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.Were this not true, the "fixed" stars of constellations would become unrecogniz-able in a short period of time.We know from historical records that they stay the same.Michael Collins said, "The basic idea behind the Apollo guidance and navigation systemwas simple enough.It all began with the stars, whose position in inertial space was wellknown and unchanging.They are so far away, of course, that they appear the same whetherone is on earth or a mere lunar distance away." 2While preparing for the Moon landings he claimed that navigation was his personal hairshirt.He goes on to say, "I had made several trips to Massachusetts Institute of Technologynear Boston, and had tried my level best to suffer through a couple of weeks of "simple"explanations of the system by their experts, but I always came away shaking my head." 3Perhaps he felt he was being told nonsense something like, "The framus wittigates onthe thrum rod activating the holcroid.Once it dizzies you are halfway home." Over theNASA MOONED AMERICA! / Rene Space Navigation / Chap.7 p.61years whenever I run into something that doesn't make sense I have great problems with it.Icannot memorize it and I can't work with it.For their navigation package NASA went to MIT early in the game and asked for amethod that would give the Apollo program the ability to go to the Moon and back.Acouple of professors produced the package on time.In fact it was one of the few times thatanyone met a NASA schedule.Michael Collins was designated the navigator for Apollo 11.In his book he lists the 37navigation stars they were to use, plus their corresponding octal numbers which identifiedthem to the computers.Here's how Michael explains that navigation package."The astronaut, peering out through either his telescope or his sextant findsone of the chosen few, superimposes a + on it, and pushes a button at the instant ofperfect alignment.He then tells the computer which star it was, by numbers.Repeatingthis process on a second star allows the computer and the platform to determine whichway the spacecraft is pointing.So we now know which way is up? Well, not exactly,because "up" is a rather fragile concept meaning away from the center of the earth, adirection opposite the gravity vector used to clutch us tightly by.But suppose wecannot even see the earth in our window, suppose we are floating free of earth's gravity.What now, M.I.T.? Back to our friendly stars.We simply define a new up-down andleft-right, using the stars in place of earth.All will be well as long as we all play thegame by the same rules, as long as the ground controllers send us instructions using thesame stellar frame of reference.Now we are free of all terrestrial conventions and cancorrect our course to and from the Moon by pointing in the proper direction relative to4the stars.Collins seems to be saying that the sextant had a cross hair in its optics.But sextantsdon't have cross-hairs.Curiously, I went sniffing through his book and found out that sureenough he was talking about a sextant.Almost 100 pages later he continues:"Unlike Gemini, however, Apollo has a fancy computer tied to the optics, and now Icall on it for help; it responds by swinging the sextant around until it points at where itthinks Menkent is.Aha! There it is, in plain view, and it's a simple task for me to alignthe cross-hairs precisely on it and push a button at the instant of alignment.Now I repeatthe process using Nunki, and the computer pats me on the back by flashing theinformation that my measurements differ from its stored star angle data by.01 degree.Itdisplays this information as 00001.In M.I.T.-ese, a perfect reading of 00000 is calledfive balls." 5Aha! There it is, in plain view: he does claim his sextant has a cross-hair, but this cannotbe true! A sextant is an instrument that uses mirrors mounted on a calibrated movable leg.The essence of the instrument is to superimpose one object over the image of anotherthereby measuring the angle between them.On Earth, one of the objects is usually thehorizon but here he is measuring the arc distance between two stars.As I said, there is noreason to have a cross-hair.The instrument he probably means is a theodolite.This is a telescope with cross hairswith accuracy greater than a sextant; although it is extremely hard to believe that a pilotturned astronaut doesn't know a sextant from a theodolite.NASA MOONED AMERICA! / Rene Space Navigation / Chap.7 p.62All the measurement of the arc angle between two stars could do was align the capsule.That was done by azimuth and elevation by comparison to the ship's IMU (Internal Measur-ing Unit).The stars are unchanging to instruments as gross as the finest theodolites in theworld; Collins accomplished nothing more than allowing them to know the ship's heading tothe accuracy with which the shot was made.The stored angles they speak of are the arc angles of separation between any two of thenavigation stars.The "five balls" was part of the razzle-dazzle in that they only told whetherthe shots were accurate or not.It was an obfuscation, and this man who was speciallytrained by MIT in space navigation never figured it out.Imagine that your ship is in a very high orbit around the Earth.Also imagine that youhave a gunsight right down the center of the ship.Now you point the whole ship at oneparticular star and then take great pains to damp out all the ship's motions so you're still"aimed" at that star.After one orbit, as you came out from behind the Earth, you look forthat star.Would you be shocked to see that the star was still in the gun sight? In fact, wouldyou be surprised to see it stay there, day after day, no matter the time period? Six monthslater the Earth will have carried you halfway around the solar system, but your ship wouldstill be pointing at that star.In fact, that same star should be fixed in your gunsight for years [ Pobierz całość w formacie PDF ]
