To Reach Mars, the Human Body May Need Some Updates

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If humans are ever going to get to Mars, we’ll need engineers to design new rockets and other hardware. Will we also need scientists who can alter our genes? In a provocative new book, Dr. Christopher E. Mason of Weill Cornell Medicine argues exactly that.

The problem, Mason says, is that human bodies are exquisitely adapted to life on Earth, and aren’t likely to hold up well during the long journeys required to settle the moon and Mars. One day soon, however, advances in genetics and medicine — such as the CRISPR gene-editing technology, or CAR T-cell therapies, in which immune cells are re-engineered to fight cancer — might be used to help astronauts better withstand the rigors of spaceflight.

Mason has been researching such issues for years. He led one of the teams chosen by NASA to study the impact of long-term space travel on identical twins Scott and (now Senator) Mark Kelly after the former spent a year on the International Space Station. Mason’s lab also specializes in cancer research. Both fields inform each other, and the long-term plan for human survival that Mason outlines in “The Next 500 Years: Engineering Life to Reach New Worlds.” The following interview has been edited for length and clarity.

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Adam Minter: I was about 100 pages into your book and I had a vision of you as a judge on “Shark Tank.” Jeff Bezos or Elon Musk is on stage presenting a Martian business plan. And you ask, “This is all very good, but how are you going to keep these people alive?”

Christopher Mason: Yes, I’d want to say, “Thanks for propelling and careening humans into space — but what steps are we taking to make sure that we of course do no harm?”

AM: For 60 years, we’ve thought of rockets and space capsules and computers as the bounds on our ability to explore space. But you argue that in fact human biology is the bound.

CM: Yeah, it is. But I’m not saying it has to be. Maybe we’ll be pleasantly surprised at the glorious plasticity of the human physique’s response and humans will do just fine. Or if you just dig deep enough on Mars, maybe you can be protected under the regolith from radiation. You might be fine. But deep-space missions, going beyond the inner planets, or even just one long mission to Mars and back, will be pushing the limits of what we know. It’s also approaching the estimated lifetime limits of radiation for human exposure.

AM: So based on what you learned from the Kelly twins, what are the major health risks for, say, a Mars mission?

CM: Every astronaut is a little biomolecular snowflake, where they’ve got distinct responses to space flight. But all of them face the same hazards: the change in gravity and the radiation. Those are the two biggies we consistently see. We can see that these are driving changes in the body, such as the bones, muscles and genes. But then also we see these other factors — the isolation you have, you’re away from friends, family — that is a really key cognitive component you have to track.

AM: Should we say to an astronaut who goes on a two-year mission, “Odds are you’re incurring health risks and probably shortening your life?”

CM: I don’t know if I’d go so far as to say it’s shortening your life. We just don’t know. Astronauts are among the most monitored and examined patients. They actually get the benefit of some of the best health care in the world. And they’re already really healthy when they go up. But we do know it likely increases long-term risk of cardiovascular disease and cancer, based just on the radiation exposure alone.

AM: Scott Kelly wrote that he didn’t feel normal for about seven to eight months after returning to Earth. Do you know what accounts for that? 

CM: The one-year mission was harder than his previous ones. There’s a chance the longer missions might actually be harder on the body in a nonlinear fashion. It’s not just twice as hard for twice the time, it might be four times as hard. We don’t have enough data to know if that increases when you go to a three-year mission on Mars and back, for example.

We can see the genes that were inside his cells responding to space flight, even months afterward. The genes activated for DNA repair were still activated at a higher level than before he went into space. We’ve also done continuous and additional sampling to keep track of that, and we can say almost all the genes have reverted back to normal.

AM: How far along are scientists in terms of being able to perform some of the engineering techniques discussed in the book? For example, should you be turning genes on and off to protect someone from radiation on a temporary basis?

