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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. 

American Astronaut Tracy Caldwell Dyson discusses 20 years of continuous human presence on the International Space Station.

When ISS Expedition 1 began in November 2000, it marked the start of an unprecedented era of peaceful cooperation in space, paving the way for hundreds of residents and visitors from countries around the world to conduct science onboard the most complex structure ever built in space and further exploration of the Moon, Mars and beyond. In the first segment of a two-part series celebrating the 20th anniversary of continuous human presence in space, Caldwell Dyson reflects on her experiences onboard the ISS and how the space station community benefits humanity’s future.

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

  • Excitement and challenges of living and working in space
  • The vital role of international and commercial partnerships
  • How ISS influences future space exploration


Related Resources

International Space Station

NASA Counts Down to Twenty Years of Continuous Human Presence on International Space Station

Video: A Bridge Above: 20 Years of the International Space Station

Space Station 20th: First NASA Research on ISS

APPEL Courses:

International Project Management (APPEL-IPM)

Leading Complex Projects (APPEL-LCP)

Lifecycle, Processes & Systems Engineering (APPEL-vLPSE)


Tracy Caldwell Dyson Credit: NASA

Tracy Caldwell Dyson was selected as an astronaut by NASA in 1998. Caldwell Dyson is a veteran of two space flights. She has designed, constructed and implemented electronics and hardware associated with the study of atmospheric gas phase chemistry, and has developed and presented numerous papers on methods of chemical ionization for the spectral interpretation of trace compounds. In 2007, Caldwell Dyson flew aboard the Space Shuttle Endeavor on STS-118, where she served as a Mission Specialist. In 2010, she served as Flight Engineer for Expedition 23/24. She has logged more than 188 days in space, including over 22 hours in three spacewalks. Caldwell Dyson has a bachelor’s in chemistry from California State University, Fullerton and a Ph.D. in chemistry from the University of California at Davis.


Tracy Caldwell Dyson: I cherish the experience that I had onboard the space station.

We’ve built a community on this planet that humanity’s future will certainly lean on with this work that we’ve done on the space station and the continuous human presence we’ve had.

I’m grateful to have seen where we started and where we are today because it gives me such hope going forward, especially as we look to the Moon and Mars and beyond, and knowing that there’s no way we’re going to get there without our partnerships.

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

I’m Deana Nunley.

On November 2, 2000, an American astronaut and two Russian cosmonauts arrived at the International Space Station, marking the start of continuous human presence in space. Now, almost 20 years later, 240 people from 19 countries have visited the space station. The unique microgravity laboratory has hosted more than 2,800 research investigations from scientists in over 100 nations.

Today on the podcast, we begin a two-part series on ISS 20. Our guest is Astronaut Tracy Caldwell Dyson, who lived and worked aboard the ISS for 174 days in 2010 as a Flight Engineer for Expeditions 23 and 24. She performed three successful contingency spacewalks, logging over 22 hours of spacewalk time.

Tracy, thank you so much for joining us on the podcast.

Caldwell Dyson: Deana, it’s my pleasure. Thanks for having me.

Host: As we approach this celebration of 20 years of human presence on the International Space Station, what stand out to you as the most remarkable achievements along the way?

Caldwell Dyson: You can’t just wrap it up into several different achievements. I look at it as a whole from assembling a complex research facility entirely in the vacuum of space side-by-side with 11 international partner nations to utilization of that complex research facility to the groundbreaking research that’s being done with not only our international partners but our commercial partners, our partners from academia and industry to what we’re doing with the space station to enable exploration beyond low-Earth orbit. Every hour of that space station from the time we designed it to when we built it to when we started utilizing it to today is full of achievements that have been remarkable in that direction going forward.

Host: Do you think there’s a general understanding of what an incredible feat it is to have humans living and working in space continuously for 20 years?

Caldwell Dyson: I certainly think the space exploration community has a grasp of it, but I’m not so sure that the public at large really does. And I think that today with the new surgence of commercial companies and the space program getting more talked about in the public, I think that folks are starting to grasp it, but I don’t know that they’re there quite yet.

Host: When you think about how humanity benefits from the International Space Station, do you have like a top five or top 10 list?

Caldwell Dyson: I don’t know if I have discrete points on a list, but I think humanity of course benefits from the boldness of what we’re doing with the International Space Station. And I think that boldness really inspires and it’s revitalized an interest I think in science and technology. Because of the new ways that we have to approach problems when you have to overcome all the challenges of living and working, not to mention getting to space.

