21
$\begingroup$

If ISS was designed this way, couldn't the astronauts have a quick escape if the ISS is destroyed (severe meteor shower, re-entry, uncontrollable fire, explosive decompression, etc.) while they are asleep.

The crew cabins are also centralized on the station, so they would be quick to access.

Improve this question
$\endgroup$
6
  • 10
    $\begingroup$ 1) To turn every sleeping compartment into an escape module would add a lot of mass, not even counting a propulsion and guidance system, heat shield etc. 2) Not every astronaut sleeps in a dedicated sleeping compartment. I recall hearing of an astronaut that was authorised to sleep in one of the labs, so long as they secured themselves to fixed objects. 3) Meteor showers can be detected well ahead of time, and stray meteors too small to track are unlikely to cause a catastrophic failure that needs to be quickly acted on. 4) The greater danger would probably then be an unbalanced astronaut,, $\endgroup$
    – Andrew Thompson
    May 8, 2017 at 7:56
  • 6
    $\begingroup$ .. panicking and activating the eject functionality unnecessarily. $\endgroup$
    – Andrew Thompson
    May 8, 2017 at 7:56
  • 21
    $\begingroup$ By admittedly loose analogy, why aren't cruise ship cabins also lifeboats? It's a question of disaster event type with associated crew risk, probability of occurrence, and cost effectiveness of the method of escape. Every added system brings its own life cycle costs, reliability issues, fitness/availability for use at any given moment, crew training requirements, maintenance requirements, and risks associated with its use (or potential inadvertent or mis-use) even if in perfectly working order. Sometimes adding additional systems for a given contingency isn't the best solution. $\endgroup$
    – Anthony X
    May 8, 2017 at 16:16
  • 11
    $\begingroup$ Isn't this question basically the same as "Why don't the astronauts aboard the ISS sleep in the Soyuz capsule?" $\endgroup$
    – vsz
    May 9, 2017 at 6:14
  • $\begingroup$ Plus, how much time is actually spent in one's cabins versus at work, at play, etc.? $\endgroup$
    – Teacher KSHuang
    May 9, 2017 at 11:12

2 Answers 2

Reset to default
64
$\begingroup$

Primarily, because without a lot of extra equipment, they could at best be space coffins for the astronauts.

First, they share life support with the rest of the station. Air circulated through them is scrubbed of CO2 in the station's scrubbers. Heat is regulated through station's radiators. This all is powered by station's solar panels. And that's just for breathable atmosphere of reasonable temperature.

Now add to this:

  • airlock/hatch with undocking mechanism. That's not nearly as simple as it sounds, if you get into details of what that entails.
  • propulsion, to deorbit the pod (or it will float in space until the astronaut dies) - a launch to ISS takes months of planning at least, so no, "rescue mission" is not really an option.
  • attitude control, so that the propulsion deorbits the pod instead of sending it into a higher orbit or into a spin
  • heat shield for reentry. The power output during reentry is of order of gigawatts. Your typical heater for home is 1-2 kilowatts. This is a million times stronger. Shielding against this sort of heat is an enormous challenge
  • parachute
  • survival supplies, and a beacon for locating the landed capsule, because it can land pretty much anywhere on Earth, except polar regions.

...and probably a bunch of other stuff I missed.

From a simple box, this turns into a fully featured spacecraft. And you want a bunch of these, one per crew member. The cost becomes... astronomical.

