Larry Niven played around with an interesting form of suspended animation in his 1966 Ballantine title World of Ptavvs. While the usual science fictional imagining is of a crew in some sort of cryogenic deep freeze, Niven went all out and envisioned a means of suspending time itself. It’s an ingenious concept based on an earlier short story in Worlds of Tomorrow, one that so aggressively pushes the physics that the more subtle delights of characterization and perspective come almost as afterthoughts. Niven fans like myself will recognize it as taking part in his ‘Known Space’ universe.
In the absence of time manipulation, let’s plumb more modest depths, though these can be tantalizing in their implications. In the last post, Don Wilkins described new work out of Washington University on inducing states of torpor – life processes slowed along with temperature – in laboratory experiments involving rodents. The spectrum from torpor to suspended animation has intervals that may suit our purpose. At the Interstellar Research Group’s Montreal symposium, John Bradford examined technologies with interplanetary as well as interstellar implications, though as he pointed out, they differ greatly from our cryogenic imaginings.
No deep freeze, in other words, and an experience for the crew that is far more like sleep – a very deep sleep – than the profound stoppage of metabolism that might keep a crew on ice for centuries. Bradford, who is CEO and principal engineer at Atlanta-based SpaceWorks, has explored the subject in two NIAC studies. His review for the Montreal audience took note of where we are today, when placing humans into a reduced metabolic state is relatively well understood, and therapeutic hypothermia is a medical treatment that can involve inhaled gases, cold saline injection and ice packs.
What particularly intrigued me in Bradford’s presentation (available here) is that there are numerous documented stories of human survival in extreme conditions, including one Anna Bagenholm, who survived submersion in an ice-covered lake for three hours. There are even some indications that some form of hibernation may have been present in early hominins, as evidenced by remains found in Spain involving changes in bone structure and density that imply cycles of use and disuse. Bradford’s NIAC work involved a mission design for Mars and Ceres in which the crew cycled through torpor states alternating with active periods. This notion of cyclic hibernation seems promising if we can discover ways of using it that maintain crew health both physical and mental.
Image: Suspended animation the ‘old-school’ way. This is an image from the 2016 film Passengers, involving a crew that is put into stasis inside hibernation pods.
Can we implement torpor in deep space? It’s a fascinating issue, one that may offer a path to manned interstellar travel if we can reduce trip times down to perhaps 50 years, a number Bradford chooses because, in conjunction with increases in human longevity, it offers missions where the balance of a human life is lived before and after the mission. The challenges are huge and already familiar from our space activities aboard the ISS. Muscle atrophy can be profound, as can bone loss and demineralization. An interstellar crew would confront exposure to galactic cosmic rays, while shielding exacts a mass penalty. There is also the matter of consumables.
Let’s face it, the human body is simply not designed for being off-planet, nor do we have even a fraction of the information we need to really assess such things as interplanetary missions with human crews from the physiological point of view. Until we have a dedicated research lab in orbit, we’re reduced to theorizing based on data from the ISS and manned missions that have never gone beyond the Moon.
If we can induce torpor states, we could drastically reduce the bulk of crew consumables needed for missions to another star, but let’s be clear about the kind of mission we’re talking about. A breakthrough in some sort of Alcubierre-like drive would eliminate the need for hibernation. On the other hand, absent the ability to take humans to 10 to 20 percent of lightspeed, we need to look to generation ships as the only viable way to move adult humans to an exoplanet, perhaps considering the possibility of using AI and human embryos raised at destination.
That’s why Bradford is really looking at ships moving fast enough that an interstellar crossing could be made within decades, and here we can look at such possibilities as induced ‘profound hypothermia’ that drops the body temperature below 20 ℃, a procedure used today in extreme cases and generally as a last resort. Perhaps more useful and certainly less drastic is gene-editing to enhance what may be in-built hibernation capabilities. Combine increased human longevity with some form of induced torpor and you come up with mission scenarios involving cycles of torpor and full wakefulness. Indeed, a 4-week cycle of torpor between periods of wakeful activity can reduce the perception of a 50-year transit to another star to a ten year period.
