Positive Impacts

01Houston, we have a podcast.

02Welcome to the official podcast of the NASA Johnson Space Center, Episode 403, Positive Impacts.

03I'm Dane Turner, and I'll be your host today.

04On this podcast, we bring in the experts, scientists, engineers, and astronauts, all to let you know what's going on in the world of human spaceflight and more.

05The second member of Astronaut Group 23, also known as the Flies, is headed to the International Space Station.

06Chris Williams will be traveling to the ISS aboard Soyuz MS-28 to be part of Exhibition 73 and 74 alongside the crew of NASA's SpaceX Crew-11.

07Chris grew up in Potomac, Maryland.

08He graduated from Stanford University in 2005 with a bachelor's degree in physics and earned a doctorate in physics from MIT in 2012, where his research was in astrophysics and early universe cosmology.

09He then became a board-certified medical physicist, completing his residency training at Harvard Medical School in Boston.

10Before he became an astronaut, he worked as a clinical physicist and researcher in the Radiation Oncology Department at the Brigham and Women's Hospital and Dana-Farber Cancer Institute in Boston.

11His research focused on developing new image guidance techniques for cancer treatments, and he was the lead physicist for the Institute's MRI-guided adaptive radiation therapy department.

12Let's find out more about this multi-talented astronaut ahead of his first spaceflight.

13Chris, welcome to Houston, we have a podcast.

14Thanks for coming on the show today.

15Oh, thanks very much for having me.

16I'm super excited to be here.

17I'm a big fan of the podcast, so it's a real pleasure to be on it, get a chance to be on it.

18That's wonderful.

19So let's start from the beginning.

20Where are you from, and what was life like growing up for you?

21Yeah, so I was born in New York City, but grew up mostly in Potomac, Maryland, so the DC suburbs.

22And yeah, I was always, I don't know where it came from, but I was always super interested in space and wanting to be an astronaut as far back as I can remember as a kid.

23And so that kind of led me down the path of wanting to be a scientist.

24And so I, you know, I kind of always grew up interested in science, interested in exploring and wanting to kind of follow that path.

25You've got multiple physics degrees, a bachelor's from Stanford and a doctorate from Massachusetts Institute of Technology, and you did research in astrophysics, radio astronomy, and cosmology.

26I'd love to know some more about what you were studying.

27Yeah, absolutely.

28So what I worked on for my, for my, my doctorate, my PhD was trying to study the very, very early universe.

29And so the, I can give you a really brief history of the universe in, in, in, in, in five minutes.

30So we think the universe is about 13.8 billion or so years old.

31Our earth has only been around for four and a half of that.

32But if you look at the universe today, we see a lot of structure.

33We see stars and galaxies with, you know, that are big, dense objects with the vacuum of space, you know, with nothing between them.

34But if you, if you look back at the very early universe, and we have something called the cosmic microwave background, which kind of gives us this little baby picture of the universe at only 380,000 years old.

35And we see that at the time of the cosmic microwave background, the universe was super uniform, like to one part and a hundred thousand, the same everywhere, 70% hydrogen, 30% helium.

36And over the intervening billions of years, little just areas of slightly higher density caused gravity to sort of collapse that super uniform, super homogeneous, super the same everywhere universe down into the stars and galaxies we see today.

37And one of the challenges is that as astronomers, we look at stars and galaxies to tell us what's going on in the universe.

38And before stars and galaxies existed, it's kind of hard to figure that out.

39So one of the things that we can use is, I told you the universe is 70% hydrogen.

40Well, hydrogen actually interacts with radio waves.

41It can produce or absorb radio waves.

42And so we can actually build an array of radio antennas that can look for this radio signal from hydrogen and try to look at how did this sort of collapse of the universe happen from this very, very uniform universe to this clumpy universe where we have stars and galaxies today to see how those first stars formed.

43So radio waves are a great way to do that.

44We're also trying to use things like the James Webb Telescope to look back for older and older galaxies.

45It's all kind of different ways of getting at this sort of time period of the universe that we call the epic of reionization or the cosmic dark ages.

