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Post by ka9q on Feb 18, 2012 13:30:19 GMT -4
I've never seen it expressed so succinctly. In one flash I understood why we have all those space movies with Imperial Star Cruisers firing their rockets continually as they move across the galaxy at constant speed.
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Post by ka9q on Feb 16, 2012 5:41:13 GMT -4
I also think the Shuttle program was a bad move that set back NASA for decades.
During Apollo, everybody correctly understood that the cash river from Congress was not going to continue after the moon landings. They needed to make space flight more affordable, more sustainable somehow.
But in a classic example of "groupthink", everybody got it into their heads that lowering mission costs meant "reusable launch vehicle". Meanwhile, the guys (they were all guys then) who actually flew these things grumbled about returning to earth as spam in a can. Real pilots don't land under parachutes. Real pilots land on a runway with their hands on the control stick, exhibiting their skills for all to see!
So we got the Shuttle. Despite budget cuts and schedule overruns, it was still promised to be everything to everybody. Expendable launchers were to become obsolete; every satellite was to be launched on the Shuttle.
Well, that sure changed quickly after Challenger. By the end of the program it had happened again, so we lost 14 astronauts and two orbiters. Two very expensive orbiters because after all they were designed to be reusable. And sadly, the Challenger and Columba disasters also have a fair bit of hubris in them. NASA thought that rocket engines would be so reliable that they wouldn't need an Apollo-style launch escape system. And unlike Apollo, with its small and well protected thermal protection system, the Shuttle adopted a huge, fragile and totally unprotected one -- again because of the requirement for reusability.
We do need to lower the cost of space flight, especially human space flight, to make it sustainable. But that won't happen with simple-minded mantras like "reusable launch vehicle".
In fact, launcher reusability is a mirage. Like any other rocket, nearly all of the shuttle's launch mass is propellant that's certainly not reusable. Propellant, of course, costs money. And quite a bit of it was required to get such a heavy orbiter into orbit -- heavy because of things like thermal tiles, wings and landing gear that are there just to make it reusable.
Yes, a big Shuttle selling point was its unique capability to fix satellites on orbit or to bring them back to earth. But why? How many times was that actually done? Yes, the Hubble upgrades were impressive to watch. And in the early days, Shuttle astronauts also fetched a few communications satellites whose kick motors had failed. But how many satellites, including Hubble, are actually more expensive than a Shuttle launch? I would say "few or none", so those fetch and repair flights were just uneconomic stunts. Nor could the Shuttle even reach geostationary orbit or the special orbits of the GPS satellites. It had been planned to reach sun synchronous polar orbit with its many weather, spy and earth resources satellites but Challenger put an end to that. So the shuttle essentially did nothing to reduce the costs of building, launching, operating and replacing satellites.
But again I think these were largely stunts that didn't make economic sense. We're much more likely to reduce launch costs through straightforward improvements in manufacturing productivity. When you make only a few of something, each one is bound to be expensive. When you make many, you always find ways to make each one more cheaply.
People have to be clever in looking for ways to save money throughout the design of a mission or missions, not just at launch. Reusability may make much more sense elsewhere. For example, starting with Apollo 10 every mission took a brand new lunar module all the way to the moon and then threw it away in pieces just because its tanks and batteries were empty. Not only did that discard a very expensive piece of hardware, it threw away the work done by the Saturn V and the CSM in getting it all the way to lunar orbit.
Because the transportation costs are extremely high and are likely to remain so, we need much longer missions to amortize the cost of each astronaut. We need to use each piece of equipment as long as possible. And above all, we need to use in-situ resources. Apollo didn't even use sunlight, the most ubiquitous resource in the inner solar system, but that was okay because its missions were so short. We'll have to figure out how to make what we need from the moon itself. We already know how to make oxygen; the others are being worked on.
Everything will have to change to make lunar exploration practical, and because I'm afraid we can't do a whole lot to reduce earth launch costs the missions themselves will have to change.
