Jupiter's moon Europa has enough ingredients to sustain life

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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.

Back in 1997 the Galileo Jupiter probe skimmed the watery moon of Europa and now it appears it got a facefull from a water plume 1,000km (621 miles) wide.

The Galileo data are consistent with earlier observations by the Hubble Space Telescope that captured signs of presumed plumes at the limits of detectability.

Scientists have re-examined 20-year-old data from a Jupiter spacecraft, and their discovery may considerably improve the chance we'll find alien life in the solar system.

If the existence of the plumes is confirmed and they are linked to Europa's ocean, they could provide a tantalizingly straightforward way to sample the moon in search of signs of life. So the team reanalysed Galileo's magnetic data with modern computers and techniques, including a simulation by Zianzhe Jia, a space scientist at the University of MI, of what a plume would do to Galileo's instruments.

Turns out plumes give off a distinctive signal that a magnetometer can measure. "But this has made me a believer", says Morgan Cable, an astrochemist at the NASA Jet Propulsion Laboratory who was not involved in the research. The problem is, landing a spacecraft on Europa and drilling through the mile or more of ice on its surface is an expensive and technologically challenging feat.

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The researchers found that, during this flyby, Galileo detected a significant change in Europa's magnetic field, as well as a brief but big increase in the density of plasma, or ionized gas. "It's very interesting that one can look at old data like these with new analysis tools like models and simulations".

"We saw very peculiar changes in the magnetic signal, something I don't think has been explained in the past", team member Xianzhe Jia from the University of MI tells Nadia Drake at National Geographic. Galileo actually did a flyby of that location, and it was the closest one we ever had. So a team of United States astronomers went back and took a second look at data collected by the Galileo spacecraft during its eight-year stay in the Jovian system. This plume of water points toward an environment on the moon which would be habitable by human beings.

Is there life beyond Earth? Because geologic processes move material from underground to the surface, the reverse may also be happening, transporting surface materials highly oxidized by Jupiter's harsh radiation down through the ice.

Scientists with the Cassini mission were able to identify water plumes protruding from Saturn's moon Enceladus by measuring perturbations in the magnetic fields surrounding the satellite. "We can stare with really good telescopes in Earth orbit as much as we want, but to really answer the question, you have to go there and do the measurements". "We'll surely see something we totally don't expect at Europa". NASA's Europa Clipper spacecraft, now scheduled to launch in 2022, is created to fly closer than we've ever gotten to the Jovian moon. Each spacecraft would reach the mysterious world less than three years after launch. Sometimes, when the telescope has looked, it has observed water vapor emissions coming from the surface of Europa. She's looking forward to NASA's next mission to the giant planet. It's going to happen. Robert T. Pappalardo, mission scientist for the Clipper, tells Chang it may be possible to reroute the clipper to pass over the purported plume. 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.

He added: "If there's life at Europa, it'd nearly certainly be an independently evolved form of life".

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