Gravity. Fact check. Potential Spoilers.
October 20, 2013 8:58 PM   Subscribe

I just saw Gravity this weekend...

In doing follow-up reading about scientific accuracy, I came across some talk about suicide in space. Some people believe that Apollo astronauts had suicide pills in case something went wrong. Someone 'in the know' said that the film was accurate: if it came to that, oxygen could just be turned off for a gentle end to things. So... question:

How long would it have taken Sandra Bullock's character to die after turning off the oxygen in the Soyuz capsule? Bonus points for a timeline of possible physical effects she would have experienced along the way.
posted by mazola to Science & Nature (14 answers total) 6 users marked this as a favorite
Probably longer than you might think:
In general, the brain can withstand up to three to six minutes without oxygen before brain damage occurs, but this may vary from person to person. If the brain goes without oxygen longer than this, serious and often irreversible damage is likely to take place. After ten minutes, severe neurological damage has generally occurred. Very few people regain any cognitive function after the brain has gone 15 or more minutes without oxygen.
Note how the coldness can lengthen duration as well.

Regarding symptoms: Cerebral hypoxia - signs and symptoms.

This is more general, but more on this page if you scroll down to symptoms. This is more relevant to stroke/heart attack patients and recovery but still.
posted by smoke at 10:51 PM on October 20, 2013

I think you need to clarify. Are looking for how long it take a person to die after having their oxygen cut odd or how long would it take a single person to use up all the current oxygen in the three person Soyuz descent module?
posted by Brandon Blatcher at 1:30 AM on October 21, 2013 [2 favorites]

Response by poster: Yes I'm looking for the specifics of the movie. When Bullock turns the oxygen off the capsule ceases to be fed new oxygen, but still contains the existing. From that starting point what is the timeline and what would her character experience on their way to asphyxiation?
posted by mazola at 6:00 AM on October 21, 2013

According to this page on a NASA website, the Soyuz descent module has 141 cubic feet of habitable space. From there one could guess how much space Bullock's character would take up, which would roughly determine how much air was left. Then lookup how much air a resting human uses up and how quickly and you'd have a rough number.

The character of Ryan Stone would probably be dreaming of her daughter as she asphyxiated. Possibly her life back on Earth.
posted by Brandon Blatcher at 6:26 AM on October 21, 2013 [1 favorite]

Response by poster: According to this, "the average adult at rest inhales and exhales something like 7 or 8 liters (about one-fourth of a cubic foot) of air per minute."

So that would about 9 hours before the capsule oxygen fully depletes?

Any idea when a person would begin feeling the effects of asphyxia in the hypothetical Soyuz situation and when the air would be too 'thin' to be useful (I'd assume death would occur before the oxygen is 100% depleted)?
posted by mazola at 8:31 AM on October 21, 2013

You might find these calculations on how long a person can survive in an enclosed volume of air useful.
posted by blue_beetle at 8:34 AM on October 21, 2013 [1 favorite]

Response by poster: So I'm getting about 7 hours, discounting the effects of CO2 build-up (which I assume would not come into play as the capsule's CO2 filters would still be operating, yes?).
posted by mazola at 11:54 AM on October 21, 2013

Response by poster: Sorry, was doing it wrong.

141 cubic feet = 2.5168 m3

2.5168 m3 x 0.061 day/m3 = 0.1535248 day = 3.685 hours

Again, discounting CO2 build-up.
posted by mazola at 1:42 PM on October 21, 2013

The high levels of CO2 would probably kill you before the low levels of O2.

The 1986 Lake Nyos mass asphyxiation event is an interesting example; estimates of PCO2 during the event are between 18 - 28%. Ok, so maybe not a perfect example, but you get the idea.
posted by oceanjesse at 6:41 PM on October 21, 2013 [1 favorite]

Response by poster: But would CO2 be a factor? Isn't it removed via a filter system?
posted by mazola at 7:15 AM on October 22, 2013

I guess it depends on how the Environmental Control and Life Support System fails.
posted by oceanjesse at 8:20 AM on October 22, 2013

More information about the Amine Swingbed. Also, they have an email address at the bottom of this page to which you can direct general questions.
posted by oceanjesse at 8:24 AM on October 22, 2013

Response by poster: More on CO2 build-up (and chronology of effects).
posted by mazola at 8:06 AM on October 25, 2013 [1 favorite]

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