www.sciencemag.org/content/340/6129/138.2short Phoenix & Perchlorates Meteorite ALH84001 Archea & PerchloratesMars Society Switzerland
It seems now well established that the surface of Mars is covered with perchlorates, as the Atacama Desert where they were sought (and found!) after following the results of the Viking probes experiments. This is not surprising considering the similarity of both environments. These perchlorates should result from the action of the Sun’s ultraviolet radiations which facilitate the oxidation of chlorinated elements in the soil, in the absence of water (and therefore in arid environments). On Mars, oxygen (the oxidant!) comes from some free oxygen in the atmosphere and from CO2 molecules. The problem with perchlorate (ClO4- anion) is that they are extremely hydrophilic and corrosive ("bleach" is sodium chlorate which, once electrolyzed, gives hydrogen and sodium perchlorate), and they easily decompose carbonic elements. When heating perchlorates with organic compounds, you get chlorohydrocarbons in addition to water and carbon dioxide (this was checked by heating magnesium perchlorate with organics in the Atacama Desert). These chlorohydrocarbons have been identified on Mars by the two Viking as well as Phoenix after they heated soil samples in the three very different parts of the planet where they landed. The first sample examination by the SAM laboratory aboard Curiosity, once again showed, after heating and gasification of the rock, the simultaneous release, at about 400 ° C, of chlorine compounds and oxygen molecules, and therefore the presence of perchlorates. There is now no doubt, that perchlorates are ubiquitous on the surface of Mars. The next step is to understand why no organic compounds have yet been found on the surface of Mars. On Mars, as well as on Earth, the surface should be covered with organics from meteorites that bombard it since the dawn of time, not even considering those organics that could result from a biological process such as the one we experienced on Earth. As scientists thought that the fact of heating the samples could be the cause of the destruction of organics by "exciting" perchlorates, the SMS ("Sample Handling System," through which all samples have access to the internal instrument) of Curiosity’s lab SAM, were equipped with a few cups which contain a reagent which will allow wet analyzes at cold (or low) temperatures. Since there are only seven cups, NASA and SAM officials are very cautious. For the time being, they work on the interpretation of data received by the test signals which are not clear enough. It might be that there was a leak of liquid reagent or that the pipes, locks and valves of the instruments retained some terrestrial molecules. We must therefore wait some more but the prospects are exciting because, as it is almost certain that perchlorates have so far destroyed organic molecules when heated together, we should soon know, with these experiences at "cold" temperatures, what are these organic molecules that were present and which disappeared. As we also now know that archaea can thrive on perchlorates, we may consider the possibility of finding evidence of past or present existence of "cousins" of these "microbes" on the surface of Mars! If interested, you can purchase the latest Science article which elaborates on this matter:
PIA16817. Image Credit: NASA/JPL-Caltech/GSFC (March 12th 2013) Data of this graph come from the anlysis by SAM laboratory of dust drilled from a mudstone slab (first drilled sample). Oxygene released at close to 400°C indicates the presence of perchlorates.
PIA16575. Image Credit: NASA/JPL-Caltech/GSFC (Dec.12th 2012). Data of this graph come from the analysis by SAM laboratory of Martian windrift dust . The oxygen curve, with a maximum at close to 400°C indicates the presence of perchlorates.
Perchlorates everywhere!
Is Mars the origin of Life? No Methane on Mars! Meteorite Y000593