From Earth orbit to the Moon and Mars, explore the world of human spaceflight with NASA each week on the official podcast of the Johnson Space Center in Houston, Texas. Listen to in-depth conversations with the astronauts, scientists and engineers who make it possible.
On Episode 263, learn how NASA’s Neuroscience Lab is finding ways to help astronauts in reduced levels of gravity on future exploration missions to the Moon and Mars. This episode was recorded on August 19, 2022.
Transcript
Pat Ryan (Host): Houston, we have a podcast! Welcome to the official podcast of the NASA Johnson Space Center, Episode 263, “A Delicate Balance.” I’m Pat Ryan. On this podcast we talk with scientists, engineers, astronauts, and other folks about their part in America’s space exploration program. And today it’s scientists, as we get into the details of what being in space does to your puny human body. The most obvious consequence of your being off of the Earth and in the reduced gravity environment of space is as plain as can be: you float! Now, speaking for myself, and I think most of the rest of us, that would be outstanding, but beyond the gee whiz-ness of you floating, and also past the concerns surrounding, well, how do I work when everything else is floating, too, there is another concern that is both immediate and long-term. And that is, what effects does reduced gravity have on your body, on your health, right now and potentially down the road? Since even before the first American flew in space more than 60 years ago, scientists have been working to answer those questions and to develop countermeasures to those deleterious effects so men and women in space will be able to do work. Today, we’re going to talk about that with two NASA scientists at the forefront of the research into the effort to make space safer for the humans who go there. Dr. Scott Wood is the neuroscience laboratory manager at the Johnson Space Center and the lead scientist in the sensorimotor science discipline. He earned his doctorate in the Department of Otolaryngology at the Baylor College of Medicine in Houston and has participated in flight investigations since joining the neuroscience laboratory in the 1980s. He now serves as a subject matter expert for NASA’s Human Research Program and the Crew Health Countermeasures team. Also with us today is Dr. Mill Reschke, recently retired from the neuroscience laboratories at JSC after a NASA career that began in 1972 – think Apollo astronauts. He earned his doctorate in sensory physiology, psychophysics, and vestibular and audio function, and his NASA work has centered on — well, actually it continues to focus on, because he’s still working even though he retired — he’s focused on changes to the human sensorimotor system during and after exposure to long-duration spaceflight, as well as the development of countermeasures to be used on future such missions, including the ones to Mars. The sensorimotor guidelines for future exploration: here we go.
[Music]
Host: I’m not sure who was the first person to recognize that there was no gravity in space, and that the conditions there weren’t necessarily ideal for human beings whose bodies evolved to live in this “perfect” pull of gravity that we’ve all known all of our lives. But while the United States, and the Soviet Union and Russia, and other nations of the world have been putting people on rockets and sending them out to space, they’ve also been working to understand how the conditions in space affect people and what we can do about that. So I’d like to start by getting into some of the details of those effects. Scott, what effect does the lack of, for lack of a better term, normal gravity, our normal gravity, what is the lack of it, what is the effect that it has on human beings in space?
Scott Wood: So, that’s a great question. It, it really affects a lot of different systems. There is some deconditioning that occurs in the musculoskeletal areas. The cardiovascular system deals with the, the shifting of fluids that, that goes headward. Our, our interest in the neuroscience lab has been really focused on what this means in terms of your body’s ability to orientate yourself, sense motion and control motion. So we have some specialized gravity receptors in our inner ear that detect your, normally detect your orientation relative, relative to gravity, and so when you’re in weightlessness there’s, they’re providing a different signal. So the brain has to recalibrate what information it’s getting from those sensors.
Host: Is it a different signal, or the lack of a signal?
Scott Wood: It’s a, it can be a different signal.
Host: OK.
Scott Wood:You could, you could think of it that way because you’re still moving about, you’re still accelerating; it’s just the cues that you’re getting are different. And especially the way you combine cues from the different sensory systems like vision, and your ability to interact with your support surfaces is completely different. You’re not having to offset the, the weight of your limbs as you reach for things and as you move your legs. So just the way you interact with your environment is completely changed.
Host: Is it, that would have a tremendous impact on, in doing any kind of task, wouldn’t it? Mill.
Mill Reschke: Oh, yeah, yeah. The, the, the, the issue that we struggle with in trying to do this kind of research is removing gravity before they ever fly in, into space. And one of the tools that we have and that we brought back to NASA early was parabolic flight.
Host: Right.
Mill Reschke: And it, that’s the first experience that most people have with removing gravity and having to interact with the, the situation that you are going to occur in, in spaceflight itself.
