Updates James Webb Space Telescope updates

[Thunder Chicken]

Need to coarse tune all 18 mirror. This will start any moment and continue next 2 weeks.
Then L2 insert burn.
Than 3 month fine mirror alignment and instrument calibration.

Why do the optics tuning and alignments take so long? I understand that the telescope has to chill and reach thermal equilibrium to avoid thermal distortion, but my back of the envelope heat transfer calculations suggest that should take days to a few weeks, not months. Maybe they are looking for "more 9s" closer to equilibrium before doing the fine alignments and taking first data? Shedding the last few degrees will be a slow process.

 

[TheShuttleExperience]

@Soumya-8974 and @N_Molson indeed. We are entering a new era for sure. And Artemis is just one amazing part of it, next to JWST. If we work together, we can truly achieve some amazing stuff. The word "impossible" will most likely become more and more meaningless in the future ?

 

[JDat]

Why do the optics tuning and alignments take so long? I understand that the telescope has to chill and reach thermal equilibrium to avoid thermal distortion, but my back of the envelope heat transfer calculations suggest that should take days to a few weeks, not months. Maybe they are looking for "more 9s" closer to equilibrium before doing the fine alignments and taking first data? Shedding the last few degrees will be a slow process.

From my knowledge how it works:
18 mirror segments on main mirror and 1 segment(?) on secondary mirror
Each segment on main mirror have 6 servos on corners + 1 servo to change shape/bending for segment.
Secondary mirror have 6 servos/

Calibration process ( program in GWBASIC ):
10) Coll down sensors
20) Point JWST to "calibration star".
30) Take photo.
40) Download image.
50) Analyse.
60) Send tuning commands to servo.
70) Repeat (goto 20) until all segments aligned.
80) L2 insert burn
90) More sensor chilling
100) Imaging (detector) Sensor test and calibration
110) More mirror aligment.

Couterquestion: why origami deployment took 2 weeks? You can activate all deployment mechanisms and do it in 16 hours...

 

[GLS]

Couterquestion: why origami deployment took 2 weeks? You can activate all deployment mechanisms and do it in 16 hours...

My guesses are: (1) DSN time, (2) available power several motors at once, and probably the big one is (3) making sure the previous step was well performed and things are ok before continuing.
Anyway, there's no rush as it will take a long time for the telescope to cool to it's operating temperature.

 

[GLS]

https://twitter.com/x/status/1481367392596942863

 

[GLS]

https://twitter.com/x/status/1481730041331560448

 

[JDat]

Some info why mirror segment deployment and alignment takes many months:
https://blogs.nasa.gov/webb/2022/01/13/mirror-mirroron-its-way/

 

[GLS]

Another step

https://twitter.com/x/status/1483944717826068484

 

[GLS]

https://twitter.com/x/status/1484283631409549317

 

[JDat]

Ok! JWST arrived at his new home! Congrats to all!

 

[mahdavi3d]

https://twitter.com/x/status/1485695028622209032

 

[GLS]

https://twitter.com/x/status/1488263730165125123

 

[JDat]

On last few days I am already observing 28 MBit/sec data downlink from JWST on 25.9 GHz. Looks like JPL guys taking selfies from L2 orbit.

https://eyes.nasa.gov/dsn/dsn.html

 

[GLS]

On last few days I am already observing 28 MBit/sec data downlink from JWST on 25.9 GHz. Looks like JPL guys taking selfies from L2 orbit.

https://eyes.nasa.gov/dsn/dsn.html

It can't point to the Earth.

 

[JDat]

Selfie was a joke.

 

[mahdavi3d]

 

[Sbb1413]

Updated my wall collage with the inclusion of another Falcon 9 rocket (carrying a batch of Starlinks) and one of the early images taken by JWST. My wall collage is growing quite rapidly and will likely include Saturn V in 2024, at the 55th anniversary of Apollo 11.

Anyway, glad to see the telescope is working as planned.

 

[N_Molson]

You definitively should include a R-7/Soyuz rocket, its something iconic.

 

[mahdavi3d]

 

[GLS]

https://twitter.com/x/status/1497246052214349849