RESEARCH by Edinburgh University scientists could help Nasa discover life on the planet.

They have boosted hopes of finding Martian life by identifying locations which Nasa’s Mars 2020 should concentrate on when gathering samples.

The next-generation robot will carry a sophisticated mobile geology lab designed to search for signs of Martian life, such as primitive algae or bacteria.

Rocks made of compacted mud or clay are the best bet because they are rich in iron and a mineral called silica, which helps preserve fossils.

Mudstones rich in silica and iron-bearing clays formed in the ancient lakes and rivers of Mars during the Noachian and Hesperian periods of Martian history between three and four billion years ago.

At that time the planet’s surface was abundant in water, which could have supported life.

Microbial life could also have been preserved in silica or calcite-rich hot spring deposits – although these have yet to be found on Mars – and possibly in salt rocks.

Study leader, Dr Sean McMahon, of the University of Edinburgh school of physics and astronomy, said: “There are many interesting rock and mineral outcrops on Mars where we would like to search for fossils.

“But since we can’t send rovers to all of them we have tried to prioritise the most promising deposits based on the best available information.”

The “field guide” published in the Journal of Geophysical Research will also assist a similar planned mission by the European Space Agency.

The researchers say the rocks are much better preserved than those of the same age on Earth.

Mars is not subject to plate tectonics – the movement of huge rocky slabs that form the crust of some planets – which over time can destroy rocks and fossils inside them.

The analysis reviewed studies of fossils on Earth and assessed the results of lab experiments replicating Martian conditions and identified sites to be explored for traces of ancient life.

The US space agency’s Mars 2020 rover will collect rock samples to be returned to Earth for analysis by a future mission. A similar mission led by the European Space Agency is also planned in the near future.

Fossils on Earth are typically associated with the hard remains of bones. But any evolution on Mars most likely stopped with microbial organisms – and did not advance to complex life forms.

Finding the right environmental conditions for preserving soft bodies is much more difficult.

Habitable conditions are thought to have existed on the red planet billions of years ago.

Scientists have suggested early Mars was cold and wet – not unlike Antarctica today. Dissolved salts in Martian oceans would have kept water liquid even at sub-zero temperatures.

Another theory proposes the planet was once wetter and warmer than previously thought – similar to the sizzling Mojave Desert of Nevada.

Either way, enough liquid water should have been present for microbial life to have gained a foothold.