Ice is a much more complex object than it seems, and researchers have just identified a new form.
In the eyes of the general public, all ice cream is alike; in any case, it is a solid water crystal. But for physicists, it’s a whole different story; At the atomic scale, ice can take very different forms depending on the conditions in which it crystallizes. Unlike other solids, it even exhibits exceptional variety with no less than 20 documented forms of ice. And American researchers have just added a new one to this catalog, with potential implications in astronomy.
This discovery comes from the Laboratory of Extreme Conditions, located on the campus of the University of Nevada. Despite this evocative name, researchers do not work on the unforgiving deserts of this state with its scorching weather. It’s even quite the opposite: they study the behavior of water under very high pressure, which the researchers suggest could be present inside many exoplanets.
To work on this, you must first start by recreating the phenomenal pressure conditions that prevail in such an environment. It is something that we are quite incapable of replicating on a large scale; but it becomes much more affordable and even relatively easy when working on small volumes.
Pressure, an essential component of exotic ice cream
The researchers therefore called on a great classic of geology and materials science: a diamond anvil cell. The concept is as simple as its name suggests. The operation of the machine is based on the exceptional hardness of the diamond; it is therefore possible to subject it to incredible forces without risking rupture.
A boon for researchers; this means they can trap a sample of any material between two synthetic diamond jaws. This then makes it possible to test the physical limits and the behavior of the material – in this case, water – under very high pressure.
Under these extreme pressure conditions, the water instantly turns into ice. But at this stage, it is still a relatively disorganized cluster of crystals. To facilitate the transition to purer and above all different forms of ice, the researchers used a new technique that involves bombarding the cell with a laser.
Gradually, the researchers continued to increase the pressure while periodically melting the ice using the laser. They were thus able to observe the transition between different well-known forms, such as “Ice-VII” ice with its cubic mesh crystal lattice, or “Ice-X” ice, a rare and very special form in many respects.
Potentially abundant ice on other planets
But in the middle of this parade, they also spotted a strange element: a whole new form of ice never observed until now, now called Ice VIIt. It’s a finding that might seem trivial and unexciting to anyone who doesn’t work in a materials science lab. But it’s actually a very interesting item, especially in astronomy.
Because, as the researchers themselves admit, this work “recalibrates our entire understanding of the composition of exoplanets”. Indeed, the researchers suggest that this form of ice could exist in abundance on some exoplanets outside our solar system; they could therefore have harbored life as we know it. This work could therefore make it possible to refine analyzes of potentially promising new exoplanets.