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Post by JayUtah on Feb 4, 2010 19:10:00 GMT -4
Porphyry, your characterisation of Jay's memory is wildly out of place.And inaccurate. (I'm sure he won't mind me saying).I don't; however in practice one relies as little upon memory as necessary, referring instead to published data where available. I'll explain this dichotomy below. ...it is similar to the ability of many musicians to hold complex tunes in their heads and produce them on demand when handed an instrument.An apt analogy, and another feat I can do as well. I can direct large sections of Handel's Messiah from memory. Why? Because I've performed it 1-2 times a year for the past 30 years. Similarly I work with a local composer who has written a set of sacred oratorios and suites. It comprises a bound volume of music some three inches thick. I can perform it largely from memory. Why? Because I recorded it for commercial release some ten years ago (and rehearsed it intensely) and because I perform it 1-2 times a year. And I can cite several examples of engineering designs I can reproduce from memory. Why? Because I work with them routinely in the course of my employment. This is the kind of proficiency that arises naturally when one is significantly employed in some field (either paid or unpaid). If one performs music a lot, one becomes proficient with the music. If one creates mechanical and control systems designs, one becomes proficient with them. This proficiency separates experts from laymen. Laymen don't believe that level of proficiency because they don't experience it. A counter-example: I've never been formally trained in dance, and I dance on stage for theater only at most once a year. Learning and assimilating choreography is quite difficult for me compared to many of my colleagues who have more training in dance. Why? Because in having to learn many different choreographies, they have learned how to learn choreography. Hoax believers typically deny the value of bona fide expertise, for to recognize it would be simultaneously to admit they don't have it and therefore don't have what is necessary to make appropriate comment. As part of that denial, the special properties of human memory that attend expertise must also be denied. Now the dichotomy (at least for engineering). We require engineering practice to be rigorously precise and accurate. Thus even though an engineer may know some design pattern from memory, he should always consult published sources to make sure the result is correct. Although a reasonably accurate and comprehensive memory arises naturally out of frequent use, it is not always a good thing to rely upon.
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Jason
Pluto
May all your hits be crits
Posts: 5,579
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Post by Jason on Feb 4, 2010 19:18:14 GMT -4
I'm afraid I must be a pedant here. While the second serial of season 16 is indeed The Pirate Planet, the seasons at that time straddled the Christmas and New Year period, and season 16 started in the later part of 1978. (I must confess to having to double check the precise transmission dates here, but I never claimed to be able to the date every episode, just to name them! ) The second serial of 1978 was actually the final serial of season 15, which was The Invasion of Time starring Tom Baker as the Doctor, Louse Jameson as Leela, and John Leeson as the voice of K9. It was also notable for some very bad tinfoil aliens (quite apt for this thread!) and a cockney Sontaran.... Meanwhile, back on topic.... Your Doctor Who credentials appear to be authentic. Personally I thought the tinfoil wasn't nearly as laughable as the costumes the aliens had when they materialized and started being played by actual actors, but then that's part of the charm of that particular series, isn't it?
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Post by dwight on Feb 4, 2010 20:23:20 GMT -4
Woah woah woah. Hang on a second. Are you telling me that Dr Who was played by an actor and the aliens were people inside costumes, and that it wasn't <sob> a documentary???
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Post by gillianren on Feb 4, 2010 22:57:23 GMT -4
The term is "historical document."
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Post by Jason Thompson on Feb 5, 2010 9:03:10 GMT -4
Don't be absurd, of course it's not real. It's actually a government-sponsored alien deterrent. We beam all these shows into space that depict failed alien invasions of Earth (or usually London) and any aliens that pick them up think Earth is too well defended to attack.
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Post by ka9q on Feb 13, 2010 10:31:36 GMT -4
The term is "historical document." Oh, all those poor people stranded on Gilligan's Island...
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Post by ka9q on Feb 13, 2010 10:32:53 GMT -4
And who owns the "IP" of the LM? Think carefuly before you answer. Any Apollo patents by now have expired and have passed into the public domain.
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Post by ka9q on Feb 13, 2010 11:27:02 GMT -4
I thought that the pure oxygen in Apollo 1 caused a flammability problem Pure oxygen at greater than sea-level air pressure (since they were simulating positive pressure for the test) caused the flammability hazard. 5 psi of pure oxygen is only about the same amount of O 2 as is present in the atmosphere, hence no greater a flammability hazard. I wondered about this for a very long time until I finally found some references that say the partial pressure of O 2 is not the only factor in the fire hazard. Adding a diluent (inert) gas like N 2 or Ar to a constant partial pressure of O 2 decreases the fire hazard, probably by helping to carry away heat. The specific approach chosen was to fill the cabin before launch (and during tests) with 60% O 2 and 40% N 2. The N 2 came from a ground supply, so there was no need to change the spacecraft. The astronauts still breathed 100% O 2 in their pressure suits, which they put on several hours before launch. If you look at any picture of Apollo astronauts headed to the pad, you'll see they're wearing their helmets and carrying portable O 2 sources. They also cooled the suit but I'm not sure how -- the obvious approach is to use LOX, which would also make the unit compact. They had to prebreathe O 2 this early so that most of the N 2 would be flushed from their bodies by launch time to avoid the bends when the cabin pressure drops within a minute from sea level to about 5 psi. This was not a theoretical hazard - in his book Carrying The Fire Michael Collins said that he experienced a mild case of the bends - painful knees - during his Gemini mission. When the cabin pressure reaches 5 psi, the large vent closes and the environmental control system (ECS) maintains 5 psi with pure O 2. A smaller vent remained open so that over the next day or so, the remaining N 2 in the CM cabin was slowly purged with pure O 2 from the ECS, bringing the O 2 fraction in the cabin asymptotically close to 100%. (Remember that 2/3 of the N 2 in the cabin at launch had already been dumped through the vent as the cabin dropped to 5 psi.) Wasn't 60% O 2 still a fire hazard? Yes, but far less severe than 100% O 2 - and the Apollo project had made a major effort to remove flammable material from the cabin. The enrichment was necessary to guarantee a sufficiently high partial pressure of O 2 at 5 psi right after launch when the astronauts remove their helmets. 60% of 5 psi is 3 psi, and the partial pressure of O 2 at sea level is 21% of 14.7 psi or 3.1 psi - pretty close.
