Water on Mars – not surprising

Hundred days to dig, sweep, sniff and scrutinize a small handkerchief of Martian soil.  This was the beginning of the Mission of Curiosity, the NASA rover, soon after his arrival on the red planet in August 2012.


 Source: – Courtesy NASA/JPL-Caltech

The results of those hundred days served in part to ensure the proper functioning of Curiosity, are now published in Science in a series of five articles that describe mineralogy and chemistry of two points close to the landing place of Curiosity: a rock renamed Jake_M and a mass of sand and sediment not far called Rocknest. Jake_M (the team of Curiosity has taken from the very beginning the habit of giving human names to rocks) was the first structure encountered by Curiosity and is the protagonist of the first study, signed by M. Stolper and his colleagues and based on data from the Alpha X-ray Particle Spectrometer. It turned out to be an igneous rock of a type so far never observed on Mars, with a chemical composition very similar to rocks found on Earth on islands and fault zones. The other four studies focus on Rocknest sediments, which were met immediately after the rover during his trip, scanned with lasers of Remote Micro-Imager ChemCam, CheMin X-ray Instrument and the Sample Analysis at Mars (SAM), a tool that allows you to heat samples of material in the absence of oxygen and analyze the gases they release. This latest study, signed by Laurie Leshin and his colleagues at Rensselaer Polytechnic Institute probably will attract more attention.  Analysis of volatile compounds released by heating the Martian samples reveals a considerable (2 percent) concentration of water, along with significant parts of carbon dioxide, oxygen and sulphur compounds.  All, it goes without saying, very interesting compounds since the main objective of Curiosity is studying whether the Martian environment was ever suitable for life.


False-color image of gully channels in a crater in the southern highlands of Mars, taken by the High Resolution Imaging Science Experiment camera on the Mars Reconnaissance Orbiter.


The SAM also has analyzed the distribution of isotopes of carbon and hydrogen, which is extremely similar to that observed in the atmosphere: a proof that the soil of this area has interacted extensively with the atmosphere. According to Roberto Orosei from Radio Astronomy Institute of the INAF, Bologna, Deputy Principal Investigator of the MARSIS radar on the Mars Express probe, that it is not very surprising “but was completely predictable.  The water stunt has nothing to do with ice discovered by Phoenix digging beneath the surface, or orbital measurements by Odyssey on the abundance of hydrogen in the first meters of Martian soil.  This is the water molecules present in the atmosphere that have somehow subscribed to dust grains over time “.

Orosei explains that “this article looks like a dress rehearsal to demonstrate the ability of Curiosity to make analysis of unprecedented complexity and sensitivity, and provide a reference for interpreting the future measures.  The chosen material, dust carried by the wind, is the less promising matter that exists to search for traces of life on Mars, and the compounds contained in it are almost certainly of inorganic origin.  The real goal of Curiosity is a deposit of minerals formed in the presence of water, as already identified carbonates in orbit by Mars Express.  At that point we will know if there are chemical compounds that indicate the presence of past or present life.  The surface of Mars today is sterile, bombarded by ultraviolet light and cosmic rays, and dry over a terrestrial desert.  Traces of living organisms became extinct, or maybe even if they survive underground, they are extremely difficult to find and identify correctly, both for their lack of quantity and the subtlety of the differences between the forms of the same molecule produced by inorganic reactions and from the metabolism of living beings “.  In short, concludes Orosei, “Curiosity has only warmed muscles, has not yet begun the real work.  There is every reason to continue to hope to receive high-profile news from Mars, though we may want some time before finding the right rock to study.  In short, the best is yet to come “. Curiosity is currently en route to the crater Gale, in whose surroundings will make his most significant scientific analysis.

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