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#420 by ppb on 13 Jun, 2022 16:27
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Classic case of confirmation bias.Hubble sat in storage for four years with that flaw. Another case of years of opportunity, and inadequate testing.
Not possible to test in the spacecraft configuration. Testing had to be done on the mirror. Don't even know if testing was feasible in the telescope configuration.
The additional four years would have made no difference. Two existing refractive null correctors had already demonstrated the fault in the HST primary mirror BEFORE the mirror was built into the optical assembly. However, the new Reflective Null Corrector that Perkin-Elmer had constructed specially for Hubble, showed NO error.
Perkin-Elmer willingly chose to ignore the results from the existing refractive null correctors: they believed that only their new Reflective Null Corrector was telling "the truth".
However, after STS-31 the fault in Hubble's primary mirror was traced all the way back to a design error in Perkin-Elmer's new Reflective Null Corrector.
The results from the older refractive null correctors turned out to have been correct all the time.
Summarizing: the fault in Hubble's primary mirror was known AND confirmed at an early stage. But Perkin-Elmer believed those measurement results themselves to be faulty. Any additional testing in the "storage" years would not have changed that attitude.
But I digress. -
#421 by rsdavis9 on 13 Jun, 2022 16:39
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P-E didn't have the experience that Kodak had having built over 70 mirrors including those for the KH-11s, but P-E submitted the lower bid wanting to develop the skillset. P-E's equipment had a measuring point with a protective cap to prevent it from damage, and the measurements were made to the cap instead of to the measuring point itself leading to a 2mm error. (I don't think this was ever reported) In the end, Kodak's mirror team were brought in to figure out P-E's problem. One benefit was that during the delays, there had been so much advancement in digital camera technology, that the replacement optics package was really an enhancement. At one point P-E must have realized that they were in over their heads since they subcontracted Kodak to build a backup mirror, which didn't have the flaw and is the one now on display. P-E never ran end-to-end tests or even compared the two mirrors and instead relied on their machine that built the mirror to test the mirror. So another example of failure due to lack of end-to-end and independent testing and why the engineers doing the testing should be as qualified and empowered as those doing the development.
I remember reading about this exactly as described in sky and telescope. So it was reported.
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#422 by LouScheffer on 13 Jun, 2022 19:45
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I have have heard (but cannot confirm for obvious reasons) that the KH-11 program did indeed possess an end-to-end test bench for optical telescopes the size of Hubble. This makes sense - here is such a test bench that is publicly known. However the barriers to using it were quite significant (security clearances, transporting the telescope, and so on) so instead PE relied on tests of individual components.Hubble sat in storage for four years with that flaw. Another case of years of opportunity, and inadequate testing.
Not possible to test in the spacecraft configuration. Testing had to be done on the mirror. Don't even know if testing was feasible in the telescope configuration.
Even with piecemeal testing there were lots of other opportunities to catch the error, as many have pointed out. Kodak, the backup mirror maker, proposed to have each company test the other company's mirror, then NASA could pick the best one. This would have instantly shown the two mirrors are different and hence at least one of them was wrong. However, it was dismissed as an unnecessary expense as the two mirrors seemed similar in quality as measured by their manufacturers. -
#423 by DRSmith on 13 Jun, 2022 20:30
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However, after STS-31 the fault in Hubble's primary mirror was traced all the way back to a design error in Perkin-Elmer's new Reflective Null Corrector.
What I read said that the design was correct, but the technician assembling the null corrector got a spacer in the incorrect location. The null corrector was never physically tested against its specs. That was in a book I lent out and never got back; Amazon searches give me only books that are much more recent than the one I had, so I can't quote it exactly. -
#424 by Comga on 13 Jun, 2022 21:34
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P-E didn't have the experience that Kodak had having built over 70 mirrors including those for the KH-11s, but P-E submitted the lower bid wanting to develop the skillset. P-E's equipment had a measuring point with a protective cap to prevent it from damage, and the measurements were made to the cap instead of to the measuring point itself leading to a 2mm error. (I don't think this was ever reported) In the end, Kodak's mirror team were brought in to figure out P-E's problem. One benefit was that during the delays, there had been so much advancement in digital camera technology, that the replacement optics package was really an enhancement. At one point P-E must have realized that they were in over their heads since they subcontracted Kodak to build a backup mirror, which didn't have the flaw and is the one now on display. P-E never ran end-to-end tests or even compared the two mirrors and instead relied on their machine that built the mirror to test the mirror. So another example of failure due to lack of end-to-end and independent testing and why the engineers doing the testing should be as qualified and empowered as those doing the development.
What I read said that the design was correct, but the technician assembling the null corrector got a spacer in the incorrect location. The null corrector was never physically tested against its specs. That was in a book I lent out and never got back; Amazon searches give me only books that are much more recent than the one I had, so I can't quote it exactly.