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Post by ka9q on Feb 13, 2010 11:33:04 GMT -4
A more direct source is ntrs.nasa.gov/This is the NASA Technical Reports Server. Just type in some Apollo keywords and you'll be amazed at the amount of stuff that comes back. Not all of it is available on line, but most of it is and the rest can be obtained on paper or microfilm. How the hoaxers can maintain with a straight face that "all the blueprints were destroyed" when a site like this exists is exhibiting far more cognitive dissonance than I can comfortably comprehend.
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Post by Glom on Feb 13, 2010 18:11:58 GMT -4
Wasn't 60% O 2 still a fire hazard? Yes, but far less severe than 100% O 2 - and the Apollo project had made a major effort to remove flammable material from the cabin. The enrichment was necessary to guarantee a sufficiently high partial pressure of O 2 at 5 psi right after launch when the astronauts remove their helmets. 60% of 5 psi is 3 psi, and the partial pressure of O 2 at sea level is 21% of 14.7 psi or 3.1 psi - pretty close. I prefer the Space Shuttle's way of doing it. Just use a more Earth bound atmosphere. (I am right about that, right?)
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Post by cos on Feb 13, 2010 18:42:00 GMT -4
I wish you hadn't shown me this. I have just spent an hour reading such fascinating papers as; 'A study to determine optimum lunar lighting conditions for visual selection of LEM touchdown point' The detail and research that went into every aspect of the mission is astounding and it is here for all to see (thousands of man years of work). Only someone speaking from complete and utter ignorance can make outrageous statements concerning documentation. Someone recently on these boards made the (false) accusation that there were no blueprints for the Saturn V. Even if this were true, what point were they trying to make? That the Saturn V didn't exist?!!
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Post by Ginnie on Feb 13, 2010 19:13:01 GMT -4
I wish you hadn't shown me this. I have just spent an hour reading such fascinating papers as; 'A study to determine optimum lunar lighting conditions for visual selection of LEM touchdown point' The detail and research that went into every aspect of the mission is astounding and it is here for all to see (thousands of man years of work). You're not kidding! I've downloaded 400 page PDF files on many occasions cursing so much information. Sometimes the overabundance is a burden when trying to find something specific.
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Post by ka9q on Feb 14, 2010 0:03:58 GMT -4
I prefer the Space Shuttle's way of doing it. Just use a more Earth bound atmosphere. (I am right about that, right?) Yes, the shuttle and ISS use air, as does just about everything the Russians have ever flown in. There are definite drawbacks to using air. The structure has to handle the higher pressure. The life support system has to be considerably more complex to store nitrogen and meter it out appropriately. Unlike in a pure O 2 system where you merely feed the cabin through a pressure regulator, a mixed gas system has to continually measure the mixture ratio and add the appropriate gases in the right amounts. Loss of pressure due to metabolism requires only that the O 2 be replaced, while loss of pressure due leakage requires both. (I suppose it's an advantage of a mixed-gas system that you can more easily distinguish between the two kinds of losses.) Probably the biggest operational complication to an ordinary air atmosphere comes when you have to do an EVA. On Apollo you'd just put on your suit, check for leaks, and dump the cabin atmosphere. Not on the Shuttle or ISS. The astronaut must spend hours breathing pure O 2 to purge the N 2 from his/her tissues before he/she can tolerate the drop to low pressure necessary to make the suit tolerably flexible in a vacuum. I'm not sure about the procedure, whether it requires that you keep your helmet on during the entire prebreathe interval or whether you can fill the airlock with pure O 2 and sit in there with your helmet off (e.g., to eat) while you wait.
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Post by gwiz on Feb 14, 2010 7:32:05 GMT -4
I'm not sure about the procedure, whether it requires that you keep your helmet on during the entire prebreathe interval or whether you can fill the airlock with pure O 2 and sit in there with your helmet off (e.g., to eat) while you wait. Since they refer to it as a "camp out" in the airlock, probably the latter.
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Post by Glom on Feb 14, 2010 9:28:42 GMT -4
They spend the preceding night in Quest where the air is low pressure oxygen. It is a little camp-out. Then they put masks on to keep breathing pure oxygen while the airlock is normalised and the door is open so they can clean up. Then they return to the airlock with their buddies, the pressure is dropped a bit so they can take their masks off and not get their blood saturated with nitrogen while still allowing their buddies to breathe. They suit up, go into the actual airlock, where the depressurisation happens and they open the hatch.
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