Apollo 17: A Little More Controversy

[Evan Burton]

Still looking up the answers to my questions? Let me know when you are ready.

[Duane Daman]

Tell me - what was the increase in exposure by raising the visor, and what was its effect?

I'm not sure if this what you're asking but I found this .

"The gold layer reduced the light transmittance of the visor to only 2 percent compared to approximately 15% for a standard neutral visor depending on type. The same sort of gold layer was applied also to astronaut's helmets to protect them from the damaging ultraviolet rays in the 200 to 300 millimicrons range."

http://www.flightgear.dk/flash.htm

The effect of raising the visor ?

The astronaut would no longer be protected from the dangerous effects of solar radiation on the Moon .

"Other solar radiation, particularly ultraviolet rays may cause severe sunburn in a few seconds."

http://en.wikipedia.org/wiki/Human_adaptation_to_space

Edited January 25, 2008 by Duane Daman

[Dave Greer]

Tell me - what was the increase in exposure by raising the visor, and what was its effect?

I'm not sure if this what you're asking but I found this .

"The gold layer reduced the light transmittance of the visor to only 2 percent compared to approximately 15% for a standard neutral visor depending on type. The same sort of gold layer was applied also to astronaut's helmets to protect them from the damaging ultraviolet rays in the 200 to 300 millimicrons range."

http://www.flightgear.dk/flash.htm

The effect of raising the visor ?

The astronaut would no longer be protected from the dangerous effects of solar radiation on the Moon .

"Other solar radiation, particularly ultraviolet rays may cause severe sunburn in a few seconds."

http://en.wikipedia.org/wiki/Human_adaptation_to_space

Duane

The section of the Wiki article you quoted from referred to physiological effects of astronauts completely unprotected while in the vacuum of space, i.e. no spacesuit or helmet.

An astronaut raising his sun visor would still be protected from UV light by two things: his protective visor, and his pressure helmet. Both were made of Lexan, which is quite opaque to UV light below 385nm.

EDIT: the visors used by astronauts during EVAs on the ISS are quite similar. Check out the following image. One astronaut has his gold visor partially raised, the other doesn't. There are plenty of other images of ISS EVAs showing astronauts with the gold visor raised. You might want to let your Youtube buddy Mr Magoo know about this, because he's using footage from the film Deep Impact as "scientific proof" that the Apollo astronauts would have been blinded by the sun.

http://uk.youtube.com/watch?v=kkRG3EaEGfk

http://spaceflight.nasa.gov/gallery/images...088-702-024.jpg

Edited January 25, 2008 by Dave Greer

[Duane Daman]

What astronauts do with their outer protective gold visors while in LOW EARTH ORBIT has nothing to do with what they should have done with them on the Moon .

The lunar surface is completely radioactive ... Deep space is constantly bombared with deadly cosmic ray radiation once you go through and past the Van Allen Radiation belts and almost a quarter of a million miles onto the Moon.

Raising a gold protective visor in low earth orbit can not be used as a proper comparison or rebuttal in this case .

Here is a quote about just one of the dangers of space travel from scientist von Braun in his 1960 book: First Men to the Moon:

"Finally, there is the Van Allen Radiation Belt (page 69). Just a little over a year ago we didn't even know it existed. Explorer I, equipped to measure the intensity of the previously mentioned cosmic radiation, gave us the first indication that there was something completely unsuspected up there. Two more Explorers unveiled the fact that the earth is surrounded with two concentric, doughnut-shaped rings of "trapped radiation." Electrically charged particles apparently mainly electrons endlessly circle around and up and down the magnetic field lines which connect the magnetic North and South Poles like a grid of meridians. When a rocket flies through this belt the trapped electrons impinge on its skin like raindrops hitting an aircraft which is flying through the clouds. Very much in the same fashion as the impinging raindrops cause sound waves audible within the airplane cabin, the impinging electrons produce an electromagnetic radiation inside the cabin. Physicists use for this kind of radiation the German word bremsstrahlung (slow-down radiation), but it is actually something quite similar to X-rays. It is this bremsstrahlung that we have to watch in the Belt." (First Men to the Moon, p.19)."

http://www.reformation.org/general-groves.html

None of the Apollo astronots ever mentioned hearing the "raindrops" radiation hitting their spacecraft .

"Out in deep space, radiation comes from all directions. On the Moon, you might expect the ground, at least, to provide some relief, with the solid body of the Moon blocking radiation from below. Not so.

