How to keep astronauts healthy on missions to Mars
When the first astronauts reach Mars, they will be expected to carry out heavy physical tasks after many months of traveling in weightlessness without the benefits of the exercise machines or the Earthside therapists that help astronauts on the International Space Station (ISS) to readapt to gravity. To learn more about how to keep space travelers healthy on such long missions, New Atlas talked to Draper scholars from Harvard and the MIT Health Science and Technology Program, Rachel Bellisle and Tom Abitante, about two new technologies that hold potential for keeping astronauts healthy in zero gravity.
New Atlas: We've long had people in space safely, some of them for well over a year. What's the problem we're facing that needs to be solved here?
Tom Abitante: The main problem is that astronauts lose bone and muscle mass while in space.They can spend time in space safely, but when they come home to Earth after being in space for a year, they're whisked away to physical therapy. When we go to Mars, these astronauts are going to be expected to do physical work when they get there, but muscle and bone loss and the loss of general fitness create a high risk of injury. The current method to prevent this is exercise. However, going to the Moon or Mars, you're not going to be able to carry with you the gear for a large, robust exercise program. We're looking at ways you can get the bone and muscles working that would prevent the loss without lugging massive exercise equipment to Mars?
New Atlas: So the goal is to prevent bone loss and muscle atrophy from occurring?
Rachel Bellisl: More than that, it's the fact that your body is no longer loaded by gravity, which changes so many systems. Bone and muscle are the two great examples, but it can be even more. It's anything that's affected by the physical load that you experience every day.
New Atlas: Such as?
Tom Abitante: One is the little organs in your inner ears that are always telling you what way is down. In space, there's no down. While that has an initial effect of maybe getting motion sickness, or some spatial disorientation, over long periods of time it can actually affect some kind of your coordination and proprioception, like to your posture and gait. Lots of times when astronauts come back to Earth, it takes them a few days to readjust.
Rachel Bellisle: It can be weeks, depending on the kind of effects we're looking at, to be able to get around and get used to having the forces of gravity on you again.
New Atlas: What are the alternatives to having exercise equipment on long missions to the Moon or Mars?
Rachel Bellisle: We definitely know that the countermeasure protocol is going to look completely different than it does now. There's probably going to be smaller exercise equipment. Our goal is to supplement that. I think there's ways to do that with wearables. Is there a garment that you can wear to add to your conventional protocol every day? I'm studying a skinsuit that reapplies some of that mechanical loading on the body. It's essentially a skin-type garment that squishes the body vertically and reactivates a lot of the load receptors that are usually inactivated in the microgravity environment.
New Atlas: What are these load receptors and what do they do?
Rachel Bellisle: Your body is full of these biological sensors that measure how gravity applies to your body on Earth. There are some in your bones that prompt your bone to maintain strength, and there's some in your muscles, too. Your muscles have to understand how much force they need to apply to walk. When you don't have all of those sensory inputs from gravity, those processes are interrupted. The receptors have to adapt to microgravity, then they have to adapt again to Earth when you get back. This is a big problem for adapting to Mars after a long trip in zero gravity.
New Atlas: Could you tell us a little about the skinsuit?
Rachel Bellisle: These skinsuits are a passive fabric garment, so there aren't any actuators. It's a little like a soft exoskeleton that's a tight bodysuit. It's a couple sizes too small and calculated perfectly for an individual so that we apply a load on an anchor point on the shoulders, then stretch the fabric and anchor it underneath the feet with straps. We have to make this comfortable to make sure that astronauts want to use these devices.
New Atlas: So how long would you have to wear one of these suits?
Rachel Bellisle: It depends on the application. The European Space Agency actually worked with the skinsuit to prevent some back pain in space and they would have some subjects wear the suit for eight hours. But there are other ideas that it should be worn for an hour or two while exercising.
New Atlas: Tom, you're taking a completely different approach to this. Can you tell us about it?
