Off Topic > General Discussion
James Webb Space Telescope
Luke Pemberton:
--- Quote from: bknight on August 29, 2015, 09:18:47 PM ---Actually I wasn't thinking about a vacuum chamber test, the article said they were remodeling it to accommodate the telescope. I was rather hoping the guys in charge would check out all the mirrors and alignments so we don't have a repeat of Hubble.
--- End quote ---
I would would like to hope too that they learn lessons from the Hubble mirror problem. The JWST mirror is impressive and there are many different problems with its deployment compared to Hubble. I should imagine that the mirror polishing was overseen to avoid the quality control issues that almost ended Hubble before it started.
bknight:
--- Quote from: Luke Pemberton on August 30, 2015, 10:00:30 AM ---
I would would like to hope too that they learn lessons from the Hubble mirror problem. The JWST mirror is impressive and there are many different problems with its deployment compared to Hubble. I should imagine that the mirror polishing was overseen to avoid the quality control issues that almost ended Hubble before it started.
--- End quote ---
I hold the same hope. NASA has done remarkable missions, but every so often the smallest overlooked problem derails their performance. Not to throw stones but:
1. Miscalculation of distance parameters allows Mars probe to crach into the surface.
2. O-ring problems with the external SRB's didn't pose a significant threat to any mission until Challenger
3. Foam strikes observed on many/all(?) of shuttle launches didn't pose a threat until Columbia.
4. Mirror imperfections in Hubble even during 1-2 years in cold storage waiting for the Shuttle to regain flight status.
That's all I can remember at this time.
Allan F:
5: Testing shoddy wiring and flammable materials in a high-pressure pure O2 atmosphere.
bknight:
--- Quote from: Allan F on August 30, 2015, 03:39:57 PM ---5: Testing shoddy wiring and flammable materials in a high-pressure pure O2 atmosphere.
--- End quote ---
Yes that was a biggie.
smartcooky:
--- Quote from: Luke Pemberton on August 29, 2015, 08:56:52 PM ---
--- Quote from: bknight on August 29, 2015, 08:30:44 PM ---Yes, sir.
--- End quote ---
Well, unless others here want to correct me, a vacuum test would not have picked up that error. The error in the mirror was due to a contractor rushing a step in the calibration of an interferometer.
http://carpetbomberz.com/2012/04/05/charlie-pellerin-on-leadership/
--- End quote ---
I think he means just do some bloody testing before committing to launch.
Hubble was undone by budget cuts and pressure to finish the task. This resulted in short cuts being taken, and one of those short cuts was to not test the mirror. A simple focault test at ANY stage before the mirror was installed would have picked up the problems with the mirror's "figure". Even an amateur telescope maker wouldn't dream of installing his newly ground and aluminised mirror into the tube without doing a focault test.
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