46That's incredible.

47And so you were studying this cosmic background radiation and you, were you working on the antennas and arrays that you were using to study it?

48Yeah.

49So my, my, what I was sort of the most passionate about was working on the hardware and the instrumentation.

50And so the, the, the specific project that I worked on was something called the, the Murchison Widefield Array.

51And so it was a, an array of radio antennas that we were building and developing out in actually the Western Australia and outback basically.

52And so as a graduate student, I got to sort of travel out to the middle of the middle of a very remote area of Western Australia and, you know, sort of help build some radio antennas, hook them up and, you know, sit in a little, sit in a little shipping container, trying to, you know, debug and write software to make them all talk to each other and, and produce images of, of the sky so that we could try to get at this, this, this signal from the epic of reionization.

53And we also learned a whole, a whole lot of other things too, about just what the sky looks like at these radio frequencies.

54That is absolutely incredible.

55So before you came to NASA, you were working as a clinical physicist doing cancer imaging research.

56How did you go from astrophysics to medicine?

57That's a great question.

58And I mean, it's, yeah, I, I, it seems like a pretty big departure from what I'd been doing.

59So I, I'd kind of gotten interested in, in, in the idea of doing something in the medical field a little bit further back when I, when I finished up with my undergrad, I was working at a, at a research lab doing astronomy research, but I, you know, sort of down the street from my house, there was a, a volunteer fire department.

60And I was like, Oh, that sounds like something that could be kind of like fun and interesting to, to do or to get involved in.

61And so I, I started, I started volunteering, got trained as an EMT and a firefighter and started just sort of doing that on a volunteer basis.

62And I found that I really liked it.

63I think that, you know, there, I felt like I got a lot of satisfaction out of knowing that like, and when I went into, to work a shift that at the end of the shift, I would, I would have really made a very direct and immediate positive impact on somebody's life.

64And, and so I kept doing that, you know, throughout grad school, volunteering as an EMT and just really, really enjoyed it and felt a lot of satisfaction about being able to help and give back in that way.

65And as I was getting towards the end of graduate school, I, you know, like a lot of things, I kind of, opportunities kind of happen by happenstance sometimes.

66And I was at a friend's wedding where another one of my friends who was, who was a doctor, you know, was saying, Hey, you know, there's a big need for physicists in, in medicine, in particular in radiation oncology, where we use radiation to, to treat, treat cancer.

67And, you know, he was saying, you know, you, you know, a lot about physics and you seem to like some medicine stuff.

68So you should, you should check this out.

69And, you know, so it piqued my interest of something that I could, you know, maybe, maybe, maybe learn a little bit more about, cause it was something I had really never heard of before.

70And I, I ended up reaching out to a few folks that were in this field.

71And one of the, one of the people that I talked to wasn't, had been an astronomer before and switched into medical physics and said, you know, Hey, give me a call.

72Well, I'll, you know, I'll tell you a little bit about what it was like.

73And I, I was struck by, you know, how much of what I knew and had learned as an astronomer would actually, you know, be useful and apply very directly to, to, to medicine.

74And so, you know, a lot of what we do as a medical, so as a medical physicist, what you do is you work on, or what I predominantly worked on was cancer treatments and how we can use medical imaging.

75So CT scans and MRIs to more precisely, uh, and accurately target, uh, uh, cancer with, uh, with beams of radiation to, to treat the cancer while, while, while doing, uh, as little sort of secondary damages as, as we possibly can.

76And a lot of the techniques that we use in imaging and figuring out how to, how to, uh, you know, sort of how to localize it.

77A lot of the math behind that imaging is the exact same math that actually you use in a radio telescope to make an image.

78It's a Fourier transform.

79Uh, and it, so it was kind of neat to see that like a lot of the imaging processing, image processing techniques that I'd used as an astronomer actually carried over pretty directly into medicine.

80And, and, and then, you know, the, beyond that, this, the, the approach you, you build to thinking about how to attack problems, both in research and in, you know, operationally how to, how to build and execute things like that.

