[meteorite-list] New Images Reveal Threatening Conditions That Two Rovers Face in Giant Martian Dust Storm

[Ron Baalke]

http://www.news.cornell.edu/stories/Aug07/Mars.images.html

New images reveal threatening conditions that two rovers face in 
giant Martian dust storm

Cornell University
Aug. 29, 2007

The mighty Mars rovers Spirit and Opportunity continue to persevere 
in brutal conditions, as revealed in images of the sun they are 
sending home. The images show how opaque the Martian atmosphere has 
been in the face of a raging, two-month dust storm.

To understand the gravity of the storm, engineers and astronomers 
monitor the situation by examining the images of the sun and 
measuring the amount of dust or the opacity of the atmosphere.

Emily Lakdawalla of the Planetary Society assembled the mosaic of 
images, which were taken daily by the panoramic cameras (Pancams) on 
both rovers, Spirit and Opportunity. The images were calibrated by 
students in Cornell's MarsLab image-processing facility and made 
available through collaboration with Jim Bell, Cornell professor of 
astronomy and the principal investigator on the rovers' Pancam 
imaging team.

"Emily's mosaics are quite remarkable. They show a rover's-eye view 
of the storm getting worse, and this little light bulb we call the 
sun getting dimmer and dimmer and dimmer as the dust clouds built 
up," said Bell.

Since June, a massive dust storm has engulfed much of the Martian 
surface. The storm has put the rovers in danger, as they depend upon 
solar power to run during the day and to survive the harsh, cold 
Martian nights. As dust clouds block the sunlight and dust settles on 
the solar panels, the rovers' energy is depleted. Only wind can 
remove the dust, Bell said.

For the rover Spirit, the Jet Propulsion Laboratory (JPL) in 
Pasadena, Calif., reports that even though the Martian sky above 
Gusev Crater is clearing, solar power levels remained fairly low and 
constant dust now appears to be accumulating on the solar panels. 
Between sol -- a Martian day -- 1283 (Aug. 12) and sol 1286 (Aug. 
16), the atmosphere cleared by about 35 percent, leading to daily 
energy levels of about 300 watt-hours (the amount of energy needed to 
light a 100-watt bulb for three hours). Typical levels before the 
dust storms were around 700 to 900 watt-hours for the rovers.

On the other side of Mars, Opportunity, now waiting to enter Victoria 
Crater from the rim, is currently experiencing its lowest power 
levels to date. The sky was so dark in mid-July that less than 200 
watt-hours of daily energy was available, according to JPL. But skies 
are slowly clearing, offering hope that the rover will be ready for a 
descent into the crater soon. Opportunity benefited from wind blowing 
some dust off solar panels on Aug. 22. Under gradually clearing 
skies, Opportunity's solar panels were producing about 300 watt hours 
daily by Aug. 24.

The Jet Propulsion Laboratory, a division of the California Institute 
of Technology, Pasadena, manages the Mars Exploration Rover Project 
for the NASA Science Mission Directorate, Washington, D.C.