Both the Spirit and Opportunity have provided an amazing amount of science from Mars. Even though Spirit is no longer mobile, it still has missions to accomplish.
From the link:
NASA has spent several months trying to free the Mars Exploration Rover Spirit from a sand trap. Now, engineers are calling it quits. After six years of exploration, and significant scientific discoveries, the rover will remain a stationary science platform.
“Spirit is not dead; it has just entered another phase of its long life,” said Doug McCuistion, director of the Mars Exploration Program at NASA Headquarters in Washington, D.C., in a press release.
Assuming it survives the upcoming Martian winter, the rover will continue its scientific endeavors for several months to years.
This view from the front hazard-avoidance camera on
NASA’s Mars Exploration Rover Spirit shows the position
of its front wheels following a backward drive on Jan. 23, 2010.