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Old 12-14-2013, 12:58 PM   #1
Unstung
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Article Plumes on Europa?

A couple days ago, the news broke that geysers coming from Europa's subsurface have finally been observed, an event that has been predicted to occur on the icy moon. An ultraviolet Hubble image from December 2012 captured the event. It's not possible to be absolutely certain about the event, but the photo looks convincing:


Looking in the ultraviolet was the best way to see this 200 kilometer high eruption. Jupiter's strong magnetic field accelerates particles, producing intense radiation belts around its moons which are also sources of the particles. The high energy particles strike water molecules released from Europa's geyser, emitting ultraviolet light.

The reason geysers have not been observed until recently is a result of Europa's position relative to Jupiter when previous images were captured. Europa has a slight eccentricity, and when closer to Jupiter, vents are squeezed shut. A similar effect has been observed at Enceladus, with plumes that are three times brighter at apoapsis than periapsis.

Active geysers makes understanding some characteristics of the moon easier. A spacecraft can fly into a plume and sample its composition, like Cassini at Enceladus. Hopefully the new discovery will strengthen the case for a Europa mission that helps answer a decades-old question. Life on Europa?


NASA: "Hubble Space Telescope Sees Evidence of Water Vapor Venting off Jupiter Moon"
ESA/Hubble: "Hubble discovers water vapour venting from Jupiterís moon Europa"
Bad Astronomy: "Europa Erupts! Possible Geyser of Water Seen on Jupiterís Moon"
The Planetary Society: "The Plumes of Europa"
BBC: "Jupiter's icy moon Europa 'spouts water'"
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Old 12-14-2013, 10:34 PM   #2
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Wouldn't that mean the ice is much thinner than currently thought -- at least where the geysers are?
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Old 12-15-2013, 12:00 AM   #3
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Quote:
Originally Posted by kamaz View Post
 Wouldn't that mean the ice is much thinner than currently thought -- at least where the geysers are?
Note how I wrote that the geysers are coming from the subsurface. Their source is currently unknown, and may be much closer to the surface and separate from the ocean buried 10 to 100 kilometers deep.
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Originally Posted by ESA/Hubble
 "The discovery that water vapour is ejected near the south pole strengthens Europa's position as the top candidate for potential habitability," said lead author Lorenz Roth of the Southwest Research Institute in San Antonio, Texas. "However, we do not know yet if these plumes are connected to subsurface liquid water or not." The Hubble findings will be published in the 12 December online issue of Science Express, and are being reported today at the meeting of the American Geophysical Union in San Francisco, California, USA.
[...]
Roth suggests long cracks on Europa's surface, known as linea, might be venting water vapour into space. Similar fissures have been photographed near Enceladus's south pole by the Cassini spacecraft. It is unknown how deep inside Europa's crust the source of the water may be. Roth asks, "Do the vents extend down to a subsurface ocean or are the ejecta simply from warmed ice caused by friction stresses near the surface?"
[...]
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