ALH-77005, a Martian rock found in Antarctica, contains numerous mineralized ‘biosignatures,’ including coccoidal, filamentous structures and organic material, according to a team of scientists from Hungary.
An artist’s impression of habitable Mars. Image credit: Daein Ballard / CC BY-SA 3.0.
“Our work is important to a broad audience because it integrates planetary, earth, biological, chemical, and environmental sciences and will be of interest to many researchers in those fields,” said team leader Dr. Ildiko Gyollai, a researcher at the HAS Research Centre for Astronomy and Earth Sciences in Budapest.
“The research will also be of interest to planetologists, experts of meteorite and astrobiology as well as researchers of the origin of life, and to the general public since it offers an example of a novel aspect of microbial mediation in stone meteorites.”
Thin section of ALH-77005: poikilitic texture of olivine with pyroxene cumulate grains, the studied melt pocket (rectangle) mostly composed of olivine. Image credit: Gyollai et al, doi: 10.1515/astro-2019-0002.
The achondrite meteorite ALH-77005 was found partially imbedded in the ice at the Allan Hills site in South Victoria Land during the Japanese National Institute of Polar Research mission in 1977-1978.
It had a rounded shape and its surface was partially ablated and roughly-polished by wind-blown ice.
Its age is estimated to be about 175 million years, with an exposure to cosmic rays of about 3 million years.
Thin section of ALH-77005 in plane polarized light: the area studied by FTIR spectroscopy is marked by rectangle, where the strong putative microbially mediated alteration was observed. Image credit: Gyollai et al, doi: 10.1515/astro-2019-0002.
Dr. Gyollai and co-authors analyzed a thin section of ALH-77005 by optical and FTIR-ATR microscopy.
They were able to detect the presence of coccoidal and filamentous structures (probably built by iron-oxidizing microbes); organic material; biogenic minerals, like ferrihydrite, goethite, and hematite.
“The other signatures for biogenicity of ALH-77005 are strong negative δ13C, enrichment of iron, manganese, phosphorus, zinc in shock melt support scenario,” the researchers said.
“Our study proposes presence of microbial mediation on Mars.”
The team’s paper was published online in the journal Open Astronomy.
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Ildikó Gyollai et al. 2019. Mineralized biosignatures in ALH-77005 Shergottite – Clues to Martian Life? Open Astronomy 28 (1): 32-39; doi: 10.1515/astro-2019-0002
