AS NASA’s Mars rovers Spirit and Opportunity roll on, six months beyond their expected lifetimes, Opportunity has inexplicably started extracting more power from its solar cells.
When the mission began in January, the cells provided about 900 watt-hours per day. That dropped to 500-600 watt-hours by June, as dust accumulated on the solar panels and sunshine dwindled with the advance of the Martian winter at the landing site.
But since mid-September the panels have been generating more than 700 watt-hours per day. That was a month before the Martian midwinter, so more sunlight cannot be the explanation.
The rover team…
