As long as the robotic rovers are able to continue to be productive, they will continue to be supported by ground controllers at the Jet Propulsion Laboratory in California.
The NASA article, which announced the mission extension, is “NASA Extends Operations for Its Long-Lived Mars Rovers.” The article is found at website: http://www.nasa.gov/mission_pages/mer/mer-20071015.html.
The two rovers landed on the Martian surface about three weeks apart in January 2004. Their mission, at that time, was scheduled to last about three months. Now, as of October 2007, the mission has far exceeded the expectations of the mission managers--both in duration and in scientific knowledge acquired about Mars.
Mars Exploration Rover-B (MER-B), commonly called Opportunity, landed on Mars on January 25, 2004—specifically landing at the Meridiani Planum. Currently, the six-wheeled, solar-powered Opportunity is descending into the Victoria Crater, still within the Meridiani Planum region.
MER-A, often called Spirit, landed on the surface of Mars on January 4, 2004. It landed on the opposite side of Mars from its sister rover Opportunity—in the region called the Gusev crater. As of October 7, Spirit is at Humboldt Peak, at Site 3a. As of October 3, Spirit has traveled about 4.5 miles—or, more precisely, 7,244.32 meters.
The home Web page for the Mars Exploration Rovers, by NASA’s Jet Propulsion Laboratory, is: http://marsrovers.jpl.nasa.gov/home/index.html. Detailed information is available on various aspects of the mission.