Hubble Space Telescope finds plumes of water erupting from Europa

NASA's Hubble Space Telescope has found signs of water vapor spewing from the surface of Jupiter's icy moon Europa. The water appears to shoot about 125 miles high and may come from the global ocean thought to be beneath the moon's surface.

The discovery, to be published in the Astrophysical Journal, whets the appetite of scientists who want to investigate whether the distant world could harbor life.

"If there are plumes emerging from Europa, they're significant because it means we may be able to explore (its ocean) for organic chemicals or even signs of life, without having to drill through unknown miles of ice," team leader William Sparks, an astronomer at the Space Telescope Science Institute, said Monday.

Europa's ocean holds about twice as much water as Earth's oceans do. Like Saturn's much-smaller moon Enceladus, it is one of the solar system's frigid water worlds, both of which might have the chemical ingredients for life to exist beneath their surface. Scientists have already found evidence for hydrothermal vents on Enceladus, which on Earth provide fertile grounds for deep-sea microbial life.

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Such plumes are well documented on Enceladus, spewing from "tiger stripe" cracks that are squeezed and stretched by tidal forces. NASA's Cassini spacecraft has even flown through the plumes, sampling their contents. On Europa, however, trying to find the plumes is much more of a challenge, scientists said.

"Whereas on Enceladus the geology makes it a little bit obvious where the activity has been, on Europa there's activity everywhere, which could lead to plumes or could muddy the interpretation," said Britney Schmidt, a researcher in Georgia Tech's School of Earth and Atmospheric Sciences.

In 2012, a team led by Lorenz Roth of the Southwest Research Institute found signs of water shooting out near the moon's southern pole. Now, Sparks' team found plumes by using essentially the same method that astronomers use to find planets around far-off stars.

As a planet transits in front of its star, a tiny slice of starlight will filter through the world's atmosphere. Scientists can look at what's missing in that sliver of light to determine the composition of the planet's atmosphere.

Jupiter doesn't make its own light, but it reflects quite a bit of the sun. Scientists realized they could study Europa's atmosphere by watching how Jupiter's reflected ultraviolet luminescence filtered through it.

Over 15 months, the scientists observed Europa passing in front of Jupiter 10 times. And on three of those occasions, they saw plumes of what appears to be water vapor erupting from the surface.