Host: Well, you’re, we talk, in training astronauts we try to create the conditions that they will encounter, but what you’re saying is that gravity is such a condition that it’s damn near impossible for us to, to remove it, to let people see what that’s like, right? Explain how the parabolic flights mimic that, that condition?
Mill Reschke: Well, most people think that the airplane just dives. It, it doesn’t; it, it does in fact dive rather dramatically and then pulls up and it’s the pull-up, when you reach a gravitational state of, of zero for a period, depending on, on the velocity of the airplane it can last anywhere from 20 to 30 seconds. Do that over and over again for as, as many as 60 parabolas. And it’s, it’s very interesting to watch people that are, are, are experiencing it for the first time.
Host: Now, that’s 20 or, 20 or 30 seconds at a time, but when you do it 60 times that’s not all consecutive, right? There’s, you, you feel gravity again in between them.
Mill Reschke: Yeah. Yeah. That, yeah. Generally, depending on the amount of time that you spend in, in a weightless state on a parabolic flight, is, is related to the amount of gravity that you have to pull. So the higher the gravity during the initial pull-up is going to be, range anywhere from two and a half to, to three g.
Host: Let me back us up a bit here. When did NASA start investigating how weightlessness impacted the sensorimotor functions?
Mill Reschke: I don’t think when NASA began to, to first consider putting people into space that weightlessness was really a big consideration.
Host: Uh hmm.
Mill Reschke: And it only became more of an issue throughout the, the, the later Apollo flights and certainly the, the Skylab missions, the shuttle flights. And then as duration increased in terms of how long they were going to remain in a weightless environment, NASA did realize that we had a problem. And the problem was how do we essentially condition people to fly in a weightless environment for a long period of time? The answer to that is, we really don’t.
Host: Yeah.
Mill Reschke: It’s…
Host: Because we can’t mimic the condition for them long enough?
Mill Reschke: Right. Yeah. You’re, you’re, basically the only kind of tool that you have that allows you to, to do that is parabolic flight. And NASA canceled its parabolic flight program several years ago.
Host: Right. Let’s stay back in the past first. Mill, tell me how you got interested in, and involved in this research in the first place?
Mill Reschke: Well it, it all started in graduate school.
Host: Yeah.
Mill Reschke: I had a very good professor who had in fact done a considerable amount of work at Wright-Patterson Air Force Base. And I became his student and, did work at Wright-Patterson with him. That’s first time I met an astronaut was at Wright-Patterson…Story Musgrave.
Host: When was that?
Mill Reschke: Yeah.
Host: When was that?
Mill Reschke:Oh, gosh. That, I’ve been at NASA for 50 years.
Host: Right.
Mill Reschke: That was way before that. The 19, late 1960s.
Host: 1960s.
Mill Reschke: Yeah.
Host: And how did you get from that situation to coming to work at NASA?
Mill Reschke: It, it was an accident. I, I had graduated and, from Miami University in Oxford, Ohio, and was just looking for a job. I got a teaching position at Franklin Pierce University in New Hampshire. I was never a teacher. And, fortunately, after about a year or less than a year, actually, it was one semester…
Host: Wow.
Mill Reschke:…at Franklin Pierce, I got a call from NASA saying, send us a resume, we, we’d like to maybe give you a job. And that was in 1972.
Host: And what was that first job?
Mill Reschke: First job was really just following people around and, and, and looking. We actually, that, those were the, the Apollo flights, and we were beginning to test people, their balance before flight and after flight, as well as looking at vestibular function in more generalized clinical ways. And basically, that was how I started. The laboratory here that I had when I, when I first began to work was dedicated more to sleep and some other brain functions. The, the primary equipment that was available at that time was a bed, and…
Host: [Laughter] High tech.
Mill Reschke:…yeah; and a soundproof room.
Host: Outstanding. Scott, while we’re on the subject, tell me about your educational background and how you ended up here…in labs that had more than just beds.
Scott Wood: [Laughter] That’s right. I came at the beginning of the shuttle program, or early in the shuttle program, when motion sickness was starting to become more of a concern with these shorter flights. And so I joined Mill — actually I worked for Mill, and he mentored me in my early career, between undergraduate and graduate school. So I just really fell in love with the subject matter, and I wanted to do more. And so I, I pursued a, my doctorate degree at Baylor College of Medicine so I could remain affiliated with the lab. I, I’ve departed on occasion: I, I went and worked for a little bit at a, a nonprofit hospital in Portland, Oregon in, in the same field in look, looking at vestibular disorders; I worked with the Navy in Pensacola, Florida, where some of this early space research was done, so I got to be part of some of the work they were doing in military aviation world; did a stint in academia but I, I keep coming back to the lab here.
