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If you’re curious about life elsewhere in the solar system, then of course Venus (for better or worse) and Mars have been in the headlines.
But perhaps the best place to look has been and still is Europa, Jupiter’s frozen moon. We have known for decades that it has an ocean of liquid water below its surface and that the moon’s core can be rocky and hot, which could provide nutrients to all the alien beasts that swim there via vents. hydrothermal.
It is also possible that there are interesting chemicals on the surface, which could be carried through the water through cracks. The problem is, what is there? Not long ago, traces of sodium chloride – table salt – were found there; Remember that life here began in the Earth’s oceans, which are salty. So it’s interesting. Magnesium salt (epsomite) may also have been found.
But other species of salty molecules have been difficult to pinpoint. They are characteristicless in many observed wavelengths, making them difficult to detect. But new research could change that: Scientists have discovered that ice glows when bombarded with radiation and various salts it contains change the glow in a characteristic way, which makes them potentially identifiable.
It could be extremely useful! Jupiter’s magnetic field bombards Europe with powerful radiation. Very powerful; if you were left outside unprotected on the moon’s surface, it would give you a lethal dose within minutes (although freezing to death and choking may be more immediate issues). Subatomic particles like electrons and protons get trapped in Jupiter’s fierce magnetic field. The planet is spinning fast (a day on Jupiter lasts about 10 hours), so the magnetic field is moving around Jupiter faster than Europa, causing these particles to snap at very high energies towards the back of the moon (this that we call the rear hemisphere), the side opposite to the direction in which it orbits.
If there is salt ice there, would that injection of radiation make it glow and help us find it?
To find out, scientists cooled both pure water ice and ice containing various salts to Europa-like temperatures (-170 ° C or -280 ° F), then slammed it with high energy electrons like what you reach the surface of Europe. As they expected, the ice shone, but when they changed the lineup, what they found shocked them.
The spectrum (ie light from ice broken down by color) of pure ice had three important characteristics: a bump at a wavelength of 330 nanometers (in the near ultraviolet), a “shoulder” (like the edge of a bump) at 440 nm (blue) and a large, wide bump that peaks at 525 nm (green). These are probably all due to water and its constituents (H2O, hydroxode or OH and oxygen). This general pattern persisted regardless of the salts used, but the size of the bumps changed significantly.
For example, adding table salt caused the 525nm large peak to drop a bit, but the 330 peak only a little. The sodium carbonate (Na2CO3) almost erases the big peak!
In other words, the shape of the overall spectrum changes in a measurable way depending on the chemicals in the ice.
It has never been seen this way before. Previous studies have looked at, for example, short-term radiation in ice (zapping it briefly), but in this new one, they held the beam for long periods of time, to mimic real conditions over Europe.
It’s very interesting. Why? Because in a few years, NASA will launch the Europa Clipper, a mission to Jupiter which will orbit the giant planet and perform numerous overflights very close to Europe. It’s equipped with a camera that has multiple color filters and, according to the new data, should be able to get enough information about the actual spectrum of the ice to get a feel for what salts may be trapped in it.
Scientists even simulated what they expected to see using the Clipper’s wide-angle camera on its Europa Imaging System instrument, and found that the different colors of salt ice could be detected as it passed through the sea. rear hemisphere of Europe. It would have to be on the night side for the Sun not to interfere (and the geometry would probably have to be carefully chosen to exclude Jupiter from the Europan sky as well, because that big disgusting planet in the sky would light things up as well.), but many passes should be possible.
They note that observations from the ground and using Hubble haven’t seen it, but it’s pretty faint unless you’re there. In fact, if you were orbiting the moon, you might be able to see it with the naked eye. So, depending on the salts present, you might see the night side of Europa glowing lightly in blue, green or teal. So pretty!
If the salts are there, and if they glisten, it will tell scientists what kind of chemistry could be happening both on the surface of Europe and within its ocean, hidden forever under a thick shell of ice. . Could there be alien fish swimming there?
We don’t know, but we’re getting closer all the time to find out.
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