|
|
Post by ka9q on Nov 13, 2011 14:18:16 GMT -4
why are you pursuing this argument, i know a gas cools as it expands. Then why did you cite a combustion temperature (and not even one for the actual propellants) and imply that was the temperature of the gas that you allege impinged on the Mylar thermal blankets of the LM?There's entirely too much "guessing" here, most of it by you.The only one coming close to "twisting [an] argument into dead end non-sense" here is you. We are trying to clear up your misconceptions and to steer you to good references, but for some reason you seem to be resisting. I believe some of us do, but I never have. I'm an electrical engineer with a strong side interest in spacecraft and space flight. I learned what I know about Apollo from the open literature that is available to you too. |
|
|
|
Post by Jason Thompson on Nov 13, 2011 14:18:35 GMT -4
Give me a scientific theory why stars can only be seen form earth, or as some suggested also in the shadow of the earth or shadow of the moon? Cabin lights or sun coming thru the windows comments are just deflections from the issue. On the contrary, they are very much part of the issue, because they affect how the eye responds to light. You cannot simply say 'they are irrelevant'. The 'scientific theory' you want is the way the eye works. There are two ways in which your eye responds to low light levels. Your pupil expands to allow more light in, and a light sensitive protein called rhodopsin is synthesised in the retinal cells. The more rhodopsin, the more response to any give light stimulus. Pupil dialtion or contraction takes milliseconds. Rhodopsin synthesis takes minutes, but it is broken down by strong light in milliseconds. That means that inside a lit cabin, on the lunar surface or in a spacecraft into which the Earth or sun are shining the astronauts eyes will be resopnding to high light levels and hence there will be little rhodopsin and contracted pupils. Star light is too dim to generate a response under those conditions. Once it gets dark your eyes will begin to adapt, and stars will begin to show up. The brightest ones will be seen first, the rest not for several minutes. As soon as a bright light source comes into view the dark adaptation is lost and the stars once again fade from view. You can see the stars clearly from Earth because they are only out when the light levels are already much lower than daylight, so your eyes are set up to receive lower light levels. You can try this yourself on a clear night. Try and see the stars through your window with the lights on. Then go outside and watch the stars for several minutes and see how they become clearer. Then shine a torch in your eyes for a short while and see what happens to your ability to see the stars. The stars can be seen in cislunar space and on the moon IF the astronaut spends time allowing his eyes to dark adapt. While going about the rest of their business they will be unable to see stars if they just take a glance out of the window or up at the sky. |
|
|
|
Post by ka9q on Nov 13, 2011 14:28:52 GMT -4
Neil said the sky is deep black when viewed from cislunar space, only earth sun and moon are visible, with maybe some astronauts reporting possible sighting of planets. And that's exactly what I would have expected him to say. By definition, cislunar space is the space between the earth and the moon. Both objects appear relatively small so eclipses are rare and there is almost continuous sunlight. Under those conditions the Apollo astronauts' eyes would not be dark adapted and they'd be very unlikely to see the stars with their unaided eyes. This is the central issue! Both cabin lighting and sunlight shining through the windows directly affect the ability of the human eye to perceive the very low levels of light from the stars. Let me ask you this. It was almost continuous daytime in cislunar space, and it was daytime during the entire lunar surface stays of all the Apollo missions. Why do you find it unusual or suspicious that people would be unable to sight the stars with their own eyes during the daytime? |
|
|
|
Post by Jason Thompson on Nov 13, 2011 14:45:51 GMT -4
There IS no simple yes or no!
Whether or not stars can be seen depends on the condition of the eyes, and that depends on the ambient light levels. The fact that there is video is beside the point. Yes, the floodlights were off, but the camera had a display screen that was lit up, so the astronauts were looking at that to see what the picture they were sending to Earth looked like, which itself compromised their dark adaptation.
I have just given you a pretty decent summary of how eyes work and that is the KEY element of your question (and before you ask me for my source, I am a professional biochemist: my source is the degree I took to get that position).
