Mars rover reveals new details about Red Planet’s water history

Findings suggest water may have once percolated through some rocks on Mars

Scientists have discovered the presence of water-altered minerals and organic compounds on the Red Planet that suggest water may have streamed across the Martian terrain billions of years ago.

Researchers, including planetary scientist Eva Scheller from MIT, used the SHERLOC instrument aboard the Perseverance Mars rover to measure the chemical composition of rock samples from the Jezero Crater – the site of an ancient lake and river bed.

They published the results in a trio of papers in the journals Science and Science Advances on Wednesday.

Since the Perseverance rover landed on the Jezero crater on Mars in February 2021, scientists have been analysing data collected by the craft to look for signs of water and organic chemicals indicative of the presence of ancient life on Mars.

The area around the Jezero Crater has been of particular interest to scientists as they suspect it was likely once a river delta.

“These kinds of environments on Earth are places where life thrives,” astrobiologist Amy Williams, one of the long-term planners for the Perseverance mission from the University of Florida in the US, had said.

“The goal of exploring the Jezero delta and crater is to look in these once-habitable environments for rocks that might contain evidence of ancient life,” Dr Williams said.

In one of the new studies, researchers revealed the presence of carbonate mingled with grains of olivine in the oldest volcanic igneous rock on the crater floor.

These results suggest water may have once percolated through these rocks, scientists said.

“Reactions with liquid water formed carbonates in an olivine-rich igneous rock,” they wrote in the study.

Scientists also found traces of phosphate – a key building block for life – in these rocks.

In basalt rocks of the younger Maaz formation on the Jezero crater, researchers also found evidence of salts called perchlorates, which are negatively charged molecules made of a chlorine atom and four oxygen atoms.

These perchlorates, scientists suspect, may have formed when Mars had liquid water.

“Perchlorates are easily dissolved, and therefore perchlorates likely formed when these rocks were last exposed to liquid water,” scientists wrote in the study.

While studies suggest perchlorates are not very hospitable to life, the water that may have led to their formation might have been conducive.

“This kind of highly oxygenated state, generally, is not great for preserving signs of life. So I suppose there can always be a possibility, but it’s probably not the number one spot you would look for habitable conditions,” Dr Scheller told tech outlet Inverse.

The studies could also shed light on the presence of ring-shaped organic compounds, but they couldn’t identify the specific chemicals.

Nasa has also held previously that the presence of organics does not necessarily mean life once existed on Mars as both biological and non-biological mechanisms could be behind the formation of these molecules.

Once the rock samples collected by Perseverance are returned to Earth in a future mission, they can be analysed more thoroughly using more powerful analytical tools to shed more life on the history of the Red Planet.