Host: There’s an attraction.
Scott Wood: There is an attraction, and it’s just a very fascinating area.
Host: We were starting to touch on the beginnings of the, of this research. Take us back to that point. Tell me, how did, how were some of the first ways in which NASA began to study how astronauts were affected by the lack of gravity?
Mill Reschke: Well, that’s, that’s a hard question. I think that, that what was observed was that as the flights became longer and longer, it was apparent that returning back to Earth was not simply a process of walking out of the spacecraft and continuing to go about your daily business. It, we were seeing difficulty in walking, difficulty in situations where vision wasn’t available to the, the returning astronauts.
Host: Where vision wasn’t available?
Mill Reschke: Yeah. Well, when you get into a darkness…
Host: Oh, OK.
Mill Reschke:…or a situation like that, you rely in those kinds of conditions on your vestibular system in many, in, in many cases.
Host: To understand which way is up.
Mill Reschke: Yeah.
Host: Among others.
Mill Reschke: Which way is up, which way am I turning, you know, why do I feel dizzy when I turn my head to the right or left or look up or look down? I’m losing my balance, what do I do?
Host: And at that time, we’re starting to see more astronauts who are experiencing more difficulty than prior astronauts had.
Mill Reschke: Yeah. It’s a, it’s a, a matter of how long you spend in a weightless state in terms of the duration that you’re going to see in, in terms of vestibular function returning to a normal Earth environment.
Host: What’s the thought about why that is? I, I, not having done any of this research, of course, myself, I can see how not having the cues of gravity would impact you, but I, apparently it continues the longer you don’t have that, that, that effect, that impact. Do we know why that is? Does your body forget, or, or, or what is it?
Mill Reschke: I don’t know if the body forgets it, but bodies ask to, to re-acclimate to the environment where it’s a normal gravity.
Host: I, I’ve heard astronauts who’ve been in space say that once they get there and they become acclimated to the lack of gravity, that they function perfectly fine; but when they return to Earth they, you know, their, their body then encounters it again. Both of those things sound to me like the body’s doing a terrific job of adapting to the circumstance it finds itself in.
Scott Wood: And that’s the point that, you know, there’s, there’s a, the most profound effects from some of these adaptation occurs very early. That’s when people experience motion sickness. But as you point out, after a few days to weeks, that effect is lessened and people adapt to that new environment. There is some period of time that there’s a slower adjustment just to being able to be more proficient with the way you move and things like that. You can tell a difference between crew members that have been in space for a few months, for example, versus a rookie crew member that just arrived, and they can tell a difference that, they’ll describe that sensation that they’re, they’re realizing that they’re able to move more efficiently. But yeah, yeah, I think that you’re right, the body’s doing a wonderful job adapting, but all that adaptation for moving efficiently in microgravity is not necessarily helping you when you have to, when you re-enter a partial or, or a full gravity, Earth’s gravity, because the brain…
Host:Or a different gravity environment.
Scott Wood:…the brain — that’s correct — the brain has to, again, reset, recalibrate what information it’s getting from those sensory systems. And it’s an integration of all the different sensory information that you have.
Host: And, and you both have, have touched on this, the, the point is that the brain is using the, the, in, it’s, what it understands about the environment that you’re in to allow you to function, and it is, it, it is smart enough to be able to know things are different so I have to act differently. Is that, is that an awful way to explain it?
Scott Wood: No, I, I think that’s a really good way. So actually, part of what we also observe is that process of adaptation is dependent on how you move when you get into that environment. So there are certain things when you’re reintroduced to Earth’s gravity that you probably want to avoid doing, like making large head movements relative to gravity; that can be pretty provocative. And you discover that pretty quickly. And so, there’s some…
Host: “Provocative” meaning?
Scott Wood: Evoking motion sickness.
Host: Yeah. OK.
Scott Wood: Leading to vomiting. Yeah. Yes. Yeah. So there are certain movements that people will try to avoid when they’re going through that early parts of the adaptation. And so part of what we’re researching is really looking at how we can help crew members go through this period, be more efficient in terms of incrementally exposing themself and adapting to that new environment, because there are smart and not-so-smart ways to reintroduce yourself to this gravity environment and, and hasten that adaptation.
Host: Well, let’s, let’s expound on that for a minute. What, what ways did we, years ago, try to allow people to re, re-adapt, that we found that worked and that didn’t work?
Mill Reschke: Well, I think in terms of the re-adaptation, exercise programs have always been one of the primary tools. That’s not necessarily in our field, but it does, it does force people to move, and the more you move the quicker you’re going to be adapted to that environment.
Host: Are you thinking about exercise while still in space or after you’ve returned?
