Originally posted by SDK1987
I expect they have tested this as well. It's tough to get a environment of 44K
Yeah, that was the whole big thing with the heat shield.
I don't know why that one point should be still at 63K when all the others are below the 44K cutoff.
The lowest is 33K — tried to find somewhere that discusses this, but haven't found one so far.
It's interested if you can find it. It's a unusual environment to get a temperature of less than 40K (-233C).
Originally posted by SDK1987
It's interested if you can find it. It's a unusual environment to get a temperature of less than 40K (-233C).
I think 1.5 million km away from earth qualifies as "unusual environment"
This has just been added: https://jwst.nasa.gov/content/webbLaunch/whereIsWebb.html
the red dot on the light blue line indicates where they turned the "cryo-cooler" on.
It is an active cooling system — see: https://webb.nasa.gov/content/about/innovations/cryocooler.html
If you look at the temperature plot, you can see that the line with the active cooler has a target of 7K
Good luck with that
https://jwst.nasa.gov/content/webbLaunch/whereIsWebb.html?units=metric <
Stage six has been completed:
https://jwst.nasa.gov/content/webbLaunch/whereIsWebb.html?units=metric
We're now waiting for the active cooler to cool the infra-red sensor down to 7K — it's at 15K now
If you click the "temperature plots" button on the above page you'll see ...
Wow that was fast!
The temperature of the Mid-infrared instrument is already below 7K
https://jwst.nasa.gov/content/webbLaunch/whereIsWebb.html?units=metric <
Originally posted by SDK1987
That's fast for sure.
Here is a description of how it works.
This cryocooler uses helium gas to carry heat from MIRI’s optics and detectors out to the warm side of the sunshield. To manage the cooldown process, MIRI also has heaters onboard, to protect its sensitive components from the risk of ice forming. The Webb team has begun progressively adjusting both the cryocooler and these heaters, to ensure a slow, controlled, stable cooldown for the instrument. Soon, the team will turn off MIRI’s heaters entirely, to bring the instrument down to its operating temperature of less than 7 kelvins (-447 degrees Fahrenheit, or -266 degrees Celsius).
This page has a much more detailed explanation, and is a bit easier to understand
https://blogs.nasa.gov/webb/2022/04/06/webbs-mid-infrared-instrument-cooldown-continues/
And this one gives details of the cryocooler
https://webb.nasa.gov/content/about/innovations/cryocooler.html
The temperature of the MIRI (Mid-InfraRed Instrument) has been stable at 6K for a few days now.
They will likely be moving to final mirror alignment ahead of schedule.
It must be difficult to remote-control the JWST, since it is 1.5 million km from earth.
Each command sent by radio will take 5 seconds to get there, and any feedback another 5 to get back.
I expect colder than 6k is almost not possible. It's nice everything works fine in a cold environment like that.
Originally posted by SDK1987
I expect colder than 6k is almost not possible. It's nice everything works fine in a cold environment like that.
According to one of the earlier links, such coldness is necessary because infrared is heat, so if was any warmer, the heat from the instrument would wash out the image detail.
Rather like trying to look at stars through a telescope when there is a streetlight nearby
We're now in stage 7
https://jwst.nasa.gov/content/webbLaunch/whereIsWebb.html?units=metric <
Not the JWST, but nifty space website — it shows the earth with a 24 hour delay
https://climate.nasa.gov/earth-now/#/
This was announced yesterday afternoon
https://blogs.nasa.gov/webb/2022/04/28/nasas-webb-in-full-focus-ready-for-instrument-commissioning/
Instrument commissioning is underway
https://jwst.nasa.gov/content/webbLaunch/deploymentExplorer.html#40
Originally posted by SDK1987
Nice pictures already. Hopefully they get even better pictures in the future.
Now we wait
