Europa Plumes: New Evidence Found for Water on Jupiter Moon

Gwen Vasquez
May 15, 2018

Previous estimates had suggested the moon's crust might be tens if not hundreds of kilometers thick-too thick, that is, to allow direct exploration of its potentially life-friendly ocean anytime soon.

Before ending its mission in 2003 with a planned crash into Jupiter's atmosphere, Galileo reported the first data suggesting a liquid water ocean under Europa's surface. But the only evidence of these plumes came from some blurry images captured by the Hubble Space Telescope.

Nasa scientists are on the verge of exploring Jupiter's ocean moon Europa for signs of alien life. His new study, outlining the possibility of Europa plumes, was published May 14 in the peer-reviewed journal Nature Astronomy.

Turns out plumes give off a distinctive signal that a magnetometer can measure.

"During Galileo, we'd always known there was something weird during this flyby", Cynthia Phillips, a scientist at NASA's Jet Propulsion Laboratory in Pasadena, California, was quoted as saying. There it will perform 45 flybys past Europa, getting as close as 16 miles above the moon's surface.

They found that during Galileo's closest flyby of Europa, it detected a major shift in the moon's magnetic field and a substantial increase in plasma density.

Xianzhe Jia, an associate professor at the University of MI who led the team that re-assessed the Galileo data, said the location, duration and variations seen in the magnetometer and plasma wave data are consistent with the presumed plume seen by Hubble.

"When we look at those data carefully, what we found is there's some odd magnetic signals in those data that have never been explained before", Jai says.

"When we first saw those images, I think a lot of us in the community were very excited", says planetary scientists Xianzhe Jia from the University of MI.

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On its closest flyby, Galileo swept over Europa at more than 2,230 miles per hour. But he's not the only one thrilled by the new finding.

The newly analyzed Galileo data could help solidify evidence for the plume's existence. They believed these fluctuations might be due to perturbations from a water plume in the plasma surrounding the Moon.

To make sense of those measurements and ensure they were not merely due to background fluctuations produced by Jupiter itself, Jia and his team compared them with computer simulations of how a plume would affect the plasma and magnetic field around Europa along the path Galileo took. Such a sea could provide shelter to bacterial life akin to that found in the depths of Earth's oceans.

Now, with two spacecraft and several independent instruments reporting similar findings, it's harder to deny that Europa is venting water vapour into space.

In the meantime, evidence that Galileo flew through a plume of water vapor jetting from the interior of Europa has fired imaginations.

Hunt for clues in the universe to answer one of humanity's biggest questions: Are we alone? "We'll surely see something we totally don't expect at Europa". Each spacecraft would reach the mysterious world less than three years after launch.

"And one of the really exciting things about detection of a plume is that that means there may be ways that the material from the ocean - which is likely the most habitable part of Europa because it's warmer and it's protected from the radiation environment by the ice shell - to come out above the ice shell". If plumes are indeed spewing vapor from Europa's ocean or subsurface lakes, Europa Clipper could sample the frozen liquid and dust particles. In both cases, the data indicate plumes erupted from roughly the same region, a known thermal "hot spot" on the moon's surface. And NASA is working on a mission that could do just that. It's going to happen.

Pappalardo is Europa Clipper's project scientist. The Europa Clipper, named for the innovative, streamlined ships of the 1800s, will launch in the 2020s and arrive at Europa after a few years.

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