James Webb Space Telescope begins historic mission

[ovrszd]

maybe what he is saying is that solar and wind investments are paying back right away into the grid. also see that as keeping some usage from the grid being needed.
Cant see any payback in our time from the telescope. though.... its going to ( i hope) be interesting data

Again I ask, paying who?

 

[etpm]

Sunlight side versus dark side? Or that's how I interpret the data?

Exactly, sunlit vs dark side. About a 600 degree differential. That's why they need so many shades. And the imaging device still needs to be cooled some. The light the telescope is made to see has been redshifted way into the infrared spectrum. If the imager is too warm the IR light it gives off would swamp out any light falling on it from the far reaches of space. Light emitted about 13 billion years ago! I don't know but I think the primary mirror does not need cooling beyond the ambient temp on the cold side. I think any light it emits will not matter because it will not be focussed onto the secondary mirror.
Eric

 

[ovrszd]

My question was why aren't we seeing that 600 degree differential now? Earth emitting enough heat to minimize the difference?

 

[etpm]

My question was why aren't we seeing that 600 degree differential now? Earth emitting enough heat to minimize the difference?

I don't know exactly. I would need to look at where the JWST is in relation to the earth. But certainly part of the reason is that heat is being absorbed by parts of the JWST and then being re-emmitted by other parts. This would lower the heat differential. Also, once the shields are up any heat striking them will be mostly reflected away. That would keep the hot side hot. And even though the hot side might be pretty hot it may not be keeping a bunch of energy from making it to the cold side. Just small amounts of really hot particles and light. Even then just imagine how little energy the JWST must capable of detecting. I wouldn't be surprised if it can detect single photons.
Eric

 

[dstig1]

The sun shield is not yet up and it is not in the final orbit position. I was surprised they put up the temps prior to sun shield deployment. When I just went to the site a pop-up appeared describing the temp measurements. Basically they are taking readings from the hot side (facing the sun, eventually behind the sun shield in 3 locations. 1 near the center (temp b) and 2 of them out near the edges (averaged to make temp A). Temps C&D are similar on the cold side. When I just reloaded the Whereiswebb page it re-appeared, so try that and you can see where it is measuring. I also found it reappears if you click on the temp displays. It looks like the sun shields start to deploy, one piece at a time starting tomorrow for the next 3 days. It will be interesting to see what happens to the temps after that.

 

[ruffdog]

The Aft Momentum Flap just opened!

 

[ovrszd]

It's covered 45% of the distance to orbit in 17% of the time. It's forward speed is really going to drop the last ten days of it's flight to orbit.

 

[ruffdog]

The sunshades are opening.

 

[cqaigy2]

I'm all for the telescope, but... our success as a species on Earth is more likely tied to problems going on here, not in space.

Fortunately, we live in a world where there are many choices, not just two.

 

[ArlyA]

Says with the heat shield deployed the machine will be cooling down. Hard to believe all the parts can work.

NASA’s Webb Space Telescope Ready for Sunshield Deployment and Cooldown

With Webb’s first major structural deployments completed and the observatory’s Deployable Tower Assembly extended, we are taking a step back to learn more about Webb’s sunshield. Observatory Project Scientist Michael McElwain, from NASA’s Goddard Space Flight Center, provided these thoughts: “The

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