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Post by nomuse on Feb 3, 2012 2:47:50 GMT -4
Just the other day, I was talking to Jarrah White. We all know his stance on Apollo. Now I'm no expert in radiation by any means of the word, and it was just last week that I even got the idea what MeV and REM was. Well Jarrah offered the following theories on why the Apollo shielding should have been about 10cm thick. I'm sure there are plenty of people here who know a lot more about radiation than me, so I'd like to tell you guys what the calculations were and I want you to debunk the holy living hell out of me. Jarrah says the outer belts had an average of 10-100MeV. I told him we could work on the principle that they were 50MeV. Now, here is what he told me. To find the "aerial density?", we must multiply 50 by .545cm^2. We have 27.25cm^2. Now he said we have to divide that by the density of the material itself. Aluminum has a density of 2.7cm^3. We get about 10.09cm^3 worth of shielding. The LM had paper thin shielding. Jarrah says this is also without all the "secondary" radiation you'd get from particles bouncing off each other and fragmenting. According to him, with these numbers, the Apollo astronauts should have absorbed 1200REM, when the official log says they absorbed 2REM. Like I said, I'm no expert, so of course the data means little until I can get a better understanding from the Pro-Apollo side (like me). By no means, I hope everyone realizes, does this mean I have doubts about Apollo. Well anyway, I was hoping some of you radiation guys could come and tell me why you don't need 10cm. Thank you! I have read that a greater concern than VA Belt radiation was the not unlikely occurrance of a high dose of radiation being delivered via a sporadic solar flare. I read that flares releasing lethal radiation doses are not uncommon. It is argued Apollo missions would not be launched into the teeth of such dangerous circumstances. This seems very reasonable to me. Notice flares can disrupt communications and even cause outages down here on Earth. The Earth's magnetic field does not sufficiently ameliorate them. And yet, every space-faring nation has seen fit to send astronauts up to the ISS to hang around for months on end hoping a flare won't hit.
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Post by nomuse on Feb 1, 2012 16:17:17 GMT -4
I've heard it claimed. Specifically, that NASA filmed in black and white in a desert in Utah, then went back and colorized a few random bits and pieces like the American Flag to make people think these were color pictures taken of a black-and-white landscape... Ignoring the whole "but it isn't black and white, you nimnods...there's lots of subtle color variation in the landscape" this mostly reminds me of the great, great Calvin and Hobbes strip where Calvin's dad is explaining color photography: runt-of-the-web.com/post/1514224572/calvins-dad-the-original-troll-scientist
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Post by nomuse on Jan 31, 2012 17:12:26 GMT -4
Well that was a great load of help! Thank you! It's called "Kerbal Space Program" and it's a load of fun. It has taught me a lot about Orbital Mechanics. Ah, another KSP fan. An early version of the game is available for free download as a demo version. It looks like a sillier, more user-friendly version of Orbiter (Orbiter doesn't have green-skinned bug-eyed astronauts). I recommend at least trying the demo. kerbalspaceprogram.com/Here's a video demonstrating a flight to the Mun: www.youtube.com/watch?v=bGd_BFu9e10And yes, it works as a nice introduction/demonstration of orbital mechanics. I laughed the first time I thought "Now I'm going to reach apogee and execute a circularization burn" and it worked. I picked up those rudiments...circularizing an orbit, etc., with the VIDEO game "Space War." They had one at the local pinball arcade and you could play for hours on a quarter as long as you were careful.
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Post by nomuse on Jan 30, 2012 17:24:02 GMT -4
Heh. I was saved by a creek while orienteering in West Virginia. Here's the set-up; thick woods, so you and your partner would progress by one guy going forward a hundred paces or so, then the rear guy yelling "move to your left! No, your other left!" until the front guy was aligned on the heading. Then the rear guy would jog up to join him. Lather, rinse, repeat.
Eventually we broke out of the woods and were on the trail I expected, but there was no creek. I was able to just barely see one peak through the trees and take a back azimuth off it, but that didn't match where we were supposed to be.
And then it clicked. I was willing to bet I had the right peak (it had a distinctive saddle shape to it), and that we'd done the bounding progression to within a few degrees of accuracy, and this was indeed the trail we were looking for. Which meant....yes indeed....I'd SUBTRACTED the GM angle instead of adding it!
I plotted our presumed position, turned around, and found the creek less than a hundred feet down the trail.
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Post by nomuse on Jan 25, 2012 5:00:57 GMT -4
Heck, I'd have enough of a bone to pick even if he were posting movie reviews. He's such a poor writer and is so proudly unaware of just how ill-organized his long rambling posts are. It is like weeds on a page; it makes me want to pull out a red pen and try to cut through to whatever (however trite) intent might be hidden within.
He's also dangerously incompetent at basic science and engineering; the kind of guy who barely bothers to skim the first few lines of a Wikipedia article before deciding he knows enough to safely run a cutting torch or install household wiring. Every post is full of lofty assurances of his own competence; a teeth-grinding experience when contrasted with the actual skills he reveals.
