The little Martian rovers could continue to roll along the planet's surface 1,000 Martian days after their first landing.
Spirit and Opportunity were originally planned for a 90-Martian day mission. (A day on Mars is 24 hours, 39 minutes, 35 seconds.) Spirit reached its 1,000-day anniversary on Oct. 25, Opportunity will reach that goal on Nov. 15.
"We knew if we got through the first Martian winters it would last until something broke," said John Callus, rover project manager at JPL.