How Long Can A Person Survive In Space?

When we gaze into the nothingness that fills the sky every night or when we were children pouring over books about space, there was one question that always filled our minds: could we survive in space? Could we live in the vast emptiness that seemed to envelope everything? The short answer is no but with the correct preparations and technology, humans living among the stars could be very possible. 

Starting with the first and foremost tool in any space travelers kit: the space suit. It is a crucial component that ensures that we survive the extremity in the short term. Surviving without a space suit is fatal in outer space. Within the ten to fifteen seconds we would become unconscious due to the lack of oxygen. Holding our breath, a mechanism to conserve air, would only accelerate our death. The molecules of oxygen would begin expanding and rupturing our organs, and before long there would be bubbles of gas in our blood causing an embolism. Emptying your lungs as much as possible may help you survive for a few more seconds, the lack of pressure in space is deadly as well. Bodily fluids begin to boil and our body expands. Moreover, due to the elasticity of our skin, we’d become a swelling mess. The boiling and melting of liquids occurs because the atmospheric pressure on Earth causes liquids to boil and gasses to form. Without that, boiling points would drop rapidly and our liquids would transform into gasses in an instant. On a less disgusting note, our eyes would not explode due to the membranes surrounding it. However, within the next minute, we would be declared brain dead as bubbles of gas block circulation around our body. Scientists have never first hand experienced this, rather compiled preexisting knowledge from experiments on other mammals and some incidences with humans.

In 1965, at the Brooks Air Force Base in Texas, a group of dogs were exposed to near vacuum pressures, becoming unconscious, paralyzed and experiencing seizures. The report meticulously detailed the many symptoms experienced by the animals during the time. As the gasses in their organs were expelled it caused vomiting, defecation and urination and upon further investigation, it was also discovered that their tongues were coated in ice and that their bodies had swelled up. Luckily, after resuming to normal pressure, the dogs shrank and were able to walk after 10 to 15 minutes.

NASA also ran experiments on chimpanzees in 1965 and 1967. Compared to the dogs, they were able to survive for up to 3.5 minutes with no apparent cognitive defects, according to the Scientific American. Exposure beyond those few minutes resulted in behavior changes. Sadly, one chimpanzee died from cardiac arrest. 

There is also information based on depressurisation accidents to help us assess how the human body would deal with such a vacuum. For example, horrifyingly in 1965, a technician at the Johnson Space Centre was trapped in a vacuum chamber, recalling that the last sensation they recalled was their tongue boiling before blacking out, causing them to lose their sense of taste for four days after finally waking up.

Source: Figure 19: Space Suits All Components Provided by NASA

Other than providing oxygen and pressurisation, space suits act as a shield to the low temperatures and radiation in space. This radiation, whether in direct sunlight or behind objects, still has the capability to create extreme temperatures from between -150 to -200°c. However, the burns or freezing would only appear later on as heat transfer in a vacuum is difficult. In general, long term exposure to radiation from the sun causes cancer, whilst charged particles in space (from solar flares or debris) may hit astronauts, of course causing further damage.

Death without a space suit is painful but what about the impacts of staying in space over long periods of time? In June 2024, NASA astronaut Frank Rubio returned from the ISS to Earth, accomplishing the feat of the longest single space flight by an American with a stay of 371 days. Since Rubio had a twin on Earth called Mark, they were able to ascertain with more certainty the effects of space on the body. 

Credit: Image from Business Insider, sourced from NASA/Bill Ingalls

Due to the low gravity environment on the ISS, his body had weakened and he had to be lifted out of it by recovery teams. The first noticeable impact was on his muscles and bones. In two weeks, scientists noticed that muscle mass can fall as much as 20% whilst over 3 to 6 months it could fall by 30%. Bones, on the other hand would begin to demineralise and lose strength; each month in space can cause 1-2% of bone mass lost, with it taking up to 4 years for the bone mass to recover! The ISS itself has exercise equipment and for 2.5 hours each day astronauts are expected to exercise and undergo training but this regime was not enough to prevent the changes. 

Other unique ways spending time in space affects the human body include: height, eye sight, gut bacteria and the brain. Height also increases since the spine elongates in space, and when arriving back to Earth, the changes in gravity may cause spine disks to slip! Some astronauts crane their necks as they enter the atmosphere to try to prevent this from happening.

Due to gravity changing how blood is pumped around our body, fluid can pool to the back of the eyes causing an oedema, which could deteriorate vision sharpness. The changes may be permanent or require a year on Earth to reverse. Despite this, the most concerning issue may be the changes to our DNA. The ends of our DNA are called telomeres, which lengthen on the ISS but rapidly shrink on return to Earth. Radiation in space may also cause DNA to mutate, as well as kill white blood cells, hindering our immune system.

So the question still stands: can we ever live in space? The first issue that comes to mind is the sheer cost of materials and fuels to send rockets and satellites into space. Many argue that the money used for space exploration can be redirected to other more pressing issues like medical research, education and fighting the climate crisis on Earth. Secondly, humanity still lacks the capabilities to maintain life in space, despite conferences like the Analog Astronaut Conference with simulations of life in space. Many problems emerged such as a shortage of oxygen, water and food and there were interpersonal challenges and psychological issues of trying to replicate a stay on a planet like Mars. Additionally, the impacts of space on human health is still largely unknown. Technically, our bodies cannot handle the radiation for long periods of time. Radiation is also unpredictable with scientists unable to pinpoint exact areas where charged particles hit in spaceships, let alone prepare for the lengthy treatments in space. 

Is it in our human nature to be curious about our natural world? How ambitious is too ambitious? We must consider the entire picture before encouraging people to pursue life away from planet Earth.

References

Conger, Cristen, and Patrick J. Kiger. “Will Humans Be Living in Space in the Next 50 Years?” Science | HowStuffWorks, https://science.howstuffworks.com/living-in-space.htm. Accessed 22 September 2024.

Gosline, Anna. “Survival in Space Unprotected Is Possible--Briefly.” Scientific American, 14 February 2008, https://www.scientificamerican.com/article/survival-in-space-unprotected-possible/. Accessed 22 September 2024.

Jones, Andrew. “How long could you survive in space without a spacesuit?” Space.com, 3 August 2023, https://www.space.com/how-long-could-you-survive-in-space-without-spacesuit. Accessed 22 September 2024.

Kwan, Jacklin. “What would happen to the human body in the vacuum of space?” Live Science, 13 November 2021, https://www.livescience.com/human-body-no-spacesuit. Accessed 22 September 2024.

Ridley, Louise. “What would happen if you were in space without a spacesuit?” BBC Science Focus, https://www.sciencefocus.com/space/what-would-happen-if-you-were-in-space-without-a-spacesuit. Accessed 22 September 2024.

Scoles, Sarah. “Why We'll Never Live in Space.” Scientific American, 1 October 2023, https://www.scientificamerican.com/article/why-well-never-live-in-space/. Accessed 23 September 2024.

“What does spending more than a year in space do to the human body?” BBC, 27 September 2023, https://www.bbc.com/future/article/20230927-what-a-long-term-mission-in-space-does-to-the-human-body. Accessed 22 September 2024.

“Why your blood would boil in space.” bbc.com, 17 June 2016, https://bbc.com/future/article/20160617-why-your-blood-would-boil-in-space. Accessed 22 September 2024.

“ Experimental Animal Decompressions to a Near-Vacuum Environment” , April 1965, https://ntrs.nasa.gov/api/citations/19660005052/downloads/19660005052.pdf Accessed 30 September 2024.