Apollo 12 and the Surveyor 3 Mystery

[JayUtah]

More specifically, Bean said the dust would "... never go down this crater" and Conrad said the dust "... probably went right over the top of it [the Surveyor]".

Let me hasten to add a correction and apology.  I mistook the characterization of the crew's statement to refer to plume behavior on flat ground, not the specific case of Surveyor in the crater.  That was my mistake, and it probably let to some confusion.  I apologize.  There is a rational basis for thinking the sheet of deflected exhaust might not have gone into a depression.  But the actual expectations depend greatly on the precise circumstances, for example whether the plume passed close enough that the post-impingement expansion would still have sufficient static pressure.

We must also consider that the behavior of dust is not exactly the behavior of the exhaust.  The path of the dust will depend first on the mechanics of entrainment, then upon purely ballistic behavior as the gas becomes too thin to effectively entrain it further.

[Derek K Willis]

Firstly, let's remember that it not me who is making the claim.

It doesn't matter who made the claim.  It matters whether the claim is consistent with knowledge.

The point the astronauts seem to be making...

Well now that's you interpreting what someone else has said.  So it ceases to be their claim and starts to be yours.  What leads you to believe the expanding post-impingement flow would be flat or remain flat?  It will be largely flat, but it will expand as it radiates outward because it still has residual static pressure until it disperses sufficiently.

So what force is involved that would make the particles "hug" the surface and travel down into the crater, rather than shoot over the edge?

By "hug the surface" I don't mean follow arbitrary contours.  I apologize if that was confusing.  But if the expanding sheet encounters a depression, the vertical expansion of the sheet as it radiates will extend into the depression so long as there remains static pressure to do so.  Previously its vertical expansion was restricted by the ground.

Since we're talking about expectations in a specialized field of study, now would be a good time for you to tell us what your education, qualifications, and experience might be in the field of fluid dynamics.  That will help us understand to what degree your expectations are informed by the principles of the field.

No, it was the astronauts' claim. Bean said the dust would never go down the crater, and Conrad said it would probably go straight over the top of the Surveyor. Both opinions are at odds with your opinion.

Is questioning my qualifications, is this the start of the ad hominems? Well, I have a degree in physics, though fluid mechanics was in no way a specialty.

So okay, run me through what you are saying. Explain why you are sure there would remain sufficient static pressure to cause the dust to go down into the crater.   

[Derek K Willis]

More specifically, Bean said the dust would "... never go down this crater" and Conrad said the dust "... probably went right over the top of it [the Surveyor]".

Let me hasten to add a correction and apology.  I mistook the characterization of the crew's statement to refer to plume behavior on flat ground, not the specific case of Surveyor in the crater.  That was my mistake, and it probably let to some confusion.  I apologize.  There is a rational basis for thinking the sheet of deflected exhaust might not have gone into a depression.  But the actual expectations depend greatly on the precise circumstances, for example whether the plume passed close enough that the post-impingement expansion would still have sufficient static pressure.

We must also consider that the behavior of dust is not exactly the behavior of the exhaust.  The path of the dust will depend first on the mechanics of entrainment, then upon purely ballistic behavior as the gas becomes too thin to effectively entrain it further.

Yes, that is what I am getting at. Which is why I asked whether - and why - you think the Surveyor was beneath the plume. At least we both now know what I am referring to.   

[JayUtah]

No, it was the astronauts' claim.

So what?

Both opinions are at odds with your opinion.

Irrelevant.  I have given the explanation for why my opinion embodies relevant physical principles.  I have no problem disagreeing with what an astronaut may have said if I believe I have a rational basis to do so.  You seem eager to have me give some vague additional authority to the source.  I have explained why I disagree with the source.  The source elucidates no rational for their opinions, so it is unclear how you want me to proceed with respect to it.

Is questioning my qualifications, is this the start of the ad hominems?