Mill Reschke: Primarily after you return.
Host: OK.
Mill Reschke: Exercise in space can actually be detrimental to the vestibular system that you’re, that you’re going to experience the movement. It’s beneficial in helping you to adapt to that environment just like it is when you return to, to Earth.
Host: And I guess the exercise is good in, in, in allowing your muscles to keep working in that environment, but you’re saying it, it’s not helping your sensorimotor system?
Mill Reschke: No, no. As a matter of fact, the vestibular system has a profound effect on the, on the sensory, or the, or the postural muscles, the, the muscles particularly in the lower part of your leg.
Host: Yeah. Tell me how, how so?
Mill Reschke: Well, it’s a direct connection from the vestibular down to those muscles through the brain stem. And if the vestibular system is, is not functioning the way you would like for it to function in a particular environment, it will definitely have an impact on the way those muscles respond when you try to move. Most people don’t, it’s, it’s very difficult to, to explain to people what the vestibular system does, but…
Host: Give it, give it a shot.
Mill Reschke:…because there’s very few examples for…sitting here around the table or moving anywhere, you don’t know about the vestibular system; it’s very silent, it works very, very silently. Only when something goes wrong with it are you aware that there’s something that is happening that is not beneficial for me.
Host: When you become ill in some way?
Mill Reschke: Yeah. When there’s some…
Host: And you, you lose your balance.
Mill Reschke:… trauma or disease that affects the vestibular system. I, most people don’t even realize that they have this system. It works very well. I usually use an example of people seeing the vestibular system in action is, I have them hold their hand out in front of their face by about a foot or so, and to, to shake their head back and forth at about one, one cycle per second, and look at the lines in the palm of your hand. Now that, that activates the semicircular canals, the, the part of the vestibular system that essentially responds to angular acceleration.
Host: OK.
Mill Reschke: But after you’ve done that, then shake your hand back and forth, and the palm of your hand is blurry. And that’s because the vestibular system is making the eyes move and remain stabilized in, in, in space.
Host: OK.
Mill Reschke: So that’s a way to learn something about the vestibular system, because it’s very quiet and like I say, you don’t know that anything, you have a vestibular system for most people until there’s a disease process or some other thing has caused the vestibular system to not function properly.
Host: Can you describe where in us the, the organs of the vestibular system are and give, which, what I think will give me a sense of how they would be impacted by the lack of gravity? We’ve started in the ear, right?
Mill Reschke: That’s, you have, the ear has two major, well, three major organs: the auditory function and the vestibular, and the vestibular system is comprised of, of a, for simplicity’s sake…
Host: Please.
Mill Reschke:…a system that responds to angular acceleration and a system that responds to linear.
Host: Forward or side to side.
Mill Reschke: Right.
Host: OK.
Mill Reschke: Or up and down.
Host: All right.
Mill Reschke: Yeah.
Host: So knowing — I, I’m trying to think of an example…anybody who’s ridden a roller coaster, I, I’m thinking, probably has some experience of how their relationship to their environment changes based on the fact that their body is in a different situation. Is that, is that a good start, Scott?
Scott Wood: Yeah. And our, our inner ear function, our vestibular function, is adapted to kind of normal movements. So as you point out, when you get in something maybe a little different than you’re normally used to experiencing, like a rollercoaster, or some of us have played this game where you spin around in circles with your head on a baseball bat and then you try to run a straight line or something like that; that’s not the way we normally move so, and, and the vestibular system provides some signals that make that challenging, that test challenging. I want to get back to something that Mill did say, though, about exercise because we have seen that some of the advanced exercise programs that we have on ISS do help you in the process of recovering, so that maintaining that muscle conditioning and, and there’s some conditioning in terms of the sense, sense of joint position and things like that, can, can be helped by that in-flight exercise. Our challenge now as we move to exploration, we won’t have this space that we have on ISS for this wonderful gym with advanced aerobic and resistive exercises. We need to be able to downsize that, and that’s, that’s I think going to be a very big challenge for us: how can we maintain that conditioning on these long-duration spaceflights?
Host: Right. The International Space Station has a, a whole module that has, is filled with some pretty remarkable exercise equipment, that you don’t have room for inside an Orion capsule…
Scott Wood: That is correct.
Host:…or, but I guess we could plan to build it on lunar outposts, that we would have more stuff that we could put into bigger, bigger rooms.
