Evenin' all, another newbie here, I've thoroughly enjoyed my visits here over the last few months, going back over the old conspiracy threads, and the occasional new one, and just thought I would weigh in with two questions of my own.

Firstly, I have most of the regular conspiracy argument explanations clear in my own head (stars, flags, shadows et al) but I got thrown recently when a mate brought up the "no dust on the lander footpads" issue, and realized I couldn't immediately access the kind of straightforward explanation I have for the rest of the hoax arguments. I've been through Clavius.org amongst others, but I'm afraid my (admittedly limited) research skills seem to have failed me. If someone could direct me to a concise and layman friendly link I would be most grateful.

Secondly, (oops, getting a bit long now, sorry)I'm curious to know if ANY of the conspiracy believers who arrive here secure in their (always seemingly) smug self confidence that they've "cracked it", if a single one one has ever admitted that they were were wrong, or do they all just either drift away or persist to point of "bannedenment" (pretty sure that is a real word)

1. Why should there be dust on the footpads?
At the risk of oversimplifying this, any dust will be "blown" outwards, and without air it would simply not linger above the footpads.

2. I can't remember any "real" Hoaxproponent who admitted being wrong, but that may be my bad memory :-). Those who are interested in the truth are honest enough to ask questions, instead of making bold claims.

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okay, but the hoax proponents state that (and this is what I'm trying to get clear in my own mind) the descent footage shows dust being blown outwards, which, being in a vacumn would drop immediately, and yet Armstrong comments on the dust below him before he steps off the LM. Is it the case that the amount of dust thrown out by the descent engine was so little that it settled in the time between the engine cutoff (at contact) and actual touchdown, leaving nothing on the footpads, but plenty on the surface around the base of the LM. Once again, just trying to get it straight in my own head.

Some of the dust is entrained in the exhaust flow and swept away into the distance, the rest isn't and therefore stays put for the astronauts to step in. It's only if there's stationary air to slow the dust that it can fall back near the LM.

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Not quite, the dust would fly in parabolic arcs away from the lander.
Depending on the initial velocity and angle it could go for hundreds of metres before hitting the ground again.

From the images it looks like several inches worth of dust was shifted during the landing, mainly from directly under the engine.
In the vacuum the exhaust gasses would disperse too much to significantly shift dust further away from the engine.

It's all about inertia. The dust, once blown outwards by the engine, will not suddenly drop vertically once the engine shuts off. It will continue on its ballistic trajectory, carrying it away from the footpads. Even if there was dust immediately above the footpads at the moment of engine shutdown the arc it follows as it settles will carry it well away from the footpads before it hits the ground again.

Conspiracy theorists paint a picture of dust billowing up in great clouds around the LM as it touches down, but this simply cannot occur in a vacuum. The behaviour of the engine exhaust, and hence the dust caught up in it, is more akin to the behviour of water in a steady stream hitting a surface. The water spreads out in all directions across the surface but does not splash around all over the place.

As to Arsmtrong commenting on the dust around the LM, there was lots of it left. It is metres deep. The LM simply wasn't hanging over it long enough to blow it all away. If you watch the film of the landings you will note in all cases that there is dust in motion right up to the second of engine cutoff, indicating there is a plentiful supply of it throughout, and most likely, after engine firing. Unless the statisitcally insignificant possibility of the LM engine firing for exactly long enough to blow all the surface dust away took place on all six landings we can reasonably conclude there would be some left on the surface for the astronauts to walk on.

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Thanks Jason, I think that just made it clear to me. So it comes down to the ballistic motion of dust in the Lunar vacumn, and the time difference between contact (engine shutdown) and actual footpad touchdown?

Ps. just noticed you're a Dr fan. I started late Pertwee, finished early Davison, but back now

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Another point to bear in mind as well is that in a vacuum, generally only the dust directly impinged by the exhaust will be dispersed. For Apollo 11, there was a degree of both forward and lateral movement of the LM as it landed (you can hear Aldrin mention it seconds before the touchdown - see transcript below). This means the LM was not 'hovering' directly over the one spot on descent scouring out all of the dust beneath in any event, but was rather drifting a little across the terrain over "fresh" beds of dust.

102:45:25 Aldrin: 4 forward. 4 forward. Drifting to the right a little. 20 feet, down a half.

102:45:31 Duke: 30 seconds.
102:45:32 Aldrin: Drifting forward just a little bit; that's good. (Garbled) (Pause)102:45:40 Aldrin: Contact Light.

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The vast majority of dust would be blown away, but a very tiny amount probably would rise *up* next to the LM, simply by chance, i.e. by bouncing off something else, or depending on exactly where and how it was on the surface and which vector forces applied to it.

But, even that dust would drop back to the surface at the same rate as the landing LM, or even faster, since LM was being braked by the engine.

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I would say it has happened a few times over the years, though more frequently it is people who are fence sitters or just confused or uninformed, rather than hard core conspiracy believers. But it is not the most common outcome.

