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If signs of life exist on Europa, Jupiter's icy moon, they might not be as hard to find as scientists had imagined, reports a new study.
Europe has an immense ocean of 3,100 kilometers under its icy shell. In addition, astronomers believe that this water is in contact with the moon's rocky core, making possible a variety of complex and intriguing chemical reactions.
The researchers therefore consider Europa to be one of the best systems of the solar system to house extraterrestrial life. Europe is also a geologically active world, so samples of the buried ocean can regularly reach the surface – for example by localized water upwelling of the ocean itself and / or by degbading similar to a geyser. by NASA's Hubble Space Telescope. [Photos: Europa, Mysterious Icy Moon of Jupiter]
NASA aims to hunt such samples in the not too distant future. The agency is developing an overflight mission called Europa Clipper, which is scheduled for launch in the early 2020s. Clipper will be closely studying Europa for dozens of overflights, some of which may be able to zoom in through the plumes suspected of water vapor of the moon. And NASA is also working on a possible post-Clipper landing mission that would look for evidence of life on the surface of Europan or nearby.
It is not known, however, how deep a Europa lander would need to dig for a chance to find something. This is because Europa is orbiting in Jupiter's radiation belts and is bombarded by fast charged particles that can transform amino acids and other possible biosignatures into […]
Tom Nordheim and his scientist Tom Nordheim Colleagues have modeled the environment of Europa's radiation in detail, showing how things are going from one place to the other. They then combined these results with data from laboratory experiments, documenting the speed with which different doses of radiation cut out amino acids (a substitute here for complex biomolecules in general).
The researchers found significant variation, with some locals from Europan (equatorial regions) getting about 10 times the radiation pounding from others (mid and high latitudes).
At the most favorable places, the team determined that a lander would likely have to dig only 1 inch (1 inch) into the ice to find recognizable amino acids. In high shooting areas, the depth of the target would be in the range of 4 to 8 inches (10 to 20 cm). (This is not to say that potential European organisms would still be alive at such depths, however, the doses are high enough to cook even the most resistant terrestrial microbes, the team members said. study.)
says Nordheim, based at the California Institute of Technology and NASA's Jet Propulsion Laboratory, both in Pasadena.
"Even in the harshest radiation zones of Europe, you really have nothing else to do but scratch surface to find material that is not heavily modified or damaged by radiation, "he told Space.com.It is good news for the future landing mission, added Nordheim.The irradiation being Apparently not a limiting factor, planners may feel free to target the areas of Europe most likely to harbor new ocean deposits – the fallout area under a plume – for example – wherever they can lie.
Scientists have still not identified such promising contact areas; Europa imagery captured so far has not been quite clear.But the work of Europa Clipper should change things, said Nordheim.
"When we will have the Clipper recognition, the images s high resolution, the situation will be completely different, "he said. "This recognition of Clipper is really the key."
The new study was published online today (July 23) in the journal Nature Astronomy .
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