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Tap into the experiences of NASA’s technical workforce as they develop missions to explore distant worlds—from the Moon to Mars, from Titan to Psyche. Learn how they advance technology to make aviation on Earth faster, quieter and more fuel efficient. Each biweekly episode celebrates program and project managers, engineers, scientists and thought leaders working on multiple fronts to advance aeronautics and space exploration in a bold new era of discovery. New episodes are released bi-weekly on Wednesdays. 

NASA Human Research Program Director Bill Paloski discusses methods and technologies to support safe, productive human space travel to the Moon and Mars.

The Human Research Program’s scientists work to predict, assess and solve the problems humans encounter in space. Paloski offers fascinating insight into solutions that address health and performance issues that could occur during human missions to distant destinations.

In this episode of Small Steps, Giant Leaps, you’ll learn about:

  • How NASA plans to address medical issues on extended missions
  • The application of artificial intelligence and 3-D printing during future missions
  • Opportunities to participate in human exploration research


Related Resources

Human Research Program

NASA Solicitation and Proposal Integrated Review and Evaluation System (NSPIRES)

One-Year Mission: Astronaut Scott Kelly and Cosmonaut Mikhail Kornienko

Artemis Program

Lunar Gateway

APPEL Courses:

Risk Management I (APPEL-RM I)

Risk Management II (APPEL-RM II)

Communicating Technical Issues (APPEL-CTI)

Space Mission Operations (APPEL-SMO)


Bill Paloski Credit: NASA

Bill Paloski
Credit: NASA

Bill Paloski is the Director of NASA’s Human Research Program (HRP), a biomedical research and technology development program within the Human Exploration and Operations Mission Directorate. HRP focuses on mitigating the highest risks to human health and performance expected during exploration spaceflight missions beyond low-Earth orbit. Paloski was previously a Professor of Health and Human Performance at the University of Houston (UH), where he was Founding Director of the UH Center for Neuromotor and Biomechanics Research. Prior to that, he was a researcher in the Neurosciences Laboratory at NASA’s Johnson Space Center for 23 years and conducted multiple experiments flown aboard the Space Shuttle, the Russian Mir Station, and the International Space Station. Paloski holds a bachelor’s in mechanical engineering from Clarkson University and a master’s and doctorate in biomedical engineering from Rensselaer Polytechnic Institute.


Bill Paloski: We are now in a phase looking at some really unprecedented missions.

I think that the challenges are going to start to mount as we go away from low-Earth orbit and into the vicinity of the Moon.

We bring in the smartest minds that we can in particular areas to work on these problems.

Deana Nunley (Host): You’re listening to Small Steps, Giant Leaps – a NASA APPEL Knowledge Services podcast featuring interviews and stories, tapping into project experiences in order to unravel lessons learned, identify best practices and discover novel ideas.

I’m Deana Nunley.

As NASA readies for a return to the Moon and traveling on to Mars, the agency’s Human Research Program is doing crucial work to ensure that astronauts are able to perform at high levels under the most demanding conditions yet for human space explorers. Human Research Program Director Bill Paloski joins us to discuss the ongoing work to address complex challenges of extended space exploration.

Bill, thank you for being our guest on the podcast.

Paloski: Oh, thank you for having me. I’m really happy to be able to provide this information to the workforce here at NASA.

Host: Could you give us a brief overview of NASA’s Human Research Program?

Paloski: Sure. We’re kind of one of those hidden programs, you know, with the huge workforce that we have and being part of the Human Exploration and Operations Mission Directorate, where most people are engineers and rocket scientists. We’re a small cadre of life scientists who are trying to understand how to make sure that crew members that go to destinations as distant as the Mars system can get there and back and work well along the way. So, we work on all the health and performance issues that might come up during a mission like that, try to do the background research that’s necessary to understand the problems that they might have. We do a lot of simulations and analogs, both on Earth and in space, to try and simulate the conditions that they might experience. And then we try to develop countermeasures or approaches to offsetting any of the untoward effects that they might experience during such a mission.

Host: As you look at how space affects the human body, what are the primary challenges and solutions the Human Research Program is focused on for future missions?

Paloski: So, we like to look at a series of what we think of as hazards in the NASA parlance; it might be better to think of them as stressors. We use a mnemonic, which is called “RIDGE,” to describe those things.

