The Martian north polar cap. A study of Martian meteorites shows that the surface of the red planet probably hasn't had significant amounts of free-standing liquid water for the last four billion years, according to a study published in the US(AFP/Nasa/File)
Technicians work on NASA's Mars Reconnaissance Orbiter (L) as it is displayed to the press at the Kennedy Space Center in Cape Canaveral, Florida, July 20, 2005. The spacecraft is scheduled to be launched on August 10 aboard an Atlas V rocket from the Cape Canaveral Air Force Station. The MRO science instruments and cameras will provide the most detailed study of the Martian surface and the planet's atmosphere ever conducted by an orbiting Mars spacecraft. At right is the protective fairing for the spacecraft. REUTERS/Joe Skipper