Cosmic ice from comets and moons is not like water

It is much less similar to water than previously thought , the most common form of ice in the universe , the low-density ice found on comets , icy moons like those of Jupiter and Saturn, and in the dust clouds from which stars and planets form. Its structure , in fact, is not completely amorphous and disorganized like that of liquid water, but contains tiny crystals about 3 nanometers across, slightly wider than a strand of DNA. This is indicated by research published in the journal Physical Review B, conducted by University College London and the University of Cambridge, which also sheds new light on the origin of life on Earth.

"We now have a good understanding of what the most common form of ice in the universe looks like at the atomic level ," says Michael Davies, who led the research, which was based on computer simulations and laboratory experiments. "This is important because ice is involved in many cosmological processes," Davies comments, "such as the formation of planets , the evolution of galaxies , and the way matter moves through the universe."

The findings are also relevant to one of the theories about the origin of life on Earth, according to which the 'building blocks' that allowed the first organisms to emerge arrived aboard an icy comet that fell on our planet. "Our results suggest that this type of ice would be a less suitable transport material for these molecules," Davies emphasizes, "because a partially crystalline structure has less space . However, the theory could still be true," the researcher concludes, "since ice also contains amorphous regions where the ingredients of life could be trapped and stored ."