Current state of the art detection instruments been sent to Mars to search for evidences of life may be not sensitive enough for the task, according to an international research team led by Armando Azua-Bustos, researcher from the Department of Planetology and Habitability of the Center of Astrobiology of Spain and HFSP Research Grant Awardee
In a paper published in Nature Communications, the international team of scientists claimed that evidences of life on Mars would be difficult, if not impossible, to detect with current instruments and techniques sent or soon to be sent to Mars. Azua-Bustos conducted a battery of analyses on Red Stone, located in the Coastal Range of the Atacama Desert in northern Chile finding that this site, a Jurassic fossil river delta is one of the closest analog models of Mars on Earth, among others, due to the prevalent presence of hematite, an oxidized form of iron which give Mars its famous red color, and also to the intercalated sediments of mudstones and sandstones, which contain a number of salts such as sodium chloride (the common table salt) and gypsum, all very similar to the environment been studied nowadays by the Perseverance rover on Mars Jezero Crater.
For this work, the team of researchers also inspected Red Stone using instruments that are currently on, or will soon be sent to Mars, searching for a number of biosignatures, molecules that could tell us whether Mars was once inhabited by microbial life. They found that such instruments depending on the protocol used, or the type of biosignature being searched for, could barely detect them or not detect them at all, highlighting that it will not be easy to say whether Mars is or was inhabited at some point of its history.
The research team also found that Red Stone samples display numerous microorganisms very difficult to identify, what the researchers proposed as the “dark microbiome”, and a mixture of biosignatures from current and ancient microorganisms that were barely detected with current standard laboratory equipment. "Either sending better, more sensitive instrumentation on Mars, that can ideally be tested in advance in sites like Red Stone or, bringing Martian samples to Earth will be required in order to better address whether life ever existed on Mars,” the researchers wrote.
Armando Azua-Bustos and his team inspected a tip of the iceberg of the Red Stone site. They are currently planning other detection techniques, as well as a better, more complete characterization of the site to better understand the lesson Red Stone may still teach. Among others, the research team still need to resolve what exactly are those still “unidentifiable” microorganisms, and how understanding sites like Red Stone may be of help for (for example) how to build a human colony on Mars.