Bodies in Space

Next year is the 50th anniversary of the Apollo 11 moon landing. Imagine you were Neil Armstrong or Buzz Aldrin travelling into the unknown. What would your list of questions for the experts have been before they blasted you into space? Luckily for us, 533 people have now travelled to Earth’s orbit and 12 have walked on the moon, so we know a little bit more about the effects of space on our bodies.

Isolated from friends and family, exposed to a vacuum and radiation, and trapped in an enclosed space with people you barely know, space can be an unfriendly place. There are five categories which NASA groups risks into: 1) gravity fields, 2) isolation/confinement, 3) hostile/closed environments, 4) space radiation, and 5) distance from Earth. So how does space affect our bodies? Working in space there is no gravity, and on Mars there is 1/3 of the gravity we have on Earth. This affects spatial awareness, hand-eye coordination, balance, and you’re likely to experience motion sickness.

On top of this, NASA has found numerous other ailments which occur due to a lack of gravity. Bones lose minerals without gravity acting on them, density dropping more than 1% per month.  The rate of bone loss for the elderly on Earth is between 1% to 1.5% per year. After returning to Earth, bone loss may not be corrected by rehabilitation, so there is a greater risk of osteoporosis-related fractures. In space you must exercise and eat properly, to reduce the loss of muscle strength and endurance which you would otherwise encounter.

muscle waste.png

Without exercise and no gravity, the fluids in your body shift upwards to your head, putting pressure on your eyes and causing vision problems. Kidney stones are also likely to occur if you are dehydrated and calcium is excreted from your bones. Nutrition is also very important. These ensure you do not compromise your health as they are required for every cell in your body to function. Here is a short video showing how astronaut Tom Marshburn hadn’t quite adjusted to life back on Earth…

What about an unprotected body in space. What if our space crew mates were fed up of our science questions, and booted us out of an airlock? Thanks to some accidents in space and test chambers, we do have an idea of what would happen. Animal testing in the 60’s also aided with these findings. Lack of air would be the first thing you’d notice. You couldn’t draw a breath but you wouldn’t pass out immediately. Your body would take about 15 seconds to use up its remaining oxygen supply. You could potentially survive for up to two minutes like this (as long as you didn’t hold your breath) without sustaining permanent injury.suffocating.png

What happens if you do hold your breath as you are pushed into space?  There is a loss in pressure as you enter the vacuum of space and as a result, the air left in your lungs would expand, rupturing them and releasing the air into your blood. So don’t breathe in when in the vacuum of space. Exhale.

burst lungs

Other than this, things are pretty much out of your hands unfortunately. The water in your body (i.e. in your skin and tissue) will start to vaporise after about 10 seconds due to the absence of atmospheric pressure.  This will make you balloon. You won’t burst as our skin is pretty tough, but it wouldn’t be pleasant. Luckily, our bodies protect our blood and regulate the pressure, so that’s safe from space. In 1965 Jim LeBlanc was exposed to near vacuum conditions when his suit sprang a leak in a test chamber here on earth. He experienced the moisture on his tongue begin to boil, and remained conscious for ~14 seconds. He was returned to normal once the chamber was repressurised.


Our atmosphere filters cosmic radiation but in the vacuum of space you would be exposed to it, unprotected. You’d likely have a nasty sunburn and also experience decompression sickness (e.g. divers sickness, or the bends), which occurs when the pressure change on the body is too quick and as a result gas dissolved in our blood (and other fluids) is released. One positive is that despite the freezing temperatures in space, our bodies would not freeze instantly. We’re actually very good at hanging onto temperature for longer than you would think. You would suffocate before you froze…


What if you died in the vacuum of space? If you’re not in a space suit you would not decompose as you would on Earth, as there is no oxygen. If you happened to be near a heat source, your body would mummify but if not, you would freeze. Even if you had a spacesuit on your body would last for a very long time as there would be no air to facilitate degradation, drifting in space for millions of years. Only three people have died in space: Georgiy Dobrovolskiy, Viktor Patsayev, and Vladislav Volkov. A faulty valve opened in the shuttle on their decent back to Earth and caused rapid decompression of the chamber.

Space is a dangerous but fascinating place, and 50 years later NASA are talking about returning to the moon in the near future. There is so much to explore, and much research to be conducted. Astronauts are incredibly brave and resilient people. Here is a great video about astronaut Scott Kelly who spent 340 days in space, while his identical twin stayed here on Earth. NASA has monitored the differences in DNA and also physical changes between the two, check out their findings here…

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