And I also think that through the global partnerships that we have that like the view from ISS, the borders just diminish to the point that you’re no longer noticing them for the goal that you’re all together working toward and that, all of humanity benefits from today and as we go forward.

Host: Are there any specifics as far as the way that humanity benefits that especially resonate with you?

Caldwell Dyson: Well, I think it’s been NASA’s mission from day one to make accessible to the public everything that we do, all of the resources that is within our power to give to the public, it’s out there. It’s at their fingertips literally today with how the Internet has opened up avenues for accessibility. And so humanity has benefited from the information just being provided to them, the insight, the inspiration, not to mention the tangibles like what we have to develop not only in technology, but in operations to do the work we do to go beyond what we’re doing today.

It has direct impact on the life that everybody leads every day from medical advances to just their cellphone technology. The fact that we have satellites in orbit are all because we tried to get the space. And also the non-tangible things of trying to work together and improve our communications when you can’t see people that you’re working with, I think have all, especially in this time that we’re in dealing with COVID and all the challenges that that presented. I think there’s a lot to be learned from how we have to overcome the challenges of our project of getting to space and applying that to the challenges that we have here on Earth.

Host: From your perspective as a chemist, what are some of the most exciting ISS experiments and research findings?

Caldwell Dyson: I think just even looking back at the time I was living onboard and working, I think the things that teach us something, obviously, that we don’t know and help us get to where we want to be. So one of my favorite ones as both an explorer and a chemist was the capillary flow experiments. These were designed to study the way liquids move in space by simply changing the shape of the container and the dimensions of the channels in which fluid traveled. And it has its applications in space flight and spacecraft design.

It allows you to transport liquids without pumps and moving parts. It reduces cost and weight and complexity in a system, but there’s terrestrial aspects as well. Tree roots use capillary systems. Medical diagnostic devices use capillary systems. And so, I’ve found that one to be exciting for not only the fundamental aspects of what we were learning, but also because it had broad-reaching applicability to life here on Earth, as well as helping us get beyond low-Earth orbit.

Host: What are some of your favorite memories of your ISS experiences?

Caldwell Dyson: Oh, certainly some of the extraordinary things like spacewalks. Those are never guaranteed and I was so blessed to have that opportunity that just the fact I got to do it alone was one of my favorite moments. Although the reason I got to go outside was because something broke and we weren’t expecting it and it was a bit of a critical component. So all of that drama aside, that was one of my favorite memories. Not only the moment I realized I got to do them, but just being outside in that environment.

I trained for so long to do one of those and I got to do three of them. And it was exciting because this was all very unexpected. It was a contingency spacewalk and it was time-critical. And it was amazing to be at the very tip of the spear of something that so many people, not just from Houston, but all around the world who were cooperating to help bring about a successful resolution to this. It was so memorable to be a part of that, that it’s one of the highlights of my time on the space station.

And then there’s little moments like when I was zooming around inside going from the lab to Node 3 and I winged around a corner, and I grabbed a handrail that I grabbed all the time in Node 1 to give myself some force getting around the corner. And in that instant, I thought to myself, ‘Oh my gosh, this is just like the mock-up.’ And I thought it was so funny because it’s a testament to how high-fidelity our mock-ups are, that you could be in space in the actual vehicle and think you’re back home in the training facility. So it was a moment where I paused and I was like, ‘I’m so grateful,’ not only for my training, but the people who trained me and with that looking out the window and the moments I could at the space station itself.

When you’re nestled in a cupola, which of course is another favorite memory of mine. But when you’re nestled there and in a 90-minute period as you go from sunset to sunset, you’re mesmerized by the fantastic view you have, the extraordinary view you have of the Earth and the stars and the Moon, but then your gaze lands on the space station itself. And you can’t help to be captivated by that alone for everything it is — not just the metal and the cables and the gears and everything that’s making it run. But when you realize the people and the hands that touched it from those who designed it, those who built it to those who are sitting in Mission Control right now commanding to it. My goodness, that was an ongoing memory of mine by living up there.

Host: Are there other stories from your time on space station that you can’t wait to share with future generations?

