EPISODE 90: EFFECTS OF SPACE RADIATION

Transcript

Robin Elgart: Radiation is a fact of our everyday life whether people know about it or not.

There might be some unique things to space radiation, but all the work that we do here in the Element has far-reaching implications down here on the ground.

We’ve had a bunch of different researchers looking into various compounds to help the body heal itself from the radiation impact and lessen the effects of radiation.

We’re going to have to come up with a different strategy when we actually have a space-faring species, when we have people spending the majority of their careers in space, which is why it is so challenging.

Deana Nunley (Host): Welcome back to Small Steps, Giant Leaps, a NASA APPEL Knowledge Services podcast where we tap into project experiences to share best practices, lessons learned and novel ideas.

I’m Deana Nunley.

As NASA prepares to send the first woman and the first person of color to the Moon, the agency’s radiation scientists at Johnson Space Center are studying how space radiation affects the human body.

Robin Elgart is a Space Radiation Element Scientist for NASA’s Human Research Program and part of the team working to keep astronauts safe on their journey.

Robin, thanks so much for joining us on the podcast.

Elgart: Thank you so much, Deana.

Host: Could you start by explaining what makes exposure to radiation in space different from radiation exposure on Earth?

Elgart: Absolutely. So, when I say radiation, what I mean is ionizing radiation. There’s two different kinds of radiation. They’re broadly categorized. There’s non-ionizing radiation, which doesn’t have enough energy to ionize matter, which all that means is knock electrons out of the atom creating a free electron and a positively charged atom. So that’s non-ionizing radiation. That does not have enough energy to make those ions.

But ionizing radiation, as you can imagine, has enough energy to actually ionize those atoms and create these free radicals, those electrons that go on and run into things and cause all sorts of havoc, as well as these positively charged atoms that have lost an electron. So now, they’re positive. And it’s those charged particles that then go on to create biological damage. Those electrons and those positively charged atoms, they want to become whole again. They’re lonely. And so, they will do anything to get whole again. So even if that means ripping apart your DNA, which they sometimes will do. So, when I talk about radiation, I’m talking about that ionizing radiation, just to be clear on that point.

And so, when we talk about space radiation versus the kind of radiation we have down here on Earth, in space we have instead of photon radiation, which is essentially high energy lights — things like gamma rays and X-rays — we have physical particles that are zipping through space at near relativistic speeds, meaning they’re traveling at a fraction of the speed of light. That’s really fast.

And these different kinds of radiation or this kind of radiation comes from three main sources when we talk about human space light. The first is what’s called trapped radiation. And that is the kind of the particles that gets trapped within our magnetosphere, the huge force field that is encircling our planet. It’s wonderful for providing us protection from that radiation. But some of those particles actually get trapped in it. And so, there are these two belts around the world that have all of these protons and electrons that are streaming about. And so, if you cross those belts, you’ll get exposed to that kind of radiation, these particles.

And then, there’s also what are called galactic cosmic rays. These are particles that have been accelerated across the universe by supernova, so stars exploding and spewing their stellar contents out there into the universe. These are made up of things, everything from hydrogen atoms that have been charged by kicking off, getting those electrons stripped off of them all the way up to uranium and even beyond. Anything in the periodic table you can think of, those particles are zipping through space.

Mainly, it’s made up of those smaller particles like protons, but there are a significant number of those larger heavy particles. We call those high-energy and high-charged particle, HZE particles. And so, you can imagine these high-energy, high-charged particles, these huge nuclei that are zipping through space. They’re kind of like little cannonballs. And down here on Earth, we have nothing like that. The kind of radiation down here, we have gamma rays, X-rays, which again high-energy light. And we have some small particles from things like radioactive decay. Your granite countertop has trace amount of uranium in it that’s giving off some radiation in the form of particles.

So, the difference between the space radiation and on-Earth radiation is that in space, it’s really those large particles that are zipping around. And we don’t really deal with any of those X-rays or gamma rays in terms of the kind of radiation that’s going to be significant enough to really impact human health.

And then, of course, that third kind of radiation is probably the most well-known out in space are from solar particle events. The Sun, every once in a while, the magnetic fields get real tangled up, and they release a ton of energy that pushes out solar protons into the solar system. And if you’re in the way of those, you get an extra dose of radiation from those protons.