When galactic cosmic rays collide with particles in the lunar surface, they trigger little nuclear reactions that release yet more radiation in the form of neutrons. The lunar surface itself is radioactive!"

http://science.nasa.gov/headlines/y2005/08...oactivemoon.htm

And this is from a NASA article about the dangers of radiation on the lunar surface .

.3.6 Temperature

The variable lunar surface temperatures are a function of solar illumination and shadows. The range of temperatures has been reported to be from 102 oK to 384 oK by Bufkin (1988), and from 102 oK to 407 oK by Bova (1987). The roughly 300 degree temperature differences can be experienced at the same time on a piece of equipment depending on its orientation with respect to solar illumination and deep space.

2.3.7 Radiation

The radiation environment of the moon is harsh. The lunar surface is exposed to the continuous flux of galactic cosmic radiation (GCR) and to infrequent periods of intense solar energetic particle activity. Particle fluxes on the lunar surface are about 1/2 of their intensity in free space because they are blocked below the horizon. Crewmembers are not protected from these ionizing particles by either an atmosphere or a magnetosphere.

The GCR flux is between 1 and 2.5 particles cm2 s-1, depending on solar activity. It consists of about 90% protons, 9% helium nuclei, and 1% heavier nuclei. GCR dose is difficult to shield; approximately 5 to 10 m of lunar soil reduces the GCR dose to terrestrial levels.

Solar protons pose a significant risk to inadequately shielded crewmembers. Very large energetic particle events, which can cause acute radiation effects, occur at intervals of 7 to 10 years. Intermediate events, which can limit mission activities, occur several times each year. For nominal flares, build-up to peak radiation intensity occurs within a few hours or less. Monitoring of X-ray precursors may provide 30 minutes to one hour of additional warning.

We must contend with life threatening radiation hazards on the lunar surface. The galactic cosmic radiation and the intense particle radiation from solar flare events are potentially significant problems for the EVA crews exploring the lunar surface, remote from the main base. It has been suggested that the radiation hazard may be aggravated by other factors in space, including stress and low gravity. In addition to the natural radiation environment, we must consider the introduction of non-ionizing radiation associated with communications systems. High atmospheric nuclear explosions on Earth, currently banned by international treaty, might also contribute to the radiation hazard on the lunar surface. (Radiation hazards and shielding requirements are considered in detail in sections 3.2.15 and 4.5)

And here's a little extra in this same article about the behavior of the lunar regolith in a 1/6 gravity environment ...Something which NEVER happened in any of the Apollo videos .

"The one-sixth gravity on the moon provides humans with a visceral sense of up and down and can be used to keep tools and equipment in place, unlike the floating environment of microgravity, but it also permits humans to fall down in the regolith should they lose their balance. It permits humans to handle larger masses with ease and reduces the energy required to move these masses. It enables humans to leap and stride, but it also permits soil to be kicked in long trajectories above the surface. Human sensitivity to radiation may be affected by the reduced gravity environment. We should take advantage of this environmental feature in our designs for equipment and procedures to support long term lunar activity, just as we design to take advantage of microgravity in orbit."

http://rigel.neep.wisc.edu/neep602/LEC22/NEAL/neal.html

Edited January 26, 2008 by Duane Daman

[Dave Greer]

What astronauts do with their outer protective gold visors while in LOW EARTH ORBIT has nothing to do with what they should have done with them on the Moon .

The lunar surface is completely radioactive ... Deep space is constantly bombared with deadly cosmic ray radiation once you go through and past the Van Allen Radiation belts and almost a quarter of a million miles onto the Moon.

Raising a gold protective visor in low earth orbit can not be used as a proper comparison or rebuttal in this case .

Both the quotes in your first post mentioned UV exposure. The Van Allen belts don't affect UV levels - the ozone layer does that. Astronauts in LEO are well above the ozone layer.

On top of that you must have missed the fact that both the pressure helmet and the protective visor are made of lexan, a material almost completely opaque to UV.

So, astronauts in LEO can raise their sun visor and not get fried by UV, just as astronauts on the moon can raise their sun visor and not get fried by UV.

