NASA’s Hubble Space Telescope data has shown that Europa has a long-term presence of vapor above its surface, according to a recent study published in the journal Geophysical Research Letters. Interestingly, these traces are only found in one hemisphere.
This qualifies as a sign of life. Researchers say that we have really good reasons for believing that it’s likely. Even if life is not there, this is a breakthrough in leading exploration projects in Jupiter. Observations from Hubble from 1995 to 2015 have shown that there are water vapors present in its atmosphere.
The knowledge came from Hubble’s database of archival spectra and images, courtesy of a new technique that also detected water vapor in the atmosphere of Jupiter’s other moon, Ganymede. The study came from Lorenz Roth, at Sweden’s KTH Royal Institute of Technology, of the space and plasma physics department. “The observation of water vapor on Ganymede, and on the trailing side of Europa, advances our understanding of the atmospheres of icy moons,” Roth said, in a press release. “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 is a light shade body because of its ice abundance on the surface. On Europa, days can reach high temperatures like -260°F. But even at these extreme conditions, water is sublimating, or undergoing a phase change directly from solid to vapor, without passing through the liquid state.
Roth looked up Hubble datasets by separating ultraviolet observations of Europa from the years 1999, 2012, 2014, and 2015, which is when the moon was positioned in several orbital positions. These observations were taken by Hubble’s Imaging Spectrograph (STIs).
It was revealed that there was a consistency in the atmosphere by interpolating the strength of emissions at various wavelengths, which enabled him to infer, inductively, that there was a long-term presence of water vapor on Europa.
This information is extremely significant for the missions to come like NASA’s Europa Clipper, the European Space Agency’s (ESA’s) Jupiter Icy Moons Explorer (JUICE), and more.