(ORDO NEWS) — To date, we have found more than a hundred meteorites that arrived from the Red Planet and at some point fell to Earth. Among them, sample ALH84001 may well be one of the most enigmatic.
This meteorite fragment was found in the Alan Hills Icefield in Antarctica in 1984. It is believed to have formed on Mars about 4 billion years ago. What has particularly intrigued scientists since its discovery is the tiny traces of organic carbon found in the rock. Could this point to early alien life on Mars billions of years ago?
Probably not, judging by the latest analysis of the fragment. Instead, the organic molecules found in a meteorite are the result of specific fluid-rock interactions similar to those that occur on Earth.
“Analysis of the origin of the minerals contained in the meteorite can serve as a window to both the geochemical processes that took place at the beginning of the Earth’s history and the potential for life on Mars,” says astrobiologist Andrew Steele of the Carnegie Institution of Science in Washington, DC.
“Hypotheses about the origin and mechanisms of formation of these organic substances include abiotic origin as a result of shock, magmatic and / or hydrothermal processes; biological origins of the alleged ancient Martian organisms and terrestrial pollution.”
To study the tiny carbon globules found in ALH84001, the team accessed a thin section and fragment of a meteorite obtained from NASA’s Johnson Space Center.
They subjected these fragments to various methods, including nanoscale imaging, analysis of the isotopes present in the rock, and spectroscopy (using light to study the chemical composition of matter).
The characteristics of the rock indicate that it could easily have been formed in the presence of non-biological or abiotic processes known to produce organic carbon molecules here on Earth. The first is serpentinization, which occurs when igneous rocks (solidified from lava or magma) rich in iron or magnesium interact with circulating water to form hydrogen.
The second process is carbonization, in which rocks react with slightly acidic water dissolved in carbon dioxide, resulting in the formation of carbonate materials. It is not clear if both processes occurred simultaneously, but the study suggests that they did not occur for an extended period of time.
“The search for life on Mars is not just an attempt to answer the question: Are we alone?” This also applies to the environment of the early Earth and answers the question “where did we come from?”
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