mersenneforum.org  

Go Back   mersenneforum.org > Extra Stuff > Hobbies > Astronomy

Reply
 
Thread Tools
Old 2011-08-24, 16:10   #12
cheesehead
 
cheesehead's Avatar
 
"Richard B. Woods"
Aug 2002
Wisconsin USA

170148 Posts
Default

Quote:
Originally Posted by Uncwilly View Post
Why was the mirror so perfect, yet in error? Maybe the blank met the right yet wrong spec.
Since the DoD would not allow its own test facility to be used on Hubble (lest secret capabilities be revealed), Hubble's mirror was tested at a facility that, while competent at large-mirror-testing, hadn't before tested one just like Hubble's/Keyhole's. That unfamiliarity may have led to the tiny mistake Paul mentioned. The unrelenting Congressional cost-cutting pressure on NASA led to not doing a different test as a doublecheck before launch.

Quote:
Originally Posted by Christenson View Post
I have a different question:
NASA (and even the Hubble) seem to be prone to "Normal Accidents" (two shuttles preventably destroyed in flight, and some within the organisation acutely aware of the danger). The HST had a major "accident" with its mirror, the public story being about mis-assembly followed by a failure to do a foucault knife-edge test known to any amateur telescope builder worthy of the name.
When Congress is breathing down your neck to cut every dollar of cost, you sometimes have to choose between doublechecking a mirror test and performing some test on another project.

Quote:
Was the KH program plagued by similar problems, with similar nontechnical causes?
Have we read of any neck-breathing-down cost-cutting pressure on the DoD KH program?

Quote:
Is the JWST program going to have the same problems -- you are busy calculating an engineering staff of thousands....
Have we read of ... oh, yes ... we have read of neck-breathing-down cost-cutting pressure on the JWST program -- just as with any other NASA project.

Last fiddled with by cheesehead on 2011-08-24 at 16:21
cheesehead is offline   Reply With Quote
Old 2011-08-24, 17:13   #13
jasonp
Tribal Bullet
 
jasonp's Avatar
 
Oct 2004

67258 Posts
Default

Quote:
Originally Posted by Christenson View Post
NASA (and even the Hubble) seem to be prone to "Normal Accidents" (two shuttles preventably destroyed in flight, and some within the organisation acutely aware of the danger).
I originally found this in a compilation of science writing. Beware, it's heartbreaking; I'll guess nobody here would have the guts to do the right thing either.
jasonp is offline   Reply With Quote
Old 2011-08-25, 20:43   #14
Christenson
 
Christenson's Avatar
 
Dec 2010
Monticello

5·359 Posts
Default

Quote:
Originally Posted by cheesehead View Post
Have we read of any neck-breathing-down cost-cutting pressure on the DoD KH program?
The problem is, we would NOT know if there was that kind of pressure on the KH11 program...therefore, the question....
Christenson is offline   Reply With Quote
Old 2011-08-25, 22:29   #15
fivemack
(loop (#_fork))
 
fivemack's Avatar
 
Feb 2006
Cambridge, England

72×131 Posts
Default

We know that the Future Imagery Architecture program went spectacularly wrong: "perhaps the most spectacular and expensive failure in the 50-year history of American spy satellite projects", with three-star General Carlson saying that part of it was a factor eight over schedule and a factor four over budget (and other references suggesting that the original budget was around $1.5 billion).

http://www.afa.org/events/conference...13-Carlson.pdf is an interesting view inside the NRO.

