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The Hubble Space Telescope...
"David A. Scott" wrote in message .1.4...
In many ways the Hubble is a failure they never even cut the mirror correctly. Do we really want a monument to that simple error. I still think we should try to build one the right way but since management has gone so far down hill its likely our next attempt would be far worse. Hubble could have done much more if it was ground correctly. The extra lenses added to it failed to make it as good as it should have been. Dead. Wrong! Firstly, extra mirrors, not lenses, and in point of fact there's no "extra" about it anymore, the individual instruments in HST now were designed with the mirrors actual shape in mind and correct for it in their optical paths, often without increasing the number of optical elements used compared with an instrument designed for a nominal Hubble mirror. More importantly, the sharpness of the light focused by HST after these corrections have been made is actually better than the design criterion for Hubble. In all aspects Hubble has far exceeded the design criteria and goals for the project, it is an unqualified success by any sensible measure. |
#12
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The Hubble Space Telescope...
Craig Fink wrote in message thlink.net...
NASA (or better yet Congress) should pull the plug on some NASA managers, instead of the Hubble Space Telescope. The Hubble Space Telescope has contributed so much to our the knowledge of the Universe it would be criminal not to put it in a museum for display along with all it's achievements. Forget that. If you can afford a mission to retrieve Hubble, you can afford a mission to service Hubble for several more years of service. Much better to keep getting useful work out of Hubble than to pour all those millions down the drain. And if you're not going to pony up to service Hubble again because it's too expensive, then it's too expensive to retrieve, and the money can be better spent on other missions. One Hubble service/retrieval mission is worth several of those better-faster-cheaper missions. It'd be criminal to waste so money on a museum piece when it can find much better uses. Mike Miller, Materials Engineer |
#13
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The Hubble Space Telescope...
"David A. Scott" writes:
In many ways the Hubble is a failure they never even cut the mirror correctly. [...] Hubble could have done much more if it was ground correctly. The extra lenses added to it failed to make it as good as it should have been. This is not true, except for the very first batch of instruments, all long since replaced. There are no additional lenses in any of the insruments designed since the flaw was uncovered. In all the new instrucments, since they need one or more mirrors to direct the light within their own optics, they just need to make one or more of these mirrors not quite flat. This restores diffraction limited optical performance without adding any new elements. Lou Scheffer |
#14
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The Hubble Space Telescope...
Leaf Fan wrote: The current thinking is that some sort of propulsion module will be attached to HST to provide a controlled re-entry at the end of HST's life. I'm getting this image of a UFO sighting in the South Seas as this silvery mirror goes flying across the sky like a giant Frisbee. Pat |
#15
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The Hubble Space Telescope...
Hi Brian,
I agree with you 100%, there is still plenty to be learned from the Hubble if it were to be brought safely back to earth. Maybe not from an astronomers point of view, but an engineering point of view. Launched in 1990, with a planned end of mission in 2010, that gives it 20 years in the low earth orbit environment. Another low earth orbit environment study, was LDEF, had it's stay in orbit extended by the Challenger disaster. But, Hubble has spent much more time in space. Plus, from an engineering standpoint, I would think it would be a great study on orbital debris. It could even be used as a control in future leo orbital debris studies. A great turn of the millennium orbital debris data point. Especially if it is allow to continue to 2010, 10 before and 10 years after the year 2000. The tube or sun-shield essentially blocks half the sky from orbital debris from impacting the inside of the tube. It's entire attitude history is well known. I would think that it would be very interesting to see what the impact distribution inside the tube looks like, as well as impacts to the mirror and exterior. It would be hard to come up with a better control data point for future orbital debris studies. It just doesn't seem right to have a dummy model of anything in a museum. Craig Fink Brian Gaff wrote: I'd have thought that it might actually be useful to get it back and examine what and how it has aged in orbit. Not having much luck are they? They lost skylab, Mir was brought down, now although its possible, nobody wants to risk it for Hubble... Well, I expect they will pay for a dummy model to be made... :-) Brian -- Brian Gaff.... graphics are great, but the blind can't hear them Email: __________________________________________________ __________________________ __________________________________ "Craig Fink" wrote in message hlink.net... | .. belongs in the Smithsonian Air and Space Museum, not spread across | the earth as a debris field. | | http://www.msnbc.com/news/994737.asp?0cv=TB10 | | begin quote | | In the wake of the space shuttle Columbia disaster, NASA pulled the plug on | any plans it had to retrieve the Hubble Space Telescope at the end of | its life so it could be displayed in a museum. | | end quote, begin rant | | NASA (or better yet Congress) should pull the plug on some NASA | managers, instead of the Hubble Space Telescope. The Hubble Space | Telescope has contributed so much to our the knowledge of the Universe | it would be criminal not to put it in a museum for display along with | all it's achievements. | | NASA management, definitely the "Wrong Stuff". Not a care in the world | about spreading Columbia all across East Texas, but worried about Hubble | debris. Not a creative or innovative thought about how to repair | Columbia on-orbit with the stuff they had on-board. No wonder they can't | figure out how to make a repair kit for the heat shield so they can | service or bring Hubble down safely. | | end rant | | Save the Hubble, from a disgraceful death, | | Craig Fink --- Outgoing mail is certified Virus Free, so there! Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.543 / Virus Database: 337 - Release Date: 21/11/03 |
#16
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The Hubble Space Telescope...
