By Benedict Zagdoun She is Life on Mars? The hope of one day finding a living organism on the red planet grows with every new scientific discovery. One near certainty of scientists: that life could be discovered in the Martian subsurface. The surface of Mars is far too inhospitable.
While 225 million kilometers from our planet, the Mars Reconnaissance Orbiter and Curiosity robot, sent by NASA, continue their mission exploration, FranceTV info you summarizes the seven major discoveries about our distant neighbor.
1 And amid flowing water
This is the latest discovery dated. And for the most fascinating hour. NASA made the announcement Monday, September 28th. Liquid water flowing on Mars. The channels running along cliffs located at the equator of Mars. They can measure up to hundreds of meters long and five meters wide. They appear only during the warmer seasons, at -23 ° C, and disappear when the temperature drops.
This phenomenon has been observed for the first time in 2011 by the US probe Mars Reconnaissance Orbiter. The flowing liquid is not quite water but brine, a saturated aqueous salt solution.
“We have not seen the water flow . Do not imagine streams. There are very, very little water, “ tempers planetary scientist François Forget, director of research at CNRS and a specialist in March, told FranceTV info. ” The traces, lines that we see take several days to form. Instead of flowing water is a simple progressive humidification, advancing little by little. ”
“The likelihood of microbial life below the surface of Mars is very high,” concludes, however Alfred McEwen, American researcher and head of the main system imaging (HiRISE) on board the US probe.
2 On the Martian soil, salt changes the ice water
The American robot Curiosity has detected the presence of salt in Martian soil. Specifically calcium perchlorate. This substance has the ability to absorb water vapor in the atmosphere. It lowers the point of freezing water, which remains liquid despite the cold that prevails on the surface of Mars. The scientists who analyzed the data collected by Curiosity published their findings in April in the journal Nature Geoscience.
When night falls on Mars, part of the water vapor in the atmosphere condenses on the surface of the Red Planet and frost. Calcium perchlorate in the soil mixes with the ice that turns into brine. And, Mars being porous soil, the water infiltrates into the ground.
3 From the glaciers hidden under dust
Glaciers belts around the red planet, in the northern hemisphere as in ‘southern hemisphere. Radar observations of Mars Reconnaissance Orbiter prove it. This is water ice, not frozen carbon monoxide, as there is also on the red planet.
These glaciers remain under a layer of Martian dust. And volume is impressive: about 150 billion cubic meters. What March cover with a layer of ice 1.1 meters. This huge reserve of ice water was identified by Danish researchers who published their analysis in the Geophysical Research Letters . It was summarized on the blog of The Obs Time Space, in March.
4 Traces of a giant Lake …
Curiosity on Mars discovered traces of what was once a freshwater lake. Mount Sharp, which rises to 5500 meters in the middle of Gale crater where the robot landed, consists of successive sedimentary deposits, as shown in the samples taken by the robot during its ascent. But “this type of deposit is formed when large amounts of water flow along the crater” and “join stagnant water to form a lake,” explain academic Copenhagen in an article published in April in the journal Nature quoted by Le Point.
There was ” a large lake spanning 155 kilometers, maybe even a series of lakes, “ says Michael Meyer, head of the Mars Exploration Program at NASA, taken by The World in December 2014. tank “has existed for millions of years, the time to form, and to dry meanwhile, accumulate enough sediment to form Mount Sharp “.
The Curiosity of boreholes have revealed clay minerals. These suggest an interaction with water. The also found sandstone also appears similar to that existing in the rivers on Earth, which suggests that a river flowed into the lake, the researchers wrote in Science in December 2013, information relayed by The World.
Even better, the analyzed rocks contain traces of carbon, hydrogen, oxygen, nitrogen and sulfur that “provide the ideal conditions for an elementary microbial life” . On Earth, tiny forms of bacterial life thrive in similar conditions.
5 … and more ocean than the Atlantic
The analysis of the Martian atmosphere with two telescopes – one European based in Chile, the other American in Hawaii – has delivered another secret. In the distant past, Mars was a wet planet similar to Earth, with lakes, rivers that carved valleys … and an ocean that was to cover 19% of the red planet. In comparison, the Atlantic occupies 17% of the surface of the Earth. Scientists have described the landscape in March in the journal Science .
Mars had enough water to be completely covered to a depth of 137 meters. But this water most likely formed an ocean that covered half of the northern hemisphere of the planet. There are some places reached depths of over 1.6 km. Given its geology, this part of Mars has long been regarded by scientists as the most suitable area to contain an ocean.
6 The soil contains nitrogen, essential for life
Curiosity collected rocks in several places of the red planet. These samples were analyzed by the laboratory mini-SAM (Sample Analysis at Mars) on board the Mars rover. The molecular study, unveiled in March, showed the presence of nitrogen. However, this gaseous body is essential to all known forms of life. It is a key part of larger molecules such as DNA, the genetic code of living beings
There is no evidence, researchers temper, that these nitrate molecules derived from a living organism yet. These nitrates are old and have been the result of non-biological processes, such as the impact of asteroids or lightning on Mars in the distant past. But this discovery provides further evidence that Mars in the past met the conditions for the existence of life.
7 Disturbing emissions of methane
Since the Gale crater in which it landed in August 2012 Curiosity has surprising detected methane emissions. In very small quantities but regular. This gas originated in part from the decomposition of the dust of the Martian soil under the influence of sunlight and organic materials carried by meteorites. However, for two months, the measures of the spectrometer and the onboard laboratory have shown that methane escaping from the ground where he was therefore produced.
Scientists of the Mars mission failed to determine The origin of this gas, as they explain in their work published in December 2014 in the journal Science . They can not tell if this methane is biological or geological origin. Methane and organic molecules found in samples collected in the rock by the drill Curiosity may nevertheless they think “indicate the presence of a past or present microbial life” . On Earth, methane comes into effect in 95% of microorganisms.
Officials from NASA have further penetrate through the secrets of Martian exploration missions planned in the next five years. Pending the first manned mission to the red planet, the US space agency plans in the horizon of 2030, at the earliest.
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