London, July 8 : Space experts are planning out an ambitious robotic spacecraft mission to return rocks from Mars to Earth, which would be tested for signs of life on Earth laboratories.
According to a report in New Scientist, though Mars is a hub of robotic activity, no mission has ever returned Martian rocks to Earth, something that scientists consider essential to understanding the history of Mars and whether it ever hosted life.
"This has been the holy grail for Mars scientists for a very long time," said David Parker of the British National Space Centre in London, UK. "We think it is doable, but it is going to take international collaboration and a lot of hard work to make it happen," he added.
Earth-based lab tests are essential for accurately assessing the abundances of different isotopes and trace elements, as well as identifying ancient life in the form of nanofossils.
With samples on Earth, scientists can double-check conclusions with a battery of different tests in labs around the world.
Landers that look for life on Mars have the drawback that the right chemical tests have to be guessed in advance. With rocks in the lab, scientists can change their approach as information unfolds.
Scientists also need to study Martian rocks in Earth-based labs to accurately determine their ages.
"You need large-scale lab equipment that you can't credibly take to the Martian surface," said Parker.
Last year, IMEWG asked a committee of scientists and engineers called IMARS (International Mars Architecture for Return of Samples) to draw up draft plans for a sample-return mission.
The team envisages launching two sets of spacecraft to Mars. One would comprise a lander, rover and ascent rocket that travels directly to Mars, gathers samples then launches them back into Martian orbit.
The second would be an orbiting mothership that receives the samples, propels them back to Earth then drops the samples into Earth's atmosphere.
The rover should roam at least a few kilometres away from the lander and drill several centimetres beneath the surface to gather rocks of different ages and types, including sedimentary rocks that record the history of water. After gathering at least 500 grams of Martian material, including samples of surface dust and the atmosphere, the rover will return to the lander, where the samples will be sealed into separate containers within a capsule.
An ascent rocket will carry the capsule into orbit then transfer the samples to the mothership, a feat never performed before.
There are various possible timelines for the mission, depending on the position of Mars. The earliest possible launch would be May 2018, with the sample returning in mid-2022.