http://www.globalsecurity.org/space/...8-fia-vick.htm has some fun lines to read between.
fivemack is offline   Reply With Quote
Old 2011-08-29, 22:01   #16
ewmayer
2ω=0
 
ewmayer's Avatar
 
Sep 2002
República de California

103×113 Posts
Default

Regarding the Hubble main-mirror FUBAR courtesy of Perkin-Elmer (aided by a compliant, insular NASA bureaucracy), I recall my Dad, who had hand-ground and tested multiple mirrors for his own humble amateur telescopes (ranging up to a 10" Newtonian; under his tutelage I also did my own multi-month hand-grind and test of a 4" Newtonian mirror in the 5th grade, and turned it into a nice little scope), being flabbergasted at the level of left-hand-ignorant-of-the-right incompetence needed to send a multibillion-dollar telescope into space without anyone catching such a major flaw with the primary mirror. I say major, in the sense a scaled-up version of the simple Foucault knife edge test amateur telescope makers have been using for over 150 years would have easily caught the problem with the HST mirror. Not only that, there was in fact a 2 completely-ground and figured HST backup mirror (made by Eastman Kodak on a similar timeline as Perkin-Elmer ... meaning NASA had both mirrors available for nearly a decade before the HST was finally launched), whose optical parameters could have been compared to the P-E-made mirror. Sure, the COSTAR servicing mission was a resounding success ... at an estimated cost [this is a conservative estimate] of a half-billion dollars and no small risk to human life. I still shake my head whenever I think about it.

Here is the money quote from Wikipedia regarding Perkin-Elmer and NASA's dance of incompetence with the HST mirror:
Quote:
The commission blamed the failings primarily on Perkin-Elmer. Relations between NASA and the optics company had been severely strained during the telescope construction, due to frequent schedule slippage and cost overruns. NASA found that Perkin-Elmer did not review or supervise the mirror construction adequately, did not assign its best optical scientists to the project (as it had for the prototype), and in particular did not involve the optical designers in the construction and verification of the mirror. While the commission heavily criticized Perkin-Elmer for these managerial failings, NASA was also criticized for not picking up on the quality control shortcomings, such as relying totally on test results from a single instrument.
And here an archived NYT piece on the "unknown backup mirror" - love the "these are very complex systems" bullshit excuse from the Hubble program manager:
Hubble Has Backup Mirror, Unused
Quote:
''It's wild,'' said Dr. Frank D. Drake, an astronomer at the University of California at Santa Cruz. ''There's a perfect mirror sitting in a crate somewhere. Any ground-based observatory that had two mirrors in preparation would have compared the two and taken the best.

''But Douglas R. Broome, the Hubble program manager at NASA headquarters, said the mismanagement charge was groundless. ''It's easy to play hindsight games like this,'' he said. ''But these are very complex designs. These are very complex issues. It's always easy to be right after the fact.'' Learning From Mistakes? ''It's a very, very unfortunate story,'' said George T. Keene, a former program manager for Eastman Kodak, the company that built the backup mirror. ''It's the kind of tragedy that's going to hurt science funding for years.''
My Comment: Aside: Bizarrely, the NYT piece misspells "manager" as "manger" not once but twice in the [unredacted] form of the above paragraph...possibly an artifact of early spell-checkers, which had little or no word-in-context checking.

The NYT piece gets even better regarding the backup mirror saga: Not only did NASA have both mirrors years ahead of their installation in the telescope, in fact Kodak delivered the backup mirror to none other than Perkin-Elmer long before P-E has finished its own mirror! Thus P-E could have easily tested both mirrors individually and together - heck, they could've been testing their own testing apparatus intended for the HST mirror on the Kodak mirror, which would have caught the flaw in the testing apparatus: "Hey, our tester indicates that this Kodak mirror is wildly out-of spec...". Jaw-dropping, head-shaking, staggering incompetence:
Quote:
Kodak started work on the backup in 1978, completing the work in 1980 and soon thereafter delivering the backup to Perkin-Elmer, according to Paul C. Allen, a Kodak spokesman.

As it turned out, the Kodak mirror was finished before the Perkin-Elmer mirror since Kodak used a more traditional method of grinding the mirror. It used a ''lap,'' or grinding instrument, that was a full 94 inches across, while Perkin-Elmer used smaller laps whose cutting and grinding were controlled by computers, according to Mr. Keene, a 37-year Kodak veteran who recently retired from the company.