So again, space radiation, much more particle-focused, just little particles zipping through like little cannonballs varying sizes. And then down here on Earth, much more lighter particle radiation and mainly X-rays and gamma rays is what we’re exposed to really in your average day-to-day life.

Host: What are the biggest risks when astronauts are exposed to space radiation?

Elgart: That’s a great question. So, there are a number of effects that we’re concerned about when humans are exposed to radiation. And whether it’s space radiation or whether it’s radiation down here on the ground, the effects are generally similar. The big difference is that we don’t necessarily know how effective the space radiation is at causing those same effects. And there may be some unique effects of that space radiation that we don’t necessarily understand because we’ve never experienced it before.

We’ve only had a few people in the world really be exposed to the kind of radiation that’s out in space compared to down here on the ground where we’ve had lots of people be exposed to terrestrial radiation. So, the main health effects that we’re concerned about are, first and foremost, the long-term health risks because the kind of radiation and the amount of radiation that we’re dealing with is not typically a lot of radiation all at once.

Down here on the ground, you may be exposed to an incendiary device. If there’s a dirty bomb somewhere and there’s a huge explosion and there’s a lot of radiation all at once, that’s not what we’re dealing with up in space. What we’re dealing with is a constant exposure to a higher background radiation.

And so, the amount of radiation really isn’t breaching into those much more acute effects. Really, they’re impacting long-term health effects. So the big one that we’re really concerned about is cancer. Cancer can be caused by radiation. Cancer can also be cured by radiation. But we know for a fact that radiation does increase cancer risk. We’ve seen that in many epidemiological studies down here on the ground of people being exposed to radiation down here on Earth.

Second is our cardiovascular effects. These are just as important. But the risk doesn’t seem to be as high compared to those in cancer. And that includes things like cardiovascular disease, cerebrovascular disease, anything really involving that cerebrovascular or cardiovascular system.

And then, thirdly are effects to the central nervous system on your brain and surrounding supporting tissue that will impact behavior and performance in mission as well as long-term health, potentially even promoting neurodegenerative diseases like Alzheimer’s disease or Parkinson’s. Now, I want to make it clear that we really haven’t seen much of this, these kind of effects to the CNS down here on Earth. This kind of effects have really only started to crop up when we’ve started to do animal studies on the effects of space-like radiation. So, we’re not exactly sure how to translate from those rodent studies to humans. You can imagine translating that information from a rodent brain to an astronaut brain is a big challenge that we face.

And then, finally, I do want to mention those acute effects. Those solar flares that I mentioned in the last question, those are really your only opportunity to receive a large dose over a short period of time that may cause what people may know as radiation poisoning or radiation sickness. We call it Acute Radiation Syndrome. And I really want to emphasize that it’s going to take a very large event, something that we really have never seen in the Space Age before to really even get to the bottom of the thresholds for any of those impacts. We anticipate that if we do see any impacts, they will be relatively minor. But because we never know what the Sun can throw at us — Mother Nature has a mind of her own — that’s why having our operational group monitoring the Sun constantly so we can get our people inside if something does come up from the Sun is so important. So, the operations are really responsible for monitoring the Sun, forecasting what might be happening and trying to do their best in keeping our astronauts as safe as achievable.

Host: What’s the current strategy to reduce health risks of space radiation exposure?

Elgart: So, there’s a couple of different strategies. Of course, our larger strategy is multifaceted because we do a lot of research, and we know just because of the nature of research, not all of our leads are going to work out. So operationally right now, they have what’s called a storm shelter for our Artemis missions, which are going to be going beyond our Van Allen belts out to the Moon. And if there is a solar particle event, the crew, if it is directed at where the crew is, they will have no shielding.

Currently on the ISS, the International Space Station, there is this beautiful magnetosphere that protects them from the majority of the impact of solar particle events, which is really helpful. But if they’re out on the Moon, they will have none of that protection from a magnetosphere. So they’ve developed a storm shelter concept where in the Orion vehicle, there are bays that are under the seats. And you basically pull out the chairs, pull out the seats, pull out all the things that are under the seats. And you build a little space fort out of all the different stuff that is under those seats to build up the mass around you to protect from those extra protons that are coming at you, which can substantially reduce the amount of radiation that is going to get to the human body. So operationally, that’s the current strategy for something like an Artemis mission.

