NASA’s Perseverance Mars rover has detected its highest concentrations of organic molecules yet, indicating the presence of ancient microbes, which scientists hope to confirm when rock samples are returned to Earth.
While the organic matter has previously been discovered on Mars, the new discovery is especially promising because it came from an area where sediment and salts were deposited into a lake—conditions that could have supported life.
“It is very fair to say that these are going to be, if not already are, the most valuable rock samples ever collected,” David Shuster, a Perseverance return sample scientist, told reporters during a press conference.
Organic molecules—compounds primarily composed of carbon that typically contain hydrogen and oxygen, but may also contain other elements—are not always produced by biological processes.
Further analysis and conclusions will have to wait for the Mars Sample Return mission, which is scheduled for 2033 and is a collaboration between NASA and the European Space Agency (ESA).
The rover, nicknamed Percy, landed on Mars’ Jezero Crater in February 2021, with the mission of storing samples that may contain signs of ancient life and characterising the planet’s geology and past climate.
It is exploring a delta that formed 3.5 billion years ago. The rover is currently exploring sedimentary rocks, which formed as a result of particles of various sizes settling in the then-watery environment.
Percy took two samples from a rock called “Wildcat Ridge,” which is about three feet (one metre) wide, and abraded some of its surface on July 20 so it could be analysed with an ultraviolet-light instrument called SHERLOC.
The findings revealed a class of organic molecules known as aromatics, which play an important role in biochemistry.
“This is a treasure hunt for potential signs of life on another planet,” said Sunanda Sharma, an astrobiologist at NASA.
“Organic matter is a clue, and we’re getting more and more of them… These results are particularly moving to me because it appears that we are in the right place, with the right tools, at a critical juncture.”
Other tantalizing hints about the possibility of life on Mars have previously been detected, including methane detections by Perseverance’s predecessor, Curiosity.
While methane is a digestive by-product of microbes on Earth, it can also be produced by geothermal reactions in the absence of biology.