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#11
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Never mind the shuttle crash, the real threat is the CAIB report
My oppinion is that the shuttle is reliable as far as launch vehicles are
concerned. Two failures out of 100 missions is pretty good. It is also a terrible idea as far as basic engineering is concerned. It is bad for the following reasons: 1. Does not have adequate crew escape systems 2. Does not have adequate redundancy. 3. Launches a lot of extra mass (the orbiter) unnecesserily The best way to launch people to orbit so far has been the apollo program's capsule type launch and return. There is no point wasting fuel to launch a heavy orbiter just to have it return to the earth later. NASA is carrying a lot of dead weight too, kind of like the shuttle. Many academic type people who produce no more than paperwork, resulting in huge costs and not enough engineering. The same is true for the rocket community. There are many people riding the wagon of SSTO or RLV projects, writing papers, charging salaries to projects that they don't contribute to. We need a low tech heavy launch system for large payloads (energia comes to mind) and we need a light weight crew launch system with adequate safeguards (LET). There is no point wasting fuel and money on having the shuttle go up and down. Manned space exploration is essential for our survival. We need a moon base, we need to go to Mars and to the asteroids ASAP. Zoltan Szakaly vtol.net |
#12
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Never mind the shuttle crash, the real threat is the CAIB report
For Hubble, there were *three* null correctors, and two out of three said that the mirror was shaped incorrectly (although unfortunately the most precise of the three was the one that said it was okay). Management *explicitly* decided that this strange discrepancy would not be investigated, because the project was already over budget and behind schedule. Henry, was this by NASA management or by Perkin-Elmer? If PE reported all to NASA and they decided that way I see no much reason to blame PE. Btw, is "Hubble Wars" the best report on this? ## CrossPoint v3.12d R ## |
#13
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Never mind the shuttle crash, the real threat is the CAIB report
In article ,
Jan C. =?iso-8859-1?Q?Vorbr=FCggen?= wrote: Several of Galileo's problems can be traced back to management. (I mean, a star tracker that's only tested in two or three orientations??? Could you provide a quick summary of what problems/constraints that caused? (Background: Galileo is an odd design, half of it spinning slowly to provide gyroscopic stability and a full-sky view for things that want it, and the other half holding a fixed orientation to support things like the camera. The star tracker -- it's more of a star scanner actually -- is on the spinning half, so it sweeps over a ring of sky.) The underlying problem, if I recall the paper correctly, is that the star tracker uses an unusual approach, and a little too much of its signal processing is hard-wired, and the very limited testing did not uncover some design weaknesses. Too much information is lost, and going from the pulse train it produces to a solid attitude determination is difficult. For some orientations of the spin axis, in fact, it's impossible... so there are directions Galileo cannot point for any length of time (it can hold any attitude briefly using gyros, but needs a star lock for long-term stability). For some substantial fraction of all attitudes, it needs to be told to settle for a fairly loose fit to the star map. And in general, the preparation of star maps for it is tricky and labor-intensive. In short, not a mission killer, but it ran up the cost and aggravation of Galileo operations noticeably. -- MOST launched 1015 EDT 30 June, separated 1046, | Henry Spencer first ground-station pass 1651, all nominal! | |
#14
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Never mind the shuttle crash, the real threat is the CAIB report
In article ,
wrote: For Hubble, there were *three* null correctors, and two out of three said that the mirror was shaped incorrectly (although unfortunately the most precise of the three was the one that said it was okay). Management *explicitly* decided that this strange discrepancy would not be investigated, because the project was already over budget and behind schedule. Henry, was this by NASA management or by Perkin-Elmer? If memory serves, this was a P-E decision. NASA supervision of the details of the optics work was limited, because this was basically a spysat shop, heavily encumbered by security restrictions that NASA was ill-equipped to deal with. ...Btw, is "Hubble Wars" the best report on this? I'm told that people who were there have a tendency to say "now wait a minute, that's not right..." every few pages. Read it for background, but it's not an entirely trustworthy account. -- MOST launched 1015 EDT 30 June, separated 1046, | Henry Spencer first ground-station pass 1651, all nominal! | |
#15
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Never mind the shuttle crash, the real threat is the CAIB report
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#16
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Never mind the shuttle crash, the real threat is the CAIB report
In article ,
Chris Manteuffel wrote: If memory serves, this was a P-E decision. NASA supervision of the details of the optics work was limited, because this was basically a spysat shop, heavily encumbered by security restrictions... Does this mean that there might have been a KH-11 that also had the faulty mirrors? Or was the confusion over the null corrector's a one-shot deal? It was a one-shot. The *shop* did other work, but the Hubble mirror itself was a special project, rather than just another mirror off the production line. -- MOST launched 1015 EDT 30 June, separated 1046, | Henry Spencer first ground-station pass 1651, all nominal! | |
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