On ISS, the operational team keeps in constant contact with the flight control team. And if there’s an event that happens, they alert them to the times where the solar particle protons are going to come in contact with the International Space Station. This happens at the North and South Poles basically, where those particles can actually trickle into our atmosphere through magnetic field lines. And so, they will tell the flight control team when the crew should maybe stay out of lower shielded areas, maybe when they should seek shelter in higher shielded areas. So operationally, that’s what’s done for solar particle events.

For the other protection strategies because then we have to start thinking about this GCR, these very highly energetic particles that are very difficult to shield. And in fact, if you put up too much shielding in front of these particles, you can actually make the problem worse. And so, let me try to explain what this looks like. So, if you took a wall. And you built it out of say ping pong balls and imagine those are the atoms that make up that shield, and you take a bowling ball and you throw it at that wall, that bowling ball is not going to care. It’s going to just keep coming. And so, instead of just having the bowling ball coming at you, you now have the bowling ball coming at you along with a bunch of ping pong balls. And so that’s what shielding can actually do for some of these very heavy particles that are part of the galactic cosmic rays. And you would need meters of water to really make a huge impact on reducing the dose from this background radiation from galactic cosmic rays. So operationally, they’re looking at things like active shielding, creating a magnetic field to try to bend these out of the way. So that’s the physical shielding protection strategy, or one of them.

And then, on the research side, what we’re doing is we’re trying to attack the problem from a biological standpoint, is how can we help the body protect itself? Are there pathways that we can help upregulate, downregulate, that will help the body better deal with the damage? And we’ve got some really exciting progress in some of our studies that are ongoing right now, showing that we may be able to find some compounds that can protect humans from developing these longer term problems using some sort of compound, some sort of drug that will help their bodies recover from these biological insults.

Host: How much more challenging is it to reduce space radiation health risks on Moon and Mars missions than, say, space station missions?

Elgart: It’s more challenging for a number of reasons. So, ISS, the International Space Station, missions are approximately one year long, six months long, and they’ve got that great protection from the magnetosphere. But I will note that the amount of radiation on a daily dose basis is pretty similar between the International Space Station and, say, on a cruise to Mars. It’s about equivalent in terms of the dose per day because, on ISS, they actually go through what’s called the South Atlantic Anomaly, which is part of that trapped radiation, actually dips down into our atmosphere a little bit lower than the rest of the belts.

They go through that belt about six to nine times per day, which makes up a substantial amount of their daily dose of radiation. So, the doses are relatively similar on a daily basis between ISS and just being out in free space, not on a planetary surface, which includes the Moon. If you get down onto the planetary surface though, the Moon or Mars actually protects you from about half of the dose because you have this huge planet beneath you, which is super helpful in terms of blocking about half of the radiation.

So, you can cut your daily dose by about half. So that’s a great thing. But for long-duration missions like Mars, the biggest challenge is time because a mission to Mars is necessarily going to take two to three years. There’s no way to get away from the radiation in that time. On ISS, we can bring them down. We can take them away from the environment once their mission is ended after six months a year. But a Mars mission, you can’t get them there any faster.

So that is one of the big challenges around a long-duration Mars mission, is that it just takes so long to get there. So, you’re constantly accruing dose, whereas on the lunar surface, that’s a little bit closer. But if we want to have a sustained presence on the Moon where people are staying longer than six months a year, we’re going to have to come up with a different strategy when we actually have a space-faring species, when we have people spending the majority of their careers in space, which is why it is so challenging.

And then, of course, there’s the aspect of the austere space flight environment is that we can’t take a lot with us. So, can we fit into the little black bag our compounds, or are there more prioritized risks that might happen in mission that have to take the priority in that little black bag because we are so space-and mass-constrained? So there’s a lot of different nuances that have nothing to do with really the research but have everything to do with logistics when it comes to these more audacious exploratory missions.