Caldwell Dyson: I think certainly folks want to hear about what it’s like to live in microgravity and what’s it like to float and all of that and watching the view. And I would definitely, I mean, I never get tired of really sharing that. I think that what I can’t wait for is to share the realities of it with future generations, especially those who are hoping to explore themselves. Those that will actually themselves be in that situation too. I guess, fortify them, future generations and future generations of explorers to fortify them with the realities, the goods and the ‘bads.’ Set them up to accept the challenges of the life it takes to succeed under those conditions. It’s a long list of things I think, but I would look forward to sharing that.

Host: How would you describe a typical day on ISS?

Caldwell Dyson: Oh, a typical day. There’s hardly one of those on board, but I would say when you’re not dealing with those extraordinary, very critical events that involve opening a hatch to the vacuum of space or grappling a space vehicle that’s hovering 30 meters in front or anything like that, your day is pretty typical like it is here if all you did was fix things and set things up. You wake up, you get dressed and eat your breakfast just like you do at home. You have a meeting in the start of your day with everybody around the world and then cameras come on and you get to work. You’re fixing things. You’re maintaining things. You’re setting things up, moving things around.

Sometimes you are the operator of an experiment. Sometimes you’re the subject of an experiment. And then there is every day a chance for you to exercise, which even if you’re one of those who don’t think — if exercise isn’t your thing, you find that once you live on board that that is something you definitely look forward to. It’s a little bit of me time and also you know how vital it is for your health as you make your way back to Earth.

But you get a midday meal. And usually you’re eating that alone for all the coming and going, that is the rest of your crewmates on board. But then you finish out your day. You have another conference at the end of the day with everybody around the world. And then you get into a period of time that we call pre-sleep. And that is you unwinding, getting ready for bed, having dinner. And that’s a time when you get to join all of your crewmates at the center of the space station for a meal, and you just kind of get to decompress like a family would, talk about the day and try to be lighthearted before you’ve got to go to bed and start it all over again. So that’s kind of a typical day.

Host: Thank you for walking us through that. Back on Earth, what do you miss most about living and working in space?

Caldwell Dyson: Oh, that’s kind of a hard one. You think it’s an easy one to answer, but it’s for me not. I think it’s the challenges of it all — the physical, the mental, the emotional is unlike anything here. Even on your hardest day, because you’ve lived in gravity your whole life and you kind of know how it all works. And so you can plan accordingly. But in space, I found even having been there for a while on my increment, there are still things you’re having to learn and overcome for the sheer community of it.

Even though there’s challenges up there, I look forward to and I miss having to stretch my mind and give in a little and really test my character by all the challenges that you faced by being in that environment. And then there’s also the part where you’re contributing to the understanding that we all have of the environment and how to live and work in it. And I’ve found that coming back from my missions and not just going through the post-flight debrief process, but just all of the time spent after that where you are contributing to the understanding everybody has of the microgravity environment, of the operational tempo, and in light of what we’re trying to do with our other programs. Artemis being the one that comes to mind as we go beyond low-Earth orbit to the Moon, being able to apply what I learned, just being immersed in that environment has been very rewarding. And I look forward to having that experience. And I cherish the experience that I had onboard the space station.

Host: Tracy, what are your thoughts on how the ISS program and the level of international and commercial cooperation have evolved over the years?

Caldwell Dyson: Oh, I tell you, I would have never seen it coming. If you had asked me when I first got here in 1998 and started working on the Space Station Program, I would have never predicted when I started here where we are today with cooperation and I would’ve missed the mark. I’ve been delighted to see how far we’ve come in terms of cooperation, our communication, and I’ll even go deeper and say what it’s done to our character. Just given our relationship with our Russian partners, for instance. I don’t think two programs could have been more different than NASA and Roscosmos and just the way we approached everything seemed to be so different.

In the beginning, there seems to be a bit of a clash and you just you wonder when the progress is actually going to happen, because there’s all this stuff you having to work through, communication barriers, cultural barriers, just approaches that are completely different. Then to today, it just seems like it’s on rails. It’s smooth. We know how to partner. We know how to communicate. We know how to compromise. We know how to value what the other is saying. And to expand our knowledge base to really take the risk of saying, ‘I’m going to listen to you and I’m going to value what you have to say and let my agenda go for a moment.’ And it’s amazing what we can learn when we let go of our own agenda.

And the fact that we actually have prioritized that and made the effort to do that, and not just let our urgency to get into space and get it done override the fact that this partnership is super important. And I’m grateful to have seen where we started and where we are today, because it gives me such hope going forward, especially as we look to the Moon and Mars and beyond, and knowing that there’s no way we’re going to get there without our partnerships.

