Martian soil samples will be collected and brought back to Earth as part of the first round-trip mission to the red planet, European and US scientists have announced.

Nasa and the European Space Agency (Esa) today signed an agreement to plan the endeavour, which could reveal if life exists or existed on Mars.

So far, efforts to explore the planet have relied on analysis of Martian soil by robotic rovers and static landers, which send data back to Earth.

But collecting samples and returning them to Earth would enable detailed examinations in laboratories using instruments that are currently too large or power-hungry to be carried the 34 million miles.

The mission is likely to involve samples obtained by a rover being loaded onto an ascent vehicle which would blast off from the Martian surface and then deploy a descent module which would parachute down to Earth.

The samples would then be subject to strict quarantine, described as “planetary protection”, aimed at preventing contamination of Earth in the event they contained Martian organisms.