Host: How does NASA research the health risks of radiation exposure beyond low-Earth orbit?

Elgart: So, we have an excellent research program if I say so myself. While we can’t conduct a lot of our research out in space because it requires so much just stuff, we do a lot of our research on animals because we cannot conduct radiation research on people. And so, we have to figure out strategies how to conduct this research down here on the ground. So we have an incredible facility up at the Brookhaven National Laboratory called the NASA Space Radiation Laboratory, or NSRL.

And this facility was tailor made to produce a beam which is made up of different heavy particles and different kinds of particles to try to simulate that GCR environment. Of course, it’s not perfect. There is no way without supernova and magnetic fields that are incredibly robust to recreate the space radiation environment down here on the ground. So we do our best with these different particles and these different particle schemes that we’ve come up with at NSRL that we can design controllable experiments and within a controlled environment.

So, our external researchers that are scattered throughout the country can go to NSRL and conduct these experiments to understand these different impacts. We have this great facility that is available for our researchers who are scattered throughout the country to be able to take advantage of a ground-based analog to conduct their research into understanding the underlying mechanisms and just the outright risks of space-like radiation into things like cancer, cardiovascular disease, and those central nervous system, or CNS, effects that might impact behavior and performance.

Host: What are some of the latest research findings?

Elgart: I’m so glad you asked that because we really had an incredible couple of months here and especially coming off of COVID, the last two years have been really challenging for our researchers because of the delays due to the pandemic. Especially right at the beginning of the pandemic, we had no idea how we were going to help our researchers get through this. Labs were shut down. But people’s salaries still had to be paid.

And for the most part, we’ve managed to sort of stumble through and limp through these last two years. And I’m so proud of our research community for sticking with us. And I think it’s really paid off because while the last two years have been incredibly challenging, we’re starting to get some really interesting results, some of which are relatively preliminary. But I can share a couple of things with you today, which is, previously, we’ve been having a really hard time getting our cardiovascular system impacts to even be able to be modeled in a rodent model because, like I said, we can’t do this research on humans. So we have to find some other model. And it’s been really challenging for us to use a rodent model.

But recently, Dawn Bowles at Duke has started to see some impacts in her model when she’s waited long enough for these things to crop up. And so, we’re really excited to see those impacts show up because what that means is that we can actually start to do the work into really characterizing this risk because that’s our first mission, is to characterize the risk, because that’s so important for decision making, both in terms of the agency’s decision making, but also for the crew. The crew has to be able to understand the risks and make the decision yes or no. I am, or I am not willing to take on this personal risk. So, we’re really excited that we’ll be able to hopefully do a better job of characterizing the cardiovascular risk from space radiation. And then, secondly is developing mitigation strategies for that because without a model that actually shows the impacts, there’s no way for us to actually develop mitigation strategies, whether those be physical or biological.

And then secondly, we’ve had a bunch of different researchers looking into various compounds. And I alluded to this a little bit earlier, various compounds to help the body heal itself from the radiation impact and lessen the effects of radiation. And it’s too early to say yet. But we’ve gotten in the last couple of months variety of data that is showing some very promising results for some of these compounds.

And in the next few months, maybe next six to eight months, we’re really excited to start seeing a conglomeration of this different data and to see how we might be able to move this forward. So all of that stuff is really exciting right now.

Host: We’ll have to follow up with you in the future and talk about that again.

Elgart: For sure.

Host: Robin, what are the potential benefits of the research beyond space exploration?

Elgart: That is a fantastic question because working for a space agency, I like to think that the things that we do are not just for the astronauts. I didn’t get into radiation research to support the health of 40 individuals, right? And I love the fact that our astronauts get to go on these incredible experiences and are doing amazing work. And I think space exploration is an incredible opportunity for humanity. Don’t get me wrong. Space exploration is, I think, a critical part of the human condition.

But I got into radiation research to help the most people I could. And so, luckily, all the work that we’re doing here in the Space Radiation Element, because radiation is radiation, while we’re dealing with different types of radiation, sure, the effects are very similar. There might be some unique things to space radiation, but all the work that we do here in the Element has far-reaching implications down here on the ground.

