Evidence of life on Mars may still be out there—but the likelihood that proof is inside a 4-billion-year old meteorite that crashed to Earth decades ago just got slimmer.
Organic compounds found in the 4-pound rock were formed by water, probably brackish or briny, flowing through the meteorite, according to a study published Thursday in the journal Science.
The compounds weren’t left there by living creatures, as an earlier theory posited. But the compounds’ presence in the rock does suggest the Red Planet is capable of forming the chemistry that could potentially lead to life, said Andrew Steele, an astrobiologist at the Carnegie Institution for Science who led the multinational team of scientists that authored the study.
“The results are tremendously positive,” Dr. Steele said in an interview. “What we’ve found is a nonlife chemical reaction that makes potential building blocks to life.”
The rock, which is believed to have been bounced off Mars’s surface and into outer space billions of years ago, was found in Antarctica in 1984. A team of NASA-led scientists who spent years analyzing it announced in 1996 that it appeared to carry evidence of ancient Martian life—a theory that lost traction for some researchers over time as technology improved and scientists extracted even more precise data.
Dr. Steele’s team used minute sample slices—often smaller than a strand of human hair—to identify and analyze the carbon-rich compounds, created as water flowed through the hot rock billions of years ago and interacted with the meteorite’s minerals.
The study’s results, he said, offer a tantalizing look at similar reactions that might have been happening around the same time on Earth and may even help with the continued search for proof of extraterrestrial life.
“These observations show a nonlife background that we can use to search for biochemistries that aren’t similar to those we find on Earth, and that background can be applied elsewhere,” said Dr. Steele, referring to Mars and Enceladus and Europa, the moons of Saturn and Jupiter that have subsurface oceans.
Dr. Steele said he is eagerly awaiting the collection of more Mars samples, which will be returned to Earth for more study in coming years.
The National Aeronautics and Space Administration launched its Perseverance Mars rover from Florida on July 30, 2020. The robotic wheeled vehicle landed last February near a crater on Mars known as Jezero. Its mission is to search for signs of past life that might have existed around the crater, formerly a lake.
After it has collected enough samples, the cargo will be carried back to Earth in two different missions set to arrive around 2030, according to Dr. Steele.
NASA didn’t respond to a request to speak with the scientists who performed the 1996 study on the meteorite, which was named Allan Hills 84001 in reference to the place where it was found.
Dr. Steele said that while his most recent work doesn’t support all of those initial findings, the 1996 study was important to the field in general.
“The 1996 team inspired and catalyzed funding and made finding life a public mission and created a generation of students coming up who are involved in this important debate,” he said.