What Happens to the Human Body in Space?

Uploaded on August 26, 2026

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What Happens to the Human Body in Space?

Join Canadian Space Agency (CSA) astronaut Joshua Kutryk and communications advisor Frédérique Paré as they explore the groundbreaking research taking place aboard the International Space Station and how it could improve healthcare on Earth. (Credits: Canadian Space Agency, NASA)

Frédérique Paré (FP): Hello Josh. Thanks for being here today.

Joshua Kutryk (JK): Hello.

FP: So you're the next CSA astronaut to be going to the International Space Station for six months, maybe a bit more. Can you tell me about what you'll be doing up there?

JK: Yeah. First and foremost, a lot of scientific research. And a lot of that research is actually related to the human body. When you put an astronaut on the Space Station in the space environment for six or seven months, a long time, it's not actually good for the astronaut's body. It suffers a lot of changes. One of the things we see, for example, is like aging. Aging is accelerating a lot of systems in space on my body are going to age faster, and so that presents a challenge for keeping astronauts healthy. But it also presents an environment that's really good for studying the human body. With long-duration space flights, we can get 10 or 20 years of equivalent data on the human body from a single mission. And so that helps us to keep astronauts safe, but also to learn things about medicine that we can apply here on Earth. And we're lucky in Canada because we actually have a lot of scientists and doctors who are investigating this now, how to keep astronauts healthy during long-duration missions. And also taking those lessons to apply them to patients here on Earth.

FP: So what do they study exactly?

JK: We see a lot of changes in the human body because of the absence of gravity, because of the radiation environment. Some good examples have to do with the red blood cell count in astronauts. For example, we see folks come back and they're slightly anemic because of changes in their blood. We're also going to be studying the cardiovascular system, muscular systems, skeletal systems. Astronauts will suffer a lot from bone loss, vision problems.

FP: Oh, vision problems. So in space, astronauts can get like a blurry vision, altered vision.

JK: Yeah, it actually depends on the astronaut, but by and large, we do see changes physically to an astronaut's vision system, right down to the actual change in the shape of their eyeball and by account of that, in their ability to use their eyes. And so that's something that we're also highly interested in.

FP: That's so interesting. Are any other parts of the body studied?

JK: The whole body is definitely affected. One of the systems we can study really closely in space is the brain, and particularly how the brain is able to keep an astronaut balanced, the neurovestibular system. Without gravity, that system all starts to act a little differently. And so in space, with the astronaut as a test subject, we're able to study problems, for example, with the neurovestibular system and then apply some of what we learn, not only to keeping astronauts safe and healthy, but also, of course, to people here on Earth.

FP: Amazing. So if I'm getting this right, you just said it, you'll be a test subject for many experiments.

JK: That's exactly right. A big part of my job is to do science on behalf of researchers from across Canada and around the world. But another big part of my job is to be the test subject itself and to be the one being sampled and investigated. Yes.

FP: I've read that maybe like 300 experiments are taking place right now on the ISS.

JK: Yeah, there are hundreds of experiments going on the Space Station at any given time. Some of them are taking place automatically, some of them involve direct astronaut involvement, but certainly hundreds would be going on right now today on the Space Station as it flies overhead of us and as we're having this conversation.

FP: That is so fascinating, the things we learn when talking to an astronaut. Thank you, Josh.

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