A captivating topic for researchers are the volcanoes located on remote frozen moons, such as [the moon Europa of Jupiter](https://www.bgr.com/science/jaw-dropping-photo-shows-jupiters-moon-europa-like-youve-never-seen-it-before/) and Enceladus, one of Saturn’s moons. These moons contain subsurface liquid water that surfaces in a phenomenon known as cryovolcanism, where water behaves unusually under such conditions. At low pressures, water can boil and freeze simultaneously, complicating predictions during a cryovolcanic eruption. Previous studies have also struggled to fully clarify the interactions between liquid, vapor, and ice in the distinctive setting of these frozen moons.
A group of researchers assembled to conduct an in-depth investigation into cryovolcanism for a clearer comprehension of the phenomenon. The collaboration included scientists from the Institute of Geophysics of the Czech Academy of Sciences, Charles University, the University of Sheffield, the Open University, and the Science and Technology Facilities Council (STFC) Rutherford Appleton Laboratory. Their findings were published in [ScienceDirect](https://www.sciencedirect.com/science/article/abs/pii/S0012821X25003292?via%3Dihub) in July 2025.
The teams performed experiments to uncover the factors that lead to cryovolcanism and found that the unique conditions on these icy moons alter the behavior of liquid water significantly. They anticipate that these discoveries will aid in future explorations of deep space.
### The replication experiments of freezing moon volcanoes
The objective was to comprehend why water exhibits such behavior that results in cryovolcanic eruptions. Locations in deep space, like [Saturn’s icy moon](https://www.bgr.com/science/enceladus-moon-ice-life/), endure extremely frigid temperatures and very low atmospheric pressure. To replicate such conditions, the team utilized the Mars Simulation Chamber at the Open University.
A plastic container was filled with slightly salted water, chilled just above freezing to simulate the subsurface environment of an icy moon. The chamber was then slowly depressurized. As pressure fell, tiny gas bubbles began to escape the water, indicating that it started boiling without external heat. This occurs because, in a low-pressure atmosphere, water boils solely due to the absence of atmospheric pressure restraining it.
As the pressure continued to decrease, the boiling became more vigorous. The boiling occurred beneath the water’s surface as well, generating gas bubbles that exerted pressure against any ice forming above. This resulted in a buildup of pressure that caused the ice to crack, allowing the pressure to escape and instigating another boiling cycle. This ongoing sequence of boiling, bubble formation, ice cracking, and pressure release slowed the freezing process. The interactions also led to uneven, bumpy ice surfaces. This suggested to the researchers that similar features observed on icy moons could be remnants of past cryovolcanic eruptions.
### Significance for the future of space exploration
Doctor Petr Broz, the lead author of this investigation from the Institute of Geophysics at the Czech Academy of Sciences, discussed the study with the [University of Sheffield News](https://sheffield.ac.uk/news/boil-freeze-bubble-crack-repeat-scientists-simulate-solar-systems-ice-volcanoes-lab). “We discovered that the freezing dynamics of water in extremely low pressure is far more intricate than we had previously believed.” He elaborated, “… The ice layer that develops is continually disrupted by vapor bubbles, lifting and fracturing the ice, which significantly complicates and prolongs the freezing process.”
The insights drawn from this study may prove beneficial for upcoming space exploration endeavors, such as [nuclear space travel](https://www.bgr.com/science/its-time-to-get-serious-about-nuclear-space-travel-new-study-urges/), which could facilitate easier journeys into deep space. The research teams aspire that their findings can help future investigations detect indicators of cryovolcanic activity from the irregular and uneven surfaces of these icy moons. They are hopeful that this research will assist in planning future missions.
Another researcher and professor from the Open University, Manish Patel, is optimistic about the outlook. He expressed to the University of Sheffield News, “These topographical irregularities […] may leave unique signatures that could be observable by orbiting spacecraft, particularly those equipped with radar, presenting a potentially novel method for identifying ancient cryovolcanic activity.” He added, “This could offer essential insights for designing future missions to these distant worlds — and enhance our understanding of the still enigmatic process of cryovolcanism.”
