Health risks in space

29 May 2018

Interview with

Julia Attias, King's College London

There are lot of health issues, beyond motion sickness, that those travelling to, or living in space will have to battle with. Izzie Clarke spoke to Julia Attias, from King's College London, about some of the health problems we may face in space...

Julia - Here on Earth when we stand up we have blood that collects generally in our lower limbs because gravity pushes it down so our heart has to work quite hard to get the blood back up towards the head to make sure that we don't pass out. Now when you're in space you generally have more blood in the chest area than what you would have on Earth so because it's already located higher up, the heart doesn't have to work as hard to get it up to the brain. So the heart loses a little bit of its strength and its muscle mass because of that exact reason. Now when you come back to Earth, the problem is that those astronauts are now re-subjected to gravity again. So the heart does have to work hard to get blood from the limbs back up to the head. But they've now got a slightly weaker heart because it hasn't had to do as much, that typically can result in something called orthostatic intolerance, which is the inability to remain in the standing posture because those cardiovascular regulation mechanisms have had a little bit of a rest and they've become a little bit weaker and inefficient in their job.

Izzie - What about the rest of our body, what's going on there?

Julia - One of the other major issues is to the musculoskeletal system, so that’s muscles and bones, and it's very similar as to what happens in both. Astronauts tend to lose muscle mass so the size of their muscles and also the function so the strength of those muscles as well. The two tend to go hand in hand, and we also lose some of our bone mineral density and that's mainly related to the same reason. So again if we think about Earth, every single day multiple times a day we're standing up and we're moving around. And what that does is enable our feet and our body to come into contact with the ground. Now that impact, that loading, is what's required to normally maintain muscle and bone strength. Because astronauts don’t have that, they don’t have anything that they’re coming into contact with, they're essentially floating. So because they lose that impact the muscles and the bones particularly in the lower limbs gets much smaller.

Izzie - So essentially your muscles and your bones waste away really?

Julia - Yes in the lower limbs they do.

Izzie -  It doesn't sound very nice.

Julia - But there's good news! This was recognised very early on. So the good thing is that there are plentiful countermeasures in place that help to prevent these things from happening. So at the moment astronauts stay on the International Space Station typically for about six months. They have a very robust exercise routine. It's comprised of about two to two and a half hours every day which really helps to maintain much of that muscle and bone mass and helps with the cardiovascular side of things as well. And there are also some some dietary stipulations that help to keep muscle and bone healthy like calcium supplements.

Izzie - And obviously out in space, we've got the sun blaring down. I mean it's bad enough here on Earth. We always put on sunscreen. So what's the risk of radiation?

Julia - Yes so the risk of radiation going to Mars is probably the biggest issue of all of them at the moment,  it’s probably the main limiting factor. Aside from the engineering feat in the craft that's going to get them there and back,  radiation is is probably the most vital risk. So at the moment on the International Space Station astronauts are still protected from the Earth's magnetic field so they do have increase radiation exposure but it's nowhere near as much as astronauts will have when they do venture to Mars.

Izzie - What sort of damage can radiation cause?

Julia - Radiation typically takes form of high speed particles, if you like. Those particles can actually tear through DNA molecules. It can damage the information that they have given for cell production. And the main issue which we can all relate to is the cancer risk.

Izzie - And so we know all the physical things. But what about what's going on in their heads? Is there a psychological impact from going into space?

Julia - The psychological aspect is really interesting and packed full of a number of factors. Their sleep is definitely an issue because at the moment on the space station astronauts have a day and night cycle every 90 minutes or so. So that's really quite difficult because you don’t get a patch of darkness. So their circadian rhythms, which are the rhythms that help to regulate day and night, are absent. So that can really take a toll on their psychological well-being but also the confinement - they're essentially stuck in a tin can for six months with people whom, of course they know, but it's not like you can run away to your bedroom if you want to have some you time.

Izzie - Yeah. Like major cabin fever really.  What do we know about long term space flight, how long do people actually spend up in space and have they looked into anything that is longer than that, because we're talking if we want to colonize somewhere like, maybe spend a lifetime or 20 years in space. Do we know anything about that?

Julia - We've learned a lot about the impact of space flight on the human body for a number of decades now which has really been valuable but we're really entering into another arena and there is still definitely a lot of research that would need to be done to help pave the way and to understand what it is exactly that we would be expecting and how best to counteract that.

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