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Post by ka9q on Feb 16, 2012 1:19:28 GMT -4
He's been pretty busy on JREF lately. As Patrick1000 he's been excoriating NASA for it's "sloppy" work on the Apollo 13 investigation.
This prompted me to go back and reread parts of the Cortland report. I was actually pretty impressed by the thoroughness of their forensic work.
Although I'm an electrical engineer, not a forensic engineer, we speak the same language and know and apply the same laws of physics. I've learned a lot by reading about their methodical methods of reasoning out cause and effect.
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Post by ka9q on Feb 15, 2012 18:46:16 GMT -4
Although the moon has no draggy atmosphere, nearly all lunar orbits are unstable due to the perturbations by the earth and sun and the moon's lumpy gravity field. Eventually they get perturbed so much that the orbital path intersects the surface.
The estimated orbital lifetimes of the abandoned LMs is usually said to be about a year. I don't know if that's just a guess or if it comes from actual orbital modeling. Once Eagle and Orion died after jettison nobody really cared what happened to them. (The other four were deorbited while still operating.) The subsatellite left in lunar orbit by Apollo 15 lasted about 15 months; the one left by Apollo 16 lasted only a month because of a non-optimal deployment orbit.
So without knowing exactly when they hit, we only know that their impact sites are somewhere in a latitude band centered on the equator and bounded north and south by their orbital inclinations. The news media uses this fact to play Chicken Little every time a large earth satellite is about to decay. They show the band on a map and proclaim that everyone and everything in it is subject to arbitrary instant death and destruction from above.
Apollo 11 landed within a degree of the equator from a very low inclination orbit, so Eagle's impact site should be the easier one to find. We only need search LRO photos for a narrow band around the equator. But I don't know if they have very high resolution photos of the moon's entire equatorial region; the narrow angle camera produces far too much data to map the entire moon.
Apollo 16's Orion landed at about 9 degrees south so its lunar orbit had an inclination of at least 9 degrees. We'd have to search the entire band between 9N and 9S to be sure of finding the site. But the moon rotates 30x slower than the earth, so if we can use an orbital model to approximate the time of the impact, say within a few days, we might only have to search the orbital path at that time.
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Post by ka9q on Feb 15, 2012 18:04:33 GMT -4
I stay in this hoax "debate" only because I learn so much (and meet some pretty knowledgeable people) while debunking the hoax arguments. I certainly know I'll never change any hoaxers' minds with logic and facts because they didn't arrive at their original positions through logic and facts. That's what I least understand about hoaxers; like most people I really enjoy learning, but they seem to learn little or nothing -- so what's their point?
So, in that theme of turning lemons into lemonade, I'm getting curious about the error sources in the early estimates of Eagle's landed position. I suppose I should comb through the mission report for these, but if Jay or Bob B. (or anyone else) have any insights or pointers to specific discussions they'd be appreciated.
As I understand it, the initial sources of location information were these:
The two onboard guidance systems' (PGNS and AGS) open-loop estimates, produced by their normal state vector integration routines (updated every 2 seconds on the PGNS?). During powered flight, they would include accelerometer readings. (I'm not sure but I think the PGNS uses the accelerometers on the IMU platform while the AGS reads body accelerometers and converts them to inertial space by reference to the backup, strap-down gyros.)
Here the potential error sources are many: in the last uplinked orbital state vector; in the moon's gravity model; in determining inertial attitude; in the accelerometers. All accumulate over time. Eagle was the first LM to fly below 50,000' so it would have been especially sensitive to errors in the local gravity field.
MSFN (ground) Doppler tracking (and ranging, I assume) during the landing. How can this work accurately during powered flight given the extra unknowns of engine thrust and direction that have to be solved for, not just the six state vector values?
Rendezvous radar tracking of the CSM by the LM relative to the ground estimates of the CSM state vector. This was probably the most accurate method, but when was it done? I know the rendezvous radar was in standby during the landing since it was the indirect cause of the computer alarms, so this would not have provided a landed position until it was turned on during a later CSM pass.
