The Opportunity rover recently celebrated 10 years on Mars, even though the mission was only planned for three months. Engineers thought the rover would conk out much sooner, in part because they believed its solar panels would quickly become caked with dust and cut off the robot's power supply. Instead, they found that wind storms actually help to clean the panels.
Over the years, Opportunity has taken several self-portraits — an overhead view of the rover made by combining several images — that give us a good idea of how much dust has accumulated on the solar panels. Compared to its first year on Mars, the rover is looking really dirty today.
Check out the transformation in the images below.
December 2004, all shiny and new:
NASA
February 2007: (This image is not as complete as the other because it was taken after a dust storm when rover power was limited)
NASA
December 2011:
NASA
January 2014:
NASA
Here's a side-by-side view of the solar panels from December 2004 (left) and today:
NASA
Shockingly these dust-caked solar panels are still working and powering the rover.
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