Atlantico: After an announcement effect which started this Thursday, September 24, NASA finally announced its discovery on Monday 28th September. The presence of water in liquid form on Mars is now proved. How can we explain such a phenomenon
Olivier Sanguy: A quick background: we know that there is water on Mars and now long since . But this water is either in solid form, ice, therefore, either as vapor
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Indeed, normally liquid water n is not possible on Mars due to atmospheric temperature and pressure conditions at the surface of the red planet. Put simply, when water ice “bottom” on Mars, it sublimates and thus goes directly from its solid form so that gas steam. But years, images of probes that revolve around Mars, including Mars Global Surveyor and Mars Reconnaissance Orbiter (it still works) show dark traces on slopes. traces that suggest the action of liquid water flowing along these slopes. We call for the RSL Recurring Slope Lineae or recurrent strokes or lines on slopes. 50 cm to 5 m wide with lengths of hundreds of meters, they appear at the equator in summer and up to mid-latitude and disappear then come the following summer. But liquid water can not exist on the surface of Mars, why these RSL? The answer given by the NASA press conference on September 28 is that it is indeed liquid water, but extremely salty with perchlorates. These act like salt sprinkling the roads in winter to avoid a form ice. On Mars, this water containing perchlorate remains liquid down to -70 ° C! Thus it can flow along slopes on some reliefs despite low temperatures and low pressure.
What was the research that made this discovery? How were conducted?
This is a work that spans several years. This is an original researcher Nepal, Ojha Lujendra the Georgia Institute of Technology in the USA, which looked on the assumption brines, these water containing perchlorate. He worked with Alfred McEwen, chief scientist of the high resolution camera HiRISE the Mars Reconnaissance Orbiter, which has acquired several images showing the appearance of RSL summer, they disappeared in the autumn and then reappear in the next summer. It is thanks to another instrument of Mars Reconnaissance Orbiter that they, along with other scientists, have come to the conclusion that exposed 28 September. The instrument in question is the CRISM spectrometer which detected the spectral signature perchlorates where there are RSL. This shows that these flows are very salty water. Certainly pa CRISM has observed the flows themselves, but traces left by them. The indices are sufficient for us to say that liquid water flows on Mars, under certain specific conditions, however.
Basically, what this discovery profoundly revolutionary? Is it likely to change the perception that we imagined Mars or the way we conduct our space research?
The discovery is perhaps not so revolutionary as such. These flows and the possible role of liquid water have been studied for several years. The novelty is that we have measures associated with serious work showing that these flows consist of brines: it therefore meets the why, ie how liquid water can exist on the surface long enough to make the famous dark traces. Surely we can say that the announcement of NASA is sinking in that it is less spectacular than speculated by some, but it also takes water well in that it addresses the problem liquid water on Mars! In fact, the interest lies elsewhere. So we hydrated perchlorates flowing on Mars. But where does this water? Is it water mixed in the basement as ice as envisaged long time? Or perchlorates they trap moisture in the Martian air as was mentioned at the press conference? It would be very interesting because then Mars would be a less arid planet than we thought until now!
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Finally, the presence of water on the red planet is it likely to encourage the presence of a life comparable to that on Earth?
This water then not really. Responsible for perchlorates as it should be, we can not say whether an enabling environment for living, although extremophile organisms could, highly conditional rigor, live with it. The perchlorates are toxic and some even excellent rocket fuel! No really a recipe for life … Most importantly, these flows are too episodic to give time to the life mechanisms of action. However, being more general, perhaps we can see that the water is present on Mars than we could theorize conservatively. But life as we know it requires liquid water. The Curiosity rover has also already demonstrated that liquid water without perchlorates, had flowed on the red planet long time ago, here about 3 billion years when the conditions of temperature and pressure were different. March has been living, but not necessarily inhabited, important nuance. Nevertheless, we see very well that the successive missions bring each piece of the Martian puzzle. Nothing proves that microbes were able in the past to develop on Mars would be of paramount importance: then we would demonstrate that life was hatched elsewhere than on Earth
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