Under the ice of Enceladus, a moon of Saturn, could play more complex geochemical processes than previously imagined by researchers. Processes likely to offer life an environment conducive to its development.
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Enceladus is a small moon of saturn. It is geologically active. Under his crust frozen, hides an ocean of water liquid betrayed by geysers steam, ice and gas various that rise hundreds of kilometers above its surface. And it is precisely these geysers that researchers from Southwest Research Institute (SwRI – United States) studied for clues revealing the conditions under the ice ofEnceladus. Their conclusion: the ocean that bathes this Moon of Saturn is more complex than expected.
“By detailing the composition of Enceladus’ geysers, we can learn more about the nature of its ocean, how it got there and whether it provides environments where life as we know it could develop”, says Christopher Glein, researcher, in a SwRI press release. And his team has just developed a new analysis technique and new geochemical models that allowed them to estimate the CO concentration2 dissolved in the ocean from that of the plume.
The latter seems to be explained by geochemical reactions between the rocky heart of the moon and the liquid water of its hidden ocean. More specifically, by dissolving and forming certain mixtures of minerals containing silicon and carbon at the bottom of this ocean. “It seems that Enceladus is the scene of an event of massive CO sequestration2 in its nucleus, an event similar to the one that researchers would like to reproduce on Earth to counter the global warming“, comments Christopher Glein.
From hydrothermal vents to life
Another phenomenon that contributes to the complexity of the heart of Enceladus is the probable presence of hydrothermal vents. The Cassini probe had first revealed the presence in the heart of geysers, of tiny particles of silica , then that ofhydrogen gaseous. Two chemicals that are considered markers of hydrothermal processes. Processes which, at the bottom of the ocean, generate hot fluids, rich in energy and loaded with minerals that allow ecosystems unique to thrive. And potentially capable of supporting life. “We found no evidence of it, but interesting clues that conducive to life could exist under the frozen crust of this moon “, notes Hunter Waite, researcher at SwRI.
Interesting clues that favorable conditions for life could exist under the frozen crust of this moon
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Researchers now imagine that the Enceladus core is composed of a carbonate upper layer and a serpentine interior. Carbonates are generally in the form of sedimentary rocks such as the limestone on Earth, while serpentinized minerals are formed from igneous rocks of a seabed, rich in magnesiumand in iron .
It is proposed that theoxidation hydrothermal iron, deeply reduced in the nucleus, forms hydrogen, while hydrothermal activity on carbonate rocks containing quartz produces fluids rich in silica. These rocks also have the potential to influence the chemistry CO2 in the ocean via low temperature reactions involving silicates and carbonates.
What you must remember
- Using new geochemical models, scientists have discovered that the CO concentration2 in the ocean of Enceladus can be controlled by chemical reactions at the bottom of the sea.
- Adding to this discovery, those earlier, of hydrogen and silica, they suggest geochemically complex environments in the rocky core.
- A complexity that has the potential to create sources of energy capable of supporting life.
Extraterrestrial oceans: NASA confirms that there is energy for life on Enceladus
The Nasa has just announced that the analysis of plumes rising from Enceladus – a moon of Saturn having oceans under a floe– had revealed the presence of a significant amount of molecular hydrogen. This hydrogen can be turned into energy by life forms thriving around hydrothermal vents. It is likely that the same is true for Europe, the famous icy moon of Jupiter .
Article by Laurent Sacco published on 13/04/2017
As Futura predicted, NASA has just announced the detection of large quantities of molecular hydrogen (H2) in the plumes mainly made up of water rising from a region of the south pole of Enceladus, a moon of Saturn. The discovery was made by the Cassini probe when it passed through these plumes in 2015. It analyzed the composition using the instrument Ion and Neutral Mass Spectrometer (INMS), originally intended to “sniff” the upper layers of theatmosphereof Titan .
As the researchers explain in an article published today in the journal Science, the presence of this dihydrogen is most certainly the product of a chemistry equivalent to that of hydrothermal sources existing at the bottom of the oceans on Earth. This molecule would probably come from the serpentinization of peridotites, in the Enceladus crust, reacting with the hot water that circulates there. However, on Earth, this molecular hydrogen is used as an energy source by Microorganisms living near hydrothermal vents via a chemical reactioninvolving carbon dioxide dissolved in water and producing methane.
A video about the discovery of hydrothermal vents on Enceladus. To obtain a fairly faithful translation into French, click on the rectangle with two horizontal bars at the bottom right. English subtitles should then appear, if they are not already there. Then clicking on the nut to the right of the rectangle, you should see the phrase “Translate subtitles”. Click to display the menu for choosing the language, choose “French”, then click “OK”. © Nasa, JPL-Caltech
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Energy-rich alien oceans for life in the Solar System?
