Author Topic: LM Ascent Stage as Lifeboat post Apollo 13?  (Read 4583 times)

Offline vericksen

  • Member
  • Posts: 6
  • Liked: 0
  • Likes Given: 0
LM Ascent Stage as Lifeboat post Apollo 13?
« on: 07/07/2011 01:54 am »
I guess I should first ask...

The LM Ascent Stage, after docking w/the CSM and offloading rocks, etc was then jettisoned, correct? I assume while both vehicles were in moon orbit...

If indeed the LM Ascent Stage was "dumped", my real question is why not carry it along as a lifeboat until an appropriate time before splashdown? The safety factor of having an extra vehicle along would offset any penalties in weight or difficulties in navigation that hauling the LM Ascent Stage, would it not? (Extra propulsion, sealed environment, electricity, etc...)

(And of course excuse me if this is an asked/answered topic. I searched a bit...)

Offline Fequalsma

  • Full Member
  • ****
  • Posts: 505
  • Liked: 57
  • Likes Given: 1
Re: LM Ascent Stage as Lifeboat post Apollo 13?
« Reply #1 on: 07/07/2011 02:44 am »
Maybe the SM didn't carry enough prop to push both the CSM and LM ascent stage into TEI?  Maybe the LM ascent stage didn't carry enough consumables to make it usable as a lifeboat? 

Offline pathfinder_01

  • Senior Member
  • *****
  • Posts: 2074
  • Liked: 271
  • Likes Given: 8
Re: LM Ascent Stage as Lifeboat post Apollo 13?
« Reply #2 on: 07/07/2011 03:12 am »
Not enough propellant to do so. Apollo 13 did not enter lunar orbit they used the free return trajectory to get home.

A normal mission would have:

Breaked into lunar Orbit using the CM.

Landed on the moon using the propellant in the Descent module of the LM

Lifted off from the moon using the propellant in the Accent module of the LM

Discared the Accesent module


Broke out of lunar orbit using the CM

Slowed down a bit before reentry using the CM.

Carring the Ascent module would have caused you to need more propellant to leave lunar Orbit which in turn would cause you to need more propellant to break into lunar orbit which in turn would cause you to need more propellant to get to lunar inejection and so on.

Apollo 13 did not enter lunar orbit. However post Apollo 13 a extra battery was added to the CM so that it could possibly limp back home if the fuel cells failed(not sure on the limits of that--i.e. how many hours did it buy). The CM was redesigned to make the cause of Apollo 13 less likely to happen.

Offline Naito

  • Full Member
  • **
  • Posts: 204
  • Toronto, Canada
  • Liked: 68
  • Likes Given: 51
Re: LM Ascent Stage as Lifeboat post Apollo 13?
« Reply #3 on: 07/07/2011 03:19 am »
I believe the ascent stage is pretty much "spent" by the time it redocks with the CM.  There'd have been very little fuel or battery power left, so it'd be mostly just dead weight reducing the performance available in the SM engine.
Carl C.

Offline Danderman

  • Extreme Veteran
  • Senior Member
  • *****
  • Posts: 10288
  • Liked: 699
  • Likes Given: 723
Re: LM Ascent Stage as Lifeboat post Apollo 13?
« Reply #4 on: 07/08/2011 03:42 pm »
Also, its questionable whether the SM contained enough prop to get the CSM/SM plus LM ascent stage back to Earth. Plus, scientists wanted seisomgraph data from the ascent stage lunar crash.

Offline Danderman

  • Extreme Veteran
  • Senior Member
  • *****
  • Posts: 10288
  • Liked: 699
  • Likes Given: 723
Re: LM Ascent Stage as Lifeboat post Apollo 13?
« Reply #5 on: 07/08/2011 03:43 pm »
I believe the ascent stage is pretty much "spent" by the time it redocks with the CM.  There'd have been very little fuel or battery power left, so it'd be mostly just dead weight reducing the performance available in the SM engine.

I would guess that the ascent stage could have remained powered via power transfer from the CSM/SM, so there would have been a benefit of the additional volume for the crew during the 3 day return.
« Last Edit: 07/08/2011 03:43 pm by Danderman »

Offline ZANL188

  • Member
  • Member
  • Posts: 91
  • Liked: 8
  • Likes Given: 6
Re: LM Ascent Stage as Lifeboat post Apollo 13?
« Reply #6 on: 07/08/2011 05:13 pm »
I believe the ascent stage is pretty much "spent" by the time it redocks with the CM.  There'd have been very little fuel or battery power left, so it'd be mostly just dead weight reducing the performance available in the SM engine.

