Does anyone know where to find a picture of the LRV throwing the lunar dust up in its perfect parabolic path? I know i've seen video of it, but I need a picture to help me in my little ongoing debate in my science class.


BTW... I've been quite succesful in converting my fellow classmates to the righteous path of science! thanks for all the help!

Try here.

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Also, look for the Apollo 16 'Grand Prix' mpegs.

This is a really good exercise, because in the absence of an atmosphere, we know that the dust kicked up by the LRV wheels must fall in a parabolic arc. The mathematics of this is fairly straightforward and you can calculate the expected height of the dust kicked up on both Earth & the Moon. You will see that at the top speed of the LRV, the 'rooster tails' would be much higher on the moon than they would be on the Earth. The height of the rooster tails in the video is what you would expect to see in the lunar gravitational field.

This means that it is not too hard to show even if the whole thing were staged in a gigantic vacuum chamber here on Earth (not possible with 2004 technology by the way!), they must also somehow have changed the strength of gravity in that chamber! Man, that is some trick!!

PM me if you like. I would be happy to run over the maths with you.
Well done on your classmates conversion, BTW! =D>

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Changing the gravity is easy with the anti-gravity UFO technology that the gubmint has. It's too bad the aliens didn't tell us how to get past those deadly Van Allen belts or NASA could have gone to the moon for real. Maybe the aliens puts them there to keep us trapped on the Earth. I guess that's enough silliness for one post.

You might also consider using video showing dust kicked up by the astronauts as they walk. It is often easier to follow the trajectory of the dust particles in this case. The spinning wheel of the LRV tends to throw up lot of dust along multiple trajectories that fan out to produce a "rooster tail". This can sometimes make it difficult to follow the parabolic trajectories.

During the "Grand Prix" the LRV was clearly bouncing - that is the wheels were not always in contact with the ground, The result of this is the "waves" of dust particles thrown up, most noticably from the rear wheels. The HBs claim this is proof of an atmosphere. What it actually shows is exactly what one would predict from Newton's laws.

Try here

http://www.apolloarchive.com/

Select "Apollo Multimedia" at left, then scroll down about 80% of the way to the Apollo 16 section. The entry you want is "view of astronaut driving the Lunar Rover". This is the film of what they called the Grand Prix. Boeing engineers (who built the rover) wanted to see if it was really as strong and versatile as they expected. So they asked the astronauts to drive it in a crazy fashion.

The first thing you notice is no clouds of dust lingering in the air for minutes. I live in a desert, and that's one of the things you can't avoid. If you drive down a dusty road like that, even when there's no wind, the dust hangs in the air for a long time. And when you wet down the dirt, you don't get rooster tails like that.

The conspiracists point out the ejection of dust in fits and starts. That's due to the wheels bouncing. They don't contact the ground with uniform pressure and so they don't eject dust at uniform pressure.

They also point to the vertical motion of the dust being disproportionate to the horizontal travel. They expect the dust to be ejected more vertically. They say the horizontal motion is limited because the dust has hit a "wall" of air and is quickly stopped.

We know this is wrong because the air acts uniformly in the direction of travel. That is, if you throw a baseball at 90 miles per hour you get air resistance in the horizontal direction because the ball is traveling horizontally. If you drop a baseball from a high building so that it reaches 90 miles per hour, you get the same amount of air resistance but this time in the vertical direction. The ball is traveling vertically.

The same with dust. If the dust is moving horizontally it is resisted horizontally. If it is traveling vertically, it is resisted vertically. In that film, the dust travels both horizontally and vertically, but the conspiracy theorists can only explain the apparent motion of the dust in the horizontal direction. They can't explain why that "wall" of air doesn't prevent the dust from falling quickly to the surface in the vertical direction.

This is how we know their explanation isn't the right one: it doesn't explain all the observations it should apply to if it were true. We see things in the film that their idea doesn't explain, but it should.

So there must be some other explanation for why the dust seems to fly up more than it does back. The answer has to do with a combination of two effects. First, the wheel digs slightly into the dirt. If you bury a wheel in a couple of inches of dirt, the angle of the wheel's tread where it just comes up out of the dirt will dictate the angle at which dirt will fly off of it when the wheel turns. Depending on how deep that is, it will be more vertical than horizontal.

Second, dirt sticks -- especially moon dirt. It's very cohesive, which means it likes to stick to itself, like cornstarch or flour. If you pass a wheel over it, it will compress into a clump under the weight of the wheel, and then it sticks to the surface of the wheel as it rotates. Not all Earth dirt does that: it doesn't stick to itself and it doesn't stick to wheels, especially if it's dry. So if some dust sticks to the bottom of the wheel in a clump, and then it rotates toward the back and finally separates, the angle of the tread at the instant the clump separates dictates the direction of all that dust.

Both of these effects increase the departure angle of the dust, suggesting that it should be more vertical than horizontal. We can explain the vertical plumes in a way that takes into account how the dust sticks, and also explains everything you see in the video.

Another feature the conspiracists overlook is the four-way steering. Both the front and rear wheels angle to steer, like new trucks do these days. But in some cases in the Grand Prix video, the chassis of the LRV is sideways to the camera, but the rear wheels are actually turned so that they're facing more away from the camera. This leads to their dust plumes being foreshortened by perspective and appearing to be more vertical than horizontal. It's like standing behind the plate at a baseball game, or behind the pitcher. The ball's great speed is not apparent because it's moving mostly toward or away from you. That's different than the view from first or third base, where the ball moves across your line of vision.

