When diamonds fall from the sky onto giant icy planets…

Amanda Souza Meteored Brazil 6 mins
Rain of diamonds on icy giants.  Credit: Greg Stewart/SLAC National Accelerator Lab
Rain of diamonds on icy giants. Credit: Greg Stewart/SLAC National Accelerator Lab

On the giant icy planets, very precious rains occur more often than you might think. Water itself is already very precious, of course, in that everything that has life depends on it, but have you ever imagined a “diamond rain”?

Researchers from the Stanford Linear Acceleration Center (SLAC) have found that oxygen increases this precipitation considered exoticbut which commonly occurs on giant icy planets, and revealed a new way to make nanodiamonds here on Earth.

The presence of oxygen makes the formation of diamonds more likely and it could happen on more planets.

For the first time, it was possible to observe the “diamond rain” thanks to an experiment in which the researchers mimicked the external temperatures and pressures found naturally deep within the ice giants, namely Neptune and Uranus.

What we know so far

The study provided a fuller picture of how this ‘diamond shower’ forms on other planetsand in parallel, how here on Earth, it could be a new way to make nanodiamonds which have a range of applications in drug delivery such as medical sensors or durable manufacturing and quantum electronics.

According to Siegfried Glenzer, director of the High Energy Density Division at SLAC, a previous study directly saw the formation of diamonds from any mixture, and since then there have been many experiments with different pure materials. However, the scientist reports that inside the planets it is much more complicated and complex because there are many more chemicals in the mix, and that is what they want to find out: what type of effect these additional chemicals have.

In collaboration with SLAC, a team led by the Helmholtz-Zentrum Dresden-Rossendorf (HZDR), the University of Rostock in Germany and also the École Polytechnique in France, published the results of the new study in Science Advances.

Try with plastic

Previously, researchers had used a plastic material made of a mixture of hydrogen and carbon (key components of the overall chemical composition of Neptune and Uranus). However, in addition to carbon and hydrogen, icy giants also possess other elements such as oxygen.

Recently, scientists opted for PET plastic, widely used in food packaging, bottles and containers. The intention was to reproduce the composition of icy planets more faithfully.

What the scientists simulated was the environment deep within the planets.  Image: HZDR/Blaurock
What the scientists simulated was the environment deep within the planets. Image: HZDR/Blaurock

Dominik Kraus, physicist at HZDR, said that PET has a good balance between carbon, hydrogen and oxygen and that is why it was used to simulate activity on ice planets.

Diamond’s best ally is oxygen

A high-powered optical laser was used in the Matter in Extreme Conditions (MEC) instrument at SLAC’s Linac Coherent Light Source (LCLS) to create shock waves on the PET, then the researchers investigated what happened to plastic.

Using a method called X-ray diffraction, scientists observed the atoms of the plastic rearranging into small diamond-like regions and were able to measure the speed and size of these regions through another method called small-angle scattering, which had not been tested previously.

The most surprising result was to determine that these diamond regions grew up to a few nanometers in width and thatwith the presence of oxygen in the material, nanodiamonds could grow at lower pressures and temperatures than previously known.

Frozen giant planets

The new findings could affect our understanding of planets in distant galaxies, as scientists believe ice giants are, in theory, the most common form of planet outside our solar system.

The Earth’s core is known to be made mostly of iron, but many experiments are still investigating how the presence of lighter elements can alter melting and phase transition conditions, as reported by SLAC scientist and contributor Silvia Pandolfi.

She added: “Our experiment demonstrates how these elements can alter the conditions under which diamonds form in ice giants. If we want to model the planets accurately, we need to get as close as possible to the actual composition of the planet’s interior.”


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