I know this issue has been discussed before but my quick search couldn't find it:

I would assume that the dirt and dust kicked up on the moon by astronauts and vehicles alike would follow trajectories different than on Earth as the moon's unique gravity causes it to settle back down. Am I correct in assuming that, if you plotted the arcs involved, the dust would follow paths different than mere slow motion of Earthly gravity effects?

RBG

Well, it would follow the same path as on earth but much slower. Also, the dust on the moon is not affected by the atmosphere, so it cannot stay suspended - it instead follows a purely ballistic arc (which you can see in the videos).

Cjl has the right of it. The effect of lunar gravity on the dust could be simulated by showing the video at a slower frame rate than it was shot at, but the lack of any billowing effects or of the dust hanging in the air cannot be faked in an atmosphere.

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I would suppose so, but personally i've never seen video clear enough to pick out individual particles of moon*, and trace their trajectory. although i guess digital analysis might allow for that.

*edit: Moon dust, got distracted by work. Sorry.

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Im thinking of a specific video that is an excellent example
It is of the rover.

As the rover drives across the dust you see two perfect arcs of dust rising and falling as they are kicked up by the back wheels(the front wheels are obscured somewhat).


If anyone knows what Im talking about and has a link...


Meanwhile a search on youtube revealed this video of the rover played at double speed here:
http://video.google.com/videoplay?do...arch&plindex=1

which claims that the effect was footage taken on earth and played in slow motion.
Im using this link because its just funny to me how the HB's will put this video out there claiming it's evidence when it so clearly shows them to be wrong. Watch the dust behave independently of an atmosphere on this HB supplied link

I would suppose so, but personally i've never seen video clear enough to pick out individual particles of moon [dust], and trace their trajectory. although i guess digital analysis might allow for that

It's not hard if you know what to look for. You can see it when the astronauts walk (the dust kicked up by their feet) and especially when they make a sharp turn with the lunar rover. If you kick up some dust on Earth, it'll billow and drift somewhat like a cloud (hence the expression, "I left him in a cloud of dust"). That doesn't happen in a vacuum. This is one of the easier points to refute the HBs' claims.

An example of what I'm talking about can be seen in this video (running at twice actual speed for some reason). Compare how the dust is behaving to how it behaves on Earth.

The only way you could duplicate that on the Earth would be to shoot the scene in a vacuum chamber. However, you'd need a very big vacuum chamber to create a set big enough. Atmospheric pressure would try to crush that chamber, so it'd need very thick walls to withstand the pressure. Building such a chamber is not a trivial task.

uhhhh

gee....

Larry Jacks am I on your ignore list?



Fazor said: (bold mine)
I prefer the pre-edit version

It reminds me of a guy I knew, who, commenting on the various twigs and leaves he found under the hood of his car (And having a propensity for exxaggerating) remarked: "Look at this! There are pieces of a tree all over my engine!"

But wait a minute cjl & gwiz. I would say this can't be simulated on Earth in slow motion.

Consider Shepard's golf drive on the moon that went "for miles" or whatever he said. It makes sense that you could drive a ball a lot further on the moon than on the Earth. Hitting the ball with exactly the same force on Earth - with the video slo-moed - would in no way produce the same results on the moon, even if only distance was considered. The arc on the moon would be far wider than the arc produced on Earth. Presumably because the ball takes longer time to fall back to earth even as it moves forward in a frictionless environment.

So a hundred yard drive on Earth would surely go much farther on the moon. Ditto anything else that was forced up from the ground - like dirt from a spinning wheel. As I say, slow-mo can not produce the distances involved.

RBG

He thinks (and it's a guess) that it went 200-400 yards, though that was one handed, in a bulky suit, with a makeshift golf club. See here:

http://www.pasturegolf.com/archive/shepard.htm

Anyway, yes, there are a lot of things, especially when shown in combination, that would cause problems for slow motion effects. You might, for example, show dust moving slowly, but it would also distort the movements of an astronaut.

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Also, the feather and the hammer, although they claim to rebuke that (without any evidence) that the feather wasn't really a feather etc...

Larry Jacks am I on your ignore list?

Certainly not. I was working on my reply and searching for the video when I got interrupted. When I posted and the screen refreshed, I saw that you'd posted the exact same link. Thinking alike and all that, don't you know.

heh heh...
I saw your post a while later and it left me scratching my head

Leave it as a double whammy for the HB's- I wonder how many will notice.

Meantime, now you know why it was double speed. Ironic part of it is that by increasing the speed they inadvertently enhanced the effect of the dust.
I nabbed a copy of the slow speed and compared them and the high speed footage demonstrates how the dust is not interacting with an atmosphere much better than the original speed does!

