Two twin Mars Exploration Rovers will seek to determine the history of climate and water at a site on Mars where conditions may once have been favorable to life. The landing sites at Gusev Crater and Meridiani Planum were selected on the basis of intensive study. These sites offer evidence that liquid water was once present. The rovers' scientific instruments will be used to read the geologic record at each site, to investigate what role water played there, and to determine how suitable the conditions would have been for life. >>>

The ESA orbiter Mars Express will carry a small lander, Beagle 2. It is called after the ship in which Charles Darwin set sail to explore uncharted areas of the Earth in 1831. After coming to rest on the surface, Beagle 2 will perform exobiology and geochemistry research. >>>