I would guess that the ascent stage could have remained powered via power transfer from the CSM/SM, so there would have been a benefit of the additional volume for the crew during the 3 day return.

Not much point of having the ascent stage as a lifeboat if it needs power from the CSM to do so.  Might just as well use the CSM.  Of what benefit would the additional volume be?

Offline Danderman

  • Extreme Veteran
  • Senior Member
  • *****
  • Posts: 10288
  • Liked: 699
  • Likes Given: 723
Re: LM Ascent Stage as Lifeboat post Apollo 13?
« Reply #7 on: 07/08/2011 05:17 pm »
I believe the ascent stage is pretty much "spent" by the time it redocks with the CM.  There'd have been very little fuel or battery power left, so it'd be mostly just dead weight reducing the performance available in the SM engine.

I would guess that the ascent stage could have remained powered via power transfer from the CSM/SM, so there would have been a benefit of the additional volume for the crew during the 3 day return.

Not much point of having the ascent stage as a lifeboat if it needs power from the CSM to do so.  Might just as well use the CSM.  Of what benefit would the additional volume be?

Try spending 3 days in 210 cubic feet of volume with 2 other guys, and then you might understand.

Offline ZANL188

  • Member
  • Member
  • Posts: 91
  • Liked: 8
  • Likes Given: 6
Re: LM Ascent Stage as Lifeboat post Apollo 13?
« Reply #8 on: 07/08/2011 06:11 pm »
I believe the ascent stage is pretty much "spent" by the time it redocks with the CM.  There'd have been very little fuel or battery power left, so it'd be mostly just dead weight reducing the performance available in the SM engine.

I would guess that the ascent stage could have remained powered via power transfer from the CSM/SM, so there would have been a benefit of the additional volume for the crew during the 3 day return.

Not much point of having the ascent stage as a lifeboat if it needs power from the CSM to do so.  Might just as well use the CSM.  Of what benefit would the additional volume be?

Try spending 3 days in 210 cubic feet of volume with 2 other guys, and then you might understand.


Let me rephrase the question:  Of what benefit would the additional volume be in a lifeboat situation?  That it's uncomfortable is a given.

Offline truth is life

  • Full Member
  • **
  • Posts: 278
  • Liked: 7
  • Likes Given: 8
Re: LM Ascent Stage as Lifeboat post Apollo 13?
« Reply #9 on: 07/08/2011 08:30 pm »
Let me rephrase the question:  Of what benefit would the additional volume be in a lifeboat situation?  That it's uncomfortable is a given.

More to the point, why would there be a need for extra volume in a lifeboat situation and not during the normal return profile? If anything, you'd expect it to be the other way around.

Offline Danderman

  • Extreme Veteran
  • Senior Member
  • *****
  • Posts: 10288
  • Liked: 699
  • Likes Given: 723
Re: LM Ascent Stage as Lifeboat post Apollo 13?
« Reply #10 on: 07/09/2011 02:34 pm »
I believe the ascent stage is pretty much "spent" by the time it redocks with the CM.  There'd have been very little fuel or battery power left, so it'd be mostly just dead weight reducing the performance available in the SM engine.

I would guess that the ascent stage could have remained powered via power transfer from the CSM/SM, so there would have been a benefit of the additional volume for the crew during the 3 day return.

Not much point of having the ascent stage as a lifeboat if it needs power from the CSM to do so.  Might just as well use the CSM.  Of what benefit would the additional volume be?

Try spending 3 days in 210 cubic feet of volume with 2 other guys, and then you might understand.


Let me rephrase the question:  Of what benefit would the additional volume be in a lifeboat situation?  That it's uncomfortable is a given.

I was discussing the rationale for keeping the ascent stage for the return journey to Earth; not necessarily as a lifeboat, but as a habitation area for the crew. For example, Apollo 10 could have returned with the LM upper stage.

Of course, I am ignoring any risks from carrying what is effectively a rocket stage for a few days.

Tags:
 

Advertisement NovaTech
Advertisement Northrop Grumman
Advertisement
Advertisement Margaritaville Beach Resort South Padre Island
Advertisement Brady Kenniston
Advertisement NextSpaceflight
Advertisement Nathan Barker Photography
0