A recent study conducted by planetary scientists at the Southwest Research Institute and KTH Royal Institute of Technology has raised questions about the evidence of steam emissions from Jupiter’s icy moon, Europa.
Artist’s impression of a steam geyser on Europa. Image credit: University of Cologne.
“The evidence for a water vapor plume on Europa is not as robust as previously believed,” stated Dr. Kurt Retherford, a researcher at the Southwest Research Institute and co-author of the original 2014 study.
In this new research, Dr. Retherford and his team examined data gathered by the Space Telescope Imaging Spectrometer (HST/STIS) aboard the NASA/ESA Hubble Space Telescope from 1999 to 2012-2020.
Their focus was on Europa’s Lyman-alpha radiation, a specific wavelength of ultraviolet light emitted and scattered by hydrogen atoms.
“A key challenge in interpreting the data at the time was accurately positioning Europa within that context,” said Dr. Retherford.
“Due to Hubble’s operational method, there remained some uncertainty about the alignment relative to the center of the image.”
“If Europa’s alignment is off by even a pixel or two, it can significantly impact our data interpretation.”
This uncertainty could mean that what researchers initially perceived as evidence of a water vapor plume might simply be random statistical noise.
“Our reanalysis has downgraded the initial confidence level of the plume’s existence from 99.9% to below 90%,” explained Dr. Lorenz Ross, a researcher at KTH Royal Institute of Technology.
“This is insufficient evidence to uphold the claims we made previously.”
“While current data does not rule out the possibility of water vapor plumes as described in the 2014 paper, it no longer offers solid evidence for their existence,” Dr. Retherford noted.
“The interpretations of previous phenomena no longer apply as they once did.”
“These new findings have prompted us to reassess our earlier paper’s conclusions regarding the presence of water vapor plumes.”
“Additionally, recent analyses provide enhanced insights into the neutral hydrogen atomic content of Europa’s atmosphere escaping from its water ice surface.”
“We remain hopeful of discovering a plume of water vapor escaping from Europa.”
“Similar water vapor plumes have been detected on Saturn’s moon Enceladus, and another of Jupiter’s moons, Io, also has plumes of sulfur dioxide venting into space.”
The team’s new paper was published in the May 5th edition of Astronomy and Astrophysics.
_____
L. Ross et al., 2026. Lyman alpha emission from Europa observed by HST/STIS. A&A 709, A59; doi: 10.1051/0004-6361/202659406
Source: www.sci.news
