the-actual-universe:Europa erupts!This science is so exciting that I’m mad it took me this long to g

the-actual-universe:Europa erupts!This science is so exciting that I’m mad it took me this long to get to my laptop and write it. Some incredible results were presented Thursday morning at #AGU13 from the Hubble Space Telescope team at NASA and ESA: Europa, one of the ice-covered moons of Jupiter…is erupting. Right now, there are geysers of water erupting from Europa. Let that sink in for a second and then read on.We already knew that one moon in the solar system had active geysers; Enceladus, which orbits Saturn. Enceladus is a small, ice-covered body with giant cracks at its south pole. The Cassini spacecraft, currently orbiting Saturn, discovered a few years ago that giant plumes of water were shooting from those cracks.That process means Enceladus is warm on its inside, maybe warm enough to sustain an ocean, maybe even warm enough to sustain life. Enceladus is heated by tidal interactions with Saturn; as the moon moves closer and farther from Saturn, the gas giant’s gravity squeezes the entire moon enough to cause it to heat.Tidal heating is very important in systems with multiple moons. In the moons of Jupiter, for example, tidal heating supplies the energy to run the gigantic volcanoes of Io. Several other moons of Jupiter, like Ganymede and Europa, are also ice covered, and missions such as Voyager and Galileo discovered that Europa’s surface is covered with the remnants of giant cracks.Those cracks suggested that there might be liquid water beneath the ice sheet of Europa; an ocean, heated by tidal interactions with Jupiter.Europa is a big moon, its radius is nearly 6 times that of Enceladus, so it takes more energy to heat a place like Europa. If Europa had an ocean, that ocean has existed for millions of years, maybe enough time for life to evolve within it.Over the last few months, the Hubble Space Telescope has taken images of Europa and found that, remarkably, it was able to see water. The water was organized towards the south pole of Europa, but it also varied with time and position.Those measurements mean that right now, there are eruptions of water taking place on Europa. Geysers, giant ones, expelling water from within the body.The Galileo spacecraft which orbited Jupiter took some images of Europa but it didn’t study it in the kind of detail Cassini has done for Saturn. It’s possible there were erupting geysers at the time Galileo was running and it didn’t see it, or it’s also possible these are new features.Consider this though…the Cassini mission had to be right next to Enceladus to find geysers on that moon. The Hubble Telescope is very far away from Europa. For Hubble to see these plumes, they have to be enormous. The amount of vapor shooting out of Europa based on the Hubble measurements is 35 times the amount shooting out of Enceladus.The Cassini spacecraft has been able to fly through the plumes at Enceladus and actively sample them. There is a mission on the way to Jupiter called Juno which will characterize the gas giant, including imaging equipment that might be able to target these plumes. However, it won’t even be able to do the kind of detailed investigation of them that Cassini has done for Enceladus. To do that will take another mission.The Planetary division at NASA has indicated that flying to Europa with a major mission is one of their top 2 priorities for science in the next decade and multiple mission concepts have been proposed to go to Europa, including orbiters and landers. In the current funding environment even going there to do a little science is almost impossible, but if the NASA budget situation becomes less dire, in the future these plumes are an incredible scientific opportunity.It’s really tough to land on Europa’s surface while still having power since it’s an orbiting moon. It’s even tougher to drill through kilometers of ice to reach the ocean. But now we know there are active geysers on Europa. Something is bringing huge volumes of liquid water to the surface and ejecting it into space. If Europa has an ocean, we can sample that ocean just by getting to orbit of the moon, we don’t need to land on it.And if there’s life in that ocean, we might be able to find it being shot out of the geysers.This is a very exciting scientific discovery and congratulations go out to the NASA and ESA teams who made it. This should shape the next decade+ of planetary exploration in the solar system.-JBBImage credit: 1, 2 -- source link

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