Наблюдения за гейзерами на Европе опровергнуты: новые данные Хаббла не подтверждают выбросы воды

Europa’s water plumes became one of planetary science’s most memorable images without ever becoming a secure photograph. Illustrations showed white geysers rising from fractures in the ice. Hubble data were translated into views of a south-polar eruption reaching roughly 200 kilometres above the moon. Mission concepts began to discuss flying through the material rather than drilling down to the ocean. The original evidence was much less visual. Hubble’s Space Telescope Imaging Spectrograph recorded a faint patch of ultraviolet emission associated with hydrogen and oxygen above Europa’s southern limb in December 2012. Lorenz Roth and his colleagues interpreted it as water molecules broken apart by energetic electrons and reported 99.9 per cent confidence in the localized feature. Many of the same researchers have now reanalysed that observation within a larger archive. Their 2026 paper finds no localized water-vapour emission in any of the suitable Hubble images, including the one behind the original claim. In a Southwest Research Institute account of the work, Roth said the confidence had fallen below 90 per cent. The correct conclusion is narrower than “Europa has no geysers.” The original Hubble feature is no longer statistically persuasive under the team’s preferred analysis. Smaller or intermittent eruptions could have escaped every observation. Other instruments have produced suggestive clues. None has yet established that a jet was seen, much less that its water travelled from Europa’s global ocean. Hubble saw ultraviolet atoms, not a white fountain Europa has an exceedingly thin atmosphere produced as sunlight and Jupiter’s radiation interact with its icy surface. Hubble can separate some of the ultraviolet wavelengths emitted by atoms in that environment. It cannot resolve Europa as a landscape in which a geyser appears like Old Faithful against the horizon. In the original 2014 Science paper, Roth, Joachim Saur, Kurt Retherford and their co-authors analysed observations from 1999 and 2012. One December 2012 image contained excess hydrogen Lyman-alpha and oxygen emission near the south pole. Energetic electrons striking water vapour can split and excite the molecules, creating just such an ultraviolet aurora. The team inferred two possible plumes with water vapour extending to an altitude near 200 kilometres. The feature appeared while Europa was close to the farthest point of its slightly eccentric orbit around Jupiter. That timing seemed physically meaningful because tidal stresses could open fractures differently as the moon’s distance from Jupiter changes. Even the contemporary NASA announcement of the Hubble result used conditional language. It described the eruption as the simplest explanation, noted that the observation required confirmation and distinguished a possible plume from the subsurface ocean already inferred through other evidence. Follow-up Hubble observations made near a similar orbital position in early 2014 did not recover the feature. A later analysis in PNAS concluded that orbital position alone was not enough to predict an eruption. That left an intermittent plume as one explanation, but a feature at the limit of Hubble’s capability as another. The same observation changes when the moon moves by a pixel The new Astronomy & Astrophysics paper is led by Roth and includes Retherford, Saur, Darrell Strobel, Melissa McGrath and Francis Nimmo from the original team, alongside ten other authors. It examines the full set of applicable Hubble/STIS observations made while Europa was sunlit and not passing in front of Jupiter. The observations were acquired in 1999 and through campaigns between 2012 and 2020. The team describes the material as 14 years of Hubble data, although it is a collection of observing epochs rather than an unbroken movie. In all, the analysis covers 23 observations. Two methodological changes matter. The first is the assumed position of Europa’s disk on Hubble’s detector. The moon covered only a small number of detector pixels, and the feature being sought sat at its edge. Shift the estimated centre by one or two pixels and counts once classified as emission beyond the limb can fall on the disk or into a different part of the background. The second change is the model of Europa’s extended atomic-hydrogen exosphere. Hydrogen around the moon scatters solar Lyman-alpha light. That diffuse glow is not a localized water plume, but it contributes photons at the same important wavelength. The new forward model included it alongside known instrumental, terrestrial and interplanetary sources before looking for local residuals. The result was clear within this dataset: Europa’s hydrogen exosphere appeared at every observing epoch, but no localized enhancement appeared in any image. That included the December 2012 observation once interpreted as south-polar water-vapour aurora. The authors performed a revealing cross-check. When they restored the earlier disk position and left the hydrogen exosphere out of the model, the old local feature returned with similar statistical significance. The data did not mysteriously change. The preferred account of what produced the light did. What a fall from 99.9 to below 90 per cent means In the Southwest Research Institute release, Roth summarised the change as a fall from 99.9 per cent confidence to less than 90 per cent. Retherford said a placement error of one or two pixels could materially affect the interpretation. Those percentages are easy to misread. They are not a direct calculation that Europa’s plumes have a particular probability of existing. They describe the statistical standing of a localized excess under specific models and assumptions. Below 90 per cent, random fluctuations are too plausible for the observation to support the certainty attached to it in 2014. The new work therefore supplies neither a confirmed plume nor proof of its absence. It says the original evidence is compatible with noise once the disk position and diffuse hydrogen signal are handled differently. A plume smaller than Hubble could detect, active only rarely or erupting outside the observed regions remains possible. This distinction mirrors a recurring problem in remote planetary science. Instruments return counts, spectra and field disturbances. The physical scene readers remember is an interpretation built from those measurements. When the interpretation changes, the original pixels remain exactly where they were. Other plume clues survive, but none closes the case The new paper reanalyses one family of Hubble observations. It does not directly rerun every other plume search. A different Hubble team used another technique while Europa crossed the bright face of Jupiter, looking for material silhouetted beyond the moon’s limb. Three of ten observations contained absorption features that could be associated with plume activity, although the authors stressed possible systematic effects