Plenty of work is going on in terms of longevity extension, ranging from research groups like the Methuselah Foundation and Altos Labs to drug trials involving replacement of molecules that tend to diminish with age and supplements like resveratrol and taurine that have promise in increasing lifespan. I’m not familiar with the details of this research, but Bradford said that there are voices in the scientific community arguing that 150 years is a reasonable goal for the average human, with the current record-holder (Jeanne Calment) having managed a startling 122.
Our scenario, then, is one in which we use induced torpor in a cyclical manner to reduce the time perception of an interstellar crossing. Therapeutic hypothermia (TH) currently involves periods of no more than three days, but as the chart above shows (drawn from Bradford’s slides), we can think in terms of two weeks in stasis with four or five days active as an achievable goal based on current research. Bradford’s NIAC work involved missions to Mars and Ceres using this cycle. Going beyond it raises all kinds of interesting questions about how the body responds to lengthy torpor states and, just as significantly, what happens to human cognition.
In the earlier post, it was mentioned in the comments that fat-tailed lemurs use torpor. Online there was some mention that lemurs that went into torpor lived longer than those that did not (sadly no journal paper reference to support that claim).
Currently, the hibernation/torpor state experiments are not long enough to determine if there is life extension or not. Reduced metabolic activity would seem to theoretically have a first-order effect of reducing the production of free radicals that ages cells. Is there any possibility that the suggested hypothermia states in presentation may provide life extension as well?
In terms of life extension we also need to tackle cancers and brain deterioration. There seems some hope that we can potentially eliminate cancers with approaches that utilize the immune system to target cancerous cells to remove them. Similarly for senescent cells. But so far preventing dementia and Alzheimers has seen little success, so it would be of little value to a torpid crew to awaken as “zombies” (explored in a schlocky scifi yet?).
In terms of life extension, we should be aware that humans live longer than other mammals when adjusted for body weight/metabolism. It is possible that life extension has little more to squeeze out in our species. As for those of extreme old age, we do need an active crew, not a senescent one.
Ideally we need some potent anti-aging technology that Bruce Sterling envisaged to drive the story in his novel “Holy Fire”. I would be happy with the anti-Alzheimers treatment that Vinge postulated in his near future story “Rainbow’s End”.
SciFi has a long history of describing various means of engineering humans to be suited to star travel e.g. Cordwainer Smith’s “Scanners”, and Fred Pohl’s post-human starship captain in “Day Million”.
But once again, it still seems that we insist that [post]humans are the agents to make the trip, possibly as unlikely as freshwater fish hoping to colonize the saltwater ocean by altering their physiology based on some anadromous fish species being able to do so. Cosmically, we are on the cusp of having intelligent machines capable of making the journey to the outer planets and the stars, avoiding all the problems of biological life support and aging. After all, ships and submarines can operate in both fresh and saltwater without having to fundamentally alter their designs.
“In terms of life extension, we should be aware that humans live longer than other mammals when adjusted for body weight/metabolism.”
That’s why we really need to study other species that live unusually long for their size, like the naked mole rat. Often they will have anti-aging mechanisms which we haven’t implemented in our own biology. NMR ribosomes are rather different from those of other species, and have a much lower error rate than ours, for instance.
Elephants and whales have genetic mechanisms that suppress cancer. But they’re apparently *different* mechanisms. If we could combine them in ourselves, cancer would basically go away as an issue.
Which would open new avenues for life extension, because one of our aging mechanisms is also a defense against cancer.
I’d say, however, that most of these approaches we could borrow from other species would probably require germ line genetic engineering to adopt for humans. You wouldn’t have these long-lived humans available as colonists for at least, oh, 50 years or so. Just in time for the propulsion technology?
Well, if you’re going to genetically engineer them anyway, maybe adding a torpor mechanism would be feasible, after all.
As cancers are started by DNA coipy/repair errors, that is the place to start. However, while we could engineer the germline DNA to increase the genes that interfere with rogue cells, we can also increase the output of the genes we have, including increasing the power of our immune system – the current new method with good success.
