Quote:
Originally Posted by Future Raptor Ace
What you said about the flight computer is not correct, it did fail! I will explain this to you as simply as I can ... the flight computer had the Eagle landing towards a giant crater which would have been bad (LEM needed a nice flat place to land) so Neil maneuvered Eagle to find a new landing spot. The computer than became over loaded because it had to do too many calculations per second. It for it had to re-account for a new trajectory, a new landing velocity, a new target spot, chaining fuel levels etc. .. everything was dynamic all at once! The computers warning lights then came on all the while Buzz was calling out the fuel level. Neil then switched off the flight computer and flew the Eagle manually in which he landed on 17-25 seconds left of fuel. The funny thing is your reference that you provided says a simplified version of what I just said ... it is funny that you dont understand your own reference!
Im sure you read popular mechanics ...
http://www.popularmechanics.com/scie...n-mars/4318170
As you can see you are wrong and have no idea what you are talking about then have the nerve to tell me im wrong lol! This is going to be my problem when going to industry ... arguing with non engineers lol! You guys think you know something because you think your logic to be intuitive and or you know some basic facts about something but in reality the real world can be counter-intuitive on a regular basis. Then when we explain to you and talk to you like an engineer you do not understand and or miss-understand what we wrote. To make matters worse when we talk to you on a simple non technical basis you feel we are over simplifying it for you and ask for more technical details. Overall I just cant stand talking to non engineers about engineering problems and I hope I never have to do it in the work place  |
Since you made an effort to address a specific point and added “documentation”, I will try to help you a little. First, you should preferably get your documentation from official sources with some context because you don’t seem to be able to analyse the information properly on your own. I quoted Margaret H. Hamilton,
Director of Apollo Flight Computer Programming MIT Draper Laboratory, Cambridge, Massachusetts and you show up with a “knuckle-biting” story from
Popular Mechanics. Are you even serious? Is your young brother or maybe a senile uncle using your computer while you are busy getting your 15000$ a year education?
You are a person who would rather be right at all cost, than admit to be a little ignorant about certain issues. You are also doing a disservice to the very NASA personal and NASA program that you are claiming to admire, while condemning others for not caring enough. You can try to fool people on AAm, but you are not fooling me. You actually have no clue what you are talking about. The guidance computer functioned extremely well and that was crucial to the alleged successful Apollo 11 landing. This is clearly stated by our friend, Margaret, and you should go read it again in my last message.
A computer generating an error message does not mean that it failed. In this case, it was the Rendezvous Radar Switch that shouldn’t have been left on ‘AUTO’ and so it provided too many useless instructions (
it was not after Neil’s intervention as you seem to think so). This overloaded the program which then generated the error codes to alert the crew that it was dropping some lower priority tasks. The program was designed to do just that. Basically, you can question the logics behind programming such a procedure, but that is not a failure of the program itself. The computer was just doing its job flawlessly. It was not immediately clear what those messages were, but after a while, it was deemed by mission control to not be a cause for major concerned. It is only after this that the landing target was determined to be unsatisfactory and that Neil took over some of the tasks to land in a location that he considered was safer. Here, there are a dozen accounts and retelling of what actually happened, but the thing that is clear is that Neil never landed in a complete manual mode (although he might have switched to that mode for a while, but it is unlikely) as he took over some tasks while the computer was still performing the others. Again, Neil decided to override some of the computer’s tasks, it does not mean that the computer failed catastrophically
as you seem to think. The point is that the computer was still needed for landing
as you don't seem to understand. Do you actually comprehend the tasks that were needed to be processed? If you go to the proper sources, you will get all the confirmations of everything I wrote, which refutes your inane out of order and undocumented description.
Here is Buzz teaching you a few very basic things about computers (
listen to the last 30s, that is the important part for your understanding):
http://www.history.com/videos/buzz-a...ters-on-apollo
Here, Buzz fails to even mention your catastrophic computer failure part of your Hollywood script:
http://www.history.com/videos/diffic...ng-on-the-moon
Here is more information about the reason the error codes were generated. You might want to read a little (and watch less movies),
since you were not aware about the fact that it was caused by the Rendezvous Radar Switch and not by Neil's take over of some of the tasks. There is also the part about why it is not a computer failure, as you wrongly believe, even after being corrected:
Quote:
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Originally Posted by http://www.hq.nasa.gov/alsj/a11/a11.1201-fm.html
I remember bumping into one of our M.I.T. engineers, George Silver, who was usually at our office at Cape Kennedy. George had been involved in and witnessed many pre-flight tests. I asked him in frustration if he had ever seen the Apollo Guidance Computer run slowly and under what conditions. To my surprise and rather matter of fact, he said he had. He called it "cycle stealing" and he said it can occur when the I/O system keeps looking for data. He had seen it when the Rendezvous Radar Switch was on (in the AUTO position) and the computer was looking for radar data. He asked "the Switch isn't on, is it?" "Why would it be on for Descent, it's meant for Ascent?"
I rushed upstairs and suggested we look at the telemetry data. Some of the M.I.T engineers found the telemetry print out, found the correct 16-bit packed word, found the correct bit, and... yikes!!!, the bit was ON. Why was it on? It had to be set in that position by an astronaut. We looked at the 4 inch thick book of astronaut procedures and there it was -- they were supposed to put in on (in the AUTO position) prior to Descent. The computer had been looking for radar data. If the astronauts were trained this way, why had this effort never shown during training sessions? (I later found out that such training was for procedures only and the Switch was never connected to a real computer.)
But there was no time now for analyses or reflections. We called Houston and delivered the cause and solution. The final countdown to Ascent was proceeding. Just before ignition, and the last message sent to the astronauts, Glenn Lunney, the Flight Director, calmly told the astronauts to "please put the Rendezvous Radar Switch in the Manual position".
The Ascent and flight proceeded without incident.
Software Engineering Postscript
The Apollo program took some heat for this "software error" that almost caused Apollo 11 to abort. At M.I.T., we always thought and most would still maintain that the system operated as designed and saved the flight. We used a priority driven executive, rather than a round robin, FIFO, or table division executive. We provided for overload, or loss of computer speed, by continuing to execute the highest priority jobs. Those jobs (tasks) that fell off the queue were of lowest priority, perhaps a display refresh or some other non-essential procedure. Had we demanded computer time for every schedule task, then time would have run out, tasks would have overlapped, data would be confused and out of sync, and the flight would have been lost. Interestingly, this experience so influenced NASA's Jack Gorman and other NASA and Intermetrics software engineers, that we fought long and hard to retain a priority, asynchronous executive for Shuttle as manifested in the HAL/S language.
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Now, you should go ask Buzz why that Rendezvous Radar Switch was left to AUTO. He has explained why and he knows that in the circumstances, it was a mistake. That is if this whole fairy tail of a moon landing actually did happen.
I suppose you will bury all this pertinent information in more “knuckle-biting” babble as soon as you can so that anyone still reading this (sure) will not be bothered to check your deficient logic, but I suppose this is the advantage you get when you post crap about Apollo missions on an Alizée forum.