New research published this week in the journal Science Express has revealed that there is water vapor in the atmosphere of Jupiter's moon Europa. The vapor was detected by NASA's Hubble Space Telescope over the moon's south pole.
Though the water vapor has been detected on Europa, the exact cause of the vapor has yet to be determined. The report's authors believe that the likeliest cause is eruptions of water on the moon's surface. Scientists have believed for years that Europa has oceans of water underneath its outer crust of ice.
"By far the simplest explanation for this water vapor is that it erupted from plumes on the surface of Europa," said Lorenz Roth, lead author of the paper and a researcher at the Southwest Research Institute. "If those plumes are connected with the subsurface water ocean we are confident exists under Europa's crust, then this means that future investigations can directly investigate the chemical makeup of Europa's potentially habitable environment without drilling through layers of ice. And that is tremendously exciting."
Roth and his colleagues believe that cracks in Europa's ice crust could be the source of the water vapor. Such a phenomenon has already been seen on the surface of Saturn's moon Enceladus.
Europa's water vapor is slightly different in that the vapor action was only detected when the moon was further away from its host planet. This suggests that Jupiter's gravity is causing large tidal shifts on Europa, which could provide more evidence that Europa has water oceans underneath its surface.
For now the information on Europa's water vapor plumes is limited. Researchers were able to detect them only very faintly using Hubble's imaging spectrograph, which recorded the ultraviolet light that serves as the evidence for water in the moon's atmosphere.
"We pushed Hubble to its limits to see this very faint emission. These could be stealth plumes, because they might be tenuous and difficult to observe in the visible light," said Joachim Saur, co-author of the paper and a planetary scientist at the University of Cologne.
(Image courtesy NASA/ESA/K. Retherford/SWRI)