81You learn that I learned as an astronomer, you know, helped me to, to, uh, you know, just sort of help me in general approaching these problems in medicine.

82That's so cool.

83You went from this, uh, radio oncology to then becoming a NASA astronaut.

84You joined the astronaut corps in 2021 as part of the class, the flies graduated from astronaut candidate training in 2024.

85Uh, what was training like?

86Yeah.

87Training was, uh, was really just an absolute blast.

88It was a lot of fun.

89Um, one of the things that I really have enjoyed about it is that every single day is different and you're really getting to learn a whole bunch of skills in just a, such a wide variety of different areas.

90Um, you know, as a, as a physicist and as a researcher, as a PhD, you know, I'm, I'm used to in my professional career, digging really deep on a, on a subject, uh, on a, on one narrow subject.

91And I think for me, one of the most fun things about this job has been, uh, getting able, being able to explore a whole variety, whole wide variety of different skillsets.

92And so, you know, one day you might be working on learning how to repair a system on the space station.

93You know, the next day you're, uh, you're underwater in a space suit doing a mock space, uh, spacewalk where you're, you know, learning how to, how to repair something on the outside of the international space station.

94Uh, the next day you're flying in a, in a, in a T-38, uh, learning aviation skills and teamwork in a fast paced environment.

95Uh, every day is different.

96And I think that that's been one of the most fun things for me.

97How soon after graduation did you get picked up for your Soyuz flight?

98Yeah.

99I, I was, uh, I was pretty lucky in that basically right at the end of ASCAN training, um, I got, I was lucky enough to, to get the call from our, our chief to, Hey, uh, you know, want to talk to you about something and, uh, got, got assigned to this mission.

100So, uh, I went right from, uh, my, my ASCAN training into, uh, into, uh, into, uh, into my, my Soyuz assignment.

101That's been a lot of fun.

102Um, it's kind of interesting.

103I think there's, uh, you know, a lot of, uh, you know, I get to talk with a lot of my classmates and, you know, uh, after you finish your candidacy training, we'll, we'll work on a lot of jobs around, uh, uh, uh, uh, what we call ground jobs, but we'll work on other positions, things like being a capsule communicator or Capcom, um, or help work on some of the development programs for, you know, like how we're trying to get back to the moon and then onto Mars.

104Um, and you get a lot of experience sort of working in, in NASA beyond, uh, just sort of your, your, your crew member training.

105And so one of the things that's been a big challenge, uh, going straight from, uh, my, my ASCAN training into being assigned is trying to pick up the things like, Oh, you know, how do I get some experience working in mission control?

106How do I get some experience, you know, doing other things that will really benefit you when you're, uh, when you're, when you're on the space station.

107How has it been training in both Houston and Russia for this flight?

108Yeah, it's been, uh, it's been a really interesting experience and, uh, and really tough.

109Um, you know, you, you have to spend a lot of time away from home, which is, uh, which is a challenge.

110I got young kids.

111And so, uh, I, I give my wife a ton of credit and, uh, and I'm super appreciative of, uh, of I think her doing the harder job of, uh, of, uh, you know, making sure everything is all right back here while I'm over uh, uh, over in star city, uh, training.

112Um, and it's been really interesting.

113Uh, I think, uh, you know, there's, uh, there's just so much history with the Soyuz program and being able to be a part of that is just absolutely incredible.

114As an ASCAN, are you exposed to any of the, the Russian Soyuz type training before you graduate?

115Not really.

116Um, we get, we get a couple little court, little, uh, classes and introduction to it.

117We have, uh, in our, uh, space vehicle mock-up facility here at JSC, uh, JSC, we have, uh, we have, uh, uh, a Soyuz mock-up and, you know, we'll, we, I think as part of our ASCAN training, we, we poked our heads into it and looked at it and like, oh, okay.

118You know, that's what, uh, you know, that's what, uh, that's what a Soyuz looks like.

119And, uh, they fit check us to make sure that we'll, uh, we'll fit in the seat.

