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The Hubble Space Telescope...



 
 
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  #11  
Old November 27th 03, 06:57 AM
Christopher M. Jones
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Default 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  
Old November 27th 03, 07:01 AM
Mike Miller
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Default 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  
Old November 27th 03, 08:19 AM
Louis Scheffer
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Default 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  
Old November 27th 03, 09:34 AM
Pat Flannery
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Default 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  
Old November 27th 03, 01:11 PM
Craig Fink
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Default 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


---
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  #16  
Old November 27th 03, 02:14 PM
Ash Wyllie
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Default 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  
Old November 27th 03, 03:30 PM
David A. Scott
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Default 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
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  #18  
Old November 27th 03, 03:40 PM
David A. Scott
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Default 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  
Old November 27th 03, 03:49 PM
David A. Scott
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Posts: n/a
Default 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  
Old November 27th 03, 04:32 PM
Explorer8939
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Default 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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