Re cosmic ray radiation. Cosmic rays weren't a major problem for Apollo astronauts because of their rarity. The sun-visor provided no protection against cosmic rays anyway - so lifting it wouldn't increase the exposure due to cosmic rays. The exposure to Apollo astronauts from cosmic rays wasn't a serious consideration - however, it will be for possible trips to Mars, where round trip missions of 2 1/2 years will increase chances of cancer in later life, and of cataracts. Apollo round trips of 2 weeks compare quite favourably with Mars round trips of 120+ weeks.

http://www.newscientist.com/article.ns?id=dn7753

http://en.wikipedia.org/wiki/Cosmic_ray

Here is a quote about just one of the dangers of space travel from scientist von Braun in his 1960 book: First Men to the Moon:

"Finally, there is the Van Allen Radiation Belt (page 69). Just a little over a year ago we didn't even know it existed. Explorer I, equipped to measure the intensity of the previously mentioned cosmic radiation, gave us the first indication that there was something completely unsuspected up there. Two more Explorers unveiled the fact that the earth is surrounded with two concentric, doughnut-shaped rings of "trapped radiation." Electrically charged particles apparently mainly electrons endlessly circle around and up and down the magnetic field lines which connect the magnetic North and South Poles like a grid of meridians. When a rocket flies through this belt the trapped electrons impinge on its skin like raindrops hitting an aircraft which is flying through the clouds. Very much in the same fashion as the impinging raindrops cause sound waves audible within the airplane cabin, the impinging electrons produce an electromagnetic radiation inside the cabin. Physicists use for this kind of radiation the German word bremsstrahlung (slow-down radiation), but it is actually something quite similar to X-rays. It is this bremsstrahlung that we have to watch in the Belt." (First Men to the Moon, p.19)."

http://www.reformation.org/general-groves.html

None of the Apollo astronots ever mentioned hearing the "raindrops" radiation hitting their spacecraft .

You are joking with this comment I hope!

"Out in deep space, radiation comes from all directions. On the Moon, you might expect the ground, at least, to provide some relief, with the solid body of the Moon blocking radiation from below. Not so.

When galactic cosmic rays collide with particles in the lunar surface, they trigger little nuclear reactions that release yet more radiation in the form of neutrons. The lunar surface itself is radioactive!"

http://science.nasa.gov/headlines/y2005/08...oactivemoon.htm

Correct. Now where is your evidence that the secondary radiation was so high that it would kill or seriously injure a suited and booted astronaut?

And this is from a NASA article about the dangers of radiation on the lunar surface .

.3.6 Temperature

The variable lunar surface temperatures are a function of solar illumination and shadows. The range of temperatures has been reported to be from 102 oK to 384 oK by Bufkin (1988), and from 102 oK to 407 oK by Bova (1987). The roughly 300 degree temperature differences can be experienced at the same time on a piece of equipment depending on its orientation with respect to solar illumination and deep space.

2.3.7 Radiation

The radiation environment of the moon is harsh. The lunar surface is exposed to the continuous flux of galactic cosmic radiation (GCR) and to infrequent periods of intense solar energetic particle activity. Particle fluxes on the lunar surface are about 1/2 of their intensity in free space because they are blocked below the horizon. Crewmembers are not protected from these ionizing particles by either an atmosphere or a magnetosphere.

The GCR flux is between 1 and 2.5 particles cm2 s-1, depending on solar activity. It consists of about 90% protons, 9% helium nuclei, and 1% heavier nuclei. GCR dose is difficult to shield; approximately 5 to 10 m of lunar soil reduces the GCR dose to terrestrial levels.

Solar protons pose a significant risk to inadequately shielded crewmembers. Very large energetic particle events, which can cause acute radiation effects, occur at intervals of 7 to 10 years. Intermediate events, which can limit mission activities, occur several times each year. For nominal flares, build-up to peak radiation intensity occurs within a few hours or less. Monitoring of X-ray precursors may provide 30 minutes to one hour of additional warning.

We must contend with life threatening radiation hazards on the lunar surface. The galactic cosmic radiation and the intense particle radiation from solar flare events are potentially significant problems for the EVA crews exploring the lunar surface, remote from the main base. It has been suggested that the radiation hazard may be aggravated by other factors in space, including stress and low gravity. In addition to the natural radiation environment, we must consider the introduction of non-ionizing radiation associated with communications systems. High atmospheric nuclear explosions on Earth, currently banned by international treaty, might also contribute to the radiation hazard on the lunar surface. (Radiation hazards and shielding requirements are considered in detail in sections 3.2.15 and 4.5)

All well and good, but again there's no evidence presented that shows how this would have made it impossible for Apollo astronauts to go to the moon? I could quote a load of information about background radiation on Earth, but how does that prove the Earth is too radioactive to live on?