Improve this answer
$\endgroup$
15
  • 2
    $\begingroup$ Can it really "land pretty much anywhere on Earth"? What happens if it lands in North Korea or an active warzone? $\endgroup$
    – Ordous
    May 8, 2017 at 12:35
  • 4
    $\begingroup$ If you check the IIS' ground track, you will see it passes over most of the world at some point, this is a deliberate choice so that multiple launch existing launch sites could be used without to much flight correction. So yes, something falling from the IIS' orbit could fall anywhere. It's unlikely as slight alterations of orbital trajectory have a dramatic impact on your landing site. But if it were to happen I'd imagine a very similar situation to what happens to foreign journalists or pilots who go down in these areas, if friendlies don't get there first, usually a hostage situation. $\endgroup$
    – CyanAngel
    May 8, 2017 at 13:09
  • 3
    $\begingroup$ The ground track was set by the location of the launch site in Russia. $\endgroup$
    – Organic Marble
    May 8, 2017 at 13:26
  • 3
    $\begingroup$ @Ordous: Then they are screwed. Simple as that. Given contact with ground station or even some time to perform calculations locally they can calculate the general region of landing. But read up on Voskhod 2 to see what happens if the planned window for landing is missed... $\endgroup$
    – SF.
    May 8, 2017 at 13:54
  • 1
    $\begingroup$ You probably don't need the life support if you deorbit immediately. If it holds pressure it will have breathable air for at least some time. $\endgroup$
    – Joshua
    May 8, 2017 at 16:02
20
$\begingroup$

Firstly the ISS doesn't have dedicated "escape pods". The Crew Return Vehicle was intended as one, but it was cancelled, so instead the ISS keeps enough Soyuz capsules docked to allow its occupants to escape in an emergency. This is a case of expedience, not of design from a blank sheet of paper.

That aside though, all capsules are only big enough to contain the astronauts, and no bigger. The larger you make it, the more fuel it takes to get it into orbit. It also costs more with all the heat shielding and other stuff, but that's secondary. The major cost with getting anything into orbit is the fuel to get it there, and the lighter it is, the less fuel you need. Also the capsules are designed to safely contain the astronauts during the ridiculously rough rides between Earth and space, but not for comfort when they're up there. So a capsule resembles a race car, not an RV.

All of this means that a capsule is just not going to be a comfortable place to sleep. Conversely, in the main habitation areas you have plenty of space to velcro your sleeping bag to the wall wherever is most convenient.

For your list of risks:-

  • Meteor showers and other debris risks are known about days or weeks ahead, and the astronauts then do shelter in the Soyuz capsules for safety, even though it's uncomfortable.
  • ISS re-entry would be known about months in advance, and simply will not happen unexpectedly (because physics).
  • A leak could happen, but that's an all-hands-on-deck emergency, and there is enough reserve air to allow the occupants to don EVA suits for repairs, or if it's not fixable then they can still get to the Soyuz capsules in time. Contrary to the bad Hollywood films that most likely inform this question, even exposure to space is not immediately fatal, and they've got enough time to get there before that happens anyway. Related question for this and actual decision tree for what to do.
  • Explosive decompression needs more than one atmosphere of pressure difference.
  • A fire is an all-hands-on-deck emergency too, and again the crew bail for the Soyuz capsules. And when fire-fighting, as per the link above:

Crew actions should provide possible ingress into their spacecraft

Improve this answer
$\endgroup$
14
  • 1
    $\begingroup$ Too many errors of fact in this answer, and no references. Downvoted. $\endgroup$
    – Organic Marble
    May 8, 2017 at 12:54
  • 1
    $\begingroup$ @MichaelKjörling: Soyuz can sustain the crew for weeks. Possible scenario for few days to reentry - MASSIVE coronal ejection. Possible scenario for hours: Kessler Syndrome. $\endgroup$
    – SF.
    May 8, 2017 at 13:50
  • 2
    $\begingroup$ @OrganicMarble Can you point out any errors of fact not yet mentioned by SF and Hobbes so they can be corrected? Also consider suggesting an edit. $\endgroup$
    – Philipp
    May 8, 2017 at 15:09
  • 1
    $\begingroup$ @Hobbes My bad - I believed they did run a rotating sleep pattern, but I'm wrong. I've editted my answer accordingly. $\endgroup$
    – Graham
    May 8, 2017 at 15:12
  • 1
    $\begingroup$ @SF As Nathan says, the question mentions re-entry as a threat to the ISS, not to the Soyuz. Given the mass of the ISS (400 tonnes), the only possible way that the ISS could be de-orbitted rapidly would be a direct impact by an extinction-level-event-sized meteorite, at which point there would be little left of the ISS, the astronauts, or (a few minutes later) Earth and every major species on it. $\endgroup$
    – Graham
    May 8, 2017 at 15:22

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct.

Not the answer you're looking for? Browse other questions tagged or ask your own question.