In addition, experts say, the Kodak mirror turned out to be optically superior to the Perkin-Elmer one. Both achieved high levels of overall smoothness, exceeding NASA specifications by having a surface with irregularities less than one sixty-fourth the diameter of a wave of neon light. But the Kodak mirror in addition had fewer of what experts call ''micro ripples.''

Last fiddled with by ewmayer on 2011-08-29 at 22:26
ewmayer is offline   Reply With Quote
Old 2011-08-30, 01:23   #17
Christenson
 
Christenson's Avatar
 
Dec 2010
Monticello

70316 Posts
Default

Quote:
Originally Posted by fivemack View Post
We know that the Future Imagery Architecture program went spectacularly wrong: "perhaps the most spectacular and expensive failure in the 50-year history of American spy satellite projects", with three-star General Carlson saying that part of it was a factor eight over schedule and a factor four over budget (and other references suggesting that the original budget was around $1.5 billion).

http://www.afa.org/events/conference...13-Carlson.pdf is an interesting view inside the NRO.

http://www.globalsecurity.org/space/...8-fia-vick.htm has some fun lines to read between.
The FIA program sounds like one of those grand computer schemes that sinks the company....where the tiny details get mixed up in the high level design. and the end result is a gordian knot that does nothing except slow everything down. Think FBI's virtual casefile project, etc...

Someone want to briefly explain micro-rippling? What's the usual spatial frequency? (Of course, with a better mirror by Kodak, ahead of time, you have to ask who got paid off, with what, and when.....to keep the competent telescope builders away from the project)

Companies like Perkin-Elmer drive out the companies that are technically effective as the cost overruns are likely very economically effective for those involved. How should a system be built and operated to avoid this effect?
Christenson is offline   Reply With Quote
Old 2011-08-30, 01:32   #18
ewmayer
2ω=0
 
ewmayer's Avatar
 
Sep 2002
República de California

101101011101112 Posts
Default

Quote:
Originally Posted by Christenson View Post
(Of course, with a better mirror by Kodak, ahead of time, you have to ask who got paid off, with what, and when.....to keep the competent telescope builders away from the project)
As the NYT piece notes, NASA set things up so P-E was completely in charge of subcontracting the backup mirror, instead of NASA itself just accepting the top 2 independent bids and testing the resulting mirrors against each other, then using the better one (which would likely have instilled the sorely-lacking sense of "this is important...we have competition" in P-E project management). A slight twist on the classic government-sponsored no-bid contract scammery.
ewmayer is offline   Reply With Quote
Old 2011-08-31, 00:35   #19
Christenson
 
Christenson's Avatar
 
Dec 2010
Monticello

5·359 Posts
Default

Incompetence like that (or using Morton Thiokol) doesn't just happen...someone has to get paid to make it happen.....so just where was/is the Baksheesh?
Christenson is offline   Reply With Quote
Old 2011-09-02, 23:14   #20
Jeff Gilchrist
 
Jeff Gilchrist's Avatar
 
Jun 2003
Ottawa, Canada

3×17×23 Posts
Default

Fun things to do with flat mirrors:

From a Flat Mirror, Designer Light: Bizarre Optical Phenomena Defies Laws of Reflection and Refraction
http://www.sciencedaily.com/releases...0901142106.htm
Jeff Gilchrist is offline   Reply With Quote
Reply



Similar Threads
Thread Thread Starter Forum Replies Last Post
Value of expensive chipsets stars10250 Hardware 16 2008-10-13 02:20

All times are UTC. The time now is 12:38.


Fri Jul 16 12:38:14 UTC 2021 up 49 days, 10:25, 2 users, load averages: 1.27, 1.45, 1.37

Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2021, Jelsoft Enterprises Ltd.

This forum has received and complied with 0 (zero) government requests for information.

Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation.
A copy of the license is included in the FAQ.