The “R” in RIDGE stands for radiation, which is present even on Earth’s surface. It gets a little bit more challenging in low-Earth orbit. It gets much more challenging when you get beyond the Van Allen Belts. The “I” stands for isolation and confinement, which really refers to the need for having a very small, cramped compartment for crew members to be in. As we go on Mars missions, it won’t be anything like the spacious environment that we have on the space station. The “D” stands for distance from Earth, which has a number of effects. When you’re far from Earth, the communications are slowed, so it means that operations need to be much more autonomous. And also, when you’re far from Earth, then the possibility of returning to Earth in a hurry if there’s some medical event that occurs is obviated. The “G” stands for gravity which, in most places, is low gravity, very low gravity of space, but also, there’s the high gravitoinertial force that crew members experience during launch and landing. And then when we get back to the lunar surface, there’s 1/6 G, which is a lot different from Earth G, and when we go to Mars, it’ll be 3/8 G. And so, a long time, 18 months in 3/8 G is another sort of a challenge that we have to overcome. And then the “E”, the final letter in RIDGE is for the environment. We live in a hostile, closed environment. We bring all of our air, water, food with us. We can’t control a lot of the environmental effects of radiation other than by using special shielding and fallout shelters, so to speak, that crew members can go to in terms of if there is, in the case of a solar particle event. And then there’s the unexpected changes in the environment, which is closed if the microbiome in the environment begins to change or begins to multiply. We’re just starting to learn about the effects of microbiomes in the built environment and the effect of all the bugs that live around us, in us, on us, and around us, and what they might do to the health and performance of crew members.

So, those are the primary stressors that we’re working on, and within those stressors, we have specific risks that we work on trying to understand.

Host: Gravity fields and space radiation are a couple of the significant risks that get a lot of attention. What’s the latest on NASA’s plans to mitigate these risks?

Paloski: So, gravity, we’ve been doing—we’ve been doing altered gravity for more than 50 years. We have a pretty good understanding of the effects of gravity on the human body, at least out through six months’ duration. We have a little bit of experience going beyond six months’ duration. And we have very good techniques for mitigating those effects. They primarily affect the bone, muscle, cardiovascular and neurologic systems. And, by using exercise, we’ve been able to mitigate most of those effects—not for the neurological systems, but for the bone, muscle and cardiovascular systems, having good exercise devices and a good exercise regimen coupled with good dietary measures seems to be pretty effective.

There is one issue that we’re really concerned about that seems to have begun to pop up since we’ve had longer—more crews in longer duration missions. And that is one that has to do with fluid shifts towards the head, because gravity’s not pulling the fluids in the body down to the feet like it does for 16 hours a day for most of us on the ground. And that seems to be resulting in some changes in vision. We call it the Space Associated Neuro-ocular Syndrome. And we’re trying to develop a good model for that on the ground right now so we can understand the mechanisms and how to counteract that. And that probably is just related to a long time in zero G or low G with no gravity pulling the fluids out of the head, so a consistent amount of fluid in the head that tends to perhaps increase the intracranial pressure and change the way that the visual system is working.

With respect to radiation, I think that radiation has been, for a long time, the big boogeyman out there, and I think that we’ve done quite a bit of work over the last 20 years. We have a partnership with the Department of Energy, and we’ve established at the Brookhaven National Laboratory something called the NASA Space Radiation Laboratory where we can create a radiation environment that mimics what we know to be the radiation environment of deep space, a series of galactic cosmic rays and protons that crew members will be exposed to. And then we can expose experimental models to that, mostly rats and mice that we expose to it, to try and understand the effects on organisms.

What we’ve learned is that there’s a probability that crew members on very long missions will end up having an increased likelihood of developing cancers. It’s a little bit higher than we would like. Our goal is to keep it at 3 percent risk of exposure induced death—that’s that 3 percent increase in the likelihood over what their terrestrial likelihood would be.

It turns out that the way we’re doing shielding, and we’re beginning to look at countermeasures similar to what people use on the ground for radiation exposure are beginning to limit the uncertainties, and I think we’re going to be able to get that number down below what’s an acceptable level within the next few years.

