Saying that NASA astronauts Butch Wilmore and Suni Williams have stuck on the International Space Station (ISS) for longer than expected is an understatement, but has now caused some experts to thing how long people could really survive up there in the wake of an apocalyptic event.
After what was meant to be an eight-day mission turned into a nine-month stay on the station, NASA reported that the latest rescue attempt via SpaceX mission was delayed until at least Friday evening on March 14 due to a hydraulics issue.
With their prolonged stay making headlines, people have started to wonder how long astronauts could actually survive up there if something happened to wipe out all life on Earth — making the ISS crew the last surviving humans.
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It’s arguably a morbid question, but an interesting one that YouTuber and educator Vsauce decided to explore. According to their analysis, astronauts wouldn’t necessarily run out of food or oxygen first, the real problem would be something much bigger.
As the above video explains, the ISS is designed to sustain life for long periods, with oxygen being recycled through electrolysis and food supplies being carefully rationed. Depending on when the last supply mission arrived, the crew could potentially have enough food to survive for around two years.
NASA has strict guidelines ensuring all food sent to the ISS has a minimum shelf-life of one year. While expired food isn’t ideal, it’s likely those astronauts wouldn’t be too picky in a world-ending scenario.
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Interestingly, there have already been real-life instances where the ISS crew had to stretch their resources. NASA previously revealed that astronauts once had to survive for eight months without any new food, water, or supplies due to three failed resupply missions. So, while tough, prolonged survival is definitely possible.
You might think starvation or lack of oxygen would be the astronauts’ biggest problem, but that’s not actually the case. The real issue is a loss of orbital altitude, as also demonstrated on the Gateway to Astronaut Photography of Earth’s ISS Space Station Orbit tutorial.
As Vsauce also explained: "The first thing they would run out of... would be altitude."
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The ISS orbits at about 258 miles (415 km) above Earth, but over time, it naturally drifts closer due to a mix of Earth's gravitational pull and the thin atmospheric drag it experiences. Under normal circumstances, supply ships would deliver propellant needed for regularly performed reboost maneuvers to keep it in position.
Without these, the station would gradually descend.
NASA’s 2024 Space Station Transition Plan backs this up, estimating in their ISS Transition Plan that without intervention, the ISS would stay in orbit for about one to two years before eventually burning up in Earth’s atmosphere. Vsauce’s prediction of around 15 months is therefore pretty spot on.