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.
Not to mention that the chances are decent that any slower than light interstellar ship, especially a significantly slower than light ship such as a sleeper ship or a world ship has a decent chance of being overtaken by an FTL ship before it even arrives at it’s destination, which would suck, especially for the sleeper ship. A world ship is still a decent idea as it’s a convenient way to transport an entire ecosystem over to a dead world, and as a space station that large is always going to be useful.
My own take on that is that we can’t assume we’ll ever achieve FTL capabilities, and should proceed under the assumption that when we get mission length down to some acceptable length, we’ll launch a manned interstellar mission. Just what that length is remains problematic, to say the least, though it’s heartening to think that with solar sail technologies not too far beyond us now, it might be possible to launch a Centauri mission with a travel time of 1000 years. This is a Gregory Matloff calculation, and such a mission would obviously require either cryopreservation or a worldship. Of course, the best scenario of all would be a sudden propulsion breakthrough into a significant percentage of lightspeed, rendering the other options moot.
The other question: a world ship becomes its own destination, in a way. If generations lived and died aboard it, would the survivors want to leave it when they reached their target star? Or would they be so accustomed to their habitat that they might study the new solar system and then move on to another?
Transportation technology notwithstanding, interstellar travel would only be justifiable if the target star-system has a water-rich oxygenated planet (or moon). Standard sci-fi scenarios of humans walking in a setting up shop are naive.
Industral Oxygenation:
On a lifeless planet, the only option would be industrial oxygenation. Doing this onan earth-size planet would require huge energy expenditures.
Earth’s atmosphere contains roughly 1.1 x 10^18 kg (~3.5×10^19 mol) of free oxygen. Lysing this much O2 from water at 495kJ/mol requires 1.6×10^22kJ. For comparison, total energy usage by humans in 1995 was ~3.3×10^17kJ. Using energy at that rate the process would take nearly 50,000 years. Even assuming that 15% atmospheric oxygen is adequate, you’d need over 35,000 years.
Note that I am assuming (1) perfect thermodynamic efficiency and (2) that none of the free oxygen gets dissolved in oceans or assimilated by crustal minerals (both obviously wrong). The energy requirement might be an order of magnitude higher. On the other hand, a race capable of interstellar journeys would likely have an eneregy source capable of faster work.
Oxygen present; complications:
Free oxygen is unstable, so the presence of abundant free oxygen would imply photosynthetic life forms capable of lysing water. This in turn implies an abundant ecology, with which colonists would have to co-exist. This might not be a simple task. One possible problem involves biochemistry: we have no a priori reason to assume that their proteins (if they have them!) use the same subset of 20 amino acids that ours do. If they don’t, native organisms would likely be inedible, and even using them as compost for our crops would be problematic.
Final note: The presence of life does not imply the presence of free oxygen. Earth was essentially anaerobic for a couple billion years after life arose. An anerobic, life-supporting planet would present both of the problems mentioned, with the additional question of whether oxygenating the atmosphere (and hence likely obliterating the biota) would be ethical.
Djlactin makes some very compelling points, basically all of which are unavoidable in considering interstellar exploration and what seems to be our shared desire for human expansion and the creation of backups for what we tend to see as a worthwhile project (our species and those around us). That said, however, our curiosity cannot be satisfied simply by the realization that most likely, we will not and cannot find a planet as habitable as our current one.
Which leads me to my question–what has been happening on the Droscher-Hauser-Heim front?
actual rod: i’m not advocating giving up on the idea of interstellar colonization. i’m just saying that it won’t be as simple as walking in and planting a few crops.
point taken.
actual rod asked above: “Which leads me to my question–what has been happening on the Droscher-Hauser-Heim front?”
Let me put out some feelers to see if any actual laboratory work has been tried, as opposed to theoretical studies, and I think the answer is no. More later, though, and for now, let me just get back to what Marc Millis told me some months back on this subject:
“This Droscher-Hauser-Heim approach is in such an early stage of development that it is premature to judge its viability. Fortunately, relatively low-cost next-steps could be taken by its proponents to help others assess the prospects, such as confirming (in the open literature) the ability of the Heim theory to predict the masses of subatomic particles, and showing the derivations and equations necessary to comprehend the other assertions.”
Thanks for your response. I’m sure the laboratory work must be preceded with a lot of theoretical study, and my question was in fact more directed towards the point made in Mr. Millis’ statement. Do you know of anyone working on the math behind Heim theory? It seems as though this was the next real step to be taken, since so little of his work (and none of Droscher and Hauser’s) seemed to be peer-reviewed. Is the peer review process under way, or am I the only one sitting on the edge of his seat?
That’s a great question, and though I don’t know what direction the theoretical work on Heim theory is taking, let me float some questions to some people who may have answers. I’ll pass along anything I find on the site.
Thanks!
Hi Paul
Apparently Droescher and co have computed the magneto-gravitic force using Heim theory from a spinning ring of bosons and have produced a value agreeing with the anomalous experimental value from a few months back.
They’re releasing a preprint in July.
PhysOrg Forum post
Adam
for our time lets send crewed mission to alpha centauri in sleeper ship at 10 %
of light velocity using fusion nuclear pulse rocket in 21 st century ..
tim
Well, there IS a peer reviewed paper by D &H now: an AIP publication
http://en.wikipedia.org/wiki/Heim_theory#First_and_second_publication_in_a_peer_reviewed_scientific_journal
http://www.hpcc-space.de/publications/documents/AIP2010Hauser.pdf