Scott Wood: Yeah. This is a challenge for us. How, how, how much do we really need? You know, what, what are the critical components? How can we make it more efficient? And for us also then, once you arrive, what, what can you do to assess the individual in terms of helping make sure that they are in a good condition to go do the task that we have [asked] them to do? One of the things that we haven’t touched on is that there’s a wide variability in responses among crew members, just like there are in those of us that ride those rollercoasters: some of us enjoy them, and some of us not so much. So, we have folks that are more impacted than others in terms of what motion sickness symptoms they experience, or how long it takes them to recover. And so that’s part of our challenge, too, is how can we provide the tools, just to be smart about making decisions about when people are ready to perform different tasks? How can we structure tasks so that people are set up for success? What aids can we provide that enable that successful performance?
Host: And you’re talking about performing those tasks while still in the space environment?
Scott Wood: Or in a partial g environment; for example, landing the vehicle or getting out of the vehicle, or doing some of the early EVA (extravehicular activity) tasks.
Host: And your point a moment ago is really that not all astronauts are created equal: given the same set of circumstances, one astronaut may respond in, to one degree and it’s, another astronaut in the same circumstances would respond differently. Better or worse, but it’s variable, it’s not all the same for everybody if, if you’ve been gone for five days or five months. Is that right?
Scott Wood: That is correct.
Host: You were about to say something, weren’t you?
Mill Reschke: No. No, no, Scott covered that really well.
Host: The, do you find that there’s a, a relationship between how long an astronaut is in this environment and how much of an effect it has? Or to use your example of no, all astronauts not being created equal, that it, it’s a function of the individual rather than the amount of time?
Scott Wood: There’s definitely effect of duration, as Mill was pointing out. We know, you know, if you think about the Apollo mission, for example, that we had four-and-a-half-day transit to that lunar surface, so that wasn’t a very long time in which they adapted to that microgravity environment, so that was analogous to some of our early shuttle flights But the shuttle flights went up to 18 days in duration. And as the shuttle flights became longer, and as we had other long-duration experience with Skylab, and on, of course, now on ISS, we have definitely seen a difference. We have some plans within the Human Research Program to actually look at these responses over longer periods of time, like with one-year missions.
Host: Right.
Scott Wood: So this is really critical for us to understand that effect of duration, because it’s going to be a longer transit to get to a Mars surface. And so one of the Design Reference Missions we’re looking at for Artemis is keeping people on the Gateway for a period of time so that we can mimic some of those longer transit times before they come to the lunar surface, and we could evaluate what we need to do to protect crew health during those longer transits. So that’s a really important part of the program looking towards Mars and preparing that Mars architecture for success.
Host: And, and I’m, I’m, you correct me if I’m wrong, but this touches on the, the research in a white paper that you guys shared with us about the studies that you’re doing, not only of how astronauts are affected in the space environment, but how they’re affected in a partial gravity and then a full gravity environment again, because we are sending them on a mission where they may encounter all of those different variables but we still want them to do work at all the different stages, and we need to be able to know how to help them still be in a condition to do that work. Is that, is that a summary of it?
Scott Wood: Yeah; there are, knowing what challenges crew members are, are going to have, and we’ve been studying that and we continue to study that, there are a number of things that we can do to help them in that state. We can be smart about how we’re planning these EVAs so we can put things that are maybe more challenging a little bit later and try some of the more simple EVAs up front. We, we could give them tools that help assess their ability to do the task, give them tools that help them be able to enhance their recovery. And of course, as we look towards exploration, we have a lot of people helping returning crews right now when they come back from ISS, there’s a lot of resources that we can bring to bear to, to even help them in the recovery process coming out of the capsule and so forth.
Host: Right, right.
Scott Wood: But we need to think more autonomously as we think about going back to the Moon and on, and on to Mars. We have to come up with self-administered tools that they can do and, and, and help enhance that recovery.
Host: The ways they can take care of themselves and each other…
Scott Wood: That’s correct.
Host:…because they’re going places where there aren’t rescue, recovery crews to help them.
Scott Wood: That’s right.
Host: Give me a, a, a summary of, of how your research is, is, is pointing? What, what are you finding about how people are impacted, and, and how, I guess — I don’t know the right way to ask this question — of, of what we can do to, to help make sure that they are in a condition to, to take care of themselves and to, to do their work at those various stages of a mission?
Scott Wood: I would like to say, just to, to, to introduce…
Host: I am sorry, I mean to look at that; go ahead.
Scott Wood:…just to introduce your, to address that question. I think Dr. Reschke has actually led one of the real pivotal, pivotal, pivotal science experiments that addresses this, the decrements that people have in that recovery process. So he, he pioneered a study that was a collaboration with our colleagues from Russia, and we were going out to the landing places in Kazakhstan and partnering with their medical professionals.
Host: Right.
