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Scientists map sulfur residue on Europa, Jupiter’s icy moon

SAN ANTONIO, TX – A team led by the Southwest Research Institute used the Hubble Space Telescope observe the moon of Jupiter, Europe, at ultraviolet wavelengths, filling a “hole” in the different wavelengths used to observe this ice-water world. The team’s near-global UV maps show concentrations of sulfur dioxide on the backside of Europa.

SwRI will continue these studies using the Europa Ultraviolet Spectrograph (Europa-UVS), which will observe Jupiter’s fourth-largest moon aboard NASA’s Europa Clipper, slated for launch in 2024. Scientists are almost certain that hidden beneath Europa’s icy surface is an ocean of salt water containing nearly twice as much water as all the oceans on Earth. This moon is perhaps the most promising place in our solar system, suitable for life beyond Earth.

“The relatively young surface of Europa is mostly composed of water ice, although other materials have been detected on its surface,” said Dr. Tracy Becker, lead author of a paper describing these UV observations. “Determining whether these other materials originated in Europe is important for understanding the formation of Europa and its subsequent evolution.”

Assessment of surficial material can provide information on the composition of the subterranean ocean. SwRI’s dataset is the first to produce a near-global map of sulfur dioxide that correlates with large-scale darker regions in visible and ultraviolet wavelengths.

“The results weren’t surprising, but we got much better coverage and resolution than previous observations,” said SwRI’s Dr Philippa Molyneux, co-author of the paper. “Most of the sulfur dioxide is visible on Europa’s ‘trail’ hemisphere. It is likely concentrated there because Jupiter’s co-rotating magnetic field traps sulfur particles spewing from the volcanoes of Io and slams them against the rear of Europe.

Io is another of Jupiter’s largest moons but, on the other hand, is considered the most volcanic body in the solar system. Jupiter’s magnetic field can cause chemical reactions between water ice and sulfur, creating sulfur dioxide on Europa’s surface.

“In addition to studying sulfur dioxide on the surface, we continue to try to understand why Europa – whose surface is known to be dominated by water ice – does not see like water ice at ultraviolet wavelengths, as this paper confirms,” Becker said. “We are actively working to understand why.”

– This press release was originally posted on the Southwest Research Institute website