We’re also looking at the advances in terrestrial medical care. So, if a crew member were to be overexposed and to be at higher risk of developing cancer that was induced by that exposure, we’ll begin to track, right after they return to Earth, any markers. It would take probably 10 to 20 years to develop such a cancer, so it’s very slow growing, and we can track those markers. And with the advances in terrestrial chemistry, it seems like in the time frame we’re talking about, we could probably largely mitigate all of the effects of that excessive radiation exposure for cancer.

There are a couple of other possibilities that the radiation exposure might bring, and one of them is on the cardiovascular system. We know that women who have been exposed or who have taken the advice of their physicians and had regular mammograms, over a number of years, a number of decades, tend to have some changes in the cardiovascular system that’s probably related to that exposure to those x-rays, and we’re trying to understand that and whether galactic cosmic rays would result in similar kinds of issues during the same time frame.

And then finally, there’s the potential for changes in the central nervous system in the brain, owing to similar effects of the exposure to radiation. We’re looking at that again in experimental models and what impacts both of those things might have. Right now, those risks are not considered the most serious risks, because it doesn’t seem like the likelihood is as high. The consequences are still fairly high, but the likelihood is fairly low at this point. But we continue to look into them and try to understand what sorts of appropriate counter measures, most likely pharmaceuticals or nutraceuticals would be used to reduce any of these kinds of effects associated with radiation exposure.

Host: With NASA shifting into high gear in preparation for human landings on the Moon and Mars, are you coming across risks and considerations that haven’t been thought about before?

Paloski: I wouldn’t say that there are any new risks that are popping up out there. We’re looking at some things that might help to fine tune some of what we already know. So, for instance, when we go to the lunar surface, at least early on, we’ll be doing a lot of extravehicular activities, EVAs or spacewalks, or moonwalks, they really will be. And with the small volume that we’re looking at, trying to take time and do pre-breathe to reduce the amount of nitrogen in the bloodstream doesn’t make a lot of sense.

And so, having an atmosphere within the cabin that might have a little bit higher oxygen concentration and a little lower barometric pressure would make a lot of sense so crew members could already be, have gone through their pre-breathe work before they get to the surface, and then they can walk out and come back in and walk out and come back in.

And we don’t know exactly the effects of the atmospheres that they’re talking about. We suspect that they’re all going to be safe, but we have to do some ground-based studies to understand that. More likely, we’ll be using these as opportunities for us to learn more about what will happen on the Mars surface. So, looking at crew members landing on the lunar surface and then doing EVAs—the early ones will be short, but we’re expecting that there might be some habitats that grow up later on, and we’ll look at the effects of long term exposure to 1/6 G and whether there is any countermeasures that might be necessary. If 1/6 G is above the threshold for the physiologic systems that are sensitive to gravity and can protect them, then that’s great. And we’ll know, if 1/6 G is protective, then 3/8 G certainly will be protective. If it’s not, then we’ll have to decide what kinds of countermeasures we might have to have on the lunar surface and perhaps on the Mars surface as well.

And then, of course, the Gateway itself is another opportunity for us to do some deep space experiments that would be related to interactions between some of the stressors that I talked about, especially gravity and radiation and we don’t have a good feeling for whether there might be some interactions between those two stressors that would be important.

Host: How do you plan to address medical issues or emergencies on long-duration missions?

Paloski: It’s not really the long duration, because we can do a long duration in low-Earth orbit on the space station and use exactly the same medical system that we have. The real critical issue is distance from Earth. And when we get farther and farther from Earth on the station today, a crew member can have a private medical conference whenever he or she wants and can talk about issues and talk about problems, and the docs, a whole back room full of docs and nurses can take care of the crew member with whatever we have on the station.

And then, the last step in any procedure, if something is really serious and we can’t take care of it on the station, then we can de-orbit the crew member and have them from low-Earth orbit into a tertiary care facility within a matter of hours or maybe, at the most, a day.

So, right now, the medical system is pretty much the same kind of medical system we’ve had forever. When we burn for Mars, we’re going to go to Mars, and we’re going to be gone for three years. And, at some points, there’s going to be 10 or more minutes’ delay in each direction for communications, because of the speed of light, because you’re so far away. And so, now, we’re in a position where anybody who’s on board that has a medical issue is going to have to rely on the resources they have there and the personnel that they have there.

