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I read an article some time ago about the opposite scenario. I searched for the article just now but didn't find it; would be curious if anyone has a link.

I remembered it something like this (but see soarfourmore's reply for a correction): what if the command module pilot became incapacitated but was still alive?

The lunar module could still dock with the command module, but the astronauts would not be able to get into the command module because the the CM pilot could not open the hatch on that side.

So their only option would be to do a spacewalk over to the command module and open an external hatch to get in.

The would not know at that point whether the CM pilot had his spacesuit helmet on or not, so they wouldn't know until they opened the hatch whether they had just killed him.

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> The would not know at that point whether the CM pilot had his spacesuit helmet on or not, so they wouldn't know until they opened the hatch whether they had just killed him.

There were windows on the command module to look in, and if they weren't sure if he was responsive/unresponsive, they could tap iron onto the command module to let Collins know they were there and spacewalking.

It's an interesting thought process though, and I would appreciate the source if you can find it

Found it!

https://spaceflightblunders.wordpress.com/2017/04/07/lunar-o...

From the article, I was wrong about not knowing whether the CMP was alive:

"Unless there was a very serious issue with the CM’s communications systems, NASA would know of the CMP’s fate immediately. Every astronaut wears biomedical sensors at all times, as part of their constant-wear garment. This telemetry is sent to the flight surgeon."

More discussion here:

https://space.stackexchange.com/questions/45426/procedure-to...

A comment from that page:

"Probably the worst scenario would be for the CMP to be alive, but disabled and not in his spacesuit. There would be no way for the other astronauts to get to the CMP without depressurizing the CM, thus killing the CMP. It's an obvious choice between three astronauts stranded in lunar orbit, versus two getting home alive. Nonetheless, I can only imagine the regret that the astronaut who would have to depressurize the CM would have."

So it is even worse than the way I remembered it: the LM pilots would likely know that the CMP pilot was alive but incapacitated and they were about to kill him.

You can survive vaccuum for a brief period of time.

> Flight recorder data from the single cosmonaut outfitted with biomedical sensors showed cardiac arrest occurred within 40 seconds of pressure loss. […] The autopsies took place at Burdenko Military Hospital and found that the cause of death proper for the cosmonauts was hemorrhaging of the blood vessels in the brain, with lesser amounts of bleeding under their skin, in the inner ear, and in the nasal cavity, all of which occurred as exposure to a vacuum environment caused the oxygen and nitrogen in their bloodstreams to bubble and rupture vessels. Their blood was also found to contain heavy concentrations of lactic acid, a sign of extreme physiologic stress. Although they could have remained conscious for almost 40 seconds after decompression began, less than 20 seconds would have passed before the effects of oxygen starvation made it impossible for them to function.

https://en.wikipedia.org/wiki/Soyuz_11

If you want to see how disabling even a little loss of pressure can be, check it this video.

https://youtu.be/7wT9-zaK3Zo

Apparently you can survive about 40 seconds in a vacuum. One option would be for one pilot to enter (as quickly as possible!) then put the CMP into a spacesuit, then re-admit the other astronaut. No clue if they could enter and re-pressurize the capsule within 30 seconds- sounds like a long-shot.

https://www.newscientist.com/article/mg20627561-700-maxed-ou...

It takes about 45 minutes to don a modern spacesuit -- and that assumes the person donning the spacesuit is assisting with the process, not incapacitated.

https://www.nasa.gov/audience/foreducators/spacesuits/facts/...

Edit: This says it can actually be done in five minutes in an emergency if one's willing to skip every safety check, but getting an unresponsive person into one seems like surely it would be more of a challenge -- particularly if the "helper" was wearing a spacesuit himself. Those things are awfully restrictive! And I would wager it's not a scenario they practiced.

https://airandspace.si.edu/stories/editorial/how-do-you-put-...

I think they are suggesting:

- Enter the command module, in spacesuit

- Quickly re-pressurize

- Help incapacitated astronaut into suit (temporarily removing own suit if necessary)

- Once both suited up, open airlock again to admit remaining astronaut

But I’m not sure if that would have been possible. Was there really a way to re-pressurize in a few seconds, 2001 style?