Scott Wood: They were a great asset, and of course, the crew to support these experiments and participate in them. So while they’re just moments after being extracted from the castle and — the capsule and carried to the, the tent, Dr. Reschke was…
Host: In the tent.
Scott Wood:…not in the tent himself, but he was, he was behind the studies that we were doing early post-missions. So this is, this was really critical for us to get a good characterization of what those decrements were and, and what we needed to be mindful of as we kind of go forward for exploration. So, having said that, I’ll, I’ll turn it over to Dr. Reschke. [Laughter]
Host: Thank you.
Mill Reschke: Well, I’m not sure where to go from that, but what we were doing in terms of testing crew members returning, as, as soon as they, they could be taken from the space capsule, was to, to make the testing that we were going to do, essentially, unavailable to anyone to watch. So the, the Russians were very helpful in that…
Host: Hence, the tent.
Mill Reschke:…providing the tent. The tent. We, we, we owned the tent, and that meant that even the Russian generals weren’t going to come in there and watch. And we did simple, very simple testing. Can you sit, stand up from a seated position? And what happens when you do that? Can you walk heel-to-toe, for example? Can you get up from the ground after you’ve lain in that position for several minutes? And what does it take to stand up? Very simple things like that, turning a corner. Walk and turn a corner.
Host: They do sound very simple.
Mill Reschke: They, they are very, very simple and very, very challenging.
Host: They are?
Mill Reschke: Yep. Very challenging. It, it’s, it’s interesting to watch the progression of the recovery, which we were able to do, particularly since we were, we began testing in the field immediately after landing. And then with the, on the U.S. side, testing again during the refli, during the, the period of time when the plane was returning and being refueled in Europe.
Host: Bringing astronauts from Kazakhstan all the way back to Houston…
Mill Reschke: Right.
Host:…during that period.
Mill Reschke: So we tested again a few hours later in Europe, and then we tested again when they returned to the U.S. And that was generally just a little under 24 hours…
Host: Right.
Mill Reschke:…that the last test was done. And then we tested every day as much as we could over a period of time until recovery was, looked like it was fairly complete.
Host: Is it a kind of a template of how people recover in that way, or is it, again, your mileage may vary depending on your astronaut?
Mill Reschke: Well, it depended on the crew, specific crew member, in terms of how fast they could recover. I think that the, what we’ve seen over the years is that the longer you’re in, in space, the longer the recovery time is going to be.
Host: OK.
Mill Reschke: Apollo astronauts recovered very quickly, typically, and the shuttle astronauts recovered almost like the Apollo astronauts, within a, a day or two they, most of them were, were functional. But then when we transitioned into the space station and longer and longer durations, what you see typically is a period of time of six months is a break point.
Host: Meaning?
Mill Reschke: Meaning that…
Host: Six months until they’re functioning normally?
Mill Reschke: No. Meaning that if you’ve been in space for six months, you are probably going to be, become having more difficulty…
Host: I see.
Mill Reschke:…vestibular sensorimotor point of view. And those periods lasting a year take the longest time to recover.
Host: Almost a direct relationship?
Scott Wood: But the recovery depends on what you’re asking them to do. So if it’s the simple task like standing up, that is a fairly quick recovery. If you have a more involved task that involves some going around obstacles and turning corners, we, we like to do the tandem walk, you know, you could think of the by-the-roadside drunk test.
Host: OK.
Scott Wood: Hopefully you’ve never experienced this.
Host: I’ve seen it on television.
Scott Wood: Yes, of course. But, you know, something challenging like that, and especially if we have them close their eyes, as Mill was mentioning earlier, with, with your eyes closed you have more reliance on the inner ear to help you with your orientation. So if we put people in those conditions the performance takes a little longer to recover on those tasks. So, and that informs us in terms of when we think about tasks that we’re going to ask crew members to do during EVA, early EVAs, we, we need to be strategic about what aids we give them, to help them do their task, as we watch, and, and observe their recovery and to the, to the new environment.
Mill Reschke: You know, the EVAs, that’s an interesting point. EVAs are typically not permitted until three days in a weightless environment, primarily because of the potential of vomiting.
Host: Right.
Mill Reschke: And if you’re in a spacesuit and vomit, there is a fairly large chance that you’re going to aspirate some of the vomitus and die.
Host: Yeah. Yeah, clearly not a, a condition that you want to, you want to do everything to prevent.
Mill Reschke: Yeah. That’s probably more than I should have said, but it’s, it’s…
Host: Well…let me ask you this.
Mill Reschke: There are limitations.