This does not mean that these life forms exist in the oceans of Enceladus, but the proof is made that there are very probably hydrothermal sources and, above all, that there is a source of chemical energy which can allow these life forms to appear and develop. We also know that in addition to containing 98% water and 1% molecular hydrogen, the plumes of Enceladus also contain carbon dioxide, methane andammonia . The oceans of this moon of Saturn therefore contain the elements C, H, O and N which are the basis of the organic molecules used by living beings. They should also contain sulfur and phosphorus but the cosmochemistry of Solar systemimplies that the rocky heart of Enceladus must have been formed from meteoritic materials which contain it.
So, what applies to Enceladus also applies to Europe? You might think so. NASA has just announced that the presence of plumes on this moon of Jupiter is more and more attested by the observations of the hubble telescope.
A video about the plumes of Europe. To obtain a fairly faithful translation into French, click on the rectangle with two horizontal bars at the bottom right. English subtitles should then appear, if they are not already there. Then clicking on the nut to the right of the rectangle, you should see the phrase “Translate subtitles”. Click to display the menu for choosing the language, choose “French”, then click “OK”. © Nasa, JPL-Caltech
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The region from which these plumes seem to rise intermittently would coincide with an abnormally hot fractured region appearing on the temperature map of the surface of Europe drawn thanks to the deceased mission. Galileo . Theexobiology seems to have a bright future in the alien oceans of the Solar System …
What will NASA reveal this evening?
NASA will announce several discoveries concerning the alien oceans this evening at 8 p.m. These discoveries certainly concern two icy moons of our Solar System: Europe (Jupiter’s satellite) and Enceladus (which revolves around Saturn). Could the Cassini mission have discovered evidence, or only clues, of the existence of life in the ocean of Enceladus?
This Monday, April 10, NASA announced that it would be giving a conference tonight (Thursday, April 13), at 8:00 p.m. Paris time, about important discoveries concerning the alien oceans. What suspense! Finally … not really if we look at the content of thead.
It is immediately stated that these findings come from researchers who use Hubble and those who are members of the Cassini mission. The two moons of the Solar System known for their oceans of liquid water are:
- Europe, for Jupiter;
- Enceladus, for Saturn.
It is therefore obvious that the discoveries in question will relate to these oceans. This is all the more obvious since the NASA press release suggests that these discoveries have direct implications for the mission. Europa Clipper (the purpose of this mission is to greatly advance our knowledge of the surface of Europe in order to better determine its habitability).
Remember, moreover, that the Hubble telescope has observed, on several occasions and in several ways, geysers of water rising fromEurope. These geysers could contain molecules indicating that there is much life in the ocean of Europe because the exobiologistes were quick to speculate on the existence of hydrothermal vents in this ocean, supplied with energy by the same tidal forces at the origin of volcanismof io. These sources would perhaps harbor life forms as there are on Earth at the level of ocean ridges . Remember that the life on Earth probably appeared in such sources.
A video about Enceladus’ overview in November 2015. To get a fairly faithful translation into French, click on the rectangle with two horizontal bars at the bottom right. English subtitles should then appear, if they are not already there. Then clicking on the nut to the right of the rectangle, you should see the phrase “Translate subtitles”. Click to display the menu for choosing the language, choose “French”, then click “OK”. © Nasa, JPL-Caltech
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Much dihydrogen detected in the plumes of water of Enceladus?
If the information revealed a few days ago by the famous site Web Astrobiology is correct, the suspense concerning the content of Nasa’s announcement this evening may not even be one anymore. Members of the Cassini mission have indeed detected significant quantities of dihydrogen (H2) in the plumes of water also rising from Enceladus during the hovering reconciled with October 28, 2015.
The objective was to pass through these plumes, 49 kilometers above sea level in a region of the South Pole where the probe had made it possible to discover, 10 years ago, an activity cryovolcanique surprising, to clarify its nature. We still know very little about their chemical composition but everything door to believe that they are there too the manifestation of an ocean ofliquid water under the surface of Enceladus.
A second video on Enceladus’ overview in November 2015. To obtain a fairly faithful translation into French, click on the rectangle with two horizontal bars at the bottom right. English subtitles should then appear, if they are not already there. Then clicking on the nut to the right of the rectangle, you should see the phrase “Translate subtitles”. Click to display the menu for choosing the language, choose “French”, then click “OK”. © Nasa, JPL-Caltech
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Why Cassini can’t find life on Enceladus
As much to say it right away, although that may make us think of certain scenes of 2010: Odyssey 2, the film adaptation of the novel byArthur Clarke, Cassini’s instruments do not have the means to detect biosignatures revealing the existence of life forms. No need to hope that NASA will announce the discovery of chlorophyllin the plumes of Enceladus. At most we could get pictures of a black monolith if reality caught up with fiction.
On the other hand, if NASA did indeed discover a lot of molecular hydrogen, it should be a fairly strong and convincing signature of the existence of hydrothermal activity in the ocean ofEnceladus. Some more complex organic molecules than those already highlighted in a previous overview at a higher altitude could also have been detected. However, it will not be possible to establish that they result from processes that are not abiotic .
To find life on Enceladus, as on Europe, we will have to wait for a future mission specifically designed for this purpose.
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