What Happens to Your Body in Space Without a Spacesuit?
What really happens if you step into space without a spacesuit? You don't explode. You don't freeze solid. Your blood doesn't instantly boil. Something much sneakier gets you first, and it's your own lungs.
I open the airlock in a T-shirt and we follow the mission clock second by second: the whoosh, why you must breathe out, your spit boiling and freezing at the same time, the real NASA vacuum-chamber accident of Jim LeBlanc, why you pass out in about ten seconds, why your body puffs up, Joe Kittinger's swollen hand at 31 km, why space is a giant thermos, the danger line at about a minute and a half, and the rescue. Plus the real air leak that sent astronauts on the space station into their capsule in June 2026.
The animation is our own art; real photos are from NASA, the U.S. Air Force and a 1971 Soviet stamp.
Chapters
- 0:00 Ten seconds in space (opens in a new tab)
- 0:27 The real air leak (June 2026) (opens in a new tab)
- 0:57 Air is pushing on you (opens in a new tab)
- 1:13 The marshmallow and the boiling water (opens in a new tab)
- 1:53 The three movie endings (opens in a new tab)
- 2:09 Second zero: the airlock (opens in a new tab)
- 2:56 Boiling and freezing at once (opens in a new tab)
- 3:22 Jim LeBlanc's vacuum accident (opens in a new tab)
- 4:08 Why you pass out so fast (opens in a new tab)
- 5:02 Puffing up (opens in a new tab)
- 5:27 Joe Kittinger's glove (opens in a new tab)
- 5:57 Why you don't freeze (opens in a new tab)
- 6:39 The danger line (opens in a new tab)
- 7:25 The rescue (opens in a new tab)
- 7:58 The answer (opens in a new tab)
Sources
- NASA Bioastronautics Data Book, 2nd ed. (SP-3006, 1973), Ch. 1 "Barometric Pressure": https://ntrs.nasa.gov/citations/19730006364 (opens in a new tab)
- FAA Advisory Circular AC 61-107B, Times of Useful Consciousness: https://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_61-107B.pdf (opens in a new tab)
- Bancroft, "Physiological Responses to Near-Vacuum" (1966): https://store.astm.org/stp46440s.html (opens in a new tab)
- Jim LeBlanc accident: NASA (via kottke.org), Space Safety Magazine (2012), Roth NASA CR-1223 (1968)
- Joe Kittinger, National Geographic, Nov 1960; USAF Museum (Excelsior): https://www.nationalmuseum.af.mil/Visit/Museum-Exhibits/Fact-Sheets/Display/Article/195681/excelsior-gondola/ (opens in a new tab)
- Soyuz 11: https://www.russianspaceweb.com/soyuz11-accident.html (opens in a new tab) ; NASA JSC: https://ntrs.nasa.gov/citations/20120006021 (opens in a new tab)
- ISS air leak shelter, June 2026: https://www.scientificamerican.com/article/astronauts-take-shelter-on-the-international-space-station-due-to-air-leaks/ (opens in a new tab)
- Photos: NASA (space station, Crew Dragon, McCandless spacewalk, Johnson Space Center Chamber A), U.S. Air Force (Kittinger), USSR postal stamp 1971 (Soyuz 11 crew)
- Music: YouTube Audio Library (Stake Out, Fire In The Sky, Ancient Civilisations by Alex Jones / Xander Jones; Drifting Memories, Obon Fog by The Mini Vandals; The Fifth Quadrant by Dan "Lebo" Lebowitz, Tone Seeker; Drone Shot by Dyalla; Pulsar, False Vacuum Decay, Taking Flight)
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