Europe is stepping up its plans to search for life on Mars with proposals for a solar-powered robot that would spend months on the Martian surface.
By Helen Briggs
BBC News Online science reporter
The Mars rover would be equipped with a portable lab, a drill, and a system to take soil samples from sites that could contain primitive life forms.
The European Space Agency (Esa) is asking scientists to come up with ideas for the 2009 mission.
What future Mars robots might look like (Nasa)
It comes as the quest to find life on the Red Planet approaches fever pitch, with two missions set to launch this summer.
The US space agency (Nasa) is sending two Mars rovers on the 100-million-kilometre journey to Mars in May and June.
The identical robots have six wheels and should be able to travel about a kilometre from where they touch down.
They are called Rover 1 and Rover 2 for now, but will eventually be named by US schoolchildren taking part in a competition.
The Esa spacecraft, Mars Express, will launch in June, carrying the British-built Mars lander, Beagle 2.
The British robot is designed to parachute on to the Martian surface and should land near the boundary between the ancient highlands and the northern plains around Christmas.
It will burrow a probe into the red soil to analyse rocks for signs of water but is unable to move from its landing site.
The next chance to launch a spacecraft to Mars comes in 2009 and Esa is already preparing for the opportunity.
The rover would be part of its ExoMars mission to study the biology of the Red Planet.
Part of Esa's Aurora programme, it is designed to pave the way for one day sending astronauts to explore the hostile territory of Mars.