Posted on 09/20/2022 10:47:05 AM PDT by Red Badger
Ruh Roh, Raggy!
WEBB Ping!....................
“Ask yourself how they could launch a billion-dollar satellite 🛰️ without checking its mirror?”
The Arrival 1996
Miri................
Going to be a while to get a service guy out there......
Oil of Old Lady’s...................
The issue is not in a mirror. The problem is in a rotating diffraction grating that acts like a prism to select the wavelength of electromagnetic spectrum (all longer wavelength than visible light) that reaches the photodetectors. The grating mechanicals seem to have unexpected drag that slows down the rotation into the desired position. It could be from temperature variations (one side of satellite is very hot and the other side is very cold) or it could be a micro meteroite strike that damaged bearing surfaces. It could be from a speck of dust that shook loose during launch.
You can bet that they are working on a triage strategy to put the diffraction grating into the position that provides the greatest value (likely the longest wavelength IR setting) in the event the grating gets stuck.
Note that this is only the medium resolution sensor, so even if it completely failed there would still be other sensors that are very valuable.
Heh
Movie quote
Those anomalies can really get you!
In the old days we called them problems.
Thanks for the observation on setting the mechanism on its best setting in case it gets stuck.
Plus all of the other sensors that are working. Not exactly “backup”, but still valuable tools.
I was watching something about Princess Diana’s wedding. They had a backup wedding dress, bridal bouquet and the main cake available in case something went wrong.
I take it the fix is all through manipulation from a computer from here?
I knew previous coworkers that worked on the Webb program and was brought in as a consultant on one problem during assembly (not design where I normally worked). I have also worked on numerous other satellite programs where I worked on every aspect as a Systems Engineer including Anomaly Detection and Resolution. This is not the main sensor on Webb and it could be cleared up by working the mechanism back and forth. But I can tell you that they will have the diffraction grating near the most valuable setting when they are trying to resolve the sticky operation. I am not involved in this issue at all, just drawing on past experience that includes Initial On-Orbit Testing of satellites that had anomalies.
Hmmm...
If I had a dollar for every experiment glitch that I’ve seen (before retiring in 1986), I’d have a new bass boat by now...
If it was a porno movie the repairman would be there in about 2 minutes
Healthy-looking lass, that.
I’m still digging on that 60s look. Don’t tell my wife.
Startrek as never the same after losing her.
The telescope is running out of film.... : )
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