Descent Engine Dust Clouds

[BDL]

Hi all. I was watching some lunar touchdown footage and noticed that the dust that the descent engine flew up had fallen down and created a small dust cloud for a little bit. Am I correct in thinking that the dust is suspended in mid-vacuum for a little bit because of the gas that ejected from the descent Engine? I’m curious as to how this works. An example would be the Apollo 15 Touchdown, where it seems (at around 14:30 in the video) a small cloud of dust is formed for little bit.

I guess I was under the impression that the gas from the descent engine would immediately disperse into the vacuum leaving no time for dust to be collected in a small cloud. I’m guessing now that this is wrong?

[VQ]

I don't think there is enough resolution on the film to differentiate between a "cloud" (dust suspended more or less statically in a gas) versus ejected dust from the engine. Remember the engine doesn't stop emitting exhaust gas the second it is shut off, so it still could be entraining some dust around the LM.

[BDL]

I don't think there is enough resolution on the film to differentiate between a "cloud" (dust suspended more or less statically in a gas) versus ejected dust from the engine. Remember the engine doesn't stop emitting exhaust gas the second it is shut off, so it still could be entraining some dust around the LM.

Makes sense. I was unaware that gas was still emitted when they landed.

[bknight]

I don't think there is enough resolution on the film to differentiate between a "cloud" (dust suspended more or less statically in a gas) versus ejected dust from the engine. Remember the engine doesn't stop emitting exhaust gas the second it is shut off, so it still could be entraining some dust around the LM.

Makes sense. I was unaware that gas was still emitted when they landed.

The engines don't stop emitting gasses instantly when they shut own.

[raven]

Not sure how much dust it would kick up, but shortly after touch down on  Apollo 11, Buzz Aldrin calls out

Okay. It looks like we're venting the oxidizer now.

[Kiwi]

...An example would be the Apollo 15 Touchdown, where it seems (at around 14:30 in the video) a small cloud of dust is formed for little bit.

I don't see a cloud there. At 11:18 the text says the DAC film was running at 12 frames per second, which might have been a bit slower than normal, so we would not be seeing things as they would actually appear to the eye. What I do see is a great variety in the forms and quantities of lunar soil (not necessarily just dust) being ejected at high speed. This would be a result of the fast scouring out of different lumps and hollows and soil densities. It's a bit like we can produce by hosing some rough, dry, bare ground with a powerful jet of water. Sometimes the jet of dust and soil is quite thin, and at other times it is dense enough to block the sunlight and briefly cast a small shadow on the surface.

Some hoax-believers expect to see a crater under the engine nozzle and I think it was Apollo 12 or 14 that did have a noticeable dish-shaped crater, but it wasn't very deep.  The Moon rarely lived up to the expectations of we ignorant Earthlings.

[raven]

Besides, if there should have been the crater conspiracy theorists so often claimed, why didn't they . . . make one?

[ka9q]

I think the propellant venting was through separate vents, not through the engine.

[Allan F]

IIRC they vented the helium pressurizing the tanks. That left an exit point for the fuel still in the tanks. I would have closed the valves to the tanks afterwards, to avoid contaminating the environment. Going out in a rubber suit when there's traces of nitrogentetroxide floating around seems like a bad idea. I know the amount of vapor encountered would be extremely low, but anyway.

[JayUtah]

IIRC they vented the helium pressurizing the tanks. That left an exit point for the fuel still in the tanks. I would have closed the valves to the tanks afterwards, to avoid contaminating the environment. Going out in a rubber suit when there's traces of nitrogentetroxide floating around seems like a bad idea. I know the amount of vapor encountered would be extremely low, but anyway.

I can't imagine it would be floating around in concentrations amounting to more than a few molecules per cubic meter.  And the ground is already contaminated heavily from the plume, so if your concern is over contaminating regolith samples, the cat's already out of that bag.

[inconceivable]

Some HBs think the lack of dust dispersion was because they were not on the moon in the first place.  Some think they were here on earth in an underground nuclear blast or storage chamber.  Possibly filled with sulfer hexaflouride.  Giving that wavy, blurry look and floating characteristics. tr432b

[Zakalwe]

Some HBs think the lack of dust dispersion was because they were not on the moon in the first place.  Some think they were here on earth in an underground nuclear blast or storage chamber.  Possibly filled with sulfer hexaflouride.  Giving that wavy, blurry look and floating characteristics. tr432b

So what and who cares what some idiots think or believe?
Now if you can show any evidence to support that hare-brained idea..... (tumbleweeds blowing, in the far distance a church bell tolls slowly, scene fades to black)

[ineluki]

Some HBs think

Yes, but they are a tiny minority among the Moonhoaxers...
Anyway, is there something you want to actually discuss or is this just another of your seagull posts?

[onebigmonkey]

Some HBs think the lack of dust dispersion was because they were not on the moon in the first place.  Some think they were here on earth in an underground nuclear blast or storage chamber.  Possibly filled with sulfer hexaflouride.  Giving that wavy, blurry look and floating characteristics. tr432b

As opposed to those HBs who think they were on the moon? 

[MBDK]

Some HBs think

Not rationally, critically, or logically, from what I have experienced.