At a press conference on Wednesday (September 10), NASA said that its Mars rover Perseverance, which has been roaming the surface of the Red Planet since February 2021, had picked up “potential biosignatures” in a rock sample that it scanned last year.
The announcement by the American space agency has triggered renewed excitement about the possibility of extraterrestrial life.
However, scientists behind the finding have underlined that the rover has picked up only potential evidence – and more studies must be carried out before any conclusion can be reached.
Perseverance’s finding
Last year, the six-wheel, small car-sized rover had come across a rock – later named Cheyava Falls – on its designated route, which seemed to possess attributes that scientists thought were worth investigating for potential microbial signatures from the past.
Based on data sent by instruments aboard the rover, scientists determined that certain chemicals and structures on the rock were such that could have been formed by living organisms billions of years ago. NASA revealed this in July 2024, but said that more detailed analysis was required.
In findings published in Nature magazine on Wednesday, NASA scientists have left open the possibility of the rock sample containing potential biosignatures. Biosignatures refer to an object or structure that may have a biological origin – that is, it may have been formed by a living organism.
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“This finding by Perseverance…is the closest we have ever come to discovering life on Mars. The identification of a potential biosignature on the Red Planet is a groundbreaking discovery, and one that will advance our understanding of Mars,” acting NASA Administrator Sean Duffy said at the press conference.
The analysis by the onboard instruments found that the rock sample was composed of clay and silt, and also contained organic carbon, sulphur, oxidised iron (rust), and phosphorus. On Earth, clay and silt are excellent preservers of past microbial life, NASA said in a statement.
Not a settled question
While exciting, the finding does not – as yet – settle the question of the possibility of life on Mars.
The particular structures or chemical compositions that aroused the interest of scientists could have been generated by non-biological processes as well, even though under conditions that do not fully align with some other characteristics of these rocks.
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“The combination of these minerals, which appear to have formed by electron-transfer reactions between the sediment and organic matter, is a potential fingerprint for microbial life, which would use these reactions to produce energy for growth. The minerals also can be generated abiotically, or without the presence of life. Hence, there are ways to produce them without biological reactions,” NASA said.
The Cheyava Falls rock will undergo more detailed analysis. Perseverance had drilled into the rock and acquired a small sample a few centimetres in size – it is one of the 30-odd samples the rover has collected from various locations on Mars so far.
It is intended to get these rock samples to Earth in a future mission. The rover has a special compartment in which they can be stored. NASA has been working on a sample return mission, but is facing uncertainty due to budget cuts imposed by the Trump Administration.
