Slowing down the biological clock is one way to get to the stars. And it’s a leading trope of science fiction, this idea that if we can’t find faster ways to travel beyond our Solar System, we can at least shorten the journey for the crew, who will wake up decades (or centuries) after departure in orbit around their destination. Cryopreservation is one approach to slowing the clock, but it’s always been plagued by the problem of tissue damage. For although some kinds of tissues can be frozen and revived, others succumb to damage from ice crystals that destroy the delicate structure of the cells.
New work at the University of Helsinki, however, offers a sudden gleam of hope on the cryopreservation front. There, researcher Anatoli Bogdan has been working with a form of water called ‘glassy water,’ and in particular a form of it known as low-density amorphous ice. It’s produced by supercooling diluted aqueous droplets, and it melts into what is known as highly viscous water (HVW).
Let’s untangle some of these terms. When you cool liquid water very quickly, the molecules don’t form into their normal crystal lattice. Instead, they become randomly oriented like the atoms of common glass, hence the term ‘glassy water.’ Keep cooling the result, as by the accumulation of μm-sized water droplets onto a metal surface cooled to below 120 K, and you can get low-density amorphous ice (LDA). The important point here is that melting LDA is more viscous than normal water, and now we can pick up what Anatoli Bogdan has to say about it in an American Chemical Society news release. It’s significant because no crystalization occurs in this process:
“It may seem fantastic, but the fact that in aqueous solution, [the] water component can be slowly supercooled to the glassy state and warmed back without the crystallization implies that, in principle, if the suitable cryoprotectant is created, cells in plants and living matter could withstand a large supercooling and survive,” Bogdan says.
And he follows with this startling conclusion:
“Damage of the cells occurs due to the extra-cellular and intra-cellular ice formation which leads to dehydration and separation into the ice and concentrated unfrozen solution. If we could, by slow cooling/warming, supercool and then warm the cells without the crystallization of water then the cells would be undamaged.”
Will cryopreservation become realistic? if so, the most intriguing possibilities are medical, including, of course, another long-standing science fiction trope, the idea of preserving someone with a deadly disease until such time as the disease can be cured. As a means of survival on a long interstellar journey, though, cryopreservation has to be weighed against the idea of the ‘world ship,’ a vast vessel in which generations live and die during the course of the voyage.
The latter makes a much greater demand on resources, and both may ultimately be circumvented by faster propulsion technologies. But cryopreservation keeps open a possibility that has intrigued interstellar thinkers for over a century, and there seems to be no reason to believe that the technology won’t one day become available.
Bogdan’s work is slated for publication in the July 6 issue of the Journal of Physical Chemistry B, a publication of the American Chemical Society.