CM: We’re at the point technically where we can do some of this. But I don’t think we’re yet at the point where we can deploy it for astronauts. I think we won’t get to deploying some of these ideas for astronauts for maybe 10 to 20 years. It’s a ways off, because we’d need to have already completed so many clinical trials and have almost no doubt about the safety and efficacy of these genetic and epigenetic therapies. But as I point out in the book, we’re doing some of this already today. There are now more than 1,000 CAR-T and CAR trials. We’re engineering cells and infusing them back into patients and they’re walking around Earth today, cured. We just haven’t tried it on this question of radiation yet, except in cells. But I think we’ll get there pretty soon.

AM:  Ten to 20 years might be the timeframe in which we’re ready to send people out on that three-year mission to Mars.

CM: Yes, it’s going to be like most medicine. Maybe it’ll be something that’s very optional. If you have two options, one that’s more dangerous, you’re not going to do the more dangerous one. You’re going to take the safest option, the one that has clinically validated therapeutics.

Vaccines are not without risk either. We tell people that if you’re going into an area with a known pathogen, get the vaccine. The analogy here is like going into a place where you know there’s a hazard and can you prevent it, even though the thing that can prevent it might not be zero risk. You have to make the calculation that that risk is less than whatever the hazard is.

AM: Chinese science comes up often in the book, and for good reason. China has really jumped on a lot of these technologies where the West has some ethical concerns and inhibitions. Is there a possibility they jump ahead in human space exploration simply because they’re more willing to take these risks?

CM: It’s likely that the answer will be in some cases yes, because we’ve already seen it. For example, the CRISPR embryos that were implanted and then born and He Jiankui is now in jail for it. [He, a Chinese biophysics researcher, claimed to have genetically edited the embryos of twin girls in 2018. He was sentenced to three years in prison the following year.] But he wasn’t put in jail until an international condemnation occurred. I think your intuition there is correct and I’ve seen it firsthand. In general, they are not as risk-averse as we are here, and their threshold for risk seems to let them jump quicker into things that we would take more time with.

AM: The idea that we should engineer humans for space will inevitably sound like eugenics to some. How do you respond to that?

CM: Eugenics was taking away liberties from people, including forced sterilization. My view is, if the technology is deployed justly and equitably and with care, it could actually increase cellular liberties, it’s really the opposite of eugenics. Instead of someone restricting what you can do with your cells, we flip it around, technology can give you the greatest possible flexibility to do things with your cells and your molecules. And then help you go to places you otherwise couldn’t.

AM: It seems likely that even many people who will never go into space will benefit from the work that you and others are doing in trying to figure out how to make people more resilient in extreme environments.

CM: Very much so. Even things like, if you’re doing radiation therapy for cancer, figuring out ways to have the adjacent regions be protected is something that helps everyone.

AM: How are the public officials you work with — at, say, NASA — reacting to the possibility of engineering humans for space?

CM: It’s too early because the technologies are only a few years old. Is this something we’re going to do next year? Or even in five years for astronauts? No. And even I don’t think we should. But are we doing it now in my lab for cancer patients? Yes, because they don’t have as much time. These cancer patients are staring the grim reaper in the face; astronauts should have a long, full life. Right now, we don’t know enough about these technologies to use them on astronauts. In the book, I propose most of it starting in 2040.

AM: How is the commercial space sector approaching these ideas?

CM: I think we’re just at the bottom of the rollercoaster, when it starts to ratchet up, getting to take the biggest hill of the ride. The momentum is building for us to very soon have a lot more people go into space than ever before. And eventually, hopefully within even a decade or a little bit longer, potentially be on Mars.

These are highly trained, super specialized, deeply filtered humans that go up. The commercial space companies are looking at people who are regular Jacks and Jills, maybe older, maybe being in less decent shape, might have other co-morbidities that might give them a higher risk. As commercial space flight opens up space, it democratizes space. We don’t know how a less fit human body will do in flight, but we’re going to find out soon. If we do this well, and carefully, soon it will be everyone’s right.

This column does not necessarily reflect the opinion of the editorial board or Bloomberg LP and its owners.

Adam Minter is a Bloomberg Opinion columnist. He is the author of “Junkyard Planet: Travels in the Billion-Dollar Trash Trade” and "Secondhand: Travels in the New Global Garage Sale."

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