120It can be a tight squeeze.

121It's a little capsule.

122It's a little capsule, although I, I mean, it's more spacious than I think, uh, I thought at first, uh, but, uh, it's still, still pretty tight squeeze.

123So, uh, but in terms of how it works and, uh, and all, and, uh, and everything we did, we didn't get too much of, uh, of exposure to that.

124So I think that's been really interesting, uh, and a great education to, to figure that out.

125So let's talk about the upcoming mission itself.

126Uh, you're headed to the ISS aboard Soyuz MS-28 with two cosmonauts.

127Can you tell us a little bit about your crew?

128Yeah, absolutely.

129So, uh, I am, uh, headed up, uh, that's absolutely right on, uh, MS-28.

130Uh, our commander is, uh, Sergei Kudzverchkov.

131Uh, this'll be his, uh, second, uh, space flight.

132He, uh, uh, he flew a few years ago on another Soyuz.

133And then, uh, the, uh, uh, the, the flight engineer is going to be, uh, Sergei Mikhaev.

134So, uh, we've got Sergei and Sergei, uh, and, uh, and he, he's, uh, he's also a rookie just like, uh, just like me.

135And then, uh, I'm, uh, I'm filling the third seat.

136And so we're, we're, uh, it's a really great crew.

137Uh, Sergei and Sergei are both just absolutely wonderful people, uh, really kind, super interested, super intellectually curious, which, uh, is really fun.

138Uh, we've had a lot of really, really great discussions, just talking and talking about things.

139And it's been, uh, been wonderful to both spend some time with them, uh, over in Star City and also to, to be able to, to, to spend some time with them in Houston, uh, through our training.

140Are you with them a lot for your training or do you guys have times where you're, you're separated because of either being in different countries or, or other factors?

141Yeah, I would say that we, uh, we sort of go back and forth, um, for a lot of my training period, I would say it was kind of roughly, uh, for the first year of your Soyuz training, you're kind of a month here, a month in Star City, a month here, a month in Star City.

142Um, and so, uh, when I'm over there in Star City, we're doing a lot of Soyuz simulations together.

143So we're spending a lot of time, sort of the three of us in a small capsule for, you know, several hours at a time, uh, you know, in, in, in suits running through, you know, running through sort of mock scenarios of, uh, of what would happen on launch, on rendezvous, on, uh, on, on, on, on departing the station, uh, as well as, uh, uh, in the ISS, uh, trainers.

144So, you know, in addition to just training for the Soyuz portion of our flight, we also work together as a crew for things like emergency scenarios on board space station.

145Um, so we do get to spend a lot of time together, but, uh, they, they also get to spend some time at home, just like I get to spend some time at home as well.

146So, yeah.

147What are your goals on your mission aboard the space station?

148Yeah, I've, I've got a lot of different goals, but I think the, the, the biggest one and the thing I'm most excited about is to, is to really be able to put my training into practice and to, to hopefully really, you know, hopefully in my goal is to do a really good job to push forward the, the science and research that we're doing on, on the space station.

149I think it's incredibly important.

150I think it's incredibly interesting and incredibly inspiring.

151And I feel really lucky to have the opportunity to contribute to that.

152And so I'm, I'm really looking forward to be able to take all of the skills I've developed both, you know, in my training, but also just in my life and to, to bring those to bear and to hopefully make a positive difference in contribution.

153Um, I'm also really excited to be able to look out the window, see a really incredible view of earth and hopefully share that.

154But, uh, I think the biggest thing for me is to, to, to, to feel like I'm really giving back and, and, and, and helping to push our, push our mission forward.

155A lot of the astronauts that we talk to have some personal goals when they're on station, whether it's, you know, looking out the window and getting some photos or, or doing their own science while they're up there.

156Do you have anything like that?

157Yeah.

158Um, you know, I think, uh, I think, uh, you know, I was certainly inspired by, uh, by Don Pettit and that, you know, a lot of, we have, we have some pretty prolific photographers.

159Um, and, you know, my, I have a, I have a background in, uh, in, uh, astronomy and imaging.

