Ice and water might not seem very exciting to most of us, but they’re actually super strange from a scientific standpoint. Researchers have now discovered a brand new type of ice that’s described as being a true “snapshot” of water, and may be found on alien worlds.
The ice in your freezer or covering the polar caps is officially known as ice I, but it’s far from the only form the stuff takes. In fact, there are about 20 different types of ice with different atomic structures, which are formed when ice or water is exposed to various temperature and pressure conditions.
Ice I is the only form that appears naturally on Earth’s surface, but others have been created in lab experiments, found deep within the planet, and are believed to exist in space and on other planets and moons like Europa.
In a new study, scientists at University College London discovered a brand new type of ice that’s very different to any others known so far. The majority of ice forms have a crystalline structure, with atoms following a uniform pattern – but this new one is amorphous, so its atoms are arranged randomly, similar to the structure of liquid water. It also has the same density as liquid water, rather than becoming less dense as ice normally does. These properties together lead the team to propose that this may actually be the true glassy state of water.
This new form of ice has been given the rather dry-sounding name of medium-density amorphous (MDA) ice. It’s only the third known form of amorphous ice, falling right in between – you guessed it – the existing high-density and low-density forms.
To create MDA ice in the lab, the team used a process called ball milling. Ordinary ice was placed in a jar with some stainless steel balls about 1 cm (0.4 in) wide, then cooled to -200 °C (-328 °F) and shaken vigorously.
“Rather than ending up with smaller pieces of ice, we realized that we had come up with an entirely new kind of thing, with some remarkable properties,” said Dr. Alexander Rosu-Finsen, lead author of the study.
Another intriguing property of the new ice is that when it’s warmed up and begins to recrystallize, MDA releases a huge amount of heat.
While you won’t find MDA ice on Earth anywhere outside a lab, the team suggests that it could exist on Jupiter’s frigid moons like Ganymede or Europa. The gas giant would exert tidal forces on regular ice in a way similar to ball milling, and the heat released when it warms up could trigger “icequakes.”
Further study of the new form of ice could help explain some of the weirdness of water that remains unknown.
The research was published in the journal Science.
Sources: University College London, Cambridge