Radiation is a fact of our everyday life whether people know about it or not. We have hundreds of thousands of radiation workers in this country. We have hundreds of thousands, millions of cancer patients in this country that are exposed to radiation. The workers are exposed on a regular basis. The human population is exposed to radiation on a daily basis. It’s just very low. But our radiation workers are exposed to higher levels on a daily basis. Our cancer patients are exposed to relatively high levels of radiation to help cure them.

If there’s anything that we can provide that will help support the health of those millions of people, then, that’s a win both for space and for the ground. And I think it’s so important that a lot of this research is being done by a public entity like NASA because it becomes free information for everyone, which I think is so beneficial. And a lot of this work wouldn’t have been done otherwise. For example, for cancer patients most of the cancer research is being done to help treatment outcomes because that is the most salient point. We want to get these people the healthiest we can so they can get to their next treatment, so they can follow through their treatment protocols to give them the best chance.

So, we’re improving therapies. We’re reducing side effects and things like that. But what NASA is really challenged to do is that we’re trying to prevent these things from happening in the first place, which is not a huge area of research right now, because there’s such a focus on treatment, which absolutely needs to be there, or preventative screening which is also a huge thing on our strategy for mitigation. We want to be a part of improving those screening strategies to make sure we are screening and surveilling our astronauts to the best of our ability. So really, everything we do here is going to impact or potentially going to impact what happens down here on the ground, which I’m personally very, very proud of.

Host: That’s remarkable. What’s the most rewarding part of your job?

Elgart: Well, that one’s easy. So the most rewarding part of my job is really the people. So the space radiation community is a relatively small niche in the research community. You have the radiation community which is already small. And then, you have a space radiation community. And so in the last two years, two and a half years, that I’ve been doing this job, I’ve really gotten to know the community better and just the incredible work and the incredible fortitude and resilience that’s in this community is really rewarding to see. So that’s the external people.

But then, there’s the internal people here at NASA. The group here at the Johnson Space Center and we also have a group over at Langley, it’s such a wild team to work with. And I mean wild in just every sense of the word. We have a great time working together. We’ve got great, bold, crazy ideas that we try to make work. The people in my element are relentless in their optimism for doing the best we can. And so working with them has really been the most rewarding part of my job. And I’m so proud to be part of this group that is just wild. And I absolutely adore being able to work with them every day.

Host: Robin, this sure has been fun. I’ve really enjoyed getting to talk with you today. Thank you so much for joining us on the podcast.

Elgart: Thank you, Deana, so much. It was such a great opportunity to join you today. And I look forward to maybe catching up maybe a little bit later when we have some more results.

Host: Oh, that would be great. Do you have any closing thoughts?

Elgart: Yeah. Actually, I do. I really want to leave people with some hope and some reality because I know that radiation is a really scary thing. When we see radiation in the media, it’s either a superhero, a super villain. It’s very scary. We talk about things like Chernobyl or Fukushima or Three Mile Island. Those are really the things that really hit you in the face when you’re thinking about radiation. And it can be very, very scary thinking about those things.

But I do want to try to instill that radiation is an exposure just like anything else we get exposed to. And radiation can be curative. There are so many uses for radiation down here on the ground that we don’t even realize that we’re using them. And it can also be beautiful. If people know or have seen the Aurora Borealis, so the Aurora Australis, that’s radiation. You are physically seeing radiation. That’s one of the scariest parts of radiation, is you can’t see it. You can’t smell it. You can’t touch it. So it’s this unknown quantity.

So, while I’m not saying that we should all go out and get radiated, that’s definitely not what I’m saying. Radiation, it really deserves to be respected rather than feared, because I think a lot of that fear can really drive reactions from people that are unhealthy. The stress associated with radiation can be very dangerous. So I really want to instill that radiation, it’s a thing. It can be dangerous. It can be curative and that it deserves respect. But hopefully, a little bit less fear.

Host: Robin’s bio and links to related resources are available on our website at APPEL.NASA.gov/podcast along with a show transcript.

If you’d like to hear more about Artemis and what’s happening at NASA, we encourage you to check out other NASA podcasts at nasa.gov/podcasts.

As always, thanks for listening to Small Steps, Giant Leaps.