NASA has discovered thrilling new evidence that there is a massive ocean under the surface of Jupiter's moon Europa, and it may be even more reachable than we thought. The evidence arises in the form of plumes of water vapor, observed by the Hubble Space Telescope in 2014 and announced now. The plumes are generally coming from Europa's South Pole, which is the similar location as some that were earlier seen in 2012, raising the prospect they are a repeating incidence.
New Observation (LEFT) of Europa’s plumes in 2014, and previous observation in 2012 (RIGHT) NASA, ESA W.SPARKS (LEFT image) L. ROTH (RIGHT image)
An investigation paper telling about the findings is to be printed in the Astrophysical Journal this week.
William Sparks, of the Space Telescope Science Institute (STScI), who led the team that made the finding, said in a meeting, "Today, we are announcing new Hubble evidence for water vapor plumes being ejected from the frosty surface of Europa. Observations specify global saline liquid water overcomes the moon at the present time, hidden below miles of ice."
A combined photo showing the plumes at the 7 o'clock position. NASA/ESA/W. Sparks (STScI)/USGS Astrogeology Science Center
These plumes believed to hold a few million kilograms of water, were found to be moving 200 km (125 miles) above the surface, before raining back down. They were detected using Hubble to image Europa as it moved in front of Jupiter. Observing the results of these images fully, the team was able to detect plumes alongside the background of Jupiter using the same method to how we find exoplanets around other stars, the transitway.
Altogether, the team detected Europa 10 times, and saw the plumes on three times, in January, March, and April 2014. This proves the plumes are repeating. More information from Hubble taken over the past two years is being examined right now to see if the plumes ascend again. That the plumes are reoccurring means a future mission to Europa like NASA's Europa Multiple Flyby Mission set to launch in the 2020s could accurately fly through a plume and take the sample of it, without touching the surface.
The plumes on three different occasions. The redder the plume, the more likely it is to be real. NASA, ESA, W. Sparks (STScI)
Some of the water may also be dropped on the surface, so if we were to send a lander in the future, it would not need to drill beneath the ice, believed to be some kilometers thick, to straight sample the ocean.
And one tempting reason to sample the ocean is that Europa appears like a good place for finding life off Earth. Manager of the Astrophysics Division at NASA, Paul Hertz said in the meeting, "On Earth, life is found everywhere there is water, energy, and nutrients. So there is different interest in any place that might hold those. And Europa might be such a place."
Obviously, that is very much thought at the moment. But these characteristics are surely going to make Europa more attractive to visit.