NASA astronomers, following deep analysis of the Hubble telescope’s archival images, have found the presence of persistent water vapour in Jupiter’s icy moon, Europa. However, the scientists explained that the vapours were mysteriously found only in one hemisphere of the moon. Europa is known to harbour a vast ocean underneath its icy surface with more water than that is found on Earth and this raises the possibility of the moon offering habitable conditions for life. 

Vapours in just one hemisphere raise questions

As per NASA, Hubble found the traces of water vapours only in Europa’s one hemisphere, which is the portion of the moon that is always opposite its direction of motion along its orbit. The agency states that previous observations of water vapour, as seen in Hubble’s photograph from 2013, were associated with plumes erupting through the ice. However, the new Hubble observations, spanning 1999 to 2015, have revealed that water vapour is constantly being replenished throughout one hemisphere of the moon. 

These findings emerged from a technique developed by Lorenz Roth of the Sweden-based KTH Royal Institute of Technology, Space and Plasma Physics, who recently discovered water vapour in the atmosphere of Jupiter’s moon Ganymede. Talking about the findings, Roth said, “The observation of water vapour on Ganymede, and on the trailing side of Europa, advances our understanding of the atmospheres of icy moons. However, the detection of a stable water abundance on Europa is a bit more surprising than on Ganymede because Europa’s surface temperatures are lower than Ganymede’s.”

Europa’s ice water result of sublimation

NASA explained that Europa reflects more sunlight than Ganymede, resulting in 60 degrees Fahrenheit cooler temperature on Europa than Ganymede. Interestingly, results revealed that water ice on Europa is sublimating i.e. transforming directly from solid to vapour without a liquid phase just like on Ganymede even at a daytime temperature of -260°F.

These findings, according to NASA, reportedly emerged after Roth delved into archival Hubble datasets, selecting ultraviolet observations of Europa from 1999, 2012, 2014 and 2015 while the moon was at various orbital positions. Moreover, he determined the abundance of oxygen in Europa’s atmosphere by using Hubble’s Space Telescope Imaging Spectrograph (STIS) and by interpreting the strength of emission at different wavelengths, revealed NASA.

(Image: NASA)