Nasa's Spirit rover finds more geological evidence of water once being present on the surface in an upland area known as the "Columbia Hills". After three months of successful exploration in the harsh Martian environment, Nasa says it will extend the rovers' mission by a further 18 months.
Scientists successfully steer the Opportunity rover free of a Martian sand dune, in which it had been stuck since late April.
Nasa's Mars Reconnaissance Orbiter lifts off from Cape Canaveral. The probe will act as a Martian 'weather satellite', providing scientists with the clearest images yet of the planet's surface. It is hoped that the probe could also shed light on the fate of the string of failed Mars missions, including Beagle 2.