Mars rocks may show signs of earlier life

Iron-rich rocks — which formed in lake beds — are the best place to seek fossil evidence of life on Mars from billions of years ago, researchers say.

It is believed that Mars supported primitive life forms around four billion years ago and the new study could aid the search for traces of tiny creatures — known as microbes — on the Red Planet.

“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,” said Sean McMahon from University of Edinburgh in Britain.

The study, published in the

Journal of Geophysical Research , said that sedimentary rocks made of compacted mud or clay are the most likely to contain fossils.

These rocks are rich in iron and a mineral called silica, which helps preserve fossils.

Abundance of water

They formed 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.

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

This is because 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.