London, July 15 : An international team of scientists is planning a 4 billion pounds mission to bring back rocks - and possibly even life - from Mars, which might take place between 2018 and 2033.
According to a report in the Telegraph, the scientists have spent the last eight months looking at ways of sending a craft to the red planet to collect samples for analysis.
It is seen as a vital step in the preparations for sending astronauts to Mars, which is unlikely to be possible before 2050.
"If you can't bring a rock back you are not going to be able to bring people back," said Professor Monica Grady, at the Open University, who co-chaired the panel of 31 experts that wrote the mission proposal.
"There's a real feeling that bringing samples back from Mars is absolutely essential if we are going to continue our Martian exploration programme," he added.
There have been seven successful landings on Mars since the US spacecraft Mariner 4 flew past it for the first time in 1965, but no lander has ever taken off from the surface again or brought anything back to Earth.
The exploratory mission would take place between 2018 and 2033, but one of the barriers is cost.
Expertise and funding from Nasa and the European Space Agency (ESA) would be essential, along with help from other space agencies.
Another potential problem is ensuring that any microbes carried by the rocks do not harm life on Earth.
Any life found on Mars must be hardy to cope with the extremes of temperature and UV radiation, which means that if the spacecraft with the samples disintegrated on re-entry there is a danger the Martian lifeforms would survive and pose a contamination threat.
According to Professor Colin Pillinger, who led Britain's unsuccessful Beagle II mission to Mars in 2003, "There's a big caveat when you start playing with Mars, and that's planetary protection. You have to be very careful not to bring anything back that might be harmful to Earth."
"Your mission has to be guaranteed, and I really mean guaranteed, to get into the Earth's atmosphere without damaging itself," he added.
NASA and ESA will decide in November whether to fund the mission's next planning stage.