Posted on 09/20/2022 10:47:05 AM PDT by Red Badger
TOPICS:James Webb Space TelescopeNASA
Webb MIRI Spectroscopy Animation
James Webb Space Telescope MIRI Spectroscopy Animation: The beam of light coming from the telescope is then shown in deep blue entering the instrument through the pick-off mirror located at the top of the instrument and acting like a periscope. Then, a series of mirrors redirect the light toward the bottom of the instruments where a set of 4 spectroscopic modules are located. Once there, the beam of light is divided by optical elements called dichroics in 4 beams corresponding to different parts of the mid-infrared region. Each beam enters its own integral field unit; these components split and reformat the light from the whole field of view, ready to be dispersed into spectra. This requires the light to be folded, bounced, and split many times, making this probably one of Webb’s most complex light paths.
To finish this amazing voyage, the light of each beam is dispersed by gratings, creating spectra that then projects on 2 MIRI detectors (2 beams per detector). An amazing feat of engineering! Credit: ESA/ATG medialab
Mid-Infrared Instrument Operations Update
The James Webb Space Telescope’s Mid-Infrared Instrument (MIRI) has four observing modes. During setup for a science observation on August 24, a mechanism that supports one of these modes, known as medium-resolution spectroscopy (MRS), exhibited what appears to be increased friction. This mechanism is a grating wheel that allows astronomers to select between short, medium, and longer wavelengths when making observations using the MRS mode. Following preliminary health checks and investigations into the issue, an anomaly review board was convened on September 6 to assess the best path forward.
VIDEO AT LINK....................
The Webb team has paused in scheduling observations using this particular observing mode while they continue to analyze its behavior. They are also currently developing strategies to resume MRS observations as soon as possible. The observatory is in good health, and MIRI’s other three observing modes – imaging, low-resolution spectroscopy, and coronagraphy – are operating normally and remain available for science observations.
VIDEO AT LINK...............
The Mid-InfraRed Instrument (MIRI) of the James Webb Space Telescope (Webb) sees light in the mid-infrared region of the electromagnetic spectrum, at wavelengths that are longer than our eyes can see.
MIRI allows scientists to use multiple observing techniques: imaging, spectroscopy, and coronagraphy to support the whole range of Webb’s science goals, from observing our own Solar System and other planetary systems, to studying the early Universe.
To pack all these modes in a single instrument, engineers have designed an intricate optical system in which light coming from Webb’s telescope follows a complex 3D path before finally reaching MIRI’s detectors.
This artist’s rendering shows this path for MIRI’s imaging mode, which provides imaging and coronagraphy capabilities. It also contains a simple spectrograph. We first take a look at its mechanical structure with its three protruding pairs of carbon fiber struts that will attach it to Webb’s instrument compartment at the back of the telescope.
The pick-off mirror, acting like a periscope, receives the light from the telescope, shown in deep blue, and directs it into MIRI’s imaging module. Inside the instrument, a system of mirrors reformats the light beam and redirects it till it reaches a filter wheel where the desired range of mid-infrared wavelengths is selected from a set of 18 different filters each with its own specific function (the beam takes a light blue color in the animation).
Lastly, another set of mirrors takes the light beam coming out of the filter wheel and recreates the image of the sky on MIRI’s detectors.
Credit: ESA/ATG medialab
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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