NASA's Mars Reconnaissance Orbiter, launched in August 2005, is on a search for evidence that water persisted on the surface of Mars for a long period of time. While other Mars missions have shown that water flowed across the surface in Mars' history, it remains a mystery whether water was ever around long enough to provide a habitat for life. The orbiter's primary mission ends about five-and-a-half years after launch, on December 31, 2010.