Host: Yeah. As you were describing it, and it seemed like a direct relationship between the longer you had been in space, the longer it took for you to, to recover. It occurred to me to ask if, if you’re going from a microgravity environment – say, in transit to Mars — and then you’re in a partial gravity environment on Mars, do you recover enough to work in that environment as opposed to rec, needing to recover to work in one gravity environment of Earth? Does, does that, does that direct relationship between the level of gravity also translate into the time it takes to recover your ability to do what you want to do?
Mill Reschke: We don’t know. The only, only model we have is, you know, the time spent on the lunar surface.
Host: Right.
Mill Reschke: And those were very brief stints. We’ve never had the chance to look at anybody returning after they’ve spent a great deal of time in a partial gravity.
Host: Yeah. Never more than a couple of weeks. Less than that.
Mill Reschke: Potentially the effect will be less dramatic in terms of return after you’ve spent a lot of time on, like, Mars, surface of Mars, or even the Moon, but we don’t know what it would look like in terms of recovery curves.
Host: What have we learned to do to help astronauts counteract the effects of reduced gravity so far?
Scott Wood: So I think there are a number of things that we look at doing in terms of, we, we alluded to this earlier, just procedures. We, we know that we can address what is asked of crew during these critical times of early adaptation, reduce some of the activities, simplify some of what crews are being asked to do. There are a number of engineering-type solutions in terms of handholds, mobility aids and things like that, that we can look at doing to make the risk of impairment less to help them be able to do their tasks. Certainly we’re, we’re doing some work with the ability of crews to take over an automated landing, for example, and, and do that successfully in terms of providing the right training, the right displays, all of those things. Certainly there’s different procedural things, you know, we can do in, in terms of having the, the, the task workload among crew members and being able to help each other and, and, and manage some of that.
Host: That was a, I think a real good example, too. You’re talking about astronauts piloting a, a spacecraft to land, on the Moon or, or wherever. This could be a task that that befalls to somebody who’s been impacted by being in a microgravity environment for months, and we know from the research that we’ve talked about here that their abilities to function may be reduced to some level from what they were before they started, and now they’re asked to do a really difficult and delicate task. And we have to find some way to make sure that they’re capable.
Mill Reschke: Well, you know, in, through, throughout the course of NASA putting people into space and, and landing, we typically always had the capability of an automated landing. It’s been rarely ever used. An astronaut is an astronaut; they, they’re going to want to, to fly the vehicle.
Host: They, they have no problem with grabbing the stick.
Mill Reschke: Right. And so it’s, it’s, I suspect that in the future, nothing is going to change that, that…
Scott Wood: But these landings were successful largely because of how we trained the crews, and we trained them very well. We trained them with a variety of different platforms: they had fixed base simulators, they had in-flight trainers — we had that for both Apollo and for shuttle. As the duration started becoming longer for shuttle, the crews were also using some onboard trainers…
Host: Right, right.
Scott Wood:…kind of maintain proficiency. So the, the key is to have that training level up so that if you do have that disruption, you’re more prone to, for example, having disorientation or just some challenges with that cognitive workload as you’re going through that adaptation, you, you’ll be able to handle that task.
Host: The fact is we’re aware of what the human astronauts’ conditions might be, and so, we’ve built the mission to, to be able to, to help them.
Scott Wood: That’s right. You know, just simple things like making sure the displays are situated so they don’t have to move their head a lot. You know, having a, having a handheld, handhold right below a display that they have to interact with, so they’re not having to reach out and touch without, they have a way to stabilize their hands, so what we know from the deconditioning we can begin to start look, talking to our providers…
Host: Folded back into the design of…
Mill Reschke:…exactly, and, you know, how can we design things to maximize success? How do we, what, what skillsets do we need to train crews to, what, what resources do we need to be able to stand up, so that folks are adequately trained and, and confident in what they’re doing?
Host: Those kind of things happening in designing Artemis missions now?
Mill Reschke: They are, they are. We are actually working with our flight operations team and within the research team to try to be very synergistic in terms of raising up some motion simulator platforms that we could look at some of these countermeasures, like training countermeasures, and things like that. So there’s, there’s a lot of exciting work to be done as we approach these missions, especially as we think about these missions with the longer transits before they do land on the Moon, so.
Host: So are there features being worked for, for these future spaceships that are going to go to Mars, or the, the habitats or the spacesuits that the astronauts would wear, that would help them in these different environments on the Moon and on Mars?
Scott Wood: Yes to all of the above. [Laughter]
Host: Yeah. OK.
Scott Wood: We have, yeah.
Host: OK.