Crew descriptions of surface landmarks during the landing and after, especially Neil's call that they would be landing long plus his description of what turned out to be West Crater. The problem here was that the terrain was so nondescript.
TV images during the EVA, though again there probably weren't any usable landmarks.
I suppose that a truly definitive position wasn't available until after the crew returned with their films and after the LRRR had been acquired by ground telescopes.
Edit: Another possible way to determine landed position was by star sightings and the local gravity vector, but I doubt that was very accurate.
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Post by ka9q on Feb 15, 2012 8:01:02 GMT -4
Thank you!
I might have sent the message you saw. If you look at that list, you'll notice that the impact locations of two Apollo LM ascent stages are unknown: those for A11 and A16. Both were abandoned in lunar orbits that later decayed long after they went dead, so there was no tracking and no direct knowledge of their impact locations. But I am wondering if new data (LRO mapping and the improved gravity models from the Japanese Kaguya and the US GRAIL missions), plus a good collective eyeball effort, just might make it possible to discover one or both of those LM impact locations.
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Post by ka9q on Feb 15, 2012 7:43:36 GMT -4
The photos of Buzz Aldrin on the surface of the moon do not show the astronaut being located uniquely upon the lunar surface at Tranquility Base. I do not know where the photos were taken but they were not taken on the moon. That is for sure. That is just idiotic. Consider what the pictures (not just from A11, but from every Apollo mission) do show: Apart from the astronauts and their own artifacts, the scene contains absolutely no signs of life or human civilization. No animals, trees, grass or other vegetation. No roads, houses or other buildings. There are no signs of any phase of water: no clouds, no haze, no lakes, rivers or oceans. There's absolutely no sign of an atmosphere. The sky is jet black even though it's daytime. Distant objects appear razor sharp, often creating optical illusions in which things appear much closer (and smaller) than they really are until an astronaut walks toward them. There's no wind; except when recently handled by an astronaut, flags remain absolutely stationary. The astronauts are wearing pressure suits to protect themselves from this environment, and their spacecraft is clearly incapable of flying in an atmosphere or in anything but a reduced gravity field. Underscoring the absence of an atmosphere, the entire surface is thoroughly saturated with craters of all sizes. Even the small craters are obviously produced by extremely high energy explosions caused by hypervelocity impacts that could not occur within a significant atmosphere. When astronauts kick up the dust layer, all the particles regardless of size follow uniform parabolic arcs, completely unimpeded by air drag. Objects in ballistic trajectories, such as the astronauts themselves when they walk, are clearly under reduced gravitational acceleration. Even on relatively flat plains, the ground is much more uneven than on the earth, consistent with low gravity. The very large scene is uniformly lit by one intense and well collimated light source that remains in a nearly constant position in the sky even when (on the later missions) the astronauts film themselves moving kilometers in one direction or another. When mountains are present in the background (again on the later missions) it is clear from the slowly changing visual perspective that they are very large and very far away, again reinforcing the size of the scene and the nature of the single light source. Said light source rises very slowly in the sky at only 1/2° per hour. (On the earth, the sun moves across the sky at about 15° per hour.) Besides this light source, there's another conspicuous object in the sky: a blue-and-white cloud-covered ball about 2° in diameter, four times the size of the moon as seen from the earth. Unlike the sun, it barely moves at all. Antennas and reflectors can be manually pointed at it and they will operate indefinitely without further adjustment. No place on earth has even one of these quite distinctive characteristics. Only one place anywhere near it has them all: Luna. Earth's moon. The place where all these pictures were taken.
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Post by ka9q on Feb 15, 2012 6:46:11 GMT -4
You deserve credit for taking this position, as so many hoax advocates claim that radiation was some sort of impenetrable barrier to human spaceflight to the moon. You may choose to give Patrick credit here, but I do not. Actually, I had intended this as damnation with faint praise...