So, we’re developing new versions of autonomous medical systems that will tie into the avionics, and  just like the autonomous engineering solutions that we’re developing for crew members to be able to repair instrumentation and equipment on the fly. We’re going to have the same thing for the medical system—which is a little more challenging, because while there’s likely to be one physician on the crew and the crew will probably be a crew of four, Murphy says that the physician is the one that will get sick and need the care. So, now, you have a geologist or an engineer who has to take care of the doctor and really has no real-time communication with experts on Earth.

So, we have to work as best we can to do the right kinds of selection and training of crew members and then hope that we have the right kinds of autonomous systems to be able to support. There’s a lot of work today on autonomous systems, monitoring and treatment for issues that are coming up that are getting smaller and smaller. The terrestrial medical device industry is moving along at a very rapid clip. And so, we’re watching them, we’re doing some testing with preliminary devices. We have a device we’re going to fly on the station probably next year if things go right that is an ultrasound system that plugs into a smartphone and guides can guide a novice person into imaging correctly some things like the heart, you know, valves in the heart or the development of kidney stones or things like that.

So, the technology is evolving and we’re trying to figure out how to work it into the medical system as we go along.

Host: Will technologies such as artificial intelligence and 3-D printing fit into future missions?

Paloski: Absolutely. I think the artificial intelligence that we would be building into the instrumentation is going to be critical for being able to understand what the skills are of the person who’s trying to take care of the other person and be able to supplement those skills.

3-D printing—we’re looking at more and more for two main medical reasons. One is that the shelf life of most drugs is very short, relative to a Mars mission. It’s unusual to have a drug in the pharmacy that has a shelf life of more than a year. Often, they’re shorter than that. We’re going to be on a three-year mission, and since there’s no resupply planned for these very long duration missions, everything that we need to use for pharmaceuticals, we’ll have to take with us.

Or, there is an evolution going on—more in Europe than in the U.S. right now—for 3-D printing of drugs. So, being able to have the basic constituents and being able to print a drug when you need it using the resources that you have available on the station. So, that’s a possibility. We’re trying also to find out how we can get the pharmaceutical manufacturers to increase the shelf life of drugs, if there are some ways that we can do that. So, we’re looking into that very carefully right now.

The other thing is that you’re also going to be taking along all of the food that you’re going to need as you go, or some of it may be pre-positioned a year or more before you go there and you’ll rendezvous with it, say, in Mars orbit. And that food, you know, the nutritional content of that food and how good it tastes is something that’s a concern for us, from a psychological perspective as well as from a physiological perspective.

So, trying to have fresh and novel food is something that we’re looking into. We probably will fly some fresh food. We’ll fly some plants. We’re trying to work on some plant experiments with our sister organization, the Space Biology Program who is very interested in plant physiology and plant science and trying to work up how we could fly crops that the crew members could use. But then 3-D printing of food becomes another possibility, and there’s a fledgling community out there that’s working on various versions of 3-D printers for food that we’re starting to look at, which might be very valuable to at least provide some novel things to eat while the crew members are on this very long mission.

Host: That’s incredibly fascinating. Let’s talk about psychological aspects of a Mars mission. What are some of the factors you’re considering and what measures are planned to keep the crew psychologically healthy during a mission that lasts for several years?

Paloski: Yeah, this is the thing that keeps me awake most at night. When you are cramped up in a small vehicle, which is—you know, I have a fairly good sized office here, but that vehicle will probably be maybe one-and-a-half times my office size—with three of your co-workers, three people who were selected by your boss or by some politician for three years. And it becomes a real challenge. It’s one thing to take a mission for a week or two. It’s another thing to take one for six months or even 12 months. The training and the teamwork for crews is really important.

On a three-year mission, it’s going to be even more important. Crews on the station today have access to cell phones. They can call friends and family whenever they want, more or less, from orbit. That’s going to go away. There’s a lot more space for people to go and be alone. That’s going to go away. There’s a lot of communication between ground control. That’s all going to go away on these missions.

