Author Topic: LM Hatch  (Read 343 times)

Offline Peter B

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LM Hatch
« on: October 04, 2019, 06:33:14 AM »
G'day everyone

One of the side stories that interests me about Apollo is the decision about which astronaut would go out first on the moonwalk - the CDR or the LMP.

The thing is, there seem to be two narratives going around. One is that NASA managers made the decision that the CDR should go out first (possibly as a way of getting Armstrong out ahead of Aldrin). The other is that the side the LM the hatch hinge was located made it impractical for the LMP to get out first.

But neither of these stories seems entirely satisfactory to me. The idea of having the CDR go out first seems a little arbitrary, although I can sort of see the reason for giving primacy to the "senior" crewman. And the idea that the hatch hinge dictated things doesn't make sense as I would have thought it would be a fairly minor issue to redesign the hatch to have its hinge on the opposite side - given the things that Grumman was redesigning on the LM (even after Apollo 11, such as the fuel tank baffles).

So does anyone have the inside story on exactly how the decision was made for who went out first, and what the logic behind the decision was?

Thank you!

Offline Allan F

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Re: LM Hatch
« Reply #1 on: October 04, 2019, 09:27:00 AM »
Redesigning a billion dollar spacecraft or telling the other guy to wait his turn?

Get in line!
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Offline Ranb

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Re: LM Hatch
« Reply #2 on: October 04, 2019, 07:25:05 PM »
What I read on the matter says it was not practical for the LMP to exit first or to changes sides with the CDR while suited up with the PLSS.  The simple solution I suppose is to change places prior to suit-up so either could go out first.  This tells me that the powers-that-be decided the CDR would be the first on the lunar surface long before the flight took place.

Offline Peter B

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Re: LM Hatch
« Reply #3 on: October 05, 2019, 09:32:26 PM »
What I read on the matter says it was not practical for the LMP to exit first or to changes sides with the CDR while suited up with the PLSS.  The simple solution I suppose is to change places prior to suit-up so either could go out first.  This tells me that the powers-that-be decided the CDR would be the first on the lunar surface long before the flight took place.

Well, that makes a lot of sense. And yet the story is presented that some time after Armstrong and Aldrin knew they'd likely be flying the first landing mission, Aldrin was lobbying to be the first one out. The story is told in a way that suggests the decision hadn't yet been made, and it took Aldrin to confront Armstrong in a scene that Collins witnessed, followed by a visit to Slayton's office, before anyone said openly that Armstrong would be first...

Certainly that's the way the story comes out in books like Chaikin's.

Offline Obviousman

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Re: LM Hatch
« Reply #4 on: October 06, 2019, 05:42:19 PM »
What I read on the matter says it was not practical for the LMP to exit first or to changes sides with the CDR while suited up with the PLSS.  The simple solution I suppose is to change places prior to suit-up so either could go out first.  This tells me that the powers-that-be decided the CDR would be the first on the lunar surface long before the flight took place.

Well, that makes a lot of sense. And yet the story is presented that some time after Armstrong and Aldrin knew they'd likely be flying the first landing mission, Aldrin was lobbying to be the first one out. The story is told in a way that suggests the decision hadn't yet been made, and it took Aldrin to confront Armstrong in a scene that Collins witnessed, followed by a visit to Slayton's office, before anyone said openly that Armstrong would be first...

Certainly that's the way the story comes out in books like Chaikin's.

It wouldn't have been practical to swap sides; they were all suited up as you have said. They couldn't have done it before as that meant the CDR would have been at the LMP station. They might have been able to do it afterwards but that meant taking off the suit, partially stowing them, changing sides, etc.

Consider also, though, that one of the early LM designs had that front hatch as a docking port; perhaps in that situation either could have gone out first. The design then changed, resulting in a square, hinged hatch. I suspect the hinge placement was almost random. I think the consideration was going to be how easy it would be open / close the hatch, from either side, and what hand the astronauts would have to use. I think it could have simply been a right-hand-dominant bias.

Offline Count Zero

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Re: LM Hatch
« Reply #5 on: October 06, 2019, 08:36:31 PM »
Note that on Apollo 9, it was the LMP who made the EVA.

That said, considering the need to have the EVA timelines & checklists written, and have the astronauts practice them as written (and make whatever changes are necessary), I would imagine the decision was made many months in advance.
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Offline ka9q

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Re: LM Hatch
« Reply #6 on: October 07, 2019, 07:05:02 AM »
I really wish people would stop arguing about this one. The real achievement was landing on the moon, which was a joint effort of the two crewmen (plus a thousand or so support people on Earth). Going out for a walk was trivial by comparison.

Offline Count Zero

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Re: LM Hatch
« Reply #7 on: October 07, 2019, 08:58:47 PM »
To me, it's not a matter of arguing.  I am simply interested in what factors drove the decision to do things a certain way.
"What makes one step a giant leap is all the steps before."

Offline Obviousman

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Re: LM Hatch
« Reply #8 on: October 08, 2019, 04:36:06 PM »
To me, it's not a matter of arguing.  I am simply interested in what factors drove the decision to do things a certain way.

Ditto. I'm curious as to what the actual reasoning was. I agree with ka9q that they both landed at the same time, and that was the most important thing.... but I am still interested in the details.