Apollo Discussions > The Hoax Theory
Surveyor 3 anomalies
Peter B:
Over at UM, a poster by the name of Derek Willis has announced his belief in the faking of Apollo 12:
https://www.unexplained-mysteries.com/forum/topic/327357-belief-in-apollo-hoax-conspiracy-could-grow/?page=6&tab=comments#comment-6729276
His post provides links to a couple of articles he's just had published at Aulis, one of which deals with the Surveyor 3 issue. In particular, he draws attention to disagreement between the Apollo 12 astronauts and Mission Control over the cause of discolouration of Surveyor 3.
During the mission, Conrad and Bean said they thought that Surveyor 3 being down inside the crater would protect it from the spray of dust blown up by the LM engine during landing - that the dust would simply blast straight across the crater. As a result they concluded that the Surveyor's brown colour was the effect of the Sun on the paint. It wasn't until some time later that one of them brushed against part of the Surveyor and found the effect was indeed dust.
Willis doesn't buy this. He still thinks the crater should have sheltered the Surveyor.
I disagree. My view is that the LM passed close enough to the edge of the crater for most of the last part of the descent that some of the engine gases sprayed directly into the crater, thus blowing dust within the crater onto the Surveyor.
However I can't prove this as I don't know how wide the exhaust spread out from the LM Descent Engine bell.
So can someone point to evidence of how wide the cone of exhaust gas was? Or explain the process?
Thank you!
Incidentally, I've invited Derek Willis here to discuss his articles.
ka9q:
In a vacuum, the plume begins to expand immediately after exiting the nozzle, even a long one designed to be efficient in vacuum. (However low the pressure at the mouth of the nozzle, it's still lower around it.) But most of the gas still goes straight out the back, and in the case of the LM just before landing hit the surface at nearly right angles. This created a very thin flat sheet of dust flying horizontally outward along the surface in all directions. Conrad flew the Intrepid around the right (north) side of Surveyor crater and landed on the far rim, so he had plenty of opportunities to blow dust onto the Surveyor.
NASA released guidelines for anyone landing near an Apollo site, and much of them dealt with how far away and what trajectory should be followed to avoid blowing dust over the artifacts at the site. I hope people follow them, because one of the things I'd be most interested in seeing is how much dust has built up at the Apollo 11, 14 and 15 LRRRs. Obviously you don't want to add more just by arriving to take a look.
smartcooky:
--- Quote from: ka9q on May 05, 2019, 03:56:29 AM ---In a vacuum, the plume begins to expand immediately after exiting the nozzle, even a long one designed to be efficient in vacuum. (However low the pressure at the mouth of the nozzle, it's still lower around it.) But most of the gas still goes straight out the back, and in the case of the LM just before landing hit the surface at nearly right angles. This created a very thin flat sheet of dust flying horizontally outward along the surface in all directions. Conrad flew the Intrepid around the right (north) side of Surveyor crater and landed on the far rim, so he had plenty of opportunities to blow dust onto the Surveyor.
--- End quote ---
This is perfectly demonstrated if you watch a rocket launch...
As the rocket climbs, and the atmosphere becomes thinner, so it is less able to "constrain" the exhaust plume
Peter B:
Yes, I absolutely understand this. My understanding is that an exhaust plume in a vacuum is conical. My question is what was the angle from vertical that this cone expanded in the case of the LM Descent Engine.
When I pointed this out to Derek Willis over at UM he replied with a photo of the exhaust plume of a Space Shuttle RCS engine. So I asked him whether that was comparable to the LM Descent Engine.
Does anyone have any knowledge of this?
JayUtah:
It's possible to compute the angle, but I don't remember how off the top of my head. I'm confident it's in Sutton and Biblarz, which I can consult when I remember where I put the book. The problem is that the boundary of the plume is not sharp. So you have to pick a cutoff density and say something like, "The half-angle of plume is X degrees out to D density." That's only one of the ways that a plume is not homogeneous, especially when underexpanded. You're still going to get the flat-sheet dispersal ka9q mentions, from the faster-moving still-somewhat-columnar core of the plume.
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