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.Were this not true, the "fixed" stars of constellations would become unrecogniz-able in a short period of time.We know from historical records that they stay the same.Michael Collins said, "The basic idea behind the Apollo guidance and navigation systemwas simple enough.It all began with the stars, whose position in inertial space was wellknown and unchanging.They are so far away, of course, that they appear the same whetherone is on earth or a mere lunar distance away." 2While preparing for the Moon landings he claimed that navigation was his personal hairshirt.He goes on to say, "I had made several trips to Massachusetts Institute of Technologynear Boston, and had tried my level best to suffer through a couple of weeks of "simple"explanations of the system by their experts, but I always came away shaking my head." 3Perhaps he felt he was being told nonsense something like, "The framus wittigates onthe thrum rod activating the holcroid.Once it dizzies you are halfway home." Over theNASA MOONED AMERICA! / Rene Space Navigation / Chap.7 p.61years whenever I run into something that doesn't make sense I have great problems with it.Icannot memorize it and I can't work with it.For their navigation package NASA went to MIT early in the game and asked for amethod that would give the Apollo program the ability to go to the Moon and back.Acouple of professors produced the package on time.In fact it was one of the few times thatanyone met a NASA schedule.Michael Collins was designated the navigator for Apollo 11.In his book he lists the 37navigation stars they were to use, plus their corresponding octal numbers which identifiedthem to the computers.Here's how Michael explains that navigation package."The astronaut, peering out through either his telescope or his sextant findsone of the chosen few, superimposes a + on it, and pushes a button at the instant ofperfect alignment.He then tells the computer which star it was, by numbers.Repeatingthis process on a second star allows the computer and the platform to determine whichway the spacecraft is pointing.So we now know which way is up? Well, not exactly,because "up" is a rather fragile concept meaning away from the center of the earth, adirection opposite the gravity vector used to clutch us tightly by.But suppose wecannot even see the earth in our window, suppose we are floating free of earth's gravity.What now, M.I.T.? Back to our friendly stars.We simply define a new up-down andleft-right, using the stars in place of earth.All will be well as long as we all play thegame by the same rules, as long as the ground controllers send us instructions using thesame stellar frame of reference.Now we are free of all terrestrial conventions and cancorrect our course to and from the Moon by pointing in the proper direction relative to4the stars.Collins seems to be saying that the sextant had a cross hair in its optics.But sextantsdon't have cross-hairs.Curiously, I went sniffing through his book and found out that sureenough he was talking about a sextant.Almost 100 pages later he continues:"Unlike Gemini, however, Apollo has a fancy computer tied to the optics, and now Icall on it for help; it responds by swinging the sextant around until it points at where itthinks Menkent is.Aha! There it is, in plain view, and it's a simple task for me to alignthe cross-hairs precisely on it and push a button at the instant of alignment.Now I repeatthe process using Nunki, and the computer pats me on the back by flashing theinformation that my measurements differ from its stored star angle data by.01 degree.Itdisplays this information as 00001.In M.I.T.-ese, a perfect reading of 00000 is calledfive balls." 5Aha! There it is, in plain view: he does claim his sextant has a cross-hair, but this cannotbe true! A sextant is an instrument that uses mirrors mounted on a calibrated movable leg.The essence of the instrument is to superimpose one object over the image of anotherthereby measuring the angle between them.On Earth, one of the objects is usually thehorizon but here he is measuring the arc distance between two stars.As I said, there is noreason to have a cross-hair.The instrument he probably means is a theodolite.This is a telescope with cross hairswith accuracy greater than a sextant; although it is extremely hard to believe that a pilotturned astronaut doesn't know a sextant from a theodolite.NASA MOONED AMERICA! / Rene Space Navigation / Chap.7 p.62All the measurement of the arc angle between two stars could do was align the capsule.That was done by azimuth and elevation by comparison to the ship's IMU (Internal Measur-ing Unit).The stars are unchanging to instruments as gross as the finest theodolites in theworld; Collins accomplished nothing more than allowing them to know the ship's heading tothe accuracy with which the shot was made.The stored angles they speak of are the arc angles of separation between any two of thenavigation stars.The "five balls" was part of the razzle-dazzle in that they only told whetherthe shots were accurate or not.It was an obfuscation, and this man who was speciallytrained by MIT in space navigation never figured it out.Imagine that your ship is in a very high orbit around the Earth.Also imagine that youhave a gunsight right down the center of the ship.Now you point the whole ship at oneparticular star and then take great pains to damp out all the ship's motions so you're still"aimed" at that star.After one orbit, as you came out from behind the Earth, you look forthat star.Would you be shocked to see that the star was still in the gun sight? In fact, wouldyou be surprised to see it stay there, day after day, no matter the time period? Six monthslater the Earth will have carried you halfway around the solar system, but your ship wouldstill be pointing at that star.In fact, that same star should be fixed in your gunsight for years [ Pobierz całość w formacie PDF ]