I think that the international and commercial cooperation, I didn’t mention that, but that is another level of complexity that I think without the experience we had with our international partners, we would have been sorely positioned to tackle such an endeavor as partnering with commercial companies. But I think given where we are today and what the International Space Station has provided, we are poised to go full forward beyond where we are today and doing it as a planet and not just individual nations or agencies.

Host: As we look toward the future, how does space station research and lessons learned influence future Moon and Mars exploration?

Caldwell Dyson: It seems like too numerous to count, but just the environment alone having to overcome microgravity, the vacuum of space, outside the space station you have the external environment to deal with. And then internally, how do you maintain a comfortable environment to the technology that we need to get there? The space station is a platform to test those things out before we get too far away to make it beyond our means to test these things. Right down to operations, like how best to set up our days as we’re getting to these new destinations, the Moon and Mars.

And we’ve got basically a 24-hour cycle on our bodies and how are we going to get the things we need done in that amount of time knowing that we’re only human kind of thing? I think being on space station and all that we’re doing to not just preserve what we’re doing on the space station, but with an eye on the future, it’s no better place to test those things out. And there’s the community and the communications that are required in order to do what we’re doing.

And so, everything that we’ve had to overcome in not just building the space station and maintaining it, but using it as a research platform. And not just scientific research, but the coordination that it takes is I think helping us learn how to be a community, a space program community, and less of a nation by nation contributing to a program, but more of a community. And going forward, I think, again, the space station is responsible for giving us that foundation so that we can do the great things and ride the rails of the experience we’ve had building the space station and using it.

Host: And then how does this spirit of exploration demonstrated by 20 years of continuous human presence in space contribute to humanity’s future?

Caldwell Dyson: I think if you talk about the we in quotes, the global “we,” what we’ve had to do in order to have continuous human presence. I mean, all that we’ve done to create and build and maintain, utilize and share this space station and the experience with our public, we’ve built a community on this planet that humanity’s future will certainly lean on with this work that we’ve done on the space station and the continuous human presence we’ve had.

Host: Tracy, it’s been so much fun having you on the podcast. Thank you so much for taking time to talk with us today.

Caldwell Dyson: Oh Deana, thank you. It’s been my pleasure and I appreciate your questions and the nostalgia, and the hope that it also brings me just thinking about it.

Host: I especially enjoyed getting to hear you talk about character and how that fits into the space station story. Thank you so much for sharing that.

Caldwell Dyson: Well, thank you.

Host: Do you have any closing thoughts?

Caldwell Dyson: Oh, no. I mean, I could blather on for longer than your listeners probably want to hear about the space station and all that we’ve done. I think when I first joined the Astronaut Program back in ’98, it seemed like the public wasn’t too interested in what we were doing. In fact, we probably had more critics than we had supporters. And I think it’s by the grace of God that our program is not only here today, but the pendulum has completely swung over to where people are wearing NASA meatball shirts.

I’m just excited about that. And it’s, again, it gives me hope because I think I’ve always and I know I’m not alone in this, but I’ve always had this belief in what we’re doing. What NASA has started and invited our partners to come and join in and to see. Over the 20 years that I’ve been here, 20-plus and have seen the way NASA has led the team. And it’s like servant leadership. It’s leadership under and supporting. And I’ve enjoyed watching how we’ve elevated the other partnering nations and our commercial partners to join on the same level and go forward with us.

When I look at it today, I think that has contributed to the popularity, if you will, of our space program, that it’s a global space program, that the public’s excited and they can actually see themselves in that environment because it won’t be long before they can actually be there and they don’t have to join the Astronaut Corps to do it. I think my parting thoughts are just the great hope that I have and the delight that I have in seeing how we have come this far and having been here, observing it and being in the midst of it has been a real privilege.

But it’s also been enriching to me to watch how we went from total chaos to the order that we have today. And now that we’re entering another realm of chaos of doing a new program, I just look forward to seeing how we tackle that as a community. Not just in the space program, but with the public and just as a planet going forward. I don’t see it as a small group anymore going to the Moon or to Mars. I see it as a planet. And I’m pretty excited about that.

Host: Many thanks to Tracy Caldwell Dyson for joining us on the podcast. You’ll find her bio along with links to topics mentioned on the show and a transcript of today’s episode on our website at

In our next episode, we’ll conclude this ISS 20 two-part series with a conversation with ISS Flight Director Royce Renfrew – and look forward to connecting with you then.

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