New Analysis of Famous Martian Meteorite Finds No Evidence of Alien Life

Apparent fossils on the Allan Hills 84001 meteorite—a bit of rock that fashioned on Mars some 4 billion years in the past—had been produced by water and never microbial Martians, in line with new analysis. But the scientists behind the unique fossil declare aren’t satisfied.

The 4-billion-year-old fragment fashioned on Mars throughout the Red Planet’s turbulent Noachian interval, was jettisoned to house by a large impression round 17 million years in the past, and landed on Earth some 13,000 years in the past. Named for the Antarctic Allan Hills during which it was discovered, the 4.3-pound (1.94 kg) meteorite is among the many oldest ever recovered.

A NASA-led group of scientists shocked the world in 1996 by daring to suggest that the worm-like carbonate globules on the meteorite had been fossils, and due to this fact the primary proof of alien life. Many scientists questioned this interpretation, positing different theories for the alleged “biomorphs,” similar to volcanic exercise, impression occasions, and publicity to water. Most scientists agree that proof of life is absent on ALH84001, however the debate continues after greater than 1 / 4 century.

The newest chapter on this saga appeared on Thursday—a brand new paper in Science that after once more makes the case for abiotic processes as being chargeable for the options seen on the meteorite. The new paper particularly argues that the natural molecules discovered on the meteorite fashioned from gradual and regular interactions brought on by groundwater sifting by cracked rocks. Astrobiologist Andrew Steele from the Carnegie Institution for Science led the brand new analysis.

Now, simply because one thing is described as “organic” doesn’t essentially imply it has something to do with life. Organic molecules are usually composed of carbon and hydrogen, and typically oxygen, nitrogen, and sulfur. Sure, these molecules are sometimes related to organic processes, however they’ll come up from abiotic processes as effectively, in what’s generally known as abiotic natural chemistry.

Of relevance to the brand new analysis, “Mars rovers have found complex organic molecules in the ancient rocks exposed on the planet’s surface and methane in the modern atmosphere,” the brand new paper reminds us. “It is unclear what processes produced these organics, with proposals including both biotic and abiotic sources.” It’s by analyzing the origin of minerals on ALH84001 that the staff sought to higher perceive the “geochemical processes occurring early in Earth’s history and Mars’ potential for habitability,” Steele, a member of NASA’s Perseverance and Curiosity science groups, defined in a Carnegie press release.

Indeed, the brand new analysis is greater than an effort to debunk the declare that ALH84001 incorporates Martian fossils. This analysis additionally speaks to the early situations on Mars and Earth, how these situations presumably set the groundwork for all times to emerge, and why Mars displays the options we see right this moment, such because the presence of methane. The “search for life on Mars is not just an attempt to answer the question ‘are we alone?’,” mentioned Steele. “It also relates to early Earth environments and addresses the question of ‘where did we come from?’”

Steele and his colleagues used nanoscale microscopic imaging, spectroscopy, and an isotopic evaluation to check the meteorite, main them to conclude that the natural molecules fashioned as the results of interactions between water, seemingly salty or briny water, and basalt rocks.

The paper says one in every of two doable geochemical processes had been chargeable for the natural synthesis: serpentinization and carbonization. In serpentinization, igneous rocks wealthy in iron or magnesium work together with circulating water, ensuing within the manufacturing of hydrogen, and in carbonization, acidic water containing dissolved carbon dioxide interacts with rocks, leading to carbonates.

The scientists say it’s not apparent which of the 2 is accountable or the precise sequence of occasions, however they do say it transpired over a chronic interval, that reactions produced organics from the discount of carbon dioxide, and that abiotic processes alone had been chargeable for the carbon-rich compounds.

The scientists behind the 1996 research aren’t impressed with the brand new paper, as The Guardian reports. They say it affords nothing new and that the interpretation isn’t supported by any proof, including that “[u]nsupported speculation does nothing to resolve the conundrum surrounding the origin of organic matter” within the meteorite.

So the controversy rages on. But this single rock gained’t reply the query as as to whether life as soon as existed, or nonetheless exists, on Mars. For that, our greatest present choice is a pattern return mission, which fortunately is already underway. NASA’s Perseverance rover is at present accumulating and depositing floor samples for a future mission to convey to Earth, presumably within the early 2030s.

More: Scientists Just Need to Follow These 7 Steps to Prove Aliens Exist.