Whether you can see stars or not ANYWHERE depends on how your eyes are conditioned to the ambient light levels. Whether you like it or not, that IS the answer to your question. Why do you even thnk it is reasonable to assume there is a simple yes or no response?
|
|
Bob B.
Bob the Excel Guru?
Posts: 3,072
|
Post by Bob B. on Nov 13, 2011 15:09:35 GMT -4
"No, he said that he couldn't see them. Big distinction." This is typical of the banter on this site, no real answer. Answer to what? What was the question? Stars CAN be seen in space, which is very well documented. Whether or not they can be seen under a certain circumstance depends on the specific conditions under which one tries to observe them. Armstrong just never put himself into a situation in which the conditions where right to see them, thus he never did. |
|
|
|
Post by trebor on Nov 13, 2011 15:30:29 GMT -4
Jason why do you continue to deflect the issue Can stars be seen in cislunar space yes or no? its a simple question So why do you continue to ignore the answers? Yes indeed they can be seen in the right conditions, and the Apollo astronauts did see them in cis-lunar space through the CM optical telescope. They even mention taking star sightings through it in the mission transcript. Neil said the sky is deep black when viewed from cislunar space, only earth sun and moon are visible And that is exactly how the 'sky' looks from space while on the daytime side of the earth. Could you get to the point. |
|
|
|
Post by PhantomWolf on Nov 13, 2011 15:49:49 GMT -4
there is video available of Apollo 11 cabin with all the lights turned off....its not an issue. This is actually incorrect. The camera's f-stop was set down so that it could film the very bright earth without it over exposing. This made the cabin appear dark. However when the camera was moved back from the window, it clearly shows that the floodlights were on, because you can see one of them.  The bright rectangular to the upper left of the window where the Earth is, is a floodlight. You can see it better later when they open up the camera to more light.  |
|
|
|
Post by ka9q on Nov 13, 2011 15:57:26 GMT -4
Here's the result using my air flow tables: Nozzle expansion ratio is 43, so exit Mach number is 5.70. At this Mach no. the absolute temperature ratio is 0.133, giving the exit temperature as 266 deg F. Can you cite your references? I understand the basic principles of rocket propulsion well enough but I don't really understand the thermodynamic details of exactly how heat energy is converted to the linear kinetic energy of the exhaust. Obviously this can't be 100% efficient since a chemical rocket is a heat engine. Is it meaningful to talk about the "efficiency" of a rocket engine as the fraction of the heat released by combustion that gets converted to the kinetic energy of the exhaust? If so, what are some typical efficiencies of rocket engines like those on the LM? |
|
|
|
Post by gillianren on Nov 13, 2011 15:59:23 GMT -4
Your problem is that you believe in the hoax for social and political reasons, but you're trying to argue it on technical grounds. And because you're unskilled in that area, you can't make any decent headway because there is no valid technical argument for the hoax. And you're here arguing with a bunch of technologists who, in the first place know this stuff very well, and in the second place are used to people making bad arguments and therefore all the tricks. We care about getting the technical history right. We don't care about your political beliefs. But please don't think that we argue the technical points because that's our way of opposing you politically, and that we "really" are here because we're in political opposition to you. In other words, don't make the mistake of projecting the converse of your political beliefs onto us as a motive. Actually, Jay, I am so not a technologist. I am only really equipped to argue the historical, social, and political aspects of Apollo. The problem is that there is no valid argument there, either. Every argument for the hoax relies on the US government being simultaneously capable of keeping the biggest secret in history and being so incompetent at it that a bunch of schmucks with no training in any relevant discipline are able to unravel it. That doesn't work in psychology, sociology, political science, or any other discipline which might be used to analyze the non-technical aspects of Apollo. |
|
|
|
Post by JayUtah on Nov 13, 2011 16:24:56 GMT -4