No, it is an attempt to ascertain your degree of understanding regarding the specialized fields you have invoked.  The finer points of the behavior of rocket exhaust plumes and of the entrainment of particulates are not things laymen are normally expected to know about.  This leads them to proceed from false assumptions and expectations and to drawn conclusions that may not be fully informed.  Your argument here has already started to venture into such expectations.  That is why I waited until it did so to make qualifications relevant.

Do you expect ad hominem attacks?

Well, I have a degree in physics, though fluid mechanics was in no way a specialty.

In what way, if any, was fluid dynamics the subject of adjudicated training or experience?  Since your claim here involves fluid dynamics, have you consulted with anyone who is a relevant expert to review it?

Here is the statement from your article.

Derek K. Willis, who was born in 1960, has a Certificate in Astronomy from the University of Central Lancashire UK. He began his career as a Research Associate at Northumbria University, and has since worked in private industry and as a Department of Trade and Industry Advisor. Derek K. Willis is currently a freelance Innovation Consultant. He has recently written Faking Apollo, a book which examines some of the anomalies associated with the Apollo missions.

Would you please go through that and describe in more detail what parts of it qualify you to speak with authority on the subjects you intend to discuss in this thread?  It mentions astronomy, but no degree in physics.  And it is vague on what you did for industry and government, or what activities comprise "freelance innovation consultant."

So okay, run me through what you are saying. Explain why you are sure there would remain sufficient static pressure to cause the dust to go down into the crater.

I didn't say I was sure.  You asked what force could possibly accomplish that.  The answer is that residual static pressure in the exhaust plume is possible.  Exhaust plumes in a vacuum are known to retain static pressure after exit.  They are known to exhibit the effects of static pressure for considerable distance after exit.  Did you consider static pressure in your analysis?

I also introduced the other possibility.  The question is not necessarily how exhaust got into the crater, but how dust did.  It is the dust we wish to explain.  I have explained how, as the density of the exhaust falls, it becomes too thin to further entrain dust, which will then transition to purely ballistic behavior.  Did you consider partial entrainment in your analysis?

[JayUtah]

Which is why I asked whether - and why - you think the Surveyor was beneath the plume.

By "beneath the plume" I assume you intend "plume" to be the direct flow from the exhaust nozzle, not the secondary flow after impingement.  Please correct me if I'm wrong.

Also, please explain why you think that's relevant.

Regarding whether we're on the same page about what your claim is, I regret the misunderstanding.  As I have only limited time to read and post this weekend, you are perfectly within your rights to insist that I read your full argument and respond only at that time.  You indulged other members here by summarizing your claim forthwith, and it was because I relied upon the summary that I stepped off on the wrong foot.

[smartcooky]

Derek: From your article

"Even in an environment of 1/6g it would be reasonable to conclude that the dust blown up by the LM’s descent engine would have settled back down, coating the footpads and other structures such as struts and equipment housings."

No, it is not reasonable to conclude this when your 1/6G environment is also a vacuum. It might seem reasonable, or even intuitive to you, because you have grown up and spent all your life living on a planet with 1000 mb of atmosphere.

On the earth, in 1000 mb of atmosphere, your conclusion would be reasonable, because a cloud of dust would form with the largest particles setting almost immediately, and smaller particles remaining suspended; the smaller the particles, the longer they remain suspended.  This is why your Hawker Harrier example is correct. The downwards thrust throws dust everywhere and the turbulence it creates brings dust back towards the aircraft. I can confirm this because I saw this personally when I was attached to 233 OCU at RAF Wittering where they flew Harrier GR3s. After landing on a grass or dirt area, dust would settle on the upper surfaces and even on the tyres. For obvious reasons, the pilot would not pop the canopy until the dust had settled. Additionally there are always tiny currents in the atmosphere (even on the calmest of days, there are tiny thermal currents) and these cause some of the smallest particles to drift back towards where they came from up to a minute or more after the downward thrust has stopped.