And here's a little extra in this same article about the behavior of the lunar regolith in a 1/6 gravity environment ...Something which NEVER happened in any of the Apollo videos .

"The one-sixth gravity on the moon provides humans with a visceral sense of up and down and can be used to keep tools and equipment in place, unlike the floating environment of microgravity, but it also permits humans to fall down in the regolith should they lose their balance. It permits humans to handle larger masses with ease and reduces the energy required to move these masses. It enables humans to leap and stride, but it also permits soil to be kicked in long trajectories above the surface. Human sensitivity to radiation may be affected by the reduced gravity environment. We should take advantage of this environmental feature in our designs for equipment and procedures to support long term lunar activity, just as we design to take advantage of microgravity in orbit."

http://rigel.neep.wisc.edu/neep602/LEC22/NEAL/neal.html

You've never seen lunar soil kicked in long trajectories in Apollo videos? Here's one such example, around the 22 second mark.

http://history.nasa.gov/alsj/a17/a17v_1653633.mov

[Gavin Stone]

None of the Apollo astronots ever mentioned hearing the "raindrops" radiation hitting their spacecraft.

You owe me a new keyboard after I spat tea all over this one after reading this comment.

Jeez Duane you are funny

[Evan Burton]

Dave has kindly done all the work I had hoped you would do, Duane. Reference your quote from Von Braun in 1960... don't forget that knowledge increases over time, with experience. Remember that in the early 1900s, there were people who said that manned powered flight would never be possible; that in the mid-1940s a senior US Army engineer said the atomic bomb could not work, and there were aeronautical engineers who believe it was impossible to travel faster than the speed of sound.

And once again, Dave has shown how you should check the claims before making them (lunar soil kicked in long trajectories). It was shown with your comments in the Cameras thread. If you think something is important, check the sources from which it occurs. If you don't believe something has occurred in videos but you have not checked to confirm that, then qualify your statement, e.g.:

"I haven't been able to view all the Apollo lunar videos, but I don't think that any of them show...."

[Duane Daman]

You are joking with this comment I hope!

It sounded to me like the radiation could actually be heard because of this statement in Von Braun's article ...

"When a rocket flies through this belt the trapped electrons impinge on its skin like raindrops hitting an aircraft which is flying through the clouds. Very much in the same fashion as the impinging raindrops cause sound waves audible within the airplane cabin, the impinging electrons produce an electromagnetic radiation inside the cabin.

If I was wrong you have my apologies ... but I didn't read any explaination as to why I was wrong ... Instead you all just posted your typical insulting, condescending mockery .

You've never seen lunar soil kicked in long trajectories in Apollo videos? Here's one such example, around the 22 second mark.

I can kick up sand on a beach in 1 g much higher and further than that video allegedly shows in 1/6 g .

Can you find any other examples of lunar regolith being kicked a long distance , or was that all you managed to locate ?

You owe me a new keyboard after I spat tea all over this one after reading this comment.

Well, you owe me a new computer screen after I put my foot through it the first time I saw your obnoxious mug show up on this forum .

Edited January 28, 2008 by Duane Daman

[Kevin M. West]

You are joking with this comment I hope!

It sounded to me like the radiation could actually be heard because of this statement in Von Braun's article ...

"When a rocket flies through this belt the trapped electrons impinge on its skin like raindrops hitting an aircraft which is flying through the clouds. Very much in the same fashion as the impinging raindrops cause sound waves audible within the airplane cabin, the impinging electrons produce an electromagnetic radiation inside the cabin.

If I was wrong you have my apologies ... but I didn't read any explaination as to why I was wrong ... Instead you all just posted your typical insulting, condescending mockery .

Well, can you hear electromagnetic radiation? That's what it says is produced by the particles.

[Dave Greer]

It sounded to me like the radiation could actually be heard because of this statement in Von Braun's article ...

"When a rocket flies through this belt the trapped electrons impinge on its skin like raindrops hitting an aircraft which is flying through the clouds. Very much in the same fashion as the impinging raindrops cause sound waves audible within the airplane cabin, the impinging electrons produce an electromagnetic radiation inside the cabin.

If I was wrong you have my apologies ... but I didn't read any explaination as to why I was wrong ... Instead you all just posted your typical insulting, condescending mockery .