Can stars be seen in cislunar space yes or no? its a simple question No, it isn't. That's your problem. You're trying to force it to be a simple question so that you can claim one or another party is lying. You aren't willing to consider the ways in which different reports can all be correct. |
|
|
|
Post by laurel on Nov 13, 2011 17:25:57 GMT -4
try this, if you were standing on the moon, in a sheltered area where you did not see anything except space, can you tell me if you will see stars? Gene Cernan said that he could see stars when he did this. Read this ALSJ page at approximately 113:19:58. www.hq.nasa.gov/alsj/a17/a17.postland.htmlBear in mind though that he spent much more time on the lunar surface than Armstrong and therefore had more time to look for stars. |
|
|
|
Post by laurel on Nov 13, 2011 17:26:48 GMT -4
Why do you say the technology is unproven? How extensively have you researched the technology? How much research have you done on this subject period? I have to wonder about that when you say they only docked three times and did three spacewalks during Gemini. Gemini 4, 9, 10, 11 and 12 all had spacewalks. Gemini 10 and 11 had two spacewalks each. Gemini 12 had three. Gemini 8, 9, 10, 11 and 12 all involved docking, in some cases docking and undocking with the Agena more than once. I also wonder if you're ignoring the pre-landing Apollo test flights (7, 8, 9, 10) for any particular reason. Were you unaware of them or are you deliberately ignoring them to make your conspiracy theory sound more credible? You even refer to "THE landing on the Moon in 1969." Are you aware that there were TWO Apollo landings in 1969? I'm sorry, but you won't convince me that the hoax theory is true when you make major errors like this. Would you care to answer my questions as long as you're here? |
|
|
|
Post by trebor on Nov 13, 2011 17:30:34 GMT -4
What is the difference in looking into space from the shadow of the earth verses the shadow side of a space capsule? On the shadow side of the earth you don't have sunlight coming in through a window. you guys keep referring to the science, what possible theory is there to explain this phenomenon if you can't see stars? The difference in light levels between a sunlit environment and starlight is huge. try this, if you were standing on the moon, in a sheltered area where you did not see anything except space, can you tell me if you will see stars? Would this be during the daytime with a very brightly lit lunar surface from one horizon to another, or on the night side? |
|
|
|
Post by PhantomWolf on Nov 13, 2011 17:30:40 GMT -4
What is the difference in looking into space from the shadow of the earth verses the shadow side of a space capsule? There is no such thing as "the shadow side of a space capsule" unless you are outside of the capsule. Regardless, when you are in space, unless you make a conscious effort to get out of the light (either by getting into a deep shadow, or by turning out the lights) and let your eyes adjust for the darkness, you won't be able to see that stars. It is this simple, and a number of people have explained the reasons why that is in some detail for you. The only person to be onboard a blacked out CM during Apollo 11 was Micheal Colins who did so while alone in orbit about the moon and stated in his book Carrying the Fire that with a blacked out CM while in the shadow of the moon that he was able to see stars. Aldrin and Armstong didn't have time on the surface to stand about for 5 mins waiting for their eyes to adjust so they could see something that wasn't overly different to what they'd see on Earth, so they didn't do it. We know they didn't because we have a good idea of what they spent their time doing, it was all planned out and recorded. Later crews did have the time and some of them took it and reported being able to see stars from the lunar surface, as long as you got ionto deep shadow and let your eyes adjust. Now it seems to me that your whole issue is based about the idea that had it been you, you would have wanted to look at the stars and they didn't so something must be wrong. Unfortunately this is a fallacy of a sample of one which based on expecting everyone to do the same things you would. The fact is that different people do things differently, and just because you would do something doesn't mean that they would do the same thing. In this case they didn't have the time or the interest to look for at stars, it is that simple. |
|
|
|
Post by dwight on Nov 13, 2011 17:38:07 GMT -4
I'm almost waiting for playdor to tell us that both Stevie Wonder and Ray Charles couldn't see stars in cislunar space so anyone who claims they can is obvious lying and not giving a straight answer.
|
|