Scott Wood: Yes. We have quite a bit of work in a variety of different platforms. We have people researching and looking at the operational impacts of those areas. So for the training aspects, for example, for what you need to be able to do to land a vehicle on the, the lunar surface, there are folks that are looking very critically at what are those skills that we need to have training address and what types of platforms we need. And so, even before the providers are ready to, to do that, people at NASA are looking at what, you know, raising up those capabilities so that we can provide some generic training that would be helpful no matter what provider is, is coming up with the vehicle or what they’re asking the crews to do, but then also having a, a platform that then the commercial providers can also take advantage of to provide the more mission-specific training that, that we need the crews to have for their vehicle.
Host: And it’s not just NASA astronauts that will feel the effects of the environment, the private astronauts would too. And they’re also…
Scott Wood: And we all have different providers, so we’ll need to have a platform that, that different providers can be able to leverage to, to provide that training.
Host: What’s next for neuroscientists at NASA? What other areas related to this are you guys working on or think ought to be worked on?
Mill Reschke: Well, there, there are several that will probably never happen.
Host: Oh.
Mill Reschke: Artificial gravity in flight…
Host: Right.
Mill Reschke:…I think would be probably one of the biggest steps we could take. Making that happen is probably going to be very, very difficult. In the past there have been several designs; none of it seems to be ever going to be implemented, however.
Host: Because it’s not feasible or it’s not…
Mill Reschke: No, it’s, it’s feasible.
Host:…it’s too expensive or…
Mill Reschke: It’s feasible; it’s probably very expensive.
Host: OK.
Mill Reschke: But maintaining a relationship to a gravitational field other than total microgravity is one of, probably one of the best things we could do. Depends on the kind of ship you have, you know, what we’re talking about now in terms of the vehicles in, in design and in use, there’s no way to really provide any kind of artificial gravity in flight.
Host: Did it involve rotation of the vehicle?
Mill Reschke: It involves rotation of the vehicle, and it has several problems that sort of trickle down through all the other sciences. If you provide rotation of the entire spacecraft, you’re going to upset a lot of people…people that have experiments that are, require an almost total vibration-free environment.
Host: Right, right.
Mill Reschke: It’s going to vibrate. There’s, there’s no doubt about it. And having a vibrating or non-vibrating environment requires a vehicle that can maybe separate, and, where you can have a daily dose of, of artificial gravity. There are other problems associated with artificial gravity, and that is the vestibular system doesn’t really appreciate being exposed to cross-coupled angular accelerations.
Host: Cross what kind?
Mill Reschke: Cross-coupled.
Host: Cross-coupled angular accelerations. OK.
Mill Reschke: Yeah. So making the environment such that you can minimize that is going to require less movement on the part of the person. Hopefully, you’ll be able to walk and run. Skylab…
Host: Right.
Mill Reschke:…was…
Host: Thinking of the same thing.
Mill Reschke:… a good example. The upper deck was fairly empty. It had water containers around the, the, the vehicle and crew members had started running on those water containers. Big circle. Yeah, they did very well. Yeah. So it’s, it’s certainly feasible.
Host: But it’s, it’s all very interesting to think about when you, when you get people who are smart enough to know the actual details of the things that have to be considered in order to make the whole thing work; it’s just, just fascinating.
Mill Reschke: Yeah. It, it all, all sort of filters down.
Host: Mill Reschke and Scott Wood, I appreciate your taking the time to talk about this. I, I love it; it was great.
Scott Wood: Thank you very much for having us.
Mill Reschke: Thank you.
[Music]
Host: Before the first people ever left this planet on top of a rocket, the scientific concerns about how the space environment might impact those people were very broad ones. Like, will they be able to breathe, or swallow? Will they be able to do any work? Could they survive the radiation? Well, over the years, scientists have learned so much about how the lack of gravity and the other characteristics of the space environment impact the operation of this human machine, and about how the body and mind react to the changing conditions in the short term while filing away data on the experience to be ready to respond when the circumstances return. The work of those researchers, men and women like Scott Wood and Mill Reschke, will be crucial to our eventual success in putting people on the Moon and Mars for longer periods of time to explore those new horizons. I want to remind you that you can go online to keep up with all things NASA at NASA.gov. In fact, you can get all the NASA news you want delivered to you every week: just go to NASA.gov/subscribe to sign up for the NASA newsletter. You can find the full category of all our podcast episodes by going to NASA.gov/podcasts and scrolling to our name. You can find all the other NASA podcasts right there at the same spot where you can find us NASA.gov/podcasts. Very convenient. This episode was recorded on August 19, 2022. Thanks to Will Flato, Gary Jordan, Heidi Lavelle, Belinda Pulido, and Jaden Jennings for their help with the production, and Scott Wood and Mill Reschke for helping us understand the issue and what’s being done to address it. We’ll be back next week.