So, they’re going to be very much autonomous and alone, and so there’s a fair amount of concern, and they’re going to be very far from Earth, so Earth will be just one of the other lights in the sky by the time they get close to the Mars system. So, you know, we’re very concerned about things like boredom and monotony and how to keep people interested, and then also, teamwork and what constitutes the selection and training of a good team so that they’ll be able to continue working as a team together for long periods of time.

And then, there are a lot of other things about making sure we have good communication and special treats and things that happen on special anniversaries. How do they talk with their family? How do they talk with their friends? How do they communicate in a meaningful way?

I think one of the things that’s in our favor is that our society, at least in the U.S., has been moving inexorably away from having direct communication and having people that are texting. Even people sitting in the same meeting are texting each other instead of whispering to each other. And so, we’re starting to get used to having more asynchronous communications. And I think that, you know, as the next generations come up and become the astronauts of the future, those people will be a little bit more comfortable with this kind of a paradigm than maybe some of the older school people would be.

But it’s really a big issue for us. We have a lot of studies that we’re doing now trying to look at all aspects of the psychological performance. We have a facility here at Johnson Space Center called HERA, which is an isolation facility that we run four times a year. We put four people in there for 45 days, and we create a number of stressors on the team. We do a number of studies, usually about 20 studies for each of these increments for a year. We’ve been doing that for five years to try and get some insight into it.

We recently completed a four-month isolation study in Moscow with an international crew that was very successful, the first time that we’ve used that facility for our studies and we’re planning, next year, to do an eight-month study, again with an international crew. Because now, we have also multicultural issues. The four crew members on this deep space mission may not all be from the same country. They may have trained in different places and they may have different cultures and different cultural norms that need to be worked on.

And then, finally, we work with the National Science Foundation and we have access to some of their stations in Antarctica. We’ve been doing studies in McMurdo Station and also at the South Pole Station for the people who are winter-overing and they can’t get out of there if there’s an emergency. They tend to be a little bit more space than we’re going to have on this vehicle and a lot more people, but it still gives us a different kind of insight into a hazardous environment that can simulate what we’re doing on the station.

And then, finally, we’re starting to do another set of one-year mission crew members. You may recall that we did Kelly and Kornienko a couple of years back for the first of our one-year studies. We’re going to do probably another 10 crew members on one-year increments aboard station, which will look at people who are trained for space, who have trained with their counterparts on the station and are seasoned explorers, and look at the effects on their cognitive abilities and their behavioral performance over one year, upcoming probably late next year or some time in the year after we’ll start that.

Host: Some of these challenges of protecting humans in the extreme environment of space seem absolutely daunting. How are NASA and its partners developing solutions that help lead to successful missions?

Paloski: We have, actually, a very good relationship with our international partners. We had some of this relationship, at least within Space Life Sciences, we had some of this relationship going back to the Apollo-Soyuz days, so for nearly 50 years. With the Russians, we did some experiments during the ‘90s, the Shuttle-Mir experiments to try and get some initial insight into that.

We’ve had an international Space Life Sciences working group, and we meet every six months. That’s all of our space station partners, plus a number of other space agencies that are interested in working together. So, we combine our efforts to try and understand what the risks are, what the questions are that need to be answered, and then we sometimes do joint studies. Sometimes we’ll say, “Okay, you do that study and give us the results, and we’ll do this study and give you the results.”

So, we have a lot of data sharing, a lot of idea sharing. So, there is a worldwide community of folks who are interested in trying to work on these problems. I’m fairly optimistic that, as we mature, we’ve evolved basically solutions to all of the problems that we’ve encountered in the past and been able to anticipate a number of other problems that we managed to avoid having come to fruition because we already knew how to handle it ahead of time.

We are now in a phase looking at some really unprecedented missions that we’re starting to do the same thing. We’ve been, for about 15 years, HRP has been funded and we will continue to do this until all the problems are solved. But I think we have a good handle on how to solve them and what the solutions need to be. Some of it is basic scientist. About three-quarters of our workforce is actually scientists out in universities, government laboratories, and not intramural scientists at NASA. We do a lot of grants to external people. So, we bring in the smartest minds that we can in particular areas to work on these problems, and then we have enough space life sciences folks who understand the operational environment to be able to turn solutions that are merely interesting research solutions out in academia into something that’s an operational solution for NASA going forward.

