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We know about 200 moons in the solar system, but some are more interesting than others, at least in the pursuit of life.
Europe, orbiting Jupiter, has long been one of the hottest candidates. The surface is certainly not hot at all, it is made of ice. But under the ice, which is 27 kilometers thick, it can act from an ocean.
Although no one knows what extraterrestrial life looks like, it is reasonable to assume that floating water is an important prerequisite. That's what you can read in this case from 2017.
The extreme gravity of Jupiter can create friction in the heart of Europe, which in turn can provide enough heat to maintain a floating sea in progress. This is what is called tidal warming.
But if there is a life in Europe, how should we discover it? It is no small feat to build a machine capable of drilling through dozens of kilometers of ice on the Moon of Jupiter, although it is also on the drawing board, according to Gizmodo.
Life can leave traces that can be discovered in a much easier way. Scientists have already discovered that he will geyser off the ice in Europe. The water can carry things from the sea to the interior. Here we are talking about amino acids, the building blocks of life, that could confirm where there is life in Europe.
But it's more complicated than it is. These tiny traces of life can be destroyed in the extreme environment around Europe, mainly by the incredibly powerful radiation of Jupiter's magnetic field.
Distinct patterns of the interior of Europe. It is still uncertain whether Europe has a thin ice cover, as on the left, or a thick ice cover, as on the right. (Image: NASA)
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Destroy traces?
The possibilities of detecting traces of life in Europe are explored in a new article in the journal Nature Astronomy. The work is led by Norwegian researcher Tom Nordheim, who works at NASA's Jet Propulsion Laboratory in California.
– Europe is, in my opinion, one of the best places to look for life in the solar system. .no
– Here you have a sea that in theory may be habitable, and probably a rich access to the chemical sources of energy that life can use.
The researchers created a data model that simulates how Europe is bombarded with particles that is trapped in the magnetosphere of Jupiter. Electrons and high-energy protons strike Europe, creating extreme levels of radiation. A human being would have a potentially dangerous dose for a single day in Europe.
But radiation can also destroy the amino acids that can be found in the upper layers. Radiation breaks down and changes the chemistry of amino acids, but can they survive in the ice?
The researchers' model shows that these traces can survive a few centimeters below the surface of the ice.
How can the surface of Europe be close when one gets closer, according to NASA. (Image: NASA / JPL-Caltech)
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Nonuniform Radiation
The model is based on radiation measurements in the magnetic field of Jupiter and on how the radiation hits Europe.
In particular, electrons will not hit uniformly across Europe, according to the article. It will be particularly intense around the equator, but then it will be less and less close to the poles.
The researchers also used knowledge about how amino acids are broken down by radiation and used in the model. They believe that amino acids will be destroyed 1-3 centimeters in ice. The most intense places have a depth of 10 to 20 centimeters
This simply means that a possible lander from Europe can look under the surface of the ice at the correct landing point for can to be finding signs of life.
There are still many uncertainties here. The sea of Europe is not yet known. The sea can be more or less salty, which also forms more or less salty ice. This can affect the penetration of radiation into the ice, and there may also be other materials in the ice that have not yet been measured.
– this is one of the things I will now look for as the next stage of the project. If there is salt in the material on the surface, it could help protect the traces of life
Then the ice will have a higher density and will protect better than the ice of pure water.
Exploration and Acid Sea
If Europe can have good living conditions, there are still many possible shores in the sea.
Several researchers have come to the conclusion that the ocean under ice in Europe can be particularly sour, which does not promise life. The very acidic sea is simply hostile to life as we know it.
– We have not measured anything yet, and the results come from geochemical models of Europe. There are a lot of variables in these models, so it's hard to tell if the ocean is really so sour in reality, says Nordheim.
– The goal is that future missions tell us more about the conditions in the ocean. Formerly a NASA mission planned and approved in Europe: Europa Clipper
The probe proposed by NASA to Europe, called Europe Clipper. It will be sent once a year in the 2020s. (Image: NASA / JPL-Caltech)
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It will be sent between 2022 and 2025, but it will not be landed.
Clipper will study the Moon of Jupiter, among others, using mass spectroscopy and radar.
This can be used to find a suitable landing point. for a future probe.
– Europa Lander is a mission currently proposed to study, says Nordheim.
This lander can potentially carry a drill that can look under the surface of the ice. If the proposal made to Nordheim and other NASA researchers describes Europe as it is in reality, it might not appear at all in the ice.
How an artist sees the lander of Europe. (Image: NASA)
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Reference:
Nordheim et al .: Preservation of potential biosignatures in the shallow subsurface of Europe. Astronomy of nature, 2018. DOI: 10.1038 / s41550-018-0499-8. Summary
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