Organic material found in a Martian meteorite does not have a biological origin, new research has determined. Instead, the organics found in this particular chunk of Mars that fell to earth were formed by a natural process involving rocks and water.
BACKGROUND: ORGANICS FOUND IN MARTIAN METEORITE
Discovered in Antarctica way back in 1984, the Martian meteorite in question is named Allan Hills (ALH) 84001. It is a piece of the red planet that traveled across the empty space between Earth and Mars before smacking into the Antarctic ice.
Previous studies of the rock showed that it contained organic molecules. On earth, organics are most commonly associated with life, so that discovery led to rampant speculation about the possibility of past (or even present) microbiological life on the 4th rock from the sun.
Now, new research seems to have put the damper on that previous excitement, determining that the organics found in ALH 84001 were likely formed by a pair of geologic processes and not extraterrestrial life. However, the team behind the latest find also says their research reconfirms Mars’ watery past, meaning evidence of life may still exist on the planet.
ANALYSIS: ABIOTIC GEOLOGICAL PROCESS FORMED ORGANICS IN MARTIAN METEORITE
“Analyzing the origin of the meteorite’s minerals can serve as a window to reveal both the geochemical processes occurring early in Earth’s history and Mars’ potential for habitability,” said Andrew Steele of the Carnegie Institute for Science in a press release announcing the latest study.
Published in the journal Science, the study involved a re-analysis of ALH 84001 that led to the new, abiotic (non-life) conclusion.
According to the release, Steele’s team, which included additional researchers from Carnegie, some folks from NASA, as well as a wide range of other specialists from various research institutions, “used a variety of sophisticated sample preparation and analysis techniques—including co-located nanoscale imaging, isotopic analysis, and spectroscopy—to reveal the origin of organic molecules in the Allan Hills 84001 meteorite.”
Those tests revealed evidence of two types of interactions between water and rock that are similar to those found on Earth. The first is called serpentinization, where a rock actually changes its minerology by chemically interacting with circulating water, thereby releasing hydrogen. In the last few decades, mounting evidence has left little doubt that such circulating water has previously been present on Mars, so this cause is consistent with those results.
The other process observed in the meteorite is called carbonization. This occurs when rocks interact with slightly acidic water that also contains dissolved carbon dioxide, ultimately forming carbonate minerals.
The researchers say they were unable to determine if these two processes affected ALH 84001 at the same time or at different times. But according to the release, “the evidence indicates that the interactions between water and rocks did not occur over a prolonged period.”
Regardless of duration, the release indisputably confirms that “the reactions produced organic material from the reduction of carbon dioxide,” and not from microscopic organisms within the Martian soil.
OUTLOOK: MARS STILL A GREAT PLACE TO SEARCH FOR EXTRATERRESTRIAL LIFE
By all accounts, this study seems to confirm once and for all that the organics found in this particular Martian meteorite came from natural geological processes, and not as a result of life on the red planet. However, Mars is still considered to be a prime candidate for finding evidence of past life.
For instance, the NASA’s Mars Perseverance rover is already stashing away samples of Martian soil researchers think may hold clues to such ancient life, samples the American space agency and the European Space Agency (ESA) hope to bring back to earth for detailed analysis by the end of the decade.
Also, some NASA scientists say they may have even found signs of current life on the red planet way back in 1976, a conclusion that at least one of them still stands by.
“These kinds of non-biological, geological reactions are responsible for a pool of organic carbon compounds from which life could have evolved and represent a background signal that must be taken into consideration when searching for evidence of past life on Mars,” said. Steele “Furthermore, if these reactions happened on ancient Mars, they must have happened on ancient Earth, and could possibly explain the results from Saturn’s moon Enceladus as well.”
“The search for life on Mars is not just an attempt to answer the question ‘are we alone?’” added Steele. “It also relates to early Earth environments and addresses the question of ‘where did we come from?’”
Follow and connect with author Christopher Plain on Twitter: @plain_fiction