Tom Abitante: Mine is a little more active. I'm looking at using electrical stimulation, specifically neuromuscular stimulation, to increase the daily action your bones get every day. This is something that they use a lot for spinal cord injury patients. They use electrodes on the muscle that send an electrical pulse through the muscle that will make it contract. This can potentially help reduce bone loss from disuse associated with being in a wheelchair or being in space. The idea is if we do these artificial contractions a couple of hundred times a day, that can keep the bone stimulated enough that these little sensors that Rachel mentioned tell the body to not reduce bone.
Because these are healthy people, there's a major factor that paralyzed patients don't have, and that's discomfort. Paraplegics can't necessarily feel that. That gives you free rein to crank it up and to let it go for longer. With healthy people, there's a limit, because obviously you want them to be able to do work while being electrically stimulated. We need to know how effective it would be and what kind of dosing we would need. We can't wait to go to Mars and see if it works.
New Atlas: It doesn't sound uncomfortable.
Tom Abitante: The idea is to use it at a baseline, but not be super uncomfortable. You definitely feel it, you're definitely aware of it. It's definitely new and different, as both Rachel and I can attest. Fortunately, there is a diminishing effect like when you hear a random white noise and your mind kind of shuts it off. That's where my research kind of comes in. What levels can people take? How many doses? How many would you need a day to replicate your normal exercise activity?
New Atlas: What's the next step with this? Are you hoping to test it in space at some point?
Rachel Bellisle: Firstly, the skinsuit has quite a heritage. It flew with the European Space Agency on the International Space Station from 2016 to 2017. Now, we've restarted some work at MIT as well to explore it further in different applications and create the new version of the suit. I've flown it this past spring on a parabolic zero-gravity flight. I'm planning to do another flight this spring as well. We're bringing it into the microgravity environment and doing some short-term testing with a participant wearing the suit, which is really exciting. I'd love for NASA to pick it up and use it. I think that would be great.
Tom Abitante: I would say I would love for it to go into space. Realistically, I think what would happen first would be a long bedroom study here on Earth where subjects lay in bed all day, and they only get up to exercise for an hour and a half.
New Atlas: What applications do you see for these technologies, aside from trips to the Moon and Mars?
Tom Abitante: The applications for me would definitely be improving the technology for spinal cord injury and associated bone loss. There hasn't been much investigation into optimization to improve bone loss therapies for people who are in wheelchairs.
Rachel Bellisle: There are two possible Earth applications I can talk about. The first is that the skinsuit is a compression garment. We can use a lot of those technology developments on Earth, especially as the skin gets more advanced, making it smart and adding sensors. Can we translate that directly into medical compression environments for things like lymphedema or deep vein thrombosis prevention and things like that? Also, there's a second application that hasn't even been explored yet. The Russians had a similar suit to this, called the penguin suit. They turned it into a therapy for children with cerebral palsy. It could have some really interesting applications for rehabilitation that haven't been explored yet, and could be a really cool translation of the technology on Earth.
New Atlas: Captain Kirk (AKA William Shatner) went into space and he's 90 years old. We know that as people get older, muscular atrophy and bone loss become a very serious problem. How could this technology aid older astronauts?
Tom Abitante: Say that you're a person that loves to take care of themselves and you go to the gym every day. That hour a day you're working out, you're getting lots of really high forces, but the other 15 hours of the day that you're awake, what are you doing? You're walking and standing up, you're going upstairs. All these tiny little forces aren't the same as squatting 500 pounds, but all these tiny little forces are what you get throughout the other 15 or 16 hours of the day.
In space, they get the same thing when they work out for an hour and a half, two hours, but the other 15 hours, they're getting nothing. So how can we kind of mend that gap? You could exercise more, but that starts to create more problems. What Rachel and I want to do is fill those other waking hours with just other little things that may be equivalent to you walking around.
New Atlas: Rachel, from what Tom says, could you see a very comfortable version of your suit that could be worn all the time as some kind of gravity simulation?
Rachel Bellisle: I think it's an option. A lot of the wearing scenarios we talk about are either overnight, or overnight for like eight hours and during exercise for two hours, or maybe during daily activity. It's something that requires testing. We need to have somebody go into space, wear the suit all day during their daily activity and ask, okay, do we continue to see all of these really positive effects that were expected with the suit over the entire day that they're working? I think it is a possible scenario for later testing.