
Daily toil

Jones says in order to be productive during a sol, the rovers need at
least 400 watt-hours. That amount of power allows an hour-long drive, a
couple hours of robotic arm work or remote sensing and a daily data
uplink to the Mars Odyssey spacecraft. To simply stay alive, they need
about 280 watt-hours.

Spirit is currently operating with about 450 watt-hours per sol, but the
available power has dropped by about 100 watt-hours over the past 50
sols, Jones says.

Both Spirit and its twin Opportunity have far surpassed the expectations
for the mission which began in January 2004 and intended to last 90
days. Principal investigator Steve Squyres, of Cornell University, New
York, US, says now that Spirit has reached its long-targeted Home Plate
outcrop, the team is "collecting data at a furious rate".

The extensively layered, semi-circular outcrop is coarsely grained at
the bottom with finer grained material higher up. Several theories could
explain such layering, Squyres says - it could be a volcanic ash
deposit, layers of ejecta from impact cratering or material laid down by
wind or water. But he says, "If you took a poll of the team right now, I
think you would find the favoured hypothesis is that it's some kind of
volcanic ash deposit."

Volcanic bombs

The team is looking for chunks of embedded material, or "volcanic
bombs", which would provide hints of a volcanic origin. He says before
Spirit has to head off towards it winter quarters, the planners hope to
manoeuvre the rover on top of Home Plate to gather more data.

The coming winter is less pressing for Opportunity, which is closer to
the equator and is still operating with about 600 watt-hours of power
each sol.

Jacob Matijevic, the rover mission team's chief of engineering, also at
JPL, said if possible, the team would like Opportunity to winter in
Victoria Crater, a large impact crater 2500 to 3000 metres away. "That
would have the same benefit as we saw in our investigations of Endurance
Crater," Matijevic says.

The journey to Victoria Crater is likely to take at least three months,
he adds.
Received on Thu 16 Feb 2006 05:11:31 PM PST

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