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Author
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Topic: Ascending the Apollo lunar module ladder
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Paul78zephyr
Member Posts: 678
From: Hudson, MA
Registered: Jul 2005
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posted 09-18-2015 08:02 PM
  
I have seen lots of footage showing the Apollo astronauts 'jumping' off the last rung of the ladder on the Apollo lunar module and in some of those videos it looks like quite a jump. Is there any footage that shows them jumping back up? |
One Big Monkey
Member Posts: 171
From: West Yorkshire, UK
Registered: Jul 2012
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posted 09-19-2015 03:21 AM
The full Apollo 11 broadcast shows Neil dong a test jump back up the ladder immediately after first descending it.The three rover missions all filmed the LM from their final parking place, so full videos of the final moments on the moon might show it depending on the orientation of the rover and LM. Your best bet is probably the full Apollo 17 TV broadcast, as I think the ladder is in the right place to be seen clearly. |
LM-12
Member Posts: 3324
From: Ontario, Canada
Registered: Oct 2010
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posted 09-20-2015 03:35 PM
After his first few minutes on the lunar surface, Dave Scott climbs back up the LM ladder to help guide Jim Irwin out the hatch. Then Scott climbs back down the ladder, followed shortly by Irwin (with his gold visor up). |
Lou Chinal
Member Posts: 1332
From: Staten Island, NY
Registered: Jun 2007
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posted 09-20-2015 05:56 PM
The height between the bottom rung and the lunar surface was the subject of a lot debate before the first landing. The legs/struts were designed to crush upon contact. Now just how much they would crush was speculation. All of the Apollo landings exerted far less force than planed.Allow me to quote Neil Armstrong: NA: "Okay, I just checked — getting back up to that first step. Buzz, it's not even collapsed too far, but it's adequate to get back up."CAPCOM: "Roger, we copy." NA: "It takes a pretty good little jump." |
LM-12
Member Posts: 3324
From: Ontario, Canada
Registered: Oct 2010
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posted 09-20-2015 06:19 PM
Jim Irwin mentions in the debrief that it was "a real struggle" for him getting back up to that first ladder rung. Pete Conrad said it was "easy" in the EVA-1 transcript. |
MadSci
Member Posts: 230
From: Maryland, USA
Registered: Oct 2008
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posted 09-26-2015 12:21 PM
Indeed the LM legs were filled with a honeycomb like material designed to be crushed as the strut compressed upon landing. This would absorb the energy of what was intended to be a fall to the lunar surface after the engine was cutoff upon the initial surface contact by the landing probe(s).However, in several cases, including Apollo 11, the engine was not cut off promptly as intended, resulting in a 'soft; landing that left the LM leg struts relatively uncompressed. Since the bottom of the slander could not be allowed to touch the ground even in a 'hard' landing, this meant it was cut off at a fairly good height above the ground (in pre-landing condition). Hence 'soft' landing flights left a good distance from the surface to the bottom of the ladder. The combination of decent speed and height of the LM at engine cut off determined the amount of strut compression, and hence the height between the bottom of the ladder and the surface on every flight. The astronauts were trained to immediately attempt to jump back up to the bottom rung before stepping onto the surface in order to determine if the maneuver was possible unassisted. If it was not, I suppose there was a contingency plan involving using a lanyard and or some form of assistance from the crewmember inside the LM to get back up safely. Fortunately, these were never needed. |
MadSci
Member Posts: 230
From: Maryland, USA
Registered: Oct 2008
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posted 09-26-2015 12:28 PM
quote:
Originally posted by LM-12:
Jim Irwin mentions in the debrief that it was "a real struggle" for him getting back up to that first ladder rung. Pete Conrad said it was "easy" in the EVA-1 transcript.
As I recall, Conrad was very concerned about hitting the Engine Cutoff switch promptly and allowing the LM to drop the final 6 feet to the surface as it was designed. The engineers were very worried that the exhaust gasses could be reflected off of the surface back into the engine bell and induce a detonation. Armstrong had been too involved in cancelling the final lateral motions of the LM to notice the Contact light in time to do this, and there was a real suspicion that they had 'dodged a bullet' as a result.Of course, as the shortest Apollo astronaut, Conrad was probably also thinking privately about making sure the LM legs compressed enough that he could make the jump! |
Mike Dixon
Member Posts: 1428
From: Kew, Victoria, Australia
Registered: May 2003
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posted 09-26-2015 02:24 PM
Another rung might have helped. Couldn't have added that much weight. |
Jim Behling
Member Posts: 1488
From: Cape Canaveral, FL
Registered: Mar 2010
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posted 09-26-2015 04:59 PM
It wasn't weight that they were worried about. It was the ladder itself if the landing gear bottomed out. They didn't want it damaged by hitting the surface or foot pads.
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Mike Dixon
Member Posts: 1428
From: Kew, Victoria, Australia
Registered: May 2003
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posted 09-26-2015 07:45 PM
Thanks Jim. I never knew that. |
MadSci
Member Posts: 230
From: Maryland, USA
Registered: Oct 2008
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posted 09-26-2015 09:01 PM
quote:
Originally posted by Jim Behling:
It was the ladder itself if the landing gear bottomed out.
Exactly. Incidentally, the Russians solved the same problem by having the last couple of rungs of the ladder fold up on hinges. As there would have been no second cosmonaut to assist from above, within the LK, they couldn't risk the sole cosmonaut being unable to make that long jump upwards.In contrast, the Americans had a second astronaut within the LM to assist if the 'jump' turned out to be more difficult than anticipated. And a $10,000/pound bounty on weight savings must have made those last rungs a pretty tempting target.  |
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