STOCKHOLM — An analysis of Hubble Space Telescope observations of Jupiter’s moon Europa from 1999 to 2020 shows no strong evidence for water vapor plumes previously reported in 2013. The ultraviolet excess once interpreted as a sign of intermittent water jets has disappeared in the new study.

Planetary astronomer Lorenz Roth of KTH Royal Institute of Technology in Stockholm led the re-examination of the data. “They disappeared. I don’t think there’s any strong evidence left.” The new analysis included 20 Hubble observations from 2013 to 2020, along with three earlier observations from 2012 and 1999.

In 2013, Roth and colleagues reported detecting excess ultraviolet light from hydrogen and oxygen atoms near Europa’s south pole, which they interpreted as evidence of water escaping through cracks in the icy surface from a subsurface ocean. Following that finding, Roth’s team observed Europa repeatedly with Hubble but did not detect the plumes again.

The recent study applied improved methods for identifying Europa’s precise edges in Hubble images, as even a one- or two-pixel error could influence the results. It also incorporated updated knowledge about Europa’s extensive hydrogen exosphere, which is detectable by Hubble and can affect ultraviolet measurements.

Roth acknowledged that plumes might still exist but remain undetected by current instruments. “The original plume or smaller ones could still be there, undetected by Hubble.” NASA’s Europa Clipper spacecraft is scheduled to arrive at Jupiter in April 2030 and will carry instruments capable of detecting smaller plumes.