Leaf Fan opined
Unfortunately many things changed after February 1. Even the official position of the astronaut office at JSC is that astronaut lives will not be risked for an HST retrieval mission, i.e. the benefit of returning HST to Earth is not worth the risko of astronaut lives. The risk is acceptable for servicing missions where the benefit is scientific knowledge. The HST Program did a study to determine what would have to be done to bring HST back to in the payload bay and while the study assumed Columbia, i.e. no external airlock, a return mission could be performed with an orbiter that has the external airlock, although additional work would have to be done (servicing hardware mods for HST to fit farther back in the bay). The current thinking is that some sort of propulsion module will be attached to HST to provide a controlled re-entry at the end of HST's life. If NASA is going to delibrately change Hubbles orbit, why not do 2 burns and boost into a 6,000km orbit and give some future generation the option of retrieving it for the Smithsonian? -ash for assistance dial MYCROFTXXX |
#17
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The Hubble Space Telescope...
(Alan Barclay) wrote in
: All the current instruments on the HST are designed to use the mirror as built. The corrective mirror were only used on the first generation of instruments Are you saying the so called correct optics have been physically removed from the HST. If so how close to the oringal design before the obvious flaw good management would have caught is it? David A. Scott -- My Crypto code http://cryptography.org/cgi-bin/cryp...c/scott19u.zip http://cryptography.org/cgi-bin/cryp...c/scott16u.zip http://www.jim.com/jamesd/Kong/scott19u.zip old version My Compression code http://bijective.dogma.net/ **TO EMAIL ME drop the roman "five" ** Disclaimer:I am in no way responsible for any of the statements made in the above text. For all I know I might be drugged. As a famous person once said "any cryptograhic system is only as strong as its weakest link" |
#18
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The Hubble Space Telescope...
Leaf Fan wrote in
: Actually, if you'd like to look at the pre-launch specs and compare them to what COSTAR and the second generation instruments' corrective optics have provided, you'll find that HST is even better now than had the mirror been ground correctly the first time. This still makes be wonder how good would the so called second generation instruments be if the damn mirror was cut corectly the first time. I tend not to belive all the NASA hype since its in there interest to make things look better than they are. Its the nature of bad management which NASA seems to have no shortage of. David A. Scott -- My Crypto code http://cryptography.org/cgi-bin/cryp...c/scott19u.zip http://cryptography.org/cgi-bin/cryp...c/scott16u.zip http://www.jim.com/jamesd/Kong/scott19u.zip old version My Compression code http://bijective.dogma.net/ **TO EMAIL ME drop the roman "five" ** Disclaimer:I am in no way responsible for any of the statements made in the above text. For all I know I might be drugged. As a famous person once said "any cryptograhic system is only as strong as its weakest link" |
#19
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The Hubble Space Telescope...
Leaf Fan wrote in
: Unfortunately many things changed after February 1. Even the official position of the astronaut office at JSC is that astronaut lives will not be risked for an HST retrieval mission, i.e. the benefit of returning HST to Earth is not worth the risko of astronaut lives. The risk is acceptable for servicing missions where the benefit is scientific knowledge. The HST Program did a study to determine what would have to be done to bring HST back to in the payload bay and while the study assumed Columbia, i.e. no external airlock, a return mission could be performed with an orbiter that has the external airlock, although additional work would have to be done (servicing hardware mods for HST to fit farther back in the bay). The current thinking is that some sort of propulsion module will be attached to HST to provide a controlled re-entry at the end of HST's life. Craig Fink wrote: Interesting its not worth the RISK OF LIFE to bring it back but it is worth the RISK OF LIFE to attach a rocket to it to up burn it up in the atmosphere. I wonder if anybody has done some sort of environmental study about the tradeoffs since the mission itself and the rocket attached will add more pollution to the air. Maybe the need to destroy is to destroy any evidence of other errors and short cuts taken by managers and those that built it. Maybe they want to make dam sure it burns up even at the RISK OF LIFE to those on the mission to destroy it so it can't be used as evidence. Just a thought but it does kind of go along with the thinking that one must not do anything that can leave physical evidence to point to management and there friends. David A. Scott -- My Crypto code http://cryptography.org/cgi-bin/cryp...c/scott19u.zip http://cryptography.org/cgi-bin/cryp...c/scott16u.zip http://www.jim.com/jamesd/Kong/scott19u.zip old version My Compression code http://bijective.dogma.net/ **TO EMAIL ME drop the roman "five" ** Disclaimer:I am in no way responsible for any of the statements made in the above text. For all I know I might be drugged. As a famous person once said "any cryptograhic system is only as strong as its weakest link" |
#20
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The Hubble Space Telescope...
There may be a lot of magic involved in that operation. In many ways,
the scenario is amazingly similar to the Skylab rescue plan, that would have used a teleoperated servicer to change the orbit of Skylab. We all know how that worked out. Leaf Fan wrote in message ... The current thinking is that some sort of propulsion module will be attached to HST to provide a controlled re-entry at the end of HST's life. |
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