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Post by nomuse on Jan 22, 2012 5:39:21 GMT -4
Naw....I wanna hear how an Earth-Orbit mission is any use at all in gathering materials to fake a mission that circles the Moon and takes pictures of the far side (as well as pictures of the Earth from much, much further than low orbit).
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Post by nomuse on Jan 19, 2012 15:10:24 GMT -4
Gah.
I do understand the need for moderation, and I appreciate that the conspiracy believers are rare in skeptical environments and have to be treated as endangered species.
But....if any other poster were to use half of Doctor Sock's insulting style, ranting, FULL CAPS, and the constant stream of insults, their post would never pass moderation and they themselves would get a stern warning.
It almost makes me want to meet him at Godlike Productions where I could tell him what I really feel.
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Post by nomuse on Jan 13, 2012 16:07:09 GMT -4
But also I was curious if anyone has thought about the radiation and where it comes from? It comes from the sun and is every where in space, right? (There is also radiation from other stars) Honest, I'm not being asinine, but this isn't the appropriate venue for those questions. You need more background on radiation, space weather, and related stuff, and it isn't efficient for people to try to type it all out in forum posts. Start browsing. Start with the articles at Clavius, for instance. so an astronaut going to the moon would experience a concentrated dose of radiation as he traveled thru the belts followed by continual doses from then on. There would be virtually no space devoid of radiation. so to say that the only danger is the van Allen belt is not valid, in space there would be continuous radiation exposure. Sort of yes. The situation is more complex; this is, again, why a straightforward answer/response format as dictated by a forum thread is not optimal. Our Sun puts out a great deal of energy and a small amount of charged particles. Of the former, all is "radiation," but only part is ionizing radiation ("Hard" UV, x-rays, etc.) The Sun's output can be plotted on a kind of curve called the theoretical black-body curve -- what this means, is that most of the radiated energy is concentrated in the visible bands. So ultraviolet light, being closer to the visible band than the really hard stuff, is the most deadly "solar radiation" from the point of view of an unprotected organism. UV is also not particularly energetic, and can be stopped easily with a bit of glass or lexan. Anyhow...the particle radiation (still called "radiation," but very different stuff) of the quiet Sun is mostly electrons and protons in lower energy ranges (1 - 10 keV). Sunspots and coronal mass ejections can (but don't always) release charged particles of much greater energies. So the primary danger of our sun to an astronaut or spacecraft comes in the form of short-duration events. These events do not occur all the time. Back to that lower-energy stuff, tho. Because it is relatively lower energy, some of it can be captured in Earth's own magnetic field, thus forming a rough flattened doughnut with several week's worth of the Sun's output collected all at once. Out of THIS stuff, it also has a curve of energy distribution; lots of particles that are too wimpy to even make it through a sheet of paper, and a small number of particles that could whack their way through the side of a car. And even within the context of this drastically over-simplified review, there is further complexity. The protons clustering in the inner belt slam into shielding and are absorbed. The electrons of the outer belt, though, have a nasty habit of braking radiation; as you slow them down in your shielding, they release the excess energy in the form of high-energy photons. And this is just the Sun. There are other sources to consider. That doesn't mean that space is unrelentingly hostile; there are dozens of significant sources in your average home. It just means you can't boil down this complex situation to a single rule that says "you must have THIS much 'shielding' to survive in space." I picture the radiation belts to be the solar wind moving past the earth, the weak magnetic field helps bend the flow of protons around the earth and are concentrated in a manner similar to air flow around a ball, a portion of the protons are absorbed by the earth much like charging a capacitor. The protons are being ejected continuously from the sun, the radiation belt is not static but is dynamic, always in flux due to sun activity and earth interaction with the solar wind other solar bodies and earth's discharging cycles. Yeah, actually. Not bad. Except that they are actually captured; it isn't just a pinched flow, it is more like the capacitor you mentioned. The VARB are "charged up" by space events and the particles remain there for some time. so its not can an astronaut withstand a few hours in the van Allen belt, it is can an astronaut withstand 7 or 8 days in increased levels of radiation? A bit overstated. There have been various voyagers that have spent a LOT longer than a few hours in the belt. It isn't impossible to shield against -- it just becomes a matter of mission trade-offs. the level of radiation in space may be calculated by considering the size of the earth and calculate how much the solar wind must be concentrated to move past the earth. about 30 earths fit between the earth and the moon, so one could consider traveling thru multiple van Allen belts to reach the moon and multiple van Allen belts back, plus all the radiation while around the moon. food for thought? Also i know proton radiation is only 1 type encountered in space. also someone was correct electrons protons and neutrons are basic, they can not change one to another. Sorry, even a cocktail-napkin sketch can go bad if you are using incorrect assumptions.
