The Opportunity and Spirit rovers are facing the most serious threat yet encountered on their 3 year sojourns on Mars, with a massive dust storm reducing power levels to their lowest ever levels. Opportunity is the worst effected of the two rovers, with direct sunlight levels to its solar panels reduced by up to 99% in the last few days. Mission scientists have been scaling back science operations for both Rovers, switching off instruments and basically hunkering the machines down in the hope that they can survive. The biggest problem is that they can't simply switch the rovers off and on again after the storm clears. A minimum amount of power is required to run heaters that keep vital core electronics from becoming too cold and Opportunity is coming perilously close to the point where it will not be able to cope. Power levels dipped on Wednesday 18th to an unprecedented 128 watt hours, prompting scientists to take the extraordinary action of suspending some of the regular communication sessions with the Rover, a contingency that has never been enacted before.