23 July 2007
An Artist's Impression of the Mars Exploration Rover
Credit: NASA-JPL
NASA's twin Mars Exploration Rovers, which have been exploring the Red Planet since January 2004, are now facing an epic challenge. For nearly a month, a series of severe Martian summer dust storms has affected the rover Opportunity and, to a lesser extent, its companion, Spirit.
The dust in the Martian atmosphere over Opportunity has almost totally obscured sunlight. Now the rover is powered only by the limited diffuse sky illumination. Scientists are deeply concerned the storms might persist for several days, or even weeks.
"We are rooting for our rovers to survive these storms, but they were never designed for conditions this intense," said Alan Stern, Associate Administrator of NASA's Science Mission Directorate.
If the sunlight is further cut back for a long period, the rovers will fail to generate enough power to keep themselves warm and operate at all, even in a near-dormant condition. The rovers apply electric heaters to keep some of their vital core electronics from becoming too cold.
Before the dust storms, Opportunity's solar panels had been generating about 700 watt hours of electricity per day, enough to light a 100-watt bulb for seven hours. When dust in the air reduced the panels' daily output to less than 400 watt hours, the rover team suspended driving and most observations, including deployment of the robotic arm, cameras and spectrometers to explore the site where Opportunity is located.
On 17 July 2007, the output from Opportunity's solar panels dropped to 148 watt hours, the lowest point for either rover. The following day, Opportunity's solar-panel output dropped even lower, to 128 watt hours.
NASA engineers are taking measures to protect the rovers, especially Opportunity, which is experiencing the major impact of the dust storm. The rovers are showing robust survival characteristics. Spirit, in a location where the storm is currently less powerful, has been commanded to save battery power by limiting its activities.
Spirit and Opportunity are located on opposite sides of Mars. The primary goal of the rovers' mission was to find evidence for past water activity on Mars. Two asteroids were named Spirit and Opportunity, to honor the six-wheeled robotic geologists.
Further Reading
Mars Exploration Rovers
http://marsrovers.jpl.nasa.gov/home/index.html
Aymen Mohamed Ibrahem
Senior Astronomy Specialist