Strange ice that could form on alien planets observed for the first time

Scientists have successfully observed plastic Ice VII, an exotic form of water previously predicted by theoretical models, shedding new light on how water behaves under extreme conditions, both on Earth and potentially on alien worlds.

In a groundbreaking study, scientists have for the first time experimentally observed plastic Ice VII, a previously theorized phase of water that could exist on distant, alien planets. While the name might evoke images of a low-budget sci-fi film, plastic Ice VII is actually an exotic and highly unusual form of ice, with implications for understanding the behavior of water under extreme conditions on far-off worlds.

The Discovery of Plastic Ice VII

Water, as we know it, typically exists in the familiar forms of liquid, gas, and solid. However, under extreme conditions, water can take on a variety of other unique phases, each with its own structure and properties. One such phase, Ice VII, was theorized over 17 years ago, but until recently, it had never been observed in a laboratory. What makes Ice VII particularly fascinating is that it forms only under incredibly high temperatures and pressures—conditions that are found in deep planetary interiors or on distant, icy moons and planets in our solar system.

An international team of researchers led the recent discovery by subjecting water to intense pressure and temperature conditions. They used high-precision instruments at the Institut Laue-Langevin (ILL) in France, where they were able to create and study the formation of Ice VII by compressing water to pressures of 6 gigapascals and heating it to 327°C (620°F).

The Structure of Plastic Ice VII

At the molecular level, Ice VII differs significantly from the familiar crystalline ice that forms in your freezer. It features a unique, interwoven cubic structure in which the hydrogen atoms are arranged in an unconventional way. As the water undergoes increased pressure and temperature, the hydrogen atoms begin to shift in dynamic patterns, resulting in a highly complex molecular structure.

One of the major challenges in studying Ice VII has been understanding the behavior of hydrogen atoms within the material. It was initially hypothesized that the hydrogens in this exotic ice phase would roam freely, but the new research revealed something surprising. Instead of rotating freely, the hydrogen atoms in plastic Ice VII appear to rotate in staggered steps. This unexpected behavior is likely due to the breaking and restoring of hydrogen bonds between molecules, offering new insight into the mechanisms of molecular rotation at extreme conditions.

A Revolutionary Technique: Quasi-Elastic Neutron Scattering

To confirm the existence of plastic Ice VII, the research team employed a cutting-edge technique known as quasi-elastic neutron scattering (QENS). This method enables scientists to trace the minute movements of particles inside substances at the microscopic level, offering a way to study the dynamics of materials like plastic Ice VII without altering their state.

According to Maria Rescigno, a physicist from Sapienza University of Rome, QENS provides a distinct advantage over other spectroscopic techniques because it can probe both the translational and rotational dynamics of materials. This allowed the team to observe how the hydrogen atoms in Ice VII were moving and how their behavior changed as the ice was subjected to heat and pressure. The results confirmed that plastic Ice VII was behaving in a manner consistent with the theoretical predictions, though the staggered rotation of the molecules came as a surprise.

The Implications for Alien Worlds

While the laboratory creation of plastic Ice VII is fascinating in its own right, it also offers valuable insights into the conditions that might exist on distant planets and moons. Experts believe that icy worlds such as Neptune, or the frozen surface of Jupiter’s moon Europa, may have once harbored plastic Ice VII in their interiors or may still contain it beneath their icy crusts. Understanding how this form of ice behaves under extreme conditions could help scientists learn more about the history and evolution of these distant worlds.

The discovery also opens up new avenues for future research. One intriguing question is how the transition to plastic Ice VII occurs. Does it happen in a continuous and gradual way, or is it more abrupt? The researchers are eager to explore this question further, as it could provide insights into the behavior of water in the universe under extreme conditions.

The Path to Superionic Water?

Perhaps even more intriguing is the potential connection between plastic Ice VII and another exotic phase of water—superionic water. Superionic water, which has been predicted to exist at even higher pressures and temperatures, is a hybrid phase where hydrogen atoms can diffuse freely through the oxygen crystalline structure. If plastic Ice VII is indeed a precursor to this phase, it could unlock new understandings of the behavior of water under the most extreme conditions in the universe.

Livia Bove, a physicist from Sapienza University of Rome, notes that the continuous transition scenario for plastic Ice VII is particularly exciting because it hints at the potential for discovering superionic water in the future. This would be a major breakthrough in the study of water and its role in both planetary science and astrobiology.

Conclusion: A Step Forward in the Study of Water

The experimental observation of plastic Ice VII marks a significant milestone in the study of water and its behavior under extreme conditions. Not only does it provide a deeper understanding of how water can exist in exotic phases, but it also holds promise for future research into the conditions of distant planets and moons. As scientists continue to probe the mysteries of water and its many forms, the discovery of plastic Ice VII is just the beginning of what could be an exciting journey into the far reaches of the universe.