and the need for caution. In 2018, researchers revisited magnetic-field and plasma-wave measurements from Galileo’s close 1997 flyby. The spacecraft had encountered a brief disturbance consistent with passing through a plume. The Nature Astronomy analysis reproduced aspects of the encounter with a simulated water-vapour source. “Consistent with” matters: a model matching a disturbance is evidence, but it is not an image or a uniquely identified sample. A ground-based result added a different piece. The Keck Observatory detected water molecules above Europa on one night in April 2016, while finding nothing on 16 other nights in 2016 and 2017. NASA’s account of that 2019 study estimated a release rate of about 2,360 kilograms per second during the detection. That was a direct spectroscopic identification of water vapour, which the original Hubble work had inferred from atomic fragments. It still did not photograph a vent or trace the gas through the ice. A transient release is a plausible explanation, but the geometry, depth and mechanism of the source were not established. Hubble archival work published in 2021 also reported water vapour spread across much of Europa’s trailing hemisphere rather than concentrated in a jet. The NASA summary of that study discussed surface-ice sublimation as a possible source. Diffuse vapour is not evidence that a geyser opened a path to the ocean. Water above Europa is not automatically ocean water Europa almost certainly contains a global salty ocean under its ice. That conclusion comes from magnetic induction, surface geology, gravity and tidal behaviour. It does not depend on the plume claim. As SpaceDaily reported in its comparison of Europa’s water volume with the accessible jets of Enceladus, the attraction of a plume is sampling. If deep ocean material naturally reaches space, a spacecraft could analyse the liquid reservoir without landing or crossing kilometres of ice. The word “if” carries two separate uncertainties. First, the eruption must be real. Second, its source must connect to the ocean. Neither has been demonstrated for Europa. Water vapour could come from a shallow brine pocket within the ice, local frictional or impact heating, or sublimation of surface frost. Jupiter’s radiation continually strikes Europa and can knock molecules and molecular fragments from the exterior. A detected hydrogen, oxygen or water signal must be separated from those processes before it becomes evidence of deep exchange. Even a genuine geyser would not label the depth from which it came. Hubble had no way to follow a fracture downward. SpaceDaily’s earlier examination of Europa’s potentially 29-kilometre ice shell shows why that connection cannot simply be assumed. Enceladus sets a much higher evidential standard The mental model for Europa’s plume came largely from Saturn’s moon Enceladus. Cassini repeatedly imaged jets rising from four long fractures near its south pole. It measured how their output changed, flew through them and analysed gas and ice grains containing water, salts, silica, organic compounds, hydrogen and phosphates. Multiple lines of evidence link those jets to Enceladus’s internal sea and to water-rock interaction at depth. That is why the plume is treated as established rather than as a marginal feature in one remote dataset. Europa has nothing equivalent so far. Its possible plumes appeared inconsistently, under different techniques, at different locations and with source rates that do not form a single simple picture. Intermittency could explain the inconsistency. Instrumental and modelling limits could explain some of it too. The contrast does not make Europa geologically dead. Fresh-looking terrain, fractures and rapidly renewed ice all point to an active outer shell. SpaceDaily recently covered Webb’s detection of crystalline surface ice that radiation should alter quickly. Surface renewal, however, can occur without a tall jet visible from Earth. Why geysers remain physically plausible Europa follows a slightly eccentric orbit and is locked so the same hemisphere faces Jupiter. The changing gravitational pull flexes the moon and dissipates energy inside it. Stresses rise and fall across the ice during each 85-hour orbit. Fractures, faults, melt lenses and briny pockets provide several conceivable routes for material to move upward. Models can produce water migration or vapour eruptions without requiring an open pipe from the ocean floor. A meteorite impact could briefly heat ice. Brine trapped within the shell could be pressurised. Tectonic motion could expose warmer material. These are mechanisms, not observations of an event. The revised Hubble result therefore leaves a scientifically ordinary but less dramatic position. Europa can vent under known physics. The available evidence has not shown conclusively that it does. Europa Clipper will search from much closer range NASA’s Europa Clipper is due to reach Jupiter in April 2030 and make dozens of close Europa flybys. As SpaceDaily noted when tracing its long route, the mission is designed to evaluate Europa’s habitability, not to return a yes-or-no life detection. Its instrument combination is well suited to the plume question. Cameras can look for jets against the limb. The Europa Ultraviolet Spectrograph can search for gas and map Europa’s tenuous atmosphere. MASPEX can identify molecules encountered around the moon, while the SUDA dust analyser can determine the composition and origin of small particles. A flyby through fresh ejecta would be valuable, but the mission does not depend on one. Radar, magnetometry, gravity, thermal imaging and surface spectroscopy can investigate the ice and ocean even if Europa remains quiet throughout every encounter. ESA’s JUICE spacecraft will make two Europa flybys with its own remote-sensing, particle and field instruments. Both missions face the same logical limit: failure to catch an intermittent eruption does not prove that none ever occurs. Repeated close observations can instead place much stronger limits on how frequent, large and geographically concentrated such events can be. The correction strengthens the eventual answer There is something valuable in the same scientific group returning to its most celebrated result and making it weaker. The original team pushed Hubble to a limit, reported a conditional interpretation and kept collecting and reprocessing evidence. A larger archive and a more complete physical model changed what the pixels could support. That is not a clean reversal from fact to error. The 2014 plume was always an inference from faint ultraviolet emission. The 2026 paper now judges that inference insufficient. Other hints survive, but none turns the picture into a conclusive observation. Europa’s ocean remains one of the strongest deductions in planetary science. Its geysers do not share that status. For now, they are physically plausible, intermittently suggested and worth searching for, but never conclusively observed and never proven to connect with the sea below.