Minerals on Mars May Preserve Life Forms
“Rio Tinto is a decent analog for what we see on Mars,” Glotch said, noting that spectral analyses suggest Martian hematite originally formed as goethite or a similar mineral that was later altered to hematite. “It’s a story similar to what they see in Rio Tinto.”
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Helping to equip a future generation of Mars rovers are fossil microbes recently found in Spain’s iron-rich river the Rio Tinto, revealing how signs of life could be preserved on Mars in the newly found minerals. The new tools that could be developed from these findings may find evidence of past life on the red planet in different methods.
Located in springs west of Seville, Spain, the area percolates up through the iron ores, deposited by geothermic activity that is more than 200 million years old. The ore’s iron sulfide minerals are dissolved from the spring water, which stains the water of the river a red color, in addition to the iron sulfide minerals dissociating to form a sulfuric acid. Showing a pH of vinegar sourness, its acid headwaters support bacteria, algae, single-celled organisms of protists and fungi.
The Rio Tinto environment has become popular with exobiologists because it creates hematite, an iron mineral. This was because of the liquid water content, and its prerequisite for life on Mars and the mineral’s presence on Mars—forming possible signs for life on the red planet, whether it is past or present. These processes may help the scientists better understand how minerals of similarity have preserved a record of life on Mars.
The evaporating river bed which forms during the Spanish summer leaves behind mineral deposits on the pool edges, creating rock terraces which developed over the years. Microbes had become coated in the area with nanoparticles of iron minerals precipitating from the pool, with the most common mineral called goethite, a rust-like iron oxide which surrounds the young microbes of fossil. In this process the oblong shapes of bacteria is preserved individually as well as bacteria forming colonies of filaments.
Larger crystals were formed 700 to 800 years ago in cemented sediments forming rock, and over time a chemical alteration was done on the minerals. The goethite has lost hydrogen and oxygen atoms which became a hematite that is stable eventually, reported recently in the Icarus Journal. In contrast, on Mars the rover Opportunity has explored the same iron-rich environment at Maridiani Planum, with similar geochemical processes.
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