John E. Bradford. Ph. D., is president and chief operating officer of SpaceWorks, Inc., an aerospace design contractor for NASA and the Department of Defense based in Dunwoody, Georgia, just north of Atlanta. The NASA Innovative and Advanced Concepts program has awarded SpaceWorks two grants since 2013 to design plans for “Mars transfer habitats” that would carry explorers—or, in the more elaborate of SpaceWorks’ two proposals, colonists—to Mars while keeping them in a state of induced torpor. It’s a state of reduced core temperature and low metabolism that would reduce the mass required of the mission (by saving on food and other supplies) while also, Bradford and his team believe, protecting them from radiation. Air & Space / Smithsonian will publish a feature on this research by Arielle Emmett in our April-May 2016 issue.
The idea of spending long spaceflights in hibernation is a familiar one in science fiction stories and movies, having been depicted in classics of the genre like 2001: A Space Odyssey and Alien. It’s also key to the premise of Passengers, a new outer-space romance starring Chris Pratt and Jennifer Lawrence that opens today. While Bradford was not involved in the writing or production of the movie (which was written by Jon Spaihts and directed by Morten Tyldum), Columbia Pictures tapped him to assist in its promotion by discussing how its story, set in some unspecified period in the distant future, reflects the hoped-for outcomes of his firm’s research.
This interview has been compressed and edited for clarity.
Air & Space: So from a speculative-science perspective, what does Passengers get right?
Bradford: A couple of different aspects. Having the crew members in individual stasis pods is a trade that we’ve made. We’re currently thinking of a more open environment, but I think we may go back to the more contained pods. [The movie’s hibernation procedure] was minimally invasive, in terms of support systems. We’re always concerned about tubes or any sort of puncturing of the skin, which present an increased risk of infection. They weren’t hooked up to any machines. They weren’t cryogenically frozen, which goes to another level of stasis. And they wore minimal clothing. We’re concerned about skin abrasions over long periods, so you don’t want a lot of contact there.
We think there are two ways, maybe, to do this. We’re hoping we can sustain [astronauts] for six months on a Mars trip, or a journey within our solar system. In the movie, it’s 120 years. But we think that if you push down the metabolic rate even more than what we’re trying to do, with a combination of some anti-aging or regenerative drug therapy you could potentially go that route. Or you could do the cryo-preservation that you sometimes see [in fiction], where we’re going to stop all cellular activity and essentially just freeze people. At those time scales, 100 years or more, there are still two approaches there. The movie erred on the non-freezing sort of approach, which is what we think is the more viable option. There are certainly companies out there that freeze people, but no real plans and no idea how to bring people back from that. We think that’s a much harder problem.
If you don’t stop all cellular activity, there would still be some aging. But with advances in medicine and reduced metabolism it would be on a much slower time scale.
The wake-up scenario was good, although you don’t have an exact feel for how long those time periods were. When Chris Pratt [who plays a hibernating passenger who wakes up prematurely when his pod malfunctions] is stumbling around and yawning, that’s similar to the conditions we’re expecting. When animals hibernate they’re not really sleeping. So they will come out of hibernation to sleep, and then go back into hibernation.
They’re not completing R.E.M. cycles in hibernation.
That’s right. So it was good that they didn’t just jump out of the pods and start flying the ship or something.
You said SpaceWorks had considered an alternative to the coffin-like individual pods, which is the way hibernation is usually depicted in science-fiction movies. What was the other idea?
Our designs now are basically an open habitat, with a shared environmental control system so everybody is in the same ambient air. We do that primarily for mass savings. Individual pods would be heavier, so we lose some of the benefit of the stasis when we do that. But it does give you more precise control at the individual level: You can control everyone’s ambient temperature. And if there were a pathogen or a sickness or something, having each person isolated like that would be beneficial. But for only six months, for the Mars focus, we were happier taking the mass savings of the shared environment. [The astronauts] wear masks, but they’re all in the same habitat.
To invoke another scenario we often see in the movies, what if there is some sort of emergency that necessitates waking the crew ahead of schedule?
You have to have contingency plans for a malfunction or if a micrometeorite or debris hits the ship, for example. How quickly can we warm people up? The warming process is slower than the cooling induction process. We’re looking for ways to accelerate that. Or if everyone wakes up, they’re all in a pretty small habitat. It’s only six months, but they’d be in for a rough ride. That’s a scenario we have to consider.
How much do you anticipate cooling the crew to induce torpor?
We drop them down by about 10 degrees Fahrenheit. The heart can only go to 28 degrees Celsius [about 82 degrees F]. Any lower and it can’t trigger the electrical impulses and pump blood. There have been cases where people go below that, down to 14 degrees C when they’re trapped in cold water. But as you approach that 28 degree mark, the heart starts to become a little erratic. We hold at about 32 degrees C [roughly 89 degrees F], which gives you some margin and that gets you about a 70 percent reduction in metabolism. Which is pretty good for a relatively small drop. A lot of times people think you have to be freezing cold to do this. But your core temperature doesn’t vary that much. Even in between when you’re active and when you’re resting at night, it changes very little. Your body has a spot it wants to be in.
What sort of tests have produced these results? Are you talking about humans who have been cooled for surgery or something else?
It’s based on the application of therapeutic hypothermia—or targeted temperature management, as they’re starting to call it now—during surgeries. Those are the data points: Reductions they see in the heart rate and oxygen demand.
The actual metabolic reduction varies from person to person. But 70 percent is generally what they see. And reducing the body’s demand for oxygen is why [surgeons] do it. Cooling starts that process. With traumatic injuries, your cells are probably being starved of oxygen anyway, so if you can lower the core temperature then the cells need less. You’re trying to match what they’re able to get to the injuries. It prevents early cell death, long-term brain damage, things like that. Cooling the body buys you more time.
Well, just to return to the movie, are you a science fiction fan? Do you like these kinds of movies?
Oh, yeah. Generally the whole office will go and see some of the bigger films, just for general inspiration. As an advanced concepts organization, we’re always looking 10 or 20 years into the future and asking how we can improve what we have now. Science fiction is a big motivator for all that.