> - Help incapacitated astronaut into suit (temporarily removing own suit if necessary) > - Once both suited up, open airlock again to admit remaining astronaut

These steps don't seem to be necessary. Since the CM can be opened from the inside towards the LM, the third astronaut could just wait in the LM and be let in that way.

I think the only question is really how quickly can you repressurize the CM.

It was basically a cone-shaped pressure vessel 3.23m tall and 3.91m wide, that's 51.71m^3 of volume. I'd estimate about 50% is taken up by machinery, so how fast can you repressurize 25m^3 to 1/3 sea level (which was apparently standard for the spacecraft)?

My guess would be it could be done pretty quickly, maybe 2 minutes?

Your insight suggests an even better solution: the spacewalking astronaut could open the internal hatch to the docked Lunar Module so its cabin air can instantly partially repressurize the Command Module

Maybe, IF the hatch can be opened when there is a pressure difference. It might be dangerous or even mechanically locked out in those cases. It may not, I have no idea.

I mean we're just guessing and spitballing here, and all of this assumes that whatever incapacitated the CMP is fixable by the other astronaut. But it does look like there may be a decent chance the CMP could survive this. Of course, he might have internal injuries or they might not be able to restart his heart. But seems like this procedure would be worth a try.

Opening the hatch was a huge pain. They'd have to disassemble the rather phallic docking mechanism (as Collins described it). Not being able to disassemble it was one of the fears Collins had about Apollo 11.

If he was incapacitated slowly, he might have time to don a spacesuit, anticipating this scenario? NASA must know.

I've been in a number of situations myself where swift incapacitation would have killed me. This is common.

Looking at other times when astronauts became ill, they tended to tough it out until too late to put on a space suit.

Similarly, Collins wrote a memo to the astronaut corps explaining that on the Mercury missions, if someone became incapacitated during EVA, they'd have to cut their life support cable and close the hatch and come home alone.

Very interesting and grim! But Mercury capsules only carried a single astronaut. You may be thinking of Gemini or Apollo?

I don’t know how fast they’d be able to enter and repressurize the capsule, but I suppose there’s a chance he could survive in that scenario. Though depending on why was incapacitated in the first place his chances may have even more diminished by whatever afflicted him.

What if the command module pilot became incapacitated but was still alive?

That's why one of the mission planning decisions was that the astronaut tasked with operating the orbiter must have previous time in space.

And they made him fly acrobatics in a jet shortly before the mission. ("Made" might be too strong a word since Collins thought it was fun.) NASA thought that might help train the inner ear to avoid the dreaded space sickness.

Apollo 15, 16 and 17 did perform nominal EVAs from the command module after the lunar landing, to retrieve film cassettes. To this day they are the only 3 deep space EVAs ever made. All others have been either in Earth orbit or on the moon.

To clarify, they were transearth EVAs, so they were not even during orbit around the moon. I recall seeing some upscaled videos on youtube of this which looked pretty unearthly.

https://www.history.nasa.gov/SP-4029/Apollo_18-30_Extravehic...

links to some vids:

https://www.drewexmachina.com/2017/12/17/a-history-of-deep-s...

I found one upscaled and interpolated to 24fps:

https://www.youtube.com/watch?v=SI4ou1PpFH0

That's soooo cool. I love the audio "This is what it means to be a spaceman! Ok, back to work." Cowboys. Highly educated and extensively trained cowboys, but still cowboys and little kids.

Also, in the article linked below, Al Worden described his transearth EVA on Apollo 15 in which he could see both the entirety of the earth and moon simultaneously in his field of vision (the only person to do so in history?). He regrets not having a camera, but he later had an artist recreate the memorable view of the moon behind Jim Irwin (included in the article).

https://www.smithsonianmag.com/smithsonian-institution/i-was...

Reminds me of Collins on Gemini 10. He did an EVA from further from Earth than anyone had ever been before. He took pictures of the Gemini capsule with Earth in the background. And then his camera fell off and drifted until space.

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