However, no such thing happens in a vacuum; no dust cloud forms. This is because there is no atmosphere. Dust thrown up follows a ballistic arc back to the ground. The largest dust particles follow the same arc, and take the same amount of time to alight as the tiniest particles. THIS is why very little, if any, dust ends up on the landing pads of the descent stage..... because there is no atmosphere - there is no turbulence and there are no air currents to bring dust particles back towards the direction they came from.

This will also explain why they expected that the Surveyor 3 lander would not be coated with dust from the landing. The only dust that would reach the Surveyor and land on it, would be those particles of dust that were imparted with enough energy by the downthrust of the descent stage to reach the lander at the end of their ballistic arcs - anything with less energy would fall short, anything with greater energy would fly over.

[Derek K Willis]

Regarding whether we're on the same page about what your claim is, I regret the misunderstanding.  As I have only limited time to read and post this weekend, you are perfectly within your rights to insist that I read your full argument and respond only at that time.  You indulged other members here by summarizing your claim forthwith, and it was because I relied upon the summary that I stepped off on the wrong foot.
[/quote]

You are playing the ad hominem game. At universities in the UK - and I presume elsewhere - you can only be a research associate if you have at least a bachelor's degree. I therefore assumed it would be implicit that I have a degree. I am beyond the age when it really matters what my qualifications are. I only mentioned the certificate in astronomy - which I did for fun a few years ago - because it has more relevance to all things lunar than does solid state physics, which was my main area of interest when I was at university.

The reason I asked people to read my article was to avoid the situation you have created. If you had read the article you would have perhaps avoided the condescension and instead addressed the point I was making. So perhaps when you get time to read the article we can start again.

 

[Derek K Willis]

Derek: From your article

"Even in an environment of 1/6g it would be reasonable to conclude that the dust blown up by the LM’s descent engine would have settled back down, coating the footpads and other structures such as struts and equipment housings."

No, it is not reasonable to conclude this when your 1/6G environment is also a vacuum. It might seem reasonable, or even intuitive to you, because you have grown up and spent all your life living on a planet with 1000 mb of atmosphere.

On the earth, in 1000 mb of atmosphere, your conclusion would be reasonable, because a cloud of dust would form with the largest particles setting almost immediately, and smaller particles remaining suspended; the smaller the particles, the longer they remain suspended.  This is why your Hawker Harrier example is correct. The downwards thrust throws dust everywhere and the turbulence it creates brings dust back towards the aircraft. I can confirm this because I saw this personally when I was attached to 233 OCU at RAF Wittering where they flew Harrier GR3s. After landing on a grass or dirt area, dust would settle on the upper surfaces and even on the tyres. For obvious reasons, the pilot would not pop the canopy until the dust had settled. Additionally there are always tiny currents in the atmosphere (even on the calmest of days, there are tiny thermal currents) and these cause some of the smallest particles to drift back towards where they came from up to a minute or more after the downward thrust has stopped.

However, no such thing happens in a vacuum; no dust cloud forms. This is because there is no atmosphere. Dust thrown up follows a ballistic arc back to the ground. The largest dust particles follow the same arc, and take the same amount of time to alight as the tiniest particles. THIS is why very little, if any, dust ends up on the landing pads of the descent stage..... because there is no atmosphere - there is no turbulence and there are no air currents to bring dust particles back towards the direction they came from.

This will also explain why they expected that the Surveyor 3 lander would not be coated with dust from the landing. The only dust that would reach the Surveyor and land on it, would be those particles of dust that were imparted with enough energy by the downthrust of the descent stage to reach the lander at the end of their ballistic arcs - anything with less energy would fall short, anything with greater energy would fly over.

Why don't you read the rest of that section in my article? If you do you will see that I describe everything that you have described - namely that clouds of dust aren't created in the vacuum of the Moon when a spacecraft such as a Surveyor or LM lands. Hence very little or no dust settles onto the spacecraft.

