[FPSPACE] Spirit rover's power is running down, due to dust storms

Peter Pesavento pjp961 at svol.net
Wed Nov 12 11:00:50 EST 2008

>From the Los Angeles Times




NASA's Mars rover Spirit imperiled by dust storms

The craft is dangerously low on power because of dust covering its solar
arrays. News of the problem comes a day after NASA declared an end to the
Phoenix polar mission.

By John Johnson Jr.

November 12, 2008

Massive Martian dust storms are threatening the survival of NASA's Spirit
rover, which has been exploring Mars for almost five years but is
dangerously low on power. 

Spirit last communicated with Earth on Sunday, when it reported that its
solar arrays had produced just 89 watt-hours of energy, which is much less
than the rover uses in a day. 

It's also the least amount of power that either Spirit, or its twin,
Opportunity, has produced over the entire life of the mission on Mars, which
began in January 2004. 

John Callas, the rover project manager at the Jet Propulsion Laboratory in
La Cañada Flintridge, said the rover's survival might be in jeopardy because
the dust-covered arrays were producing only a third as much power as they
were capable of, even before the latest dust storms hit. The storms of the
last few days have reduced the output even more, to 26.5%, he said. 

The announcement of Spirit's problems came a day after NASA declared an end
to the Phoenix mission near Mars' north pole, the first to sample ice on an
alien planet. Dust storms, and the approach of winter in the northern
hemisphere, are blamed for Phoenix's demise. 

As for Spirit, Callas said he believed the low power levels probably tripped
a built-in fault-protection system, which automatically disconnects nearly
all the rover's electronics from its batteries to keep them from draining

When that happens, mission managers on Earth lose control of the vehicle. 

Ideally, after a low-power shutdown, the rover will periodically check to
see whether the batteries have recharged. If they have, it resumes normal

"The best chance for survival for Spirit," Callas said, is to avoid a
low-power shutdown, from which it might not awake. 

To avoid draining the batteries, mission managers sent a message to the
rover Tuesday, ordering it not to communicate with Earth until Thursday. 

By then, NASA officials hope, the dust storms will have cleared and the
solar panels will be producing more power. 

After spending much of the southern hemisphere winter parked, Spirit had
only started driving again when the dust storms hit. 

The rover is currently halted at a geological feature called Home Plate. 

Meanwhile, Opportunity, which has not been compromised by the dust storms to
the same extent, is driving to a deep crater. 

The rovers have far outlasted their original life expectancy of 90 days. 

During their time on Mars, they have drilled into rocks and taken pictures
of erosion patterns that proved that large parts of the Red Planet were once
covered by seas or lakes. 

Today, the surface is much too cold for water to be in liquid form,
scientists say. 

Scientists are now using the rovers to understand how the planet changed
from a more temperate world to a barren rock.

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