I remember reading about this exactly as described in sky and telescope. So it was reported.
On one hand...
The issue with the assembly of the refractive corrector has been confirmed to me by someone who was part of the Perkin-Elmer team.
It is one of the cases of "glint" which was referred to in url=https://forum.nasaspaceflight.com/index.php?topic=53897.msg2376331#msg2376331]this post.
Some of the comments on why this occurred and was not caught are less accurate.
(Once I thought I would make a nerdy joke about spherical aberration, the optical problem with Hubble, not knowing that the NASA supervisor of the P-E mirror effort was in the front row of my audience.
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On the other hand,
NASA's Discovery Mission Kepler made the choice that only full system testing could verify the optical functionality of its Schmidt imager.
The thermal vacuum testing wound up costing the equivalent of another Discovery mission.
And, by the time Kepler did uncover a hardware issue, they were so far over budget that they were instructed to live with it, which is why the primary mission period was shortened from five years to three.
There is such a thing as too much hardware testing.
On the gripping hand,
This is going well beyond relevance to Starliner, the subject of this thread.
No one here has agreed with Boeing that full up testing of the entire software package would have been impossible or too expensive. -
#425 by jimvela on 13 Jun, 2022 21:53
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On the other hand,
NASA's Discovery Mission Kepler made the choice that only full system testing could verify the optical functionality of its Schmidt imager.
The thermal vacuum testing wound up costing the equivalent of another Discovery mission.
And, by the time Kepler did uncover a hardware issue, they were so far over budget that they were instructed to live with it, which is why the primary mission period was shortened from five years to three.
There is such a thing as too much hardware testing.
Lots of stories about the Kepler mission and its testing (as I know you know very well...)
The GSE created for that particlular Kepler test campaign had its own set of nightmares, not the least of which is that one contractor completely botched up the production of a major structural element of the OGSE leading to a massive contamination of a TVAC chamber and cost and schedule impacts for not only Kepler but all the other missions flowing through that facility.
Kepler had many other decisions, including to fly with known problematic reaction wheels because it was at risk of cancellation for cost/schedule overruns and it was (correctly) thought that it could make it through the primary mission as-it-was.
Industry hadn't yet figured out the reason those wheels were failing, and it wasn't immediately obvious at the time.
That's the tie back to the Starliner- it's not always obvious to decision makers why the clowns who spend all that time and money testing things want to do things they way they do, nor what risks they can avoid or introduce to the program by making decisions about such things. I speak as one of the test clowns, though never as a Boeing employee and only on occasion working with Boeing teammates. (and Boeing had nothing to do with the Kepler example above...)
It's tempting to avoid those complicated and expensive tests - but the risks are great if this is done. I bet Boeing would love to have a do-over on that as the cost of flying another CST-100 mission had to be at least an order of magnitude more expensive than the testing that would have found and fixed the various problems before they happened.
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#426 by DanClemmensen on 13 Jun, 2022 23:47
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Can we please get back on topic here? The piecewise vs. end-to-end testing is very interesting, but not here.
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#427 by ZachS09 on 14 Jun, 2022 00:42
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Can we please get back on topic here? The piecewise vs. end-to-end testing is very interesting, but not here.
Yeah. How close were we to even talking about Starliner anyway? -
#428 by woods170 on 14 Jun, 2022 14:03
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P-E didn't have the experience that Kodak had having built over 70 mirrors including those for the KH-11s, but P-E submitted the lower bid wanting to develop the skillset. P-E's equipment had a measuring point with a protective cap to prevent it from damage, and the measurements were made to the cap instead of to the measuring point itself leading to a 2mm error. (I don't think this was ever reported) In the end, Kodak's mirror team were brought in to figure out P-E's problem. One benefit was that during the delays, there had been so much advancement in digital camera technology, that the replacement optics package was really an enhancement. At one point P-E must have realized that they were in over their heads since they subcontracted Kodak to build a backup mirror, which didn't have the flaw and is the one now on display. P-E never ran end-to-end tests or even compared the two mirrors and instead relied on their machine that built the mirror to test the mirror. So another example of failure due to lack of end-to-end and independent testing and why the engineers doing the testing should be as qualified and empowered as those doing the development.
I remember reading about this exactly as described in sky and telescope. So it was reported.
Yes, the protective-cap-on-end-of-metering-rod debacle has been reported pubically several times. Heck, it even made it into a Discovery Channel documentary from many years ago (I believe it was called something like "Hubble, miracle in orbit"). -
#429 by FutureSpaceTourist on 17 Jun, 2022 20:34
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#430 by leovinus on 25 Jun, 2022 14:29
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From the GAO Annual assessment thread comes the puzzling snippet below. From the 2022 report. I assumed that at OFT-2 all training was done to safely operate the Starliner but it seems much more needs to be done and a large amount of software and operations are untested. And that it requires so much extra training to safely operate in all situations. Was that to be expected? Or is the report too old and all is resolved already? Thanks for any clarification.
