Jupiter’s moon Europa could glow in the dark

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You’ve probably seen numerous photos and renders of Europa, its frozen surface covered in reddish streaks. However, those images are all captured in sunlight. A new analysis from NASA’s Jet Propulsion Laboratory (JPL) suggests that there may be something interesting about the dark side of the Jovian moon. The intense radiation bombarding Europa could cause it to glow in the dark, and this could help scientists learn more about the moon’s ice caps and the ocean below.

Europa is somewhat smaller than the Earth’s moon, making it the smallest of Jupiter’s four Galilean moons, all named in honor of their discoverer, the pioneer of astronomer Galileo Galilei. Modern astronomers have become increasingly interested in Europa as missions like Voyager revealed the cracked surface and dark lines. Scientists speculated that Europa had a liquid ocean beneath the surface, kept warm by tidal warming due to Jupiter’s immense gravitational effects. Thick sheets of ice hide the interior from direct analysis, but the new JPL study claims that the glowing ice could offer some important clues.

Initially, the team was interested in studying the effects of high-energy radiation on organic compounds under the ice. To verify this, the JPL scientists built a unique instrument that was clearly specifically named to have a really cool acronym: the Ice Chamber for Europa’s High-Energy Electron and Radiation Environment Testing (ICE-HEART). They took ICE-HEART into a high-energy electron beam structure where they could launch it with radiation similar to what you would find in space near Jupiter, but the effects of that radiation were unexpected.

ICE-HEART has been designed to replicate the various types of ice present on Europa’s surface: sodium salts, magnesium salts and so on. During the experiments, the team noticed that not only did the samples glow, they also glowed in distinct spectra based on the composition of the salt. This could mean that the night side of Europa looks like a slightly bright patchwork (see above), and the pattern may be worth noting. “If Europa weren’t under this radiation, it would look like our moon appears to us – dark on the shadow side,” says lead author Murthy Gudipati. “But because it is bombarded with Jupiter’s radiation, it glows in the dark.”

The team speculates that water from the suspected underwater ocean may seep to the surface over time. Hence, the glow on the surface can tell us what is underneath and we may be able to characterize the surface simply by looking at its light spectrum. “It’s not often that we are in a laboratory and say, ‘We might find it when we arrive,'” said Gudipati. “It’s usually the other way around: you go there and find something and try to explain it in the lab. But our prediction goes back to a simple observation, and that’s what science is about. ”

Our next chance to test this hypothesis in real life could come with the Europa Clipper mission, which will be launched in 2024. After Europa reaches orbit in 2030, it will carry out more flybys which will give it the opportunity to check for any flare the dark effects.

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