The other important feature occurs most obviously at about 0:10 in the film above and again as the craft stops and sprays dust out of the side.

The conspiracists say that the dust shouldn't break up as it flies, but that it should remain clumped together since there's no air to break it apart. But this presumes that the individual dust particles all have the same initial trajectory. They don't.

If you pick up a handful of Earth dust and gravel and throw it, the heavier particles go farther. They follow mostly a ballistic trajectory, meaning their path is dictate only by motion and gravity. The light dust doesn't go very far at all. It ends up as a cloud in the air just in front of your hand. All that stuff left your hand at approximately the same speed and going in the same direction. But the lighter stuff immediately started feeling the effects of fluid dynamics -- that is, the effect of air on it. The general rule is that where velocity is equal, lighter particles are more drastically affected by the fluid through which they move than heavier particles.

The examples above don't show that difference between light and heavy particles. That is, the effects of the fluid (i.e., air) are completely missing.

So what's breaking up the "clumps" of dirt? If you throw a handful of dirt on the moon it will break up and disperse, but not nearly as badly as it will in an atmosphere, and not in the same way. When each dust particle has a slightly different trajectory, the farther they go means the more separated they become. Eventually they become too far apart to register as a "solid" object on film. If you set a bunch of particles in motion with slightly different momentums and trajectories, they'll develop into elegant patterns of swirls and retrograde (backwards) rotation that are entirely predictable from the simple laws of motion.

That's in a vacuum. If you do the same in air, the paths of the particles become very chaotic and unpredictable. That's why clouds all look different. The air currents that create them are nearly impossible to predict. (My company sells supercomputers that try very hard to predict it.) The dust patterns from the rover wheels exhibit that elegant, regular pattern and not the chaotic pattern.

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My favorite part is at the end when the rover stops suddenly and the dirt from the front tire just falls down in an arc. Blop. Very cool and I've never seen anything like that on earth either.

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I can't imagine how the HBs would even begin to explain how the behavior of that lunar soil could have been faked, especially once they find out that it is doing everything it would be expected to do in 1/6th Earth's gravity in a vacuum.

It might help you, poddo, to know exactly why small particles are affected more greatly by air than large particles.

A particle moving through air has two forces acting on it: gravity and drag. Gravity acts straight downward while drag acts in the direction opposite of the particle's velocity vector. In other words, if a particle is moving to the right, the drag force is directed toward the left, and vice versa. It should therefore be obvious that drag acts to slow a particle down.

The magnitude of the drag force is given by the formula

Fd = Cd * Rho * V^2/2 * A

where Fd is the drag force, Cd is the drag coefficient, Rho is the air density, V is the particle's velocity, and A is the area of the body normal to the flow.

The rate at which drag slows a particle (the acceleration) is given by

a = Fd/m

where 'a' is the acceleration 'm' is the mass of the particle.

Since Fd is a function of A we can see that 'a' is proportional to A and m as follows:

a ~ A/m

As a particle gets larger its area increases as a function of its diameter squared while its volume increases as a function of its diameter cubed. Since a particle's mass is proportional to it's volume we have

a ~ D^2/D^3, or
a ~ 1/D

Therefore the bigger a particle is, the less it is slowed by drag. (This assumes all particles are of the same material with the same density and the same basic geometry.)

For large particles moving at slow velocities the acceleration caused by drag is very small in comparison to the acceleration caused by gravity, thus the particles appear to follow a simple ballistic trajectory. However, for very small particles this is not true as the effect of drag becomes quite noticeable. If you where throw a handful of soil into the air the course sand sized particles would be slowed little by drag, the silt sized particles would be noticeably affected, and the smallest clay sized particles would be greatly affected. The smallest particles would form a cloud that would settle very slowly. In addition, these small particles would also be most greatly affected by air currents and wind.

In a vacuum there is no drag so the only force acting on a particle is gravity. Since the acceleration of gravity is a constant, all particles are effected the same regardless of size.

P.S. I hope this isn't too much math for you. I just thought it would be helpful to know this in case anyone challenges you.

One more thing to add. The drag coefficient is also a function of particle size. Very small particles have a larger drag coefficient than a larger particle. About 2 - 300 times. Go here, page 4

Methinks you somehow miss some attribute of the HB, that would prevent them from accepting a description of how the dirt dynamics are correct for the moon. After all, they can just look at the film and tell it is wrong.

Exactly right, Irishman. That's the same rigorous, exacting method the leading HBs (probably starting with Rene) used to determine that the LM assembly and/or ascent stage were unstable and therefore could not possibly perform controlled descents/ascents.

It works, too. For instance one glance at Bill Kaysing's trailer told me it would be unstable in a tornado. I would have liked to have performed the same "scientific" evaluation for Rene, but per the address at his web site (Ralph Rene c/o John Cook · 7938 South State Road 39 · Crothersville · IN · 47229 · USA) it appears he doesn't have a house, trailer, or even an address. 8)

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I just finished reading this interview with Neil Armstrong and I thought his comments about the dust on the Moon were interesting. When asked if there was anything about his time on the moon that surprised him, Armstrong responded with the following (page 84):