But we should always be aware that there are tradeoffs. Cellular machinery has been optimized for evolutionary niches. Just because we humans want to live longer doesn’t mean that it is best for the species. Reduce the DNA copy errors (or the mole rat’s reduced translation errors) and something gives, one of which is the rate of speciation. With zero copy errors, there are no mutations. We would still benefit from sexual reproduction to mix alleles, but this would eventually run out of steam unless the crossover consistently cut through the genes and not the DNA between them. Short-term benefit, long-term disaster. As external environmental factors cause cancers, from UV, cosmic ray secondaries, radioisotopes in the crust, and synthetic compounds, perhaps the first course of action is to reduce exposure. Living indoors in cities seems like one behavioral response to reducing cancers due to exposure to the open sky. [The mole rats figured that out too!]
While genetic engineering of humans is unethical (and illegal) for anything other than the treatment of genetic diseases, at some point our knowledge will be sufficient to do bolder experiments. At that point, there will be genetic designers creating “designer babies” with the stage set for speciation.
What were Replicants (c.f. Blade Runner) other than designer humans, banned from Earth and made to serve in the off world colonies?
“Cellular machinery has been optimized for evolutionary niches.”
I think this misunderstands how evolution works. Evolution is in a constant tug of war with entropy; Most mutations are either neutral or actively harmful, only a small minority are advantageous. And as you approach a local optimum, the gain from marginal improvements declines: The hill you’re climbing has a gentle slope at the top, but it’s also slippery. And evolution has no way of knowing that the hill it’s currently racing to the top of is just a foot hill to the mountain next door.
So, rather than ending up optimized, organisms typically arrive at a genome where the evolutionary advantage of the traits that are evolving is balanced by their tendency to decay from random mutations.
Further, of course, the longer lived a species is, the slower it evolves. And we’re already a long-lived species, and we spent most of our evolutionary history under conditions where you were likely to die at an early age even if you hadn’t aged at all.
All told, I don’t think you can consider our current genome to be optimized for our current niche, not remotely.
A key assumption I proceed from is that moving humans will require massive ships to include life support, versus light-sail, light ship designs. Another important consideration is the need for shielding which is then even more mass. The presence of life support mass obviates very high speeds, ergo the generational design.
I figure we need to conceive a generational ship that uses water (yep, plain old water) as both propellant and shielding. Water can be tweaked to provide both chemical thrust and nuclear thrust, just with different technologies. We need to get past aspirational and imaginary solutions if we want to go interstellar within the boundaries of contemporary civilization and imaginings. Think instead as if nothing will work. No worm holes for sure. No breakthroughs in energetic sources for thrust. No suspended animation. No “jump to light speed”. In other words, we must live with both actual physics of our universe and the actual mortality of our species. Still wanna go? Think in terms of an asteroid-sized source of water attached to the star ship. Think in terms of a one-way journey. Think of a multi-stage infrastructure that loads people on the star ship AFTER a solar slingshot maneuver has provided the initial acceleration (by forces that people cannot easily tolerate). Think a crew of sufficient genetic diversity is over 100 individuals, and that a large part of those must initially be embryos and sperm/egg binaries to fertilize later. Massive ship with all the components for a colony loaded on! 350 years to get somewhere close, if indeed the close in targets look suitable. Using extended generations of 35 years each, that’s 10 generations just for the journey. More for the colonization. I think I have said enough to help a reader decide if I’m talking crazy or that this might be a line of development.
Staying within known technological limits is a very conservative approach. It is effectively imagining a Victorian steampunk work projected onto their future which is our reality. For example, steam power is so poor that flight requires airships, and even then not particularly good compared to diesel engine powered airships of the early 20th century.
If you run the numbers on using water, a chemical or nuclear thermal propulsion system would require many centuries, if not millennia to reach the nearest star. Would you really get on such a ship knowing that fusion propulsion using the deuterium in the water would be far more energetic and get a starship to the same destination well in advance? Fusion propulsion is not such a leap and requires no new physics, just advanced engineering.