I was told the people at ApolloHoax were more scientific and professional than on other forums. So far I have responded to someone who didn't read any of my article, and now to you who have read a paragraph and then no more. Back when I was at university I was always told to read an entire paper before making a comment.

[JayUtah]

You are playing the ad hominem game.

Nonsense.  if you are presuming to be an authority on how properly to plan and carry out space missions, such that you can declare someone else's efforts invalid for failure to meet your expectations, then the basis of that alleged authority is not at all ad hominem.  it is, in fact, the primary point of relevance because that's what gives birth to the expectations.  If the best explanation for the discrepancy between the facts and your expectations is that your expectations are incorrect or insufficiently informed, then why cannot that be the right answer?

I am beyond the age when it really matters what my qualifications are.

Nonsense.  If you presume to speak with authority on a specialized topic, ad any age, then it is always relevant to examine the foundation for that authority.  Further, you realized a statement of authority was necessary enough to attach one to your article.  Why did it matter when you wrote the article, but now it doesn't matter here?

I only mentioned the certificate in astronomy - which I did for fun a few years ago - because it has more relevance to all things lunar than does solid state physics, which
was my main area of interest when I was at university.

I'm not sure any of it is relevant to the claims you wish to make.  It's unclear how a "certificate" in astronomy conveys a suitable foundation of expertise.  Further, you mentioned you were a "research associate" in your statement of authority, but you omitted to tell the reader that it was in a field you now don't consider particularly relevant to the subject matter.  And you went on and listed other activities without giving any details.about how, if anyway, they were relevant.

If you had read the article you would have perhaps avoided the condescension and instead addressed the point I was making.

It is not condescending to ascertain whether a claimant's expectations are properly informed.

[JayUtah]

So far I have responded to someone who didn't read any of my article...

If that's all you've gleaned from my contribution, then you've missed the point.  I've given you several points of science that you evidently did not yet consider before drawing your conclusion.  Do you intend to address those, or merely complain about how shabbily you think you've been treated?

...and now to you who have read a paragraph and then no more.

But his comments on that paragraph are valid.  You are begging important questions that clearly derive from a layman's grasp of what to expect in the space environment.  You have, in fact, received lengthy comments from people who did read the paper, which you have ignored entirely.  When I asked what your background was in the relevant sciences, you seemed to jump at the chance to be the victim of ad hominem argumentation.  If you're here just to protest, you won't find a very receptive audience.

Back when I was at university I was always told to read an entire paper before making a comment.

And have you studied entirely the sciences relevant to the comments you make in your paper?

[apollo16uvc]

Interesting thread, sucks it went into the classic "Are you qualified" pitfall. Who cares? Not every person on the internet has knowledge about every intricate detail of the inner workings of the universe. Adds or removes nothing from the debate, I think.

Sure it may be asked once by both parties so we know how we stand. But no need to quibble on about it.

[smartcooky]

Why don't you read the rest of that section in my article? If you do you will see that I describe everything that you have described - namely that clouds of dust aren't created in the vacuum of the Moon when a spacecraft such as a Surveyor or LM lands. Hence very little or no dust settles onto the spacecraft.

I did in fact read the whole article, but I merely commented on the first false assumption I came to, namely that what you stated was "reasonable to conclude" was in fact so. It was not.

I was told the people at ApolloHoax were more scientific and professional than on other forums. So far I have responded to someone who didn't read any of my article, and now to you who have read a paragraph and then no more. Back when I was at university I was always told to read an entire paper before making a comment.

Back when I was at university it was not customary to become uppity and defensive when asked to present your bona-fides. Before you go accusing others of "playing the ad-hominem" game you should ensure that you are not actually doing so yourself.

[Derek K Willis]

You are playing the ad hominem game.