160And so I'm, I'm, I'm really curious to, to get a little bit better with, um, the DSLR cameras that we have up there, but also to try to do some, we'll see if I can make it work, but to try to do some fun image processing experiments with maybe some, uh, some photos that, that, uh, that we can take and to process them in interesting ways to bring out, uh, some, some neat features.

161So we'll see if I'm able to get that done, but I want to, I want to really get good at photography because I feel really lucky to have this just very unique picture, you know, perspective on earth.

162And I, I want to take advantage of that.

163That sounds great.

164I can't wait to see what you can do with that.

165Yeah.

166Fingers crossed.

167We'll see what happens.

168What are you most looking forward to about your time on the ISS?

169Yeah, I'm, yeah, I think I'm really looking forward to, to, to, to feeling like I'm doing some, some really important and meaningful work and, and, and contributing.

170And, uh, I'm, I'm also just really looking forward to, to, to feeling what it feels like to be in space.

171Um, we've, I've thought about it and, you know, dreamed about it since I was a kid and trained for it, you know, professionally for the last few years.

172I want to, I want to see what it's actually like and, uh, and, you know, see how, you know, space and, and, and, and being in sort of like micro G does, does all these interesting things to the body and just sort of seeing how that will affect me personally, I think is just, I mean, I'm personally interested, but also I think really academically interested in understanding and thinking about like, Oh, this is interesting.

173You know, how it's, how is my brain thinking about, you know, not having an up or a down?

174How is that changing, you know, my perspective literally and, uh, seeing, seeing all that.

175Is there any way that your astrophysics background is going to be applied while you're on the ISS?

176Oh, that's a great question.

177I think, you know, indirectly for sure, uh, with a lot of, you know, sort of the ways you approach problem solving as a, as a scientist.

178Um, you know, I, I, I, I, I do, we do have a bunch of astrophysics oriented experiments, uh, going on, on, uh, on the space station.

179Um, and so I'm, I'm hopeful that I might get a chance to participate in some of those, but, um, you know, I think one of the, one of the cool things about our job as astronauts is that, you know, we come in with different backgrounds, but we all sort of train to do everything.

180And so, you know, while I hope I get a chance to, to, to be, be a part of some of the, the more physics oriented experiments, I'm also equally excited to work on some of the biology or work on some of the other things that, uh, we're also trained to do.

181And, uh, and I think are, are, are, are super interesting and impactful as well.

182That's so cool.

183Do you have any final thoughts today?

184Yeah.

185I mean, I'm just really excited to, uh, to, to share my journey and to share my, uh, my mission.

186I think, uh, I think it's, uh, I feel incredibly lucky to have this opportunity, both to find space, but also to share that experience with, uh, with everyone.

187And, uh, I'm really looking forward to being able to do that.

188And we're looking forward to seeing you up there on the space station, contributing to this mission and everything that you're going to be doing up there.

189So thank you so much for coming on Houston.

190We have a podcast today.

191Thanks.

192It's been my pleasure.

193Welcome to space.

194Thanks for sticking around.

195You can check out the latest from around the agency at nasa.gov, and you can find our full collection of episodes and all of the other wonderful NASA podcasts at nasa.gov slash podcasts on social media.

196We're on the NASA Johnson space center pages of Facebook X and Instagram.

197If you have any questions for us or suggestions for future episodes, email us at nasa dash Houston podcast at mail.nasa.gov.

198This interview was recorded on July 8th, 2025.

199I Dane Turner produced the show.

200Audio engineers are Will Flato and Daniel Tohill, and our social media is managed by Kelsey Howren.

201Houston, we have a podcast was created and is supervised by Gary Jordan.

202Special thanks to the astronaut schedulers and John Streeter for helping us plan and set up this interview.

203And of course, thanks again to Chris Williams for taking the time to come on the show.

204Give us a rating and feedback on whatever platform you're listening to us on and tell us what you think of our podcast.

205We'll be back in two weeks.

206Three, two, one.

207This is an official NASA podcast.