Newbie
In the Apollo landings, why don't the ladders go anywhere near the ground? I am not a conspiricist, and was actually asked this by a Young Earth Creationist (something to do with their flawed moon dust argument), I was just wondering if there is a proper reason for this.
Order of Kilopi
The landing gear struts were designed to collapse on touchdown to take away the impact shock. All landings were so soft, that this never happened to the extent that the ladder came close to the ground. And better having the astronauts to jump a little bit in 1/6g then having a bent ladder that may have rendered it useless.
As you see in the drawing, the primary strut could collapse 32", while the secondary one could either expand 16" or collapse 12", depending on what was needed.
The images are from Lunar Module Structures Handbook, a 5MB file.
Newbie
that's excellent, thankssorry if it has been asked before!
Order of Kilopi
Not that I can remember. :-)Originally Posted by Radical Edward
that's excellent, thanks
Established Member
Welcome to the board, Radical.
Order of Kilopi
ops: Where were my manners? Welcome here, Radical
Established Member
Welcome Edward. It's nice to see you have fine taste in anime.
Order of Kilopi
Yes, in fact, excellent taste. Say hi to Ein for me.
Order of Kilopi
Welcome, and congratulations on asking a question that, to my knowledge, has never been asked before.
Apollo 11 landed more softly than anticipated and the struts did not compress to the point where the low rung of the ladder was in easy reach. After dropping to the footpad, Neil Armstrong tested his ability to get back up to the ladder. That's why you see him drop twice.
Senior Member
Imagine that. An Apollo question that has not been asked before...I didn't know that there were "any" left!
Congratulations, and WELCOME to the board!!
Member
I always assumed the struts were like shock absorbers and would compress gently at landing but then would extend back out close to the original length. The way I'm understanding you now is that they compress and then stay at that shorter length. Is that correct?
Order of Kilopi
Welcome to the board, Edward. Asking a new Apollo question is indeed rare, congrats! =D>
Now if your YEC friend follows up on the ladder be sure to ask him why he thinks, if the mission was fake, they'd make the ladder too short when they set it up in the "studio". Hoax believers (around here we just call them "HB") like to point out what they think are anomalies without wondering why those supposed anomalies would exist if the mission were filmed.
Administrator
Wow, that brings back memories. When I was a kid in the 60's, I remember wondering why the ladder didn't go all the way down. I just assumed that they were saving weight and figured the astronaut could jump down the rest of the way in lunar gravity. I never knew about the bent ladder problem. See, you learn something new every day.
Established Member
Yes, I believe that is true. The honeycomb material crushes to absorb the impact energy. It does not spring back.
Order of Kilopi
Piston-type compression shock absorbers are heavy. You need the walls of the cylinder thick enough to contain the pressure created by the piston. They're also more useful in situations where a series of shocks will need to be absorbed, such as in automotive applications.
The LM landing struts had to absorb only one shock -- the LM landing. After that, they had no other duties. So a one-time shock attenuation system is called for here. Not only does it simplify the engineering, it can be built in a much lighter package. Crushable honeycomb isn't very massive, and the cylinder walls merely have to retain the honeycomb in place, not contain any pressure or withstand any stress.
Crushable structures are now common on car bumpers. Behind the fairing is a lattice structure of plastic or composite material that is sacrificed in a collision to absorb the energy. The advantage is increased shock attenuation capacity. The disadvantage is having to replace the bumper even after a minor collision.
Seat belts, surpisingly, work the same way. They're one-time safety devices. They stretch and deform permanently to attenuate impact.
Established Member
welcome to the Board, RE, and thank you for the question. what an interesting bit of additional knowledge that is.
Order of Kilopi
I really have to wonder what they would have done if he hadn't been able to get back up to the rung.
Established Member
Have Buzz hold his foot down so Neil could grab it would be my guess and help lift him up. Considering every contingency plan they had, I'm sure they had a just in case plan for not being able to get back in the Lander.
Established Member
1. Roll over a rock to use as a booster step.
2. Grab by hand and pull himself up.
3. Compute the expected max jump height based on suit limitations and weight in lunar gravity. Design your ladder so the maximum height is below that distance.
4. Have Buzz make a makeshift ladder extension out of duck tape.
How creative do you need?
Order of Kilopi
You could also use the equipment conveyor strap. Armstrong could either climb it like a rope until he got to the lowest step, or he could step in the loop and have Aldrin pull him up.
Armstrong might also be able to pile up equipment from the MESA, or one of the EASEP experiments.
Order of Kilopi
Actually, I find this funny. Why test it at all? If he can't get back up, the he can't get back up from his test jump!
Order of Kilopi
If you test your ability to ingress early in the EVA, you have a full load of oxygen and cooling water in the suit in which to effect a solution should you encounter difficulty. Without the test, you might find you can't ingress, but in addition to that problem you may only have half an hour of air left.
Order of Kilopi
It's better to recognize a problem with a filled PLSS than when you really have to get back soon because you run out of oxygen or cooling water. Gives you more time to think about and solve the problem. Of course, if Armstrong would have had problems, there were many options, as those already explained.
In the early stages of LM design, there was no ladder. Designers thought about and tested rope-ladders or simply ropes with knots for climbing down and up.
Harald
Established Member
Someone from the film crew would have walked on set and given him a leg up. :P
Senior Member
A question...did the Astronauts decide that the rope-ladder wouldn't work as well as a "regular" ladder, or was it the designers?
Order of Kilopi
[bSomeone from the film crew would have walked on set and given him a leg up. :P[/b]
Armstrong: Uh, could I have a half-apple?
(Explanation: Wooden boxes on which things are placed to bring them up to the right height, in theatrical contexts, are called "apple boxes". They have harmonious dimensions so that they can be stacked in different ways. Generally the formula is L=W+H, where any triplet that satisfies that relationship is an apple box. The standard dimensions are 20x8x12. A "half apple" is what you see at the right edge of http://www.clavius.org/img/dolly-upsun.jpg alongside full apple boxes. Leveling dolly track is a very common application. The comment I've attributed to Armstrong is a running joke between me and the film crews I sometimes work with. Since I'm so short, sometimes I have to stand on something to be easily framed with taller people, so I spend a lot of time asking for half-apples.)
Order of Kilopi
Something you've in common with Humphrey Bogart... ;-)
Order of Kilopi
I guess Robert Reich would need a full apple, then... :P
Senior Member
Hey there!...I resemble that remark!!
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