Should We Put Astronauts in Suspended Animation?

November 03, 2011

Exploring Other Solar Systems

In my blog about the idea of building a starship to explore other solar systems, I did leave out one crucial issue. Unless we discover a method for creating and exploiting warps in space-time, it's going to take many, many times the normal human life span to cover the immense distances involved in interstellar travel. For that reason, some futurists have pondered the notion of space missions in which crews would mate and procreate continually along the way, so that the astronauts who finally reached an extrasolar planet for the first time would actually be distant descendants of the original explorers. For this to work, of course, humans would have to be willing to have sex inside the cramped confines of a spaceship, with their colleagues in close proximity -- probably not the most conducive setting for getting in the mood, even if they take along a library of Barry White's greatest hits for inspiration. Additionally, the plan assumes that humans would be physiologically capable of conceiving and giving birth to healthy offspring in the environment of space, which has not yet been demonstrated. From Medscape, here's an intriguing scientific article on the subject, "Complicating Factors: Issues Relating to Romance and Reproduction During Space Missions."

There's also the dilemma of whether it's ethical to compel multiple generations of astronauts' offspring to serve on a mission that they didn't choose to sign up for. As FuturePundit argued in this 2005 blog post:

How dare some bunch of idealistic nut space explorers set out on a voyage that will condemn all their descendants for many generations to be born, live, and die in a relatively small confined area deep in space! The people who would be born, live, and die in such a vessel would be cut off from any planet, from scientific advances, technological advances, new cultural products, and from significant relationships with the bulk of humanity.

OK, so let's look at plan B. What if there were a way to vastly extend the life span of the original crew of astronauts, so that they would be able to survive for the hundreds or even thousands of years until they reach their destination? Iconoclastic researcher Aubrey de Grey, who considers aging merely to be an "engineering problem," thinks it eventually will be possible to identify the various processes that cause human tissue to age and to design remedies, an approach that he calls Strategies for Engineered Negligible Senescence. Here's an "Is This a Good Idea?" blog post that I wrote back in 2008 on the question of whether scientists should try to extend the human life span.) But not everybody agrees that SENS will actually become a reality, any more than we can assume that de Grey's luxuriant beard is what inspired Joaquin Phoenix to adopt the shaggy look during his hiatus from acting to pursue a career as hip-hop's version of Andy Kaufman.

But there's yet another possibility, one that's been depicted fictionally in movies such as Planet of the Apes and Alien, among others. What if astronauts could hibernate in suspended animation, slowing down their metabolic processes to a bare minimum or even putting them in a sort of standby mode similar to that of Microsoft Windows?

Suspended Animation in Nature

There is some precedent for this in nature. Some animals, such as groundhogs, do this to survive the winter (here's a New Scientist article exploring the how and why). The common wood frog actually can survive being frozen solid during the winter, because of its ability to maintain high glucose levels in its bloodstream and keep its internal organs functioning at a low rate, even as its exterior is cold and seemingly lifeless. But in order to survive space flights that could take hundreds or thousands of years, we'd have to do considerably better than those creatures.

It's been long thought that slowing down living cells for such extremely long periods would eventually cause a fatal amount of genetic damage, since the cells would be unable to repair their DNA. However, in 2005, NASA scientist Richard B. Hoover reportedly discovered bacteria that had managed to stay alive for 32,000 years while frozen in ancient Alaskan permafrost. While his finding was treated with skepticism, two years later, an international team reported that they had discovered even older microbes in Siberia, which had survived for more than half a million years. Somehow, the scientists believe, the bacteria had not only managed to stave off fatal genetic damage but to break down food to produce energy and even to reproduce at extremely low temperatures.

Preserving a human being in such a frozen state would be considerably more difficult. As Michio Kaku notes in the 2008 book Physics of the Impossible, when human tissue is frozen, ice crystals begin to form inside the cells; as the crystals grow, they can penetrate and destroy cell walls. From the National Institutes of Health's PubMed database, here's a forward-looking 1968 medical article published in Annals of Surgery on some of the obstacles to "surface-induced deep hypothermia," as the state is called. (BTW, if you happen to have Paris Hilton's email address, you might want to pass along the link; according to a 2007 Associated Press article, the heiress-starlet has invested "a large sum of money" in a laboratory where, after her death, she plans to be frozen, along with her Chihuahua and Yorkshire terrier, and then eventually revived.)

Hydrogen Sulfide to Slow Body Systems

But it might be possible to maintain a person in suspended animation without freezing. In 2006, researchers at Massachusetts General Hospital in Boston slowed down the metabolism and cardiovascular systems of mice by administering small, controlled doses of hydrogen sulfide, the foul-smelling toxic gas produced by rotting eggs and sewage, and then were able to reverse the state of suspended animation afterward. In subsequent experiments, the researchers accomplished this feat even without a reduction in body temperature, according to this Science Daily account. This approach is so promising that the Pentagon's Defense Advanced Research Projects Agency has committed nearly $10 million to the Texas A&M Institute for Preclinical Studies to investigate whether the gas and other chemical compounds can safely induce suspended animation in pigs. Here's an article from the futurist publication HPlus on the research.

As Erik Seedhouse notes in his book Trailblazing Medicine: Sustaining Explorers During Interplanetary Missions, putting astronauts in sleep mode would have other advantages as well, even on shorter trips to Mars or other destinations within our solar system. Space crews would require less food and oxygen, and they wouldn't eliminate as much waste or require regular exercise sessions. Plus, they wouldn't get cabin fever and start bugging one another incessantly.

On the downside, astronauts in suspended animation presumably wouldn't be able to stay in touch with Earth, even if we perfect a mode of faster-than-light communication -- for example, superluminal polarization current distribution -- that works over extremely long distances. Barring an immortality-bestowing breakthrough of the sort Aubrey Grey dreams of, by the time the interstellar explorers awakened in orbit around a distant extrasolar planet, everyone and everything they knew in their lifetimes most likely would be long gone. They would be representatives of an Earth that, in a sense, no longer existed, with nothing to return to. I can't help but wonder if they would be so psychologically traumatized by grief and disoriented by cultural alienation that they would find it difficult to proceed on their mission.

So what do you think? Express your opinion below.

Image Credits: EPA/JORGE ZAPATA | Michael Haegele/Corbis |