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.