So, I think we’re actually in really good shape, and I think that within the next five to 10 years, we’ll have good solutions to most of the problems that we can anticipate coming up for these three-year Mars missions.

Host: As NASA prepares for these missions to land humans on the Moon and on Mars, how would you characterize the importance of almost 20 years of human habitation and research on the International Space Station?

Paloski: I think we have a great deal of confidence in our ability to live and work in space. We know how to protect crew members from the hazards or stressors that we have in space. I think that the challenges are going to start to mount as we go away from low-Earth orbit and into the vicinity of the Moon, because of two things—the change in the radiation environment that we’ll have to be a little bit more careful about monitoring, and the change in the ability to get back to Earth quickly. The distance from Earth is small. The time delay is a second or so, if I remember correctly. So, communication will be fine, but if someone gets injured on the lunar surface, it might take a few days to a week to get back home, whereas from low-Earth orbit, you can get home fairly quickly.

But I think we’ve learned a lot about how to live and work in space. I think that the operations folks have learned a lot about how to train crews, how to select crews and train crews that can work together, and I think we’ve done that internationally in a big way. We’re just now on the cusp of starting to work with commercial partners who will be the carriers for our crew back to the station in the near future and trying to work out the details of how we have private astronauts along with government astronauts working together and training together and doing things that will work together.

It’s another step forward for us, and there might be more prevalence of that as we go into Gateway and lunar orbit and then onto the surface of the Moon. So far, all of our interactions with the medical folks from the commercial carriers has been really positive. They understand—in fact, many of them had come through NASA before they went to the commercial carriers. And what we’re beginning to develop now, the means to work together with them and come to solutions that work not only for NASA, but also for the commercial carriers themselves.

Host: We’ve talked a lot about the impact of the Human Research Program and dealing with space hazards. Could you discuss various ways the program conducts research and how people outside the program can get involved?

Paloski: Yes, of course. We’re always looking for people to get involved. Most of the work that we do, we have a very robust website that describes each of the risks that we’re working on, including everything that we know about that risk today, all the evidence that we’ve developed so far, what the strategies are that we have going forward, and what work we need in the near term.

And so, we put out research solicitations, so we solicit for proposals from anybody in the United States, basically, about three times a year—sometimes more often, but at least three times a year—to help us with solving specific problems that we have. When we have need for special individuals or for special skills that don’t come through that process, we work with the National Science Foundation and the National Institutes of Health to try and find communities of people that might not be aware of NASA’s needs and try to reach out to those communities.

A good example of that was when we did the twins study a few years ago, and we didn’t have a lot of experience and expertise in doing studies of omics and understanding how we might do studies of omics in space and what implications they might have for health and performance of crew members. So, we reached out to an external community and we got some of the best scientists, omic scientists, in the world to come and work for us, and they spent a lot of their time trying to develop the right set of experiments that we could fly on that mission and to develop the research protocols that were jointly worked on together and led to some really important publications. Not only that, but led us to a whole new line of inquiry for future astronauts.

So, we’re always looking for people. You can find our solicitations on a website called NSPIRES. It’s a NASA website that lists all the solicitations that come out, and anybody who’s interested in contributing, we’re always welcome to have new ideas to come into the program.

Host: We’ll post a link to NSPIRES on our website at Bill, thank you so much for joining us today on the show. It has been incredibly interesting to hear you talk about the Human Research Program and all the work that you and your team are doing to prepare for NASA’s future missions.

Paloski: Well, thank you very much. It’s a lot of fun to do these things once in a while.

Host: Do you have any closing thoughts? Anything that we didn’t get to today?

Paloski: No, I think you covered nearly everything that’s important here. I think that the way we do our work is often hidden and behind the scenes, but it’s really important for the crews going forward. As I think I mentioned earlier on, about half of the agency is working on human spaceflight and we’re just a small piece of that, but I think we are an important piece as we move forward and keep our eyes on Mars, which we’ll eventually get to. So, it’s really important for folks to know that we exist and if people from any of the parts of NASA start seeing some issues that they think might be health and performance related, they should contact either me or my Chief Scientist, Dr. Jen Fogarty.

Host: Links to topics discussed during our conversation, along with Bill’s bio and a show transcript, are also available at

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