Liquid ‘plume’ found on moons of Jupiter, Saturn

BALTIMORE - Scientists have found signs of potentially life-supporting chemical energy in a plume of liquid erupting from the surface of one of Saturn's moons and, for a second time, have also spotted a similar, intriguing fountain on one of Jupiter's moons, NASA announced Thursday.

The latter discovery, on the moon Europa, was led by a Baltimore astronomer using the Hubble Space Telescope, and heightens hope for what a mission there planned for the early 2020s might uncover.

Engineers at the Johns Hopkins Applied Physics Laboratory in Laurel, Md., are designing instruments to study characteristics of the ocean from which the stream is thought to be escaping.

Hubble previously spied a plume erupting from near the equator of Europa, the smallest of Jupiter's four large moons, in 2014. That prompted scientists to wonder if it was liquid water venting from beneath the body's icy crust.

They announced Thursday that they saw it again last year - and then realized it was in a spot earlier observations of Europa had shown to be unusually warm.

'That was a ‘you've got to be kidding me' kind of moment,” said Bill Sparks, the astronomer at the Space Telescope Science Institute in Baltimore who served as principal investigator on the Europa research.

Neither the Europa mission nor Cassini - the spacecraft that has been exploring Saturn and its moons for more than a decade - are designed to detect life itself. But progress in exploring the relatively near worlds has scientists hopeful they are closer to finding biological activity beyond Earth.

The findings on Saturn's moon Enceladus are more solid, scientifically speaking. The Cassini spacecraft detected hydrogen emanating from the planet while passing through that body's plume on several fly-by maneuvers.

That suggests water beneath Enceladus' ice crust is interacting chemically with the moon's rocky core, NASA officials said. Such chemistry is a source of energy, independent of sunlight, that feeds life in Earth's oceans, and scientists wonder whether it could do the same on Enceladus.

Astronomers are reluctant to say anything conclusive about the observations of Europa's plume, but Sparks said it 'at least makes it an interesting place to look” for more surprises.

He said the intermittent geyser could be coming through a relatively thin portion of Europa's icy shell - 'thin” meaning up to two miles thick - and could give an opportunity to study the moon's ocean without drilling down to reach it.

Europa is about the same size as Earth's moon, but holds more water than Earth, Sparks said.

At the Hopkins lab, engineers are designing two instruments: One to gather data from Europa's magnetic field to learn more about the thickness of its icy crust and the depth of its oceans, and another to capture images of its cracked and ridged surface.