“Leopard spots” found on a rock on Mars contain the clearest signs yet that life once existed on the red planet, NASA has announced.
The space agency said analysis of the unusual markings by the Perseverance rover has revealed they contain minerals that on Earth can be a byproduct of microbes.
Scientists can’t rule out that the spots were caused by natural geological processes.
The leopard spot-like marking on the rock. Pic: NASA/JPL-Caltech/MSSS
But Nicky Fox, associate director of NASA’s science mission directorate, said after a year of “pressure testing” the evidence, it still points to a biological origin.
“This finding by our incredible Perseverance rover is the closest we’ve actually come to discovering ancient life on Mars,” she said. “We’re really excited about that.
“But it’s a signature, a leftover sign. It’s not life itself.”
The tantalising evidence was laid down in the rocks more than 3 billion years ago.
At the time Mars was covered in lakes, rivers and perhaps even oceans. The surface water vaporised into space when the planet lost its atmosphere long ago.
The Perseverance rover has been exploring an ancient river delta in the Jezero Crater since it landed in February 2021.
The 3m-long robot has been taking detailed images of the surface, collecting rock samples and analysing material with onboard instruments.
In July last year it came across a rock NASA named Cheyava Falls that lay in a canyon once carved out by water.
Comprehensive analysis of the leopard spot-like markings on the rock, and others that resemble tiny black poppy seeds, has revealed minerals containing iron, phosphorus and sulphur.
Evidence points to these being caused by chemical processes associated with microbial life.
The only way of being sure is to bring the samples back to Earth.
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But Donald Trump’s cuts to NASA’s budget have forced a rethink of its plans to launch a joint retrieval mission with the European Space Agency.
Sean Duffy, the acting NASA chief, said: “I’ve been given an ask for spending a little less money. I think we can do that. I know we can do that.
“But I’ve told the team at NASA, if we don’t have the resources for the right missions or the right people, I will go to the president, I’ll go to Congress, I’ll ask for more money.
“But I feel pretty confident that with the money that we’ve been given, in the president’s budget, we can accomplish our mission.”
If further scientific analysis does confirm microbes once existed on Mars, then we’ll know life on Earth isn’t unique.
According to NASA every star in the night sky has an average of one planet orbiting around it.
And with the right conditions, some could also be home to life. Perhaps even intelligent alien life.