Calm down old boy - all I said was I hope youre joking.

The answer is right there in that quote from Von Braun. He's used an analogy. The raindrops hitting an aircraft flying through a cloud create a secondary effect - sound waves (you can hear the raindrops). Transfer this to the situation of a spacecraft flying through the Van Allen belts. The electrons (raindrops) hitting a spaceship (aircraft) flying through the Van Allen belts (cloud) create a secondary effect called Brehmstrahlung radiation (soundwaves). The Brehmstrahlung radiation is in the form of EM radiation, possibly xrays.

Quick primer

In a nutshell - there are two basic types of "radiation"

(1) Particle radiation: alpha particles, beta particles (electrons), protons, neutrons etc

(2) EM or electromagnetic radiation - xrays, gamma rays etc (these are exactly the same as light, radiowaves, microwaves, infrared, only with much higher energies)

When particle radiation travelling at a high velocity slows down, it emits a secondary form of radiation in the form of EM radiation (e.g. xrays). The energy of this secondary radiation is essentially dependent on two things: the original energy of the particle, and what material stops the particle. Bizarrely, if you use lead to shield against particle radiation, the seondary radiation emitted is of a much higher energy than if a less dense material is used for shielding, e.g. water, polyethylene, or aluminium. This is precisely why lead is not a good shield against particle radiation. It has its uses against xrays and gamma rays, but for shielding against high energy protons and electrons in the Van Allen belts. Another reason why it isn't used a great deal in manned spacecraft - it's very heavy, therefore difficult and expensive to get into orbit.

I can kick up sand on a beach in 1 g much higher and further than that video allegedly shows in 1/6 g .

Can you find any other examples of lunar regolith being kicked a long distance , or was that all you managed to locate ?

So can I, if I aim an almighty kick at a suitable clump of sand and deliberately kick it as far as I can. Look at the video more closely. He loses his balance and falls over, and his left boot digs into the surface. Sends up a huge spray of lunar dust, about 3 metres long. He hasn't tried to kick the dust any great distance, nor has he moved in such a way that suggests to me would create so much dust if it was filmed on Earth.

There are many examples of dust being kicked about in Apollo videos, have a seacrh on the ALSJ. I'd suggest the later missions (A15-A17) are probably better due to improved TV technology.

[Duane Daman]

Calm down old boy - all I said was I hope youre joking.

I'm calm mate ... I'm just ticked off with myself mostly for mis-reading that quote, and thereby setting myself up for more ridicule .. Since radiation can't be heard hitting the craft, I think it was a rather poor analogy to use raindrops hitting an airplane, which can be heard in the cabin .

As for the behavior of the lunar regolith, I keep reading conflicting claims .... Some articles say that it falls quickly to the ground because of the Moon being a vacuum and other articles claim that it flies high and far when disturbed .

Most videos of the astronots show the dust not kicking up any further than sand on a beach, as do the lunar buggy scenes, where the dust appears to fall very quickly back to the ground after being kicked up by the tires .

So which is it ? ... Does it fly high and linger in the slow motion of 1/6 g, or does it fall quickly, as in a vacuum ?

Here is a YouTube video showing how the "moon dust " in the Apollo videos behaves exactly like sand on a beach on Earth .

MoonFaker - Project Sandbox

Edited January 29, 2008 by Duane Daman

[Dave Greer]

As for the behavior of the lunar regolith, I keep reading conflicting claims .... Some articles say that it falls quickly to the ground because of the Moon being a vacuum and other articles claim that it flies high and far when disturbed .

That's because there's more than one thing to consider when comparing the Moon to the Earth. The lower gravity means that disturbed dust will longer to settle on the moon; whereas the lack of atmosphere conversely means that disturbed dust won't be impeded as it is on Earth. When comparing it to Earth, you'd have to pay attention to the particulate size, atmospheric conditions, etc.

Most videos of the astronots show the dust not kicking up any further than sand on a beach, as do the lunar buggy scenes, where the dust appears to fall very quickly back to the ground after being kicked up by the tires .

To do this empirically you need to know what force it applied to the dust with each step, and measure the height the dust/sand rises to, and how quickly it takes to fall. Otherwise we are just comparing subjective opinions. My subjective opinion is that the motion of the dust is what I would expect in low gravity and a vacuum (the link I gave in an earlier post being a very good example).

