Hidden, ancient rocks could contain evidence of former life on Mars

28 May 2018

Image: Jurik Peter/Shutterstock

The search for life that once existed on Mars continues, and the answer could be found in 4bn-year-old rocks near the planet’s ancient lakes.

Since we first started sending probes to Mars in the mid-20th century, humans have been searching constantly for some indication that life once existed there in some shape or form.

While a Martian meteorite sparked a brief flurry of hope for the existence of bacteria in 1996, there has yet to be a discovery that definitively proves it.

However, a team from the University of Edinburgh has suggested that iron-rich rocks near the ancient lake sites of Mars could provide invaluable clues to whether life did indeed exist on the Red Planet.

Being 4bn years old or more, these rocks – which formed in ancient lakebeds – could harbour fossilised evidence of microbes.

Formed during the Noachian and Hesperian periods of Martian history 3-4bn years ago, this time would have looked remarkably different to modern-day Mars with a surface covered in liquid water.

Helping future Mars rovers

If these rocks are discovered, the team said, they would offer a snapshot of a time far greater than any rocks from the same age found on Earth.

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

After reviewing studies of fossils on Earth and replicating Martian conditions in the lab, the team was able to identify the most promising sites on the planet to explore for traces of life. These include areas with sedimentary rocks made of compacted mud or clay because they are rich in iron and silica, which helps preserve fossils.

Dr Sean McMahon of the University of Edinburgh’s 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.”

By discovering these deposits now, NASA’s 2020 mission to send a rover to the planet could visit these specific regions if deemed viable.

Colm Gorey was a senior journalist with Silicon Republic