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Post by nomuse on Jan 6, 2012 0:27:25 GMT -4
Just bumped into this account from Fred Ordway, quite by accident. Underlines the massive effort necessary to create 2001 -- and how implausible tackling the much bigger problem of faking the Apollo Program would have been. www.visual-memory.co.uk/amk/doc/0075.htmlAnd there was also this page a link or two away: www.visual-memory.co.uk/sk/2001a/page2.htmlTalks a bit about lighting issues and the use of front projection in 2001. And, not coincidentally, shows that Dave McGowan is an idiot. The "seams" he talks about were solved by Kubrick's people before the first scene was even shot. That is...within the development of the technology itself. And, also, underlines just how non-trivial setting up for front projection is.
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Post by nomuse on Jan 5, 2012 15:48:52 GMT -4
I used to say our instincts are great -- for what life is like in a warm pressurized gas at the bottom of a gravity well. Now I say more that our instincts are best at anything that's large enough to see and small enough to pick up; anything that's within a magnitude of our own mass and length, that moves within a magnitude of a walk, etc.
Most of us just don't have an instinctive feel for the height of a skyscraper or the weight of a locomotive, any more than we have an instinctive feel for what life is like at the scale of an ant.
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Post by nomuse on Jan 4, 2012 17:40:28 GMT -4
Thanks for the welcome, echnaton, and it does look as though there's a lot of interesting stuff to be learned here. I, along with a few other people, watched the Moon landings in 1969, and I would have been astonished to hear that they would be doubted half a century later. But unfortunately, as gillianren points out, there are people who will believe anything. What puzzles me, though, is the amount of cognitive dissonance deniers have to put up with if they examine the premises of a hoax at all. You must admit that we had rocket boosters that at least flew up out of sight, don't you? And you can't fake satellites in orbit, can you? I saw Sputnik in 1957, and that means that rockets could put stuff in orbit. How much harder is it to get a rocket to the Moon, and why would you bother faking it? I don't get the thinking here. Your own cognitive dissonance will lessen when you discover more about the basis from which many Apollo Deniers proceed. Someone who doesn't understand gravity or inertia or the lever doesn't have to experience any dissonance whatsoever in constructing elaborate (but wrong) theories about spaceflight. Just check out Godlike Productions some time (if you have a flask of brain bleach handy). Almost every day there will be a new poster noticing you can see our Moon in the daytime sky, and freaking out about the aliens/chemtrails/NASA/HAARP than made this heretofore unheard-of behavior possible.
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Post by nomuse on Jan 3, 2012 7:30:17 GMT -4
Heh. I truly love these places where the basic physics of the universe shows up in unexpected -- even counter-intuitive -- ways right in the middle of something you interact with daily.
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Post by nomuse on Jan 3, 2012 4:24:51 GMT -4
Got it. Or in terms I understand, something like the Nyquist limit. So how important is lambda in real-world situations? Would you notice that a red object was more blurred than a blue one, or is the spectrum of visible light simply too narrow?
At least when I was shooting models I was able to lock down the camera and use 2-second exposures -- otherwise I could have never done it with 50 watt halogen R30's. Not sure you could get your astronaut-actors to stand still that long, though. And motion picture -- like the scenes in "From the Earth to the Moon" wouldn't work so hot.
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Post by nomuse on Jan 2, 2012 19:33:29 GMT -4
What was funniest to me is that for Episode 1, Jar-Jar was actually my favorite character. Probably because he was rendered after the CGI environments, he was the only character who actually seemed to look around and otherwise take an interest in where he was. The webcomic Darths & Droids makes him the best character, too. He's played by an eight-year-old girl, which explains a lot. I finally got around to reading "Darths and Droids" as the year was ending. "Jar Jar, you're a genius!"
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Post by nomuse on Jan 2, 2012 19:26:54 GMT -4
Yes, but as I mentioned above, that approach will bite you in other ways - a very small aperture brings on other issues like diffraction losses which will manifest in loss of sharpness. Also, the smaller the camera the smaller the sensor. Smaller sensors have lower resolution, less dynamic range and higher noise levels, especially when used at higher sensitivities (higher iso settings). To get anything near the images created by a Hasselblad loaded with medium format film and shot in sunlight in an environment with no atmosphere, you need: - a Hasselblad loaded with medium format film and shot in sunlight in .. Aha! Can you explain in more detail? This seems to make an intuitive sense but I'd like to hear more. Would help me understand why those few films that have tried to accurately produce the look of the Apollo landscape were forced to use very intense light sources. (Actually, I guess my intuition is off. DOF goes up with a narrower aperture -- I learned THAT lesson when shooting 1/72d scale military models with my old Minolta 201 and a couple of macro lenses. But a larger lens, to gather more light in the first place, is going to show more chromatic aberration and various multi-element effects, right?) So with a really small aperture, anyhow, are we talking diffraction effects because the geometry of the aperture is getting too close to the wavelength of the light in question? Or am I talking through my hat?
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