Dr. McMahon and co-authors determined that sedimentary rocks made of compacted mud or clay are the most likely to contain fossils.

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

These rocks formed during the Noachian and Hesperian periods (3-4 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,” Dr. McMahon and co-authors 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.”

The scientists reviewed studies of fossils on Earth and assessed the results of lab experiments replicating Martian conditions to identify the most promising sites on the planet to explore for traces of ancient life.

Their findings, published online May 2 in the Journal of Geophysical Research: Planets, could help inform NASA’s next rover mission to Mars, which will focus on searching for evidence of past life.

A similar mission led by the European Space Agency is also planned in coming years.

“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 prioritize the most promising deposits based on the best available information,” Dr. McMahon said.

Source: Sci News