August 18, 2009
Today marks the 2,000th Martian day, or sol, of what was initially planned as a 90-sol mission on Mars for NASA's Spirit rover.
Spirit's twin, Opportunity, will reach the 2,000-sol milestone on Sept. 8. Both rovers have found rocks altered by past action of water on Mars. Both show some signs of aging but remain capable of further scientific investigations.
Since their landing halfway around the planet from each other in January 2004, Spirit has driven 4.8 miles and Opportunity has driven 10.7 miles. Together, they have returned more than 246,000 images. Each Martian sol lasts about 40 minutes longer than an Earth day.
More information on the rovers is at http://www.nasa.gov/rovers .