Just realized I never posted the excerpts I started putting together yesterday.
QuoteIn addition, the CCP and ISS programs are concerned that operational staff may not be able to safely operate Boeing’s crewed spacecraft if there are any issues with Boeing’s flight software. CCP reported that Boeing’s approach to software development and testing created a significant backlog of software problem reports. Program officials said the operations team is being trained on operational workarounds to complete functions manually that software would normally automate. Several teams reported little capacity to safely accommodate additional operational workload that may be needed if there are any problems with Boeing’s flight software. To mitigate this issue, CCP plans to provide operational teams 6 months of training time with released software and closely monitor workload.
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#431 by seb21051 on 27 Jun, 2022 04:34
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Interesting thing I noticed. Boeing does not seem to have an FAA Commercial Re-entry License for the CST-100:
https://www.faa.gov/data_research/commercial_space_data/licenses/
Does the fact that its for NASA remove the need for such a license? -
#432 by JayWee on 27 Jun, 2022 05:33
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Interesting thing I noticed. Boeing does not seem to have an FAA Commercial Re-entry License for the CST-100:
Weird, looking at launch licenses - Orbital has a launch license for Antares (NASA), but ULA doesn't have one for Delta IV (Military).
https://www.faa.gov/data_research/commercial_space_data/licenses/
Does the fact that its for NASA remove the need for such a license?
Lockeed had reentry for Orion(NASA). SpaceX ammended its reentry license for Inspiration4 and then for once again for Axiom.
Would expect Boeing to have one for Starliner. -
#433 by deadman1204 on 27 Jun, 2022 13:40
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Interesting thing I noticed. Boeing does not seem to have an FAA Commercial Re-entry License for the CST-100:
NASA wouldn't be able to do this. Anything that flies through airspace is subject to the FAA.
https://www.faa.gov/data_research/commercial_space_data/licenses/
Does the fact that its for NASA remove the need for such a license? -
#434 by Jim on 27 Jun, 2022 15:13
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NASA wouldn't be able to do this. Anything that flies through airspace is subject to the FAA.
Not true. Goverment managed launches like SLS or ICBMs are not managed by FAA licensing. The FAA is given notice for a need to close airspace. -
#435 by deadman1204 on 27 Jun, 2022 18:00
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Well, military is obviously a different thing altogether, but doesn't SLS and all other rocket launches still need a launch license?NASA wouldn't be able to do this. Anything that flies through airspace is subject to the FAA.
Not true. Goverment managed launches like SLS or ICBMs are not managed by FAA licensing. The FAA is given notice for a need to close airspace. -
#436 by seb21051 on 27 Jun, 2022 19:02
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Which also begs the question, is Starliner not a Commercial Crew Capsule? If not, in what way does it differ from Dragon? Especially in terms of a Re-Entry License?
"COMMERCIAL CREW BASICS
NASA's Commercial Crew Program has worked with several American aerospace industry companies to facilitate the development of U.S. human spaceflight systems since 2010. The goal is to have safe, reliable and cost-effective access to and from the International Space Station and foster commercial access to other potential low-Earth orbit destinations.
NASA selected Boeing and SpaceX in September 2014 to transport crew to the International Space Station from the United States. These integrated spacecraft, rockets and associated systems will carry up to four astronauts on NASA missions, maintaining a space station crew of seven to maximize time dedicated to scientific research on the orbiting laboratory." -
#437 by JayWee on 27 Jun, 2022 19:34
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Idea: Could it be because Starliner reenters towards a military range - the White Sands Missile range?
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#438 by Jim on 27 Jun, 2022 21:04
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Well, military is obviously a different thing altogether, but doesn't SLS and all other rocket launches still need a launch license?NASA wouldn't be able to do this. Anything that flies through airspace is subject to the FAA.
Not true. Goverment managed launches like SLS or ICBMs are not managed by FAA licensing. The FAA is given notice for a need to close airspace.
No, not Government managed launches like SLS or ICBMs or Titan IVs -
#439 by Lee Jay on 27 Jun, 2022 22:15
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Well, military is obviously a different thing altogether, but doesn't SLS and all other rocket launches still need a launch license?NASA wouldn't be able to do this. Anything that flies through airspace is subject to the FAA.
Not true. Goverment managed launches like SLS or ICBMs are not managed by FAA licensing. The FAA is given notice for a need to close airspace.
No, not Government managed launches like SLS or ICBMs or Titan IVs
But government-purchased commercial launches (i.e. CRS and commercial-crew) do, correct?
)