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Found some information to the effect that Surveyor III took on some dust during the Apollo XII landing, even though the LM touched down some 180m away.

I assume this would be on the side facing Intrepid. It's still a long way for dust to travel, especially since it was moving quickly enough when it struck that some of the pitting on Surveyor is attributed to it.

ETA: Meaning to say, that only in a vacuum would the dust follow such a flat, hi-speed trajectory.

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That is one of the most serious mistakes made in the movie 2001 - A Space Odyssey.

When the translunar vehicle lands in that wonderful scene at Clavius, it's in a cloud of dust.

On Earth with an atmosphere to slow it down, yes. But on the Moon ...

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From The Earth To The Moon shows clouds of dust during the lunar landing scenes too.

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If you look at AS11-40-5920 http://history.nasa.gov/ap11ann/kippsphotos/5920.jpg you can see the trail left by the Contact probe. The soil appears to have been disturbed by the exhaust blast blast parallel to that trail. Not a smoking gun but more data to support the landing vs hoax.

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This one, for example:
The Lunar Module Too Flimsy?

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The time between contact and footpad touchdown doesn't realyl matter. In many cases the shutdown didn't happen until after the footpads had touched down anyway. Engine shutdown was performed manually by the commander when the LMP called 'contact light'. It wasn't an automatic procedure and a couple of the landing films show the engine continuing to blow dust away after the LM has touched down on the surface and stopped moving.
The point is that virtually all of the dust is being blown sideways at very high speeds by the exhaust, and hence is practically certain to fly straight over, under or past the footpads.

Oh yes. Grew up with Colin Baker and Sylvester McCoy as the good Doctor.

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"The very powerful and the very stupid have one thing in common: They don't alter their views to fit the facts, they alter the facts to fit their views." The Doctor, Doctor Who: The Face of Evil.

I have also just noticed that the half of the footpad facing the exhaust is actually covered in the black heat resistant coating, rather than the gold mylar sheets. I seem to find out something new every so often! From this you can see the direction of the 'dust blown' disturbance follows this alignment very well!

I LOVE this site! Always something new to discover!

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Hasn't there already been posted pictures of pads WITH dust on them in another thread, btw. (Thus endeth the most convoluted sentence I've posted here to date.)

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Seems likely it was dust kicked about as the astronauts moved about.
They certainly shifted a fair bit as they moved about.

My bad for a lack of clarity in my post.

My intent was to point out that most of the dust was propelled outward on a relatively flat trajectory, as opposed to billowing up in the area around the LM. Also, that with no atmosphere to impede it, it traveled quite energetically over a considerable distance.

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I can't WAIT for January 1, 2013 to arrive! Then again, I'm still waiting for October 1, 1993 ...

You'd better BET there's a spoon, Neo! THWACK!!!!

Wouldn't the pads have moved under the dust as the LEM moved sideways? So at least some dust could have landed that way. (Not saying your idea is wrong, just adding a way for the dust to get there.)

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Here's one.
AS17-134-20388

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"One does not require alien ruins in order to absorb a profound sense of wonder and mystery from the moon. That our civilization had actually visited it is miracle enough." Jason Roberts

Ah, yes. Behind the leg and beside the gymbal socket. Very good, spacebo!

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That actually looks like the dust in the foot pad was thrown up by the pad hitting the ground and not by the exhaust from the engine. Note the small pit under the pad.

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Hmmmm. I'd need footage of how the pad impacted and how the dust was "blown" out from the impact point before I'd commit either way. Which would be a little hard to get, now wouldn't it.

I guess that not being able to prove it either way proves it was a hoax.

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My thought on that particular photo is that it was kicked there by the astronaut that left all those footprints.

Fred

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The very next image:
http://history.nasa.gov/alsj/a17/AS17-134-20389HR.jpg
shows just how every single image was perfectly level, perfectly composed, perfectly focused.. grin..

The reason I looked, is that it would be nice to see a sequence of all four footpads to compare them. Was the depression entirely caused by the footpad, or was there also a little crater conveniently located there beforehand?

I might go browsing when I have time, but I don't recall seeing such a sequence in any of the missions.

Okay, to summarize:

Dust on the pads can be there because it was kicked up by the astronauts or the buggies, blown on when the pads impacted the surface, or when it comes back down from the exhausts.

Of course, there's the fourth method, the grips put it there, carefully turning the letters down (they won't repeat that mistake again.)

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It's images like that I find that still give me a little buzz, When you look at it and realize WHAT it is a picture of, WHERE it is, and HOW they got there, it still gets to me in a way that nothing else quite does.

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The most exciting phrase to hear in science, the one that heralds new discoveries, is not Eureka! (I found it!) but rather, 'hmm.... that's funny...'
- Isaac Asimov

"Entering the lottery defines you as a gambler; supporting SETI defines you as a human ... with passion and hope for the future." - Cosmopaul67 - 28th Jan 2010

Are we alone in the Universe? Are we the only intelligent life? Who knows? But the universe is so BIG, it somehow seems such a waste of space if we are ....