Hubble: Possible Water Plumes Erupting on Europa

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Hubble: Possible Water Plumes Erupting on Europa

Post by bystander » Mon Sep 26, 2016 7:59 pm

Hubble Spots Possible Water Plumes Erupting on Jupiter's Moon Europa
NASA | STScI | HubbleSite | 2016 Sep 26
[img3="This composite image shows suspected plumes of water vapor erupting at the 7 o’clock position off the limb of Jupiter’s moon Europa. The plumes, photographed by NASA’s Hubble’s Space Telescope Imaging Spectrograph, were seen in silhouette as the moon passed in front of Jupiter. Hubble’s ultraviolet sensitivity allowed for the features -- rising over 100 miles (160 kilometers) above Europa’s icy surface -- to be discerned. The water is believed to come from a subsurface ocean on Europa. The Hubble data were taken on January 26, 2014. The image of Europa, superimposed on the Hubble data, is assembled from data from the Galileo and Voyager missions.
Credits: NASA/ESA/W. Sparks (STScI)/USGS Astrogeology Science Center
"] ... 160919.jpg[/img3]
Astronomers using NASA’s Hubble Space Telescope have imaged what may be water vapor plumes erupting off the surface of Jupiter’s moon Europa. This finding bolsters other Hubble observations suggesting the icy moon erupts with high-altitude water vapor plumes.

The observation increases the possibility that missions to Europa may be able to sample Europa’s ocean without having to drill through miles of ice. ...

The plumes are estimated to rise about 125 miles (200 kilometers) before, presumably, raining material back down onto Europa's surface. Europa has a huge global ocean containing twice as much water as Earth’s oceans, but it is protected by a layer of extremely cold and hard ice of unknown thickness. The plumes provide a tantalizing opportunity to gather samples originating from under the surface without having to land or drill through the ice.

The team, led by William Sparks of the Space Telescope Science Institute (STScI) in Baltimore observed these finger-like projections while viewing Europa's limb as the moon passed in front of Jupiter.

The original goal of the team's observing proposal was to determine whether Europa has a thin, extended atmosphere, or exosphere. Using the same observing method that detects atmospheres around planets orbiting other stars, the team realized if there was water vapor venting from Europa’s surface, this observation would be an excellent way to see it. ...

In 10 separate occurrences spanning 15 months, the team observed Europa passing in front of Jupiter. They saw what could be plumes erupting on three of these occasions.

This work provides supporting evidence for water plumes on Europa. In 2012, a team led by Lorenz Roth of Southwest Research Institute in San Antonio, Texas, detected evidence of water vapor erupting from the frigid south polar region of Europa and reaching more than 100 miles (160 kilometers) into space. Although both teams used Hubble’s Space Telescope Imaging Spectrograph (STIS) instrument, each used a totally independent method to arrive at the same conclusion. ...

But as of yet, the two teams have not simultaneously detected the plumes using their independent techniques. Observations thus far have suggested the plumes could be highly variable, meaning that they may sporadically erupt for some time and then die down. For example, observations by Roth’s team within a week of one of the detections by Sparks’ team failed to detect any plumes.

If confirmed, Europa would be the second moon in the solar system known to have water vapor plumes. In 2005, NASA’s Cassini orbiter detected jets of water vapor and dust spewing off the surface of Saturn’s moon Enceladus. ...

Probing for Evidence of Plumes on Europa with HST/STIS - W.B. Sparks et al
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Re: Hubble: Possible Water Plumes Erupting on Europa

Post by neufer » Mon Sep 26, 2016 8:32 pm

[Europa's] plumes are estimated to rise about 200 kilometers before,
presumably, raining material back down onto Europa's surface.
  • Even if the plumes exceeded Europa's escape velocity of 2km/s
    they would still need another 4km/s to escape from Europa's orbit
    (or nearly that amount to make it to Ganymede).
Art Neuendorffer