Score one to the HB's for providing evidence against their claim.

I knew I'd catch myself on that. Should read "fall back to ground"... if we're talking about the moon.

And since I'm here, I should ask about this (?):

"Also, the feather and the hammer, although they claim to rebuke that (without any evidence) that the feather wasn't really a feather etc..." Neverfly

A feather & a hammer, of course, would fall back to ground at the same rate, moon or Earth, likewise heavy and light moon dirt. But that's not what you're getting at, I think.

RBG

I liked it the first time

The atmosphere prevents the feather from falling at the same rate as the hammer on Earth. On the moon, without air resistance, they demonstrated that both landed at the same time in spite of being different weights (dispelling the notion that heavier things fall faster)
My point was only that the speed at whcih the film is played wont make a difference- if that had been filmed on Earth the feather would have met air resistance and landed after the hammer.

Okay. Just wasn't sure who "they" were. Did the astronauts actually perform that experiment??? They actually took a feather with them? (If they did, I would have seen it... doesn't mean I might remember it though.)

RBG

Yep- they took a feather- and a hammer.
Ill look for the footage- or if anyone else has it im sure they will throw it on here.

its a BIG feather too

A falcon feather, in fact.

Grant Hutchison

RBG, you are correct that kicked dust will go much further. The horizontal component is the same as on Earth, but since low gravity makes the vertical rise & fall time longer, the dust has more time to travel horizontally.

This Apollo 16 clip is one of my favorite examples (1mb .mov file). You can see little kick-motions that send the dust a long way (and not a trace of billow anywhere).

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Let me tell you, it was hard work hoisting that mile wide movie set cum vacuum chamber up into the stratosphere and then letting it drop fast enough to simulate a sixth of a gee.

"Galileo was right!" SPLAT!

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OMG!!!111 That was Jay's 6,666th post! That means his avatar is gonna sprout horns & stuff. As one woo-woo said on an AoHell board long, long ago (in reference to Hale-Bopp) "It's the work of SATIN!"

Now that I remember it, the name of that thread was TELL ME ABOUT HELL-BOB. Ah the memories...

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G'day RBG

Yes, NASA especially sent a hammer on one of the missions, along with a feather. They weren't used for anything other than the experiment. ;-)

Seriously, it was on Apollo 15, and the hammer-feather experiment is one of the more memorable pieces of video from Apollo. If you go to www.apolloarchives.com you can watch an MPEG of it.

Alan Bean painting of the demonstration The Hammer and the Feather, 'cause art's better than reality.

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Has anybody though of calculating the ratio of surface time to air time during an astronaut's jaunt on the moon? I can think of several short clips of an astronaut bounding along whose surface to air time would be vastly reduced compared to a video shot in a vacuum chamber on earth. To a layman like me, it would make sense that the ratio would be different in the low gravity of the moon vs. the earth.

I could be in left field here, and I'll defer to the experts, but could such a ratio be impossible to duplicate here on earth without a harness or other artificial means? I've never seen the idea before, but it could add to the case against the HB's, not that it would change their minds.

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End of line.

That means his avatar is gonna sprout horns & stuff.

There's already an "Evil Spock" version of it.

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Nice try with the hammer - feather thing. Clearly the feather was made of lead. ;^)

But is that what the doubters say or do they believe it to be advanced compuer graphics created from the ship's computers they say couldn't have gotten them to the moon?

RBG

I don't think there's any video showing where the golf-ball went. However, there are shots of astronauts throwing other things which appear to go farther than they would on earth. The difficulty is convincing the HB of how hard the objects were actually thrown - the "speed change" argument obviously changes this.

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That would explain its lustrous, velvety tail.

Personally, I would have shown that woowoo the Gate.

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That's why you could only look at objects that you might know the weight, or force with which is was propelled. That might include a running, bounding or falling human or dust thrown up by a spinning wheel. What else would there have been?

How far can dust be propelled by that specific-sized wheel spinning at the exact rate seen? Mythbusters: If you can hear me... try that one.

I suspect even if you don't know the weights or forces involved, the earth physics that cover all the weight-to-force possibilities still would not add up to the motions and gravitational arcs witnessed on the surface of the moon.

Going back to the hammer-feather experiment. I'm curious about one thing. If you graphed out the acceleration exhibited on the moon, does this exactly reconcile with a faster camera frame rate on Earth needed overall to fake lunar gravity? Are the rates of acceleration identical in both instances?

RBG

Yes, you need a speed factor the square root of the ratio of the two gravitational accelerations, which works out about 2.4.

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