13
$\begingroup$

In the book on the ill-fated Apollo 13 mission there is a chapter that contains an overview of the consumables on board the spacecraft, and whether or not they might pose a problem to the survival of the astronauts. Because the CDR and LMP were scheduled to perform two EVAs on the lunar surface, they had ample oxygen (the atmosphere of the LEM would be vented and completely replaced twice for these EVAs) but the LEM could not support the three men because the CO2-scrubbers were insufficient.

With them having sufficient oxygen I was wondering if the crew might have survived if they had all donned their space suits (or at least the CDR and LMP, taxing the scrubbers less). My reasoning is:

  • The suits can be used inside the spacecraft using umbilical connections that draw on the LEM's ample oxygen supplies
  • For suits worn only inside the craft cooling water (another thing they did not have in excess) is not needed as the flow of oxygen provides cooling
  • If they used the PLSS backpack the CDR and LMP could even stretch the LEMs resources another 14 hours

The only way I can think of that would invalidate this approach was if the suits umbilical connectors also relied on the scrubbers on the LEM to function, but I can't find anything to confirm or deny this.

$\endgroup$
  • 7
    $\begingroup$ Note that there are two problems that must both be solved. Obviously, if there's not enough oxygen in the air, you asphyxiate and die. However, your breathing is controlled by a reflexive action that causes you to exhale whenever the CO2 concentration in your blood or lungs gets too high. That means that, if there's too much CO2 in the air (and the critical concentration is actually quite low), you can't breathe, even if there's plenty of oxygen available. So you do need both the scrubbers and the oxygen supply. $\endgroup$ – David Richerby Jan 7 '15 at 12:20
  • 1
    $\begingroup$ The book states that they had sufficient oxygen in the LEM to last the three of them at least a week. They returned to earth three and a half days after the accident (accident occured April 14 at 03:07:53, splashdown on April 17 at 18:07:41 UTC) so they had practically twice the oxygen they needed. I'm thinking maybe they could have vented the exhaled air from the suits along with the CO2, eliminating the need for scrubbers. I'm pretty sure NASA figured that wouldn't work but I'm wondering why exactly... $\endgroup$ – JDT Jan 7 '15 at 12:39
  • 3
    $\begingroup$ The problem is almost certainly CO2 concentration. According to Wikipedia, 1% CO2 causes drowsiness and 7+% may be fatal. I would guess they didn't have enough oxygen available to do enough atmosphere dumps to keep the CO2 concentration within safe levels. $\endgroup$ – David Richerby Jan 7 '15 at 13:14
  • $\begingroup$ Is there room enough inside a LM for three people wearing a 60s' space suite?!? Probably they should have been sit and don't move for the whole 3 days of the journey. $\endgroup$ – jumpjack Feb 3 '15 at 10:58
  • $\begingroup$ I doubt that there were more than two connections for suits in the LM. $\endgroup$ – Uwe Feb 19 '17 at 15:34
5
$\begingroup$

The CO2 scrubbers were certainly an issue to be solved on Apollo 13, but I believe the most difficult problem was that of power. The fuel cells on the spacecraft needed oxygen that was lost in the tank that ruptured. I doubt there would have been enough power available to operate the suits.

$\endgroup$
  • 3
    $\begingroup$ I suspected this to be the right answer, but I couldn't confirm it. However, the EECOM section of the Mission Operations Report (hq.nasa.gov/alsj/a13/A13_MissionOpReport.pdf) states: C02 scrubbing could have been accomplished by operating the CM suit compressor with two canisters installed in the canister assembly in their normal configuration. This technique would have eliminated the makeshift setup plus creating some much needed heat in the CM cabin environment. However, the power requirement for this and the initial unknown condition of the CSM Main Bus B eliminated this setup. $\endgroup$ – JDT Apr 20 '15 at 15:23
  • $\begingroup$ @JDT I wonder what the tradeoff would have been in terms of CO2 production and oxygen consumption vs scrubbing ability if they'd pulled the suit compressor apart and run it by hand... Although they likely didn't have the tools necessary to do that anyway. $\endgroup$ – Perkins Jun 13 '18 at 22:31

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

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