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Post by ka9q on Feb 12, 2012 16:21:39 GMT -4
You misunderstood me. My view is that an examination of the data on outer space radiation and the science of radiation health and disease would not be a fruitful road for prohoax types to travel down. It seems to me that the yield in terms of proving a hoax based on this approach would be exceedingly low. You deserve credit for taking this position, as so many hoax advocates claim that radiation was some sort of impenetrable barrier to human spaceflight to the moon. Now that you've been persuaded of this, it only remains to persuade you that there were no other obstacles to the Apollo flights and that they actually happened.
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Post by ka9q on Feb 11, 2012 11:51:13 GMT -4
That's the saddest thing about them -- either they're unable to learn, or they simply aren't interested in it. I have a hard time understanding both.
This applies even to whom I consider the most fascinating hoaxer, hunchbacked (we knew him here briefly as "inquisitivemind"). He claims to be an engineer and a follower of the scientific method, but he's obviously neither. But he certainly is an enigma.
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Post by ka9q on Feb 11, 2012 10:36:25 GMT -4
The one reason I stay in this debate is what I learn from it. To answer our friend's claims over at JREF I just read several of the appendices to the Apollo 13 review report and I found them fascinating. You can learn a lot by watching forensics being done.
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Post by ka9q on Feb 6, 2012 8:48:19 GMT -4
Connally consistently testified that he never saw JFK at any time during the assassination, but the Z film makes it look as though he turned to his right and did see him. But I can't be sure the angles are right, and given the sudden, severe and unexpected trauma he was experiencing I wouldn't be at all surprised if he simply didn't remember. I doubt if I would clearly remember getting shot, assuming I survived. He says he didn't hear the (second) shot that got him, he only felt it, and that also sounds very plausible.
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Post by ka9q on Feb 6, 2012 2:34:26 GMT -4
Conspiracists have made much hay of Connally himself thinking that he and JFK were hit by separate bullets. He thought Oswald's first shot hit JFK in the back/throat and the second (which he felt but did not hear) hit him.
But I think it was Gerald Posner who claims to have talked to Connally late in his life, explained the best available theory (first shot missed, second shot hit them both) and got Connally to agree that was a very plausible scenario. Connally knew guns, and he must have known that the entrance wound in his back was oval-shaped from a yawing bullet, not round from one that hadn't hit anything else yet.
Connally, being a hunter, might have been more familiar with the hollow point lead bullets used in hunting than the metal jacketed military bullets that Oswald used. In fact, I think a lot of people are, and it probably contributes at least some to the disbelief over the "single bullet theory".
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Post by ka9q on Feb 5, 2012 16:14:30 GMT -4
Buzz did take the camera at times, but he used it to document specific things on his checklist like his soil mechanics experiments, the landing pads and the underside of the LM.
There's plenty of Armstrong in the photographic record of the mission. He's on TV nearly the whole time, and he's also in the 16mm footage shot through the LMP's window. There just aren't many good Hasselblad pictures of him, that's all. One, maybe?
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Post by ka9q on Feb 3, 2012 2:16:39 GMT -4
I was really happy to see the Mythbusters examine (and re-examine) the "blown away" myth.
I regularly see conspiracists (including Apollo hoaxers) unload truckloads of vitriol on them. So they must be doing something right.
Some years ago the Mythbusters hit two cars head-on at 50 mph and Jamie said that was equivalent to one hitting a brick wall at 100 mph. I knew that wasn't true and apparently so did many other fans, so the Mythbusters revisited it. (That it involved crashing cars probably made the decision easy.) Sure enough, Jamie was shown to be wrong; two equal cars hitting head on at 50 mph suffered equal damage as one hitting a brick wall at 50 mph, not 100. Then Jamie got on camera and said "Yeah, I was wrong. But I'm okay with that, because that's how you learn." How many TV personalities (or hoaxers) say that? Not many.
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