NASA spacecraft 'flew through plume of alien water' 20 years ago

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Ever since 2012, when astronomers using the Hubble Space Telescope first spied inconclusive hints of watery plumes emanating from the subsurface ocean of Jupiter's large, icy moon Europa, space scientists have fiercely debated the claim. "It's worth noting that the scientific journal Nature Astronomy just reported that the Galileo mission, back in 1997, flew through a water plume on Europa 1,000 kilometers thick", Culberson said during an appropriations subcommittee markup in the House.

The study, led by Xianzhe Jia, of the University of MI, seems to confirm an idea that had already arisen from observations of the Hubble Space Telescope taken in 2012. The solar system's ocean worlds might be the most promising place to look. The simulated results displayed how the magnetic field interacted with a plume erupting from Europa and backed the observations noted in the Galileo data.

One version of the model included plumes on the surface of Europa, whereas another did not.

'These findings will help plan future missions to Europa, such as Nasa's Europa Clipper and ESA's Jupiter Icy Moons Explorer spacecraft, both of which are expected to arrive at Jupiter between the late 2020s and early 2030s, ' said a Nature summary.

And if plumes erupt like geysers, "there may be ways for that material from the ocean to come out above that ice shell and that means we would be able to sample it", she said.

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Inspired by the Hubble images and discussions of planned missions to revisit Europa, Jia and his team dusted off the data from two instruments onboard Galileo, gathered during the spacecraft's 11 close passes around the moon.

Researchers have long suspected that Europa sprays plumes of water into space - as Saturn's icy moon Enceladus does - and provide a shortcut to testing these ideas. Jia, however, had worked with Galileo's data when he was a graduate student, so he had a good sense for the kind of data the probe typically collected. After all, water is crucial for life on Earth, so scientists think our best bet for finding it on other planets is to locate sources of liquid water.

A bit smaller that Earth's moon, Europa's ocean resides under an ice layer 10 to 15 miles (15 to 25 km) thick, with an estimated depth of 40 to 100 miles (60 to 150 km). Jia said there was too little data to speculate at the moment, but that more research is being done.

Following this discovery, researchers reviewed data from the Galileo mission that also flew over Jupiter in the 1990s.

"If we find active plumes, then we can sail on through them and sniff and taste that stuff that's in the plume", Bob Pappalardo, a planetary scientist at NASA's Jet Propulsion Laboratory who wasn't a study author, said on NASA TV.

"Even with our wildest imagination, we always see stuff that we totally did not expect", McGrath says. That mission calls for two flybys of Europa from about 200 miles away.

This ocean appears to be in contact with Europa's rocky core, making possible a variety of interesting and complex chemical reactions.

If NASA (and the rest of us who care about the search for alien life) get lucky, those jets may be on when the Europa Clipper reaches its destination and starts its science work.

"We know that Europa has a lot of the ingredients necessary for life, certainly for life as we know it".