Nonsense.  if you are presuming to be an authority on how properly to plan and carry out space missions, such that you can declare someone else's efforts invalid for failure to meet your expectations, then the basis of that alleged authority is not at all ad hominem.  it is, in fact, the primary point of relevance because that's what gives birth to the expectations.  If the best explanation for the discrepancy between the facts and your expectations is that your expectations are incorrect or insufficiently informed, then why cannot that be the right answer?

I am beyond the age when it really matters what my qualifications are.

Nonsense.  If you presume to speak with authority on a specialized topic, ad any age, then it is always relevant to examine the foundation for that authority.  Further, you realized a statement of authority was necessary enough to attach one to your article.  Why did it matter when you wrote the article, but now it doesn't matter here?

I only mentioned the certificate in astronomy - which I did for fun a few years ago - because it has more relevance to all things lunar than does solid state physics, which
was my main area of interest when I was at university.

I'm not sure any of it is relevant to the claims you wish to make.  It's unclear how a "certificate" in astronomy conveys a suitable foundation of expertise.  Further, you mentioned you were a "research associate" in your statement of authority, but you omitted to tell the reader that it was in a field you now don't consider particularly relevant to the subject matter.  And you went on and listed other activities without giving any details.about how, if anyway, they were relevant.

If you had read the article you would have perhaps avoided the condescension and instead addressed the point I was making.

It is not condescending to ascertain whether a claimant's expectations are properly informed.

I was asked to give a brief biography at the end of the article. So I kept it brief.

But I tell you what, we can sort this out if you provide a paper with a bit of physics and a bit of maths explaining how when the LM flew past the Surveyor the dust was blown on. You know what I mean, provide something more meaty than "... there is every expectation that the Surveyor would have been pelted with the entrained dust."

And remember, don't throw this back at me by saying it is up to me to defend my claim. I am not making any claim. Al Bean said the dust would never go into the crater, and Pete Conrad said it would probably go right over the top of the Surveyor. If you are claiming they were wrong, then explain why.

[JayUtah]

Not every person on the internet has knowledge about every intricate detail of the inner workings of the universe.

Straw man.  That's not what is asked for.  When one's argument is predicated on what one expects and what one can or cannot believe, the foundation of knowledge from which those expectations and beliefs arise becomes at least relevant if not foremost.  Where a claimant bases his conclusion on his judgment, the principles of that judgment don't get a pass.  It's a variation on the first question a lawyer imagines when faced with an ipse dixit:  "How do you know that?"

Sure it may be asked once by both parties so we know how we stand. But no need to quibble on about it.

I would have been content if he had just said, "I don't have any relevant qualifications."  At least we would know that in order to refute him, we'd have to go back to first principles and offer some education.  You and many others know I have no problem explaining things to people who admit they don't know them.  But when the response to the question is immediately to complain of being persecuted, that's suspicious.  Experience has shown the wisdom of approaching a debate differently when there is reason to think the other parties are not debating in good faith.

[Derek K Willis]

Why don't you read the rest of that section in my article? If you do you will see that I describe everything that you have described - namely that clouds of dust aren't created in the vacuum of the Moon when a spacecraft such as a Surveyor or LM lands. Hence very little or no dust settles onto the spacecraft.

I did in fact read the whole article, but I merely commented on the first false assumption I came to, namely that what you stated was "reasonable to conclude" was in fact so. It was not.

I was told the people at ApolloHoax were more scientific and professional than on other forums. So far I have responded to someone who didn't read any of my article, and now to you who have read a paragraph and then no more. Back when I was at university I was always told to read an entire paper before making a comment.

Back when I was at university it was not customary to become uppity and defensive when asked to present your bona-fides. Before you go accusing others of "playing the ad-hominem" game you should ensure that you are not actually doing so yourself.

I apologize if I came across as uppity. However, I couldn't understand how you could have written what you wrote if you had read the whole article. I clearly point out that it isn't reasonable to assume a cloud of dust would be created on the Moon, so it seemed odd that you didn't mention that.