NASA is extending, for a fifth time, the activities of the Mars Exploration Rovers, Spirit and Opportunity. The decision keeps the trailblazing mobile robotic pioneers active on opposite sides of Mars, possibly through 2009. This extended mission and the associated science are dependent upon the continued productivity and operability of the rovers.
https://www.nasa.gov/home/hqnews/2007/oct/HQ_072088_Mars_Rovers_Funding_Ext.html