For something more far out, suppose that matter transport via beaming is possible. Artifacts seem like a certainty if the bandwidth is high enough. Living organisms less so, and I will concede that conscious humans will not feel like travel as the original would not feel as if they had been transported (if allowed to live) but the copy would. So instead of sending meat on the ships, you just send the transmit and receiving stations, or just the plans and a means to construct them from local materials. After centuries or millennia, the destination facility is activated and people and goods can be beamed to the destination. The transport would feel instantaneous. If such meat transport was considered unacceptable, the DNA or even just the genetic information could be sent to the destination where human cells would be implanted with the DNA and cultured in the classic seed ship concept, but without the seed ship being needed.
IDK what path technology will take, but even assuming no FTL flight is possible there are possibilities that the technologies on the horizon could be employed to circumvent the huge energies and slow worldships that seem reasonable as crewed star flight today. To me, that feels all rather retro-future, like reading Jules Verne.
Mary Shelley’s “Frankenstein; or, The Modern Prometheus” had to assume that creating a new life had to be done by reanimating dead human parts. She wrote this before we knew about genes, and long before our current gene sequencing, synthesizing, and editing technologies existed. [At my age, gene sequencing and editing wasn’t even imagined during my university education.] Today, we already have one doctor in prison for illegally editing the genes of embryos before implanting them. We are allowing both germline and somatic gene repair to correct for genetic diseases. When will our civilization accept completely synthesized genomes?
If “sleep”/wake cycles are used, those developing chronic disease/disability should be excluded from further “sleep” phases to keep the long-term population as healthy as possible.
Multiple modalities can be simultaneously used, such as Alcubierre drives & fusion reactors, and generation ships with hibernation/torpor and cryogenic techniques. With AI and robotics thrown in for good measure. And some may prefer launching from Canada (where Cannabis is legal).
Slightly on the ethical scale is trying it on a live subject, say those who are in a vegetative state. Prolonging their lives so there may be a cure later on for their issues.
Based on all the reports of open and secret whistleblower UFO testimony to Congress, I think we should just wait to see how the aliens do it. :)
I would think the 10 generation (or so) Ark would be of great interest as it assumes no technological leaps of unknown likelihood (and of low probability in the next few generations). We will learn amazing amounts about many disciplines by studying the techniques and technologies involved. I think the next few generations will unfortunately face many challenges from climate change which will reduce the available resources for projects such as this, but some money will no doubt be available unless we experience a complete civilizational crash. The future is somewhat unknown but predictions can be made based on current and projected events. We are rapidly approaching runaway greenhouse effects and we remain stubbornly on the path of high greenhouse gas generation. We will probably generate another 37 billion tons of CO2 this year instead of beginning the safer path of winding down greenhouse gas generation. Those are facts; they can readily be found online from trustworthy sources.
Gerry O’Neill’s 2nd book based on his ideas book was 2081: A Hopeful View of the Human Future. One feature was enclosed cities, what we would call arcologies (after Paulo Soleri?). These cities were climate-controlled so any environment could be created on Earth. Buckminster Fuller had proposed huge geodesic domes covering city areas like New York’s Manhattan.
Would it be possible to build such enclosed domes, perhaps connected like the Eden Project in England, to cover vast areas of the planet to both protect parts of our biosphere and learn how to maintain them? Like multiple scaled-up versions of Biosphere II, we would hone our technology so that we could be confident that space habitats and generation ships would remain viable for hundreds, if not thousands, of years, and therefore we might launch such ships to the stars with some assurance they would work for the duration of the journey.
Whether the nth generation of crew and passengers would want to leave their ship is a potential issue. Some will, some will not.
Personally, I am already of an age where I would prefer to be made unconscious for any long journey, especially for long-distance flight, and awakened at the destination.
These articles suggest means by which we humans might eventually travel to another star system. Surely more advanced and biologically different species could have mastered comparable technology and be living in the outer solar system with occasional jaunts down to observe/titillate the locals.
The claim interstellar travel is too hard for any aliens to be here is unimaginative.
You are right Neil. Just in the last couple of decades faster than light travel conceptually has progressed from absolutely impossible to merely practically impossible. I consider that enough to imagine a truly advanced civilization has mastered it or at least efficient close to light speed travel. What I said in my earlier comment was tongue in cheek but we should keep an open mind.