[meteorite-list] Mars Rover Tries To Weather Dust Storm

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Wed, 3 Jan 2007 09:22:41 -0800 (PST)
Message-ID: <200701031722.JAA28793_at_zagami.jpl.nasa.gov>

http://space.newscientist.com/article/dn10878-mars-rover-tries-to-weather-dust-storm.html

Mars rover tries to weather dust storm
Kelly Young
New Scientist
02 January 2007

NASA's newly upgraded Spirit rover will celebrate its third anniversary
on the Martian surface hunkered down to weather a dust storm.

The rover parachuted down to Mars's Gusev Crater on 3 January 2004. Its
twin, Opportunity, caught up and landed on the other side of the planet
21 days later.

Early last week, Spirit's instruments detected hazy conditions due to a
large dust storm to the south that was churning up fine dust grains high
in the atmosphere.

Because the storms block some sunlight from reaching the planet's
surface, they could be dangerous for the rovers, which rely on solar
power to generate electricity.

So on Thursday, ground controllers had Spirit stop taking scientific
measurements of an igneous rock named Esperanza and scurry over to a
slope tilted 7.4? to the north to maximise the amount of sunlight
falling on its solar arrays.

"We had to boogie on out of Esperanza," says Ray Arvidson, deputy
principal investigator for the rovers' science instruments at Washington
University in St Louis, US.

'Lily pad' approach

At one point, its solar arrays were able to generate only 267 watt-hours
per day. Rover principal investigator Steve Squyres of Cornell
University in New York, US, said controllers would start worrying about
the rover's safety if the power dipped to 250 watt-hours.

"267 was way too close for comfort," Arvidson told New Scientist.
"That's why we had to get to another site."

Moving to the new slope increased its energy output by 30 watt-hours - a
crucial boost, since the Sun is still low on Mars's horizon, from
Spirit's perspective. In comparison, the rover Opportunity is currently
producing about 600 watt-hours per Martian day on the other side of the
planet, in a region called Meridiani Planum.

Now, Spirit will take a "lily-pad" approach to exploring Mars. To ensure
its safety, it will move from one pre-designated safe haven - an area
with a north-facing slope - to another.

Once the weather improves, Spirit will likely check out another
so-called vesicular basaltic rock, similar to Esperanza. These rocks
have large holes that were created by cavities of gas in molten lava,
giving them a distinctive, sponge-like appearance. Esperanza was the
first type of vesicular basalt ever examined on Mars.

New software

The Spirit rover, constricted by power and the low Sun, has spent the
past nine months in the same location at Low Ridge Haven (see Spirit to
start digging the Martian dirt
<http://space.newscientist.com/article/dn9049-spirit-to-start-digging-the-martian-dirt.html>).
Three weeks ago, it finally got to move around before being ordered to
safety.

Spirit is also bogged down by a front wheel that will not turn.

The rovers were designed to last 90 days. To kick off their fourth year
on the planet, they have been upgraded with new software to allow them
to operate a little more independently from ground controllers.

The new software will allow them to build better maps of the landscape
to help them steer clear of obstacles. They should also be able to track
a target visually, recognising that it is the same object even when
viewing it from different angles.

They will also be able to identify dust devils and clouds, so ground
controllers will not have to sift through all of the images to identify
such features.

Because of the power constraints, Spirit has not had a chance to test
most of its new software, but it was able to autonomously detect water
ice clouds at an altitude of between 10 and 15 kilometres.
Received on Wed 03 Jan 2007 12:22:41 PM PST