I think the rooster tails is also good evidence of this being filmed in a vacuum. No atmospheric clouding. Check out these images which show how I believe the dust motion is happening.

So which is it ? ... Does it fly high and linger in the slow motion of 1/6 g, or does it fall quickly, as in a vacuum ?

It's both! But remember that particulate size will affect motion on Earth - larger particles won't be as easily affected by the atmosphere.

Here is a YouTube video showing how the "moon dust " in the Apollo videos behaves exactly like sand on a beach on Earth .

Dust goes up, dust comes down. Apart from that, I fail to see how this video proves that lunar dust behaves exactly like sand on a beach.

[Gavin Stone]

Well, you owe me a new computer screen after I put my foot through it the first time I saw your obnoxious mug show up on this forum .

It's a fair comment though. You are spouting on about how radiation will kill anyone who stands in it, without any knowledge of what radiation even is.

[Duane Daman]

It's a fair comment though. You are spouting on about how radiation will kill anyone who stands in it, without any knowledge of what radiation even is.

Certain forms of radiation will kill anyone who stands in it, and I do know what it is ... I just mis-read the sentence and because of my dyslexia thought that the comment about the raindrop soundwaves applied to the radiation hitting the spacecraft while in the Van Allen belts .... After reading it again I saw that the sound waves only applied to the airplanes traveling through rainclouds.

I think the rooster tails is also good evidence of this being filmed in a vacuum. No atmospheric clouding. Check out these images which show how I believe the dust motion is happening.

I believe it's the "rooster tail" that shows the possibility of the Rover footage being filmed in an atmosphere and not a vacuum .... As you mentioned before, it's the force applied which determines how far the dust will fly ... I believe that in 1/6 g the dust kicked up behind the buggy whould have travelled much further than it did and would have formed more of a parabolic arc ... It was James Collier who first noticed the behavior of the dust being kicked up as " hitting a wall of atmosphere" and that's why it didn't travel any further than it did , but only went so far before it fell back down to the ground.

But even if this footage does show it to be in filmed in a vacuum, we know that NASA had already spent millions of dollars to build a huge vacuum chamber during the Apollo Program in 1969, which they claimed was used for testing ... but since it measured 100 feet by 120 feet , it could have very easily been used to film a lot of the Apollo videos in .

Dust goes up, dust comes down. Apart from that, I fail to see how this video proves that lunar dust behaves exactly like sand on a beach.

If you watch the video again you will see that the "lunar dust" in the Apollo videos and the beach sand do behave exactly the same.

[Dave Greer]

Certain forms of radiation will kill anyone who stands in it, and I do know what it is

It's not so much the form of the radiation, it's how much of it gets absorbed by the body (usually calculated at the Blood Forming Organs).

For example, Gamma Rays are the most penetrative form of radiation, but they aren't as ionising as other forms of radiation such as Alpha particles and Beta particles. Alpha partciles are highly ionising, but can't even penetrate human skin, so Alpha sources aren't really hazardous unless ingested.

Anyone making claims about the Van Allen belts being an inpenetrable wall of radiation that humans can't pass through is doing little more than handwaving. I've yet to see anyone make a remotely convincing case using actual data. It's usually vague references to a "wall of deadly radiation" that needs "six feet of lead for protection, information that doesn't seem to come from a reputable scientific source for such data, and is only ever replicated on pro-hoax sites.

I believe it's the "rooster tail" that shows the possibility of the Rover footage being filmed in an atmosphere and not a vacuum .... As you mentioned before, it's the force applied which determines how far the dust will fly ... I believe that in 1/6 g the dust kicked up behind the buggy whould have travelled much further than it did and would have formed more of a parabolic arc ... It was James Collier who first noticed the behavior of the dust being kicked up as " hitting a wall of atmosphere" and that's why it didn't travel any further than it did , but only went so far before it fell back down to the ground.

I've never understood Collier's claims about a "wall of atmosphere". If there's an atmosphere then it's all around - the dust can't suddenly hit a wall of atmosphere and then immediately fall back to Earth. His claim gets more and more nonsensical the more you look at it - if this mystery wall of atmosphere is somehow capable of stopping dust dead in it's tracks, why doesn't it billow about in the thick atmosphere? How can it fall back to Earth so quickly? IMO it's quite clearly filmed in a vacuum, but obviously I have no way of proving this. I just know that Collier's explanation makes no sense.