Apollo 12 Lunar Module

[benparry]

Good evening all. First of all I would like to thank everybody for the answers to the various questions I have asked. This is the best forum I have found to date. I am in a couple of FB groups mostly believers and came across a question asked by a guy regarding the LM for Apollo 12. The original question was what happened to the accent module which I answered with a quick Google search. However I was presented with the following question. I certainly don't know the answer and wondered if anybody did


Ben Parry When the jettissoned lunar module of Apollo 12 hit the lunar ground, it hit it almost horizontally (with an angle of 3.7° relatively to the average lunar surface only, according to the mission report of Apollo 12).
It means that the horizontal vibrations were much stronger than the vertical one.
Yet, the sismometer of an ALSEP close to the crash recorded a vertical vibration consistently stronger than the horizontal ones.
Here what it recorded; the vertical vibration is the bottom one; it should have been much smaller than the horizontal ones, and it is not.
http://www.angelfire.com/moon2/xpascal/MoonHoax/Apollo16Crash/LMCrashPlots.jpg
How do you explain that Ben?

[JayUtah]

What would be the rationale for claiming that a shallow-angle impact should produce stronger horizontal seismic measurements than vertical?  That seems to assume an energy transfer scenario that may seem briefly intuitive, but doesn't really fit how glancing collisions work.

[Jason Thompson]

Ben Parry When the jettissoned lunar module of Apollo 12 hit the lunar ground, it hit it almost horizontally (with an angle of 3.7° relatively to the average lunar surface only, according to the mission report of Apollo 12).
It means that the horizontal vibrations were much stronger than the vertical one.

I would challenge him to support that assertion. An impact at those speeds is a complex and explosive event (this impact blew a 9-metre crater in the surface: not bad for a lightweight, empty spacecraft considerably smaller than 9m in size!). It's not just something knocking into the surface at some angle. You would also, over the period covered by the seismograph he shows, have ejecta from the impact crater the LM carved in the surface raining down all over the place as well, adding more complexity to the seismograph trace.

Here what it recorded; the vertical vibration is the bottom one; it should have been much smaller than the horizontal ones, and it is not.

I would chalenge him to support his assertion that the vertical vibration is the bottom one. Maybe he did and maybe there's a bit in the report that explains it, but without that I woudn't automatically assume that X and Y are horizontal and Z is vertical. Quite the reverse in fact, as generally I would consider Y vertical.

Essentially as far as I can see he appears to have made two assumtions that must be absolutely verified before he can draw conslusions: That an impact at a shallow angle produces stronger horizontal vibrations than vertical ones, and that his assignment of the Z axis as the vertical one is correct.

[Jason Thompson]

That seems to assume an energy transfer scenario that may seem briefly intuitive,

That's my thinking too: it seems intuitive but as we all know by now intuition is rarely any use in science and engineering....

but doesn't really fit how glancing collisions work.

And I'd have thought it would fit a collisions where the almost instantaneous result is an explosive vaporisation of the impactor with a significant quantity of surface displaced in the blast even less so.
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[nomuse]

The strikes me a lot like the problem some people had with craters; they expect since the impacts are at a range of angles to the surface, the majority of craters should appear lenticular.

The story I heard is it was Barringer himself shooting a rifle into dirt that helped some people get over their naive intuition about high-speed impacts.

[smartcooky]

What would be the rationale for claiming that a shallow-angle impact should produce stronger horizontal seismic measurements than vertical?  That seems to assume an energy transfer scenario that may seem briefly intuitive, but doesn't really fit how glancing collisions work.

Indeed, the reason that intuition fails them is because they do not understand what actually causes the crater... and therefore leads to its shape. Intuition leads them to believe that the shape and size of the 'crater' should be in line with the size and shape of the impactor. This is not what happens

Its is the explosive release of the asteroid's massive kinetic energy (more like a powerful bomb than an impact) released at what is effectively single point in the planet's surface, that causes the round shape of the crater is, Ejecta is thrown in every direction no matter what the direction of the impactor was.

[onebigmonkey]

So what are they claiming? That the seismometer from Apollo 12 on the moon recorded an impact of the lunar module and this proves that the seismometer wasn't there to record it?

To clarify, the Z wave is the vertical displacement of the seismometer, while X & Y record the relative horizontal displacements thanks to compression waves arriving at the instrument.

There is mention in this report

https://darts.isas.jaxa.jp/planet/seismology/apollo/The_Description_of_Apollo_Seismic_Experiments.pdf

that the Apollo 12 intrument recorded Z values anomalously and that this was corrected later, but how much that would have influenced the values shown in the PSR is unclear.

The general theory is that impacts, rather than quakes, produce a much more more pronounced signal in the X&Y axes, but the general literature I looked at briefly don't record the angle of incidence. There are a few reports out there suggesting that the records from this impact indicate a difference in lunar structure than was previously thought, based on records of missile impacts at White Sands. Comparisons with terrestrial meteorite impacts are tricky because the air compressed in front of the the meteor influences the results.

My personal and in no way expert view is that a fast moving object hitting the ground close to the recording instrument is very much going to rock its world, and the vertical displacement is perhaps a product of the proximity to the seismometer as much as anything else.

The LRO view of the site is certainly consistent with a shallow impact judging by the debris field it has generated:



from http://www.planetary.org/blogs/guest-blogs/2017/0207-finding-spacecraft-impacts-on-the-moon.html

In short, I'd ask your inquisitor to identify specifically why the seismograph is unreasonable and present evidence for it.

[benparry]

Many thanks again guys. My inqisiter as you call him is Pascal Xavier so I won't be debating with him lol it's interesting to see again however that his proof has been explained yet again lol

[Zakalwe]

My inqisiter as you call him is Pascal Xavier so I won't be debating with him lol it's interesting to see again however that his proof has been explained yet again lol

AKA "Hunchbacked"
A strange individual indeed. He claims that the A11 internal CSM video was filmed underwater with the astronauts wearing lifelike masks that had air supply tubes secreted within them. His "reasoning" for this ludicrous claim? Objects in freefall within the cabin space sisdn't move as he expected them, so instead of questioning his expectations, he falls foul of an argument from disbelief and builds an unbelievable fantasy to suit his weird world-view.
 

[benparry]

yes I am aware of his weirdness. I lost all trust in him during a video called Apollo 11 bullshit. the very first point which dealt with buzz Aldrin saluting the flag he claimed something which anybody who had reasonable eyesight could see was wrong.