[Kean1 (OP)]

Re: the "MRSA, The Metaverse & Medical Milestones" podcast. In the report about the James Webb telescope, Matt says: "It's going to be a little while to be honest. So James Webb is going to spend the next few months cooling down to operating temperature and then hopefully, by spring or summer 2022, we'll start to get some nice, pretty pictures back."

Why does an object floating around in space take months to cool down?
Cheers!
PS hope this post isn't in the wrong place!

[Kryptid]

Why does an object floating around in space take months to cool down?

In space, heat transfer by conduction or convection doesn't work because there is no air, water or other substance to help transport the heat away. The only option for cooling is radiation, which works more and more slowly the cooler the object is. This is why the classic science fiction scenario where a person instantly freezes when exposed to space is dead wrong.

[Kean1 (OP)]

Thanks Kryptid. All clear!

[evan_au]

I've been watching this webb-site over the past month as the James Webb commissioning process gets underway.

It has a real-time report of the temperature on the Sun side and the Dark side; currently the temperature difference is about 230°C (you can switch between metric & imperial units).
https://webb.nasa.gov/content/webbLaunch/whereIsWebb.html?units=metric

The other long-running activity is the mirror focusing process.
- The mirrors are stowed for launch, and folded into 3 banks
- The 3 banks are unfolded into a straight line
- Then the mirrors are moved to near their final position - it took about a week to move 1cm.
- Now the focusing process starts, aligning all the mirrors to form a single surface, with the edges aligned to well within a wavelength of light.

Overall, the commissioning process will take about 6 months...