Author Topic: James Webb Space Telescope  (Read 12284 times)

Offline bknight

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James Webb Space Telescope
« on: August 29, 2015, 09:20:53 AM »
In the recent thread with Neil Baker concerning the PLSS, one link to the massive NASA vacuum Chamber A leads me to a question.
http://www.nasa.gov/centers/johnson/engineering/integrated_environments/altitude_environmental/chamber_A/
In the link NASA is in the process of a reconstruction project to allow the James Webb Space Telescope to be tested in the chamber.  I wonder whether NASA learned from a huge past mistake in the Hubble Space Telescope to checking every detail so this won't be another black eye for them?
We won't have a way of going to the telescope with people at least to fix a mistake.  Perhaps robots could be programmed to do repairs.
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Offline Luke Pemberton

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Re: James Webb Space Telescope
« Reply #1 on: August 29, 2015, 08:15:09 PM »
I wonder whether NASA learned from a huge past mistake in the Hubble Space Telescope to checking every detail so this won't be another black eye for them?

What black eye, are you referring to the problem with the correction to Hubble's mirror?
« Last Edit: August 29, 2015, 08:27:08 PM by Luke Pemberton »
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Offline bknight

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Re: James Webb Space Telescope
« Reply #2 on: August 29, 2015, 08:30:44 PM »
Yes, sir.
Truth needs no defense.  Nobody can take those footsteps I made on the surface of the moon away from me.
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Offline Luke Pemberton

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Re: James Webb Space Telescope
« Reply #3 on: August 29, 2015, 08:56:52 PM »
Yes, sir.

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/
Only two things are infinite, the universe and human stupidity, and I'm not sure about the former - Albert Einstein.

I can calculate the motion of heavenly bodies, but not the madness of people – Sir Isaac Newton.

A polar orbit would also bypass the SAA - Tim Finch

Offline bknight

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Re: James Webb Space Telescope
« Reply #4 on: August 29, 2015, 09:18:47 PM »

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/
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.
I guess I didn't have enough coffee when I penned that this morning.
Truth needs no defense.  Nobody can take those footsteps I made on the surface of the moon away from me.
Eugene Cernan

Offline Luke Pemberton

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Re: James Webb Space Telescope
« Reply #5 on: August 30, 2015, 10:00:30 AM »
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.

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.
Only two things are infinite, the universe and human stupidity, and I'm not sure about the former - Albert Einstein.

I can calculate the motion of heavenly bodies, but not the madness of people – Sir Isaac Newton.

A polar orbit would also bypass the SAA - Tim Finch

Offline bknight

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Re: James Webb Space Telescope
« Reply #6 on: August 30, 2015, 10:13:05 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.

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.
Truth needs no defense.  Nobody can take those footsteps I made on the surface of the moon away from me.
Eugene Cernan

Offline Allan F

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Re: James Webb Space Telescope
« Reply #7 on: August 30, 2015, 03:39:57 PM »
5: Testing shoddy wiring and flammable materials in a high-pressure pure O2 atmosphere.
Well, it is like this: The truth doesn't need insults. Insults are the refuge of a darkened mind, a mind that refuses to open and see. Foul language can't outcompete knowledge. And knowledge is the result of education. Education is the result of the wish to know more, not less.

Offline bknight

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Re: James Webb Space Telescope
« Reply #8 on: August 30, 2015, 04:09:57 PM »
5: Testing shoddy wiring and flammable materials in a high-pressure pure O2 atmosphere.

Yes that was a biggie.
Truth needs no defense.  Nobody can take those footsteps I made on the surface of the moon away from me.
Eugene Cernan

Offline smartcooky

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Re: James Webb Space Telescope
« Reply #9 on: August 30, 2015, 05:31:41 PM »
Yes, sir.

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/



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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Offline ka9q

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Re: James Webb Space Telescope
« Reply #10 on: August 30, 2015, 10:46:52 PM »
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.
For these two at least, there were plenty of warnings before the disaster that simply went unheeded.

Offline bknight

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Re: James Webb Space Telescope
« Reply #11 on: August 30, 2015, 10:52:58 PM »
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.
For these two at least, there were plenty of warnings before the disaster that simply went unheeded.
Yes these two had many occurrences, not a one off.  I was just trying to note where NASA, generally performing well in a rather hostile environment, seems to not check everything to ensure mission success from time to time.  Then  putting a whose checking the checker on the system.
Truth needs no defense.  Nobody can take those footsteps I made on the surface of the moon away from me.
Eugene Cernan

Offline bknight

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Re: James Webb Space Telescope
« Reply #12 on: November 30, 2015, 07:18:25 AM »
The mirrors are being installed, here's hoping they did it correctly this time.
http://www.nasa.gov/press-release/nasa-s-webb-space-telescope-receives-first-mirror-installation
Truth needs no defense.  Nobody can take those footsteps I made on the surface of the moon away from me.
Eugene Cernan

Offline bknight

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Re: James Webb Space Telescope
« Reply #13 on: February 05, 2016, 07:06:10 AM »
The mirrors are installed.
http://www.nasa.gov/press-release/nasas-james-webb-space-telescope-primary-mirror-fully-assembled
My question what testing for the next two years will be done?
Truth needs no defense.  Nobody can take those footsteps I made on the surface of the moon away from me.
Eugene Cernan

Offline Dalhousie

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Re: James Webb Space Telescope
« Reply #14 on: February 05, 2016, 09:43:29 PM »
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.
For these two at least, there were plenty of warnings before the disaster that simply went unheeded.
Yes these two had many occurrences, not a one off.  I was just trying to note where NASA, generally performing well in a rather hostile environment, seems to not check everything to ensure mission success from time to time.  Then  putting a whose checking the checker on the system.

The Galileo antenna would be another one, several issues with Curiosity come to mind (the drills, the wheels) come to mind as areas where more checking would have been good.