* Astronomy

Spacecraft Monitoring Martian Dust Storm

A Martian dust storm that NASA's Mars Reconnaissance Orbiter has been tracking since last week has also produced atmospheric changes detectable by rovers on Mars.
Using the orbiter's Mars Colour Imager, Bruce Cantor of Malin Space Science Systems, San Diego, began observing the storm on Nov. 10, and subsequently reported it to the team operating NASA's Mars Exploration Rover Opportunity. The storm came no closer than about 1,347 kilometres from Opportunity, resulting in only a slight drop in atmospheric clarity over that rover, which does not have a weather station.
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Mars has an ethereal, tenuous atmosphere with less than one-percent the surface pressure of Earth, which challenges scientists to explain complex, wind-sculpted landforms seen with unprecedented detail in images from NASA's Mars Reconnaissance Orbiter.
One of the main questions has been if winds on present-day Mars are strong enough to form and change geological features, or if wind-constructed formations were made in the past, perhaps when winds speeds and atmospheric pressures were higher.
The eye-opening new views of wind-driven Mars geology come from the University of Arizona's High Resolution Imaging Science Experiment camera (HiRISE). As the orbiter flies at about 3,400 meters per second (7,500 mph) between 250 and 315 kilometres  above the Martian surface, this camera can see features as small as half a meter.

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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.

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Martian Skies Brighten Slightly
Mars Exploration Rover Status Report: Situation Improves; Spirit Resumes Using Robotic Arm

Slight clearing of still-dusty Martian skies has improved the energy situation for both Spirit and Opportunity, allowing controllers to increase the rovers' science observations. Spirit is even being commanded to move its arm for the first time in nearly three weeks. It will position the arm's microscopic imager to take a series of photographs of two soil targets and one rock target. Opportunity's planned science observations are for studies of the atmosphere.
Energy production from solar arrays increased to 295 watt hours on Spirit's 1,276th Martian day, or sol, which ended early Aug. 6, and to 243 watt hours on Opportunity's sol 1,255 which ended midday Aug. 5. The solar panels generate electricity from sunlight. Dust storms obscuring the sun have cut daily output as low as 261 watt hours on Spirit and 128 watt hours on Opportunity in recent weeks, compared with levels above 700 watt hours per sol before the current series of Martian dust storms began in June. One hundred watt hours is what it takes to run a 100-watt bulb for one hour.
The increased output from the solar panels, though slight, has allowed Opportunity to fully charge its batteries and Spirit to bring its batteries to nearly full charge. Also, the temperature of the core electronics module on Opportunity, which was of concern when it fell to minus  37 Celsius last week, has increased to minus 33.4 degrees Celsius.

"Conditions are still dangerous for both rovers and could get worse before things get better.  We will continue our cautious approach to the weather and configure the rovers to maintain a high state of charge on the batteries. Communication sessions with both rovers will remain limited until the skies clear further" -  John Callas, rover project manager at NASA's Jet Propulsion Laboratory, Pasadena, California, US.

Source NASA