Coffee House Musing

JWST is about 950k km out in the 11th day of its 30 day travel to the L2 point.Things are going exceedingly well, like these folks had planned this for 30 years or something.The sunshade has been completely deployed and tensioned. That was a big nail biter that just seemed to easily unfurl and straighten itself out. Again, it was as if someone planned it that way.Actually because of the Ariane 5 launch being so near perfect the controllers had extra time to go through all the release mechanisms again, like all 107 of them, to make sure everything was ready for unfolding. Then they took extra time to unfold and verify each step.But this was all planned, right?Of course, but no one really expected to be using the “best case scenario” checklist.The blessings come from the performance of the ESA’s Ariane 5 rocket. The launch was as near perfect to the perfect launch window for JWST as to allow the initial rotation of the scope, deployment of the solar array and the switch from battery to internal power to happen much sooner that normally expected.The Ariane 5 also put JWST on its orbital path so precisely that the required initial correction burns using the scope’s own thrusters were cut in duration, by more than half. That’s going to leave a lot more fuel in the tank. I haven’t seen NASA’s official numbers but the internet nerds are talking the 5-to-10 year thruster life of JWST has just been extended by at least another 5-10 years. A lot more science.I want to be optimistic. Things are going exceptionally well. Kudos to the planners, the engineers, the ones that are doing this thing. I can be quite optimistic about the human components seeing as how things have progressed. With the hopes for this scope growing ever stronger as each hurdle is crossed I dread the other shoe. Is it going to drop?[aside] Waiting for the other shoe to drop is an American idiom for waiting for disaster to strike.I fear being ghosted by JWST. That and a thousand other billiards table, bullet range, blast a grain of sand through the heart of my optic processors, scenarios. I am a seething mass of existential dread.Edited by AZPaul3, : No reason given.

XKCD's latest strip is JWST centric.

Secondary mirror positioning today.I am interested to see if the Webb images will be as visually stunning as so many Hubble images. Hubble can point in almost any direction except close to the sun. Webb is a lot more limited because it has to maintain sun-shielding at all points in its orbit around L2, but Holy Crap, the light sensitivity and the resolution increase by orders of magnitude!!!This is the most exciting joint human achievement, maybe in my lifetime!We are going to see lots and lots and LOTS of things and events that have never been imaged before!We are going to confirm or rejects thousands of hypotheses in astrophysics and cosmology!ABE: Secondary mirror deployment successfully completed today.Edited by Tanypteryx, : No reason given.

It's done. The mirror is full open and is going through hours of tight lockdown procedures.All the hard engineering points are done. Lots of tests/failure points remain on the mirror actuators, alignment, optics and what the internet nerds are calling a gentle nudge into the L2 gravity anomaly by the onboard thrusters. Then we get to go through more tests and more tests while we wait for the scope to cool down.Thermal equilibrium, a major requirement for scope operation, will take many months to achieve. The goal is 40^o Klevin (-230^oC) over the entire scope. They need to squeeze every last drop of heat they can from the thing and, down that area of the scale, trying to getting lower is a long, long process as what little heat there is needs time to slowly leak, photon by photon, into space. It's going to be a while before it's ready.No. Not anxious. Not at all.

Almost every morning I enjoy releasing captured carbon-dioxide back into the atmosphere.Blame me if you must but I will still fix my coffee in the morning.

The JWST will enter a stable orbit at L2 on Monday! It sounds like it will still be several months before we see the first images.Any guesses what they will shoot first?

I suppose the medium-sized infrared dot is out of the question since we're on the other side of the sunshade. A question occurs to me: Obviously the sunshade doesn't interfere with communications, but did communications influence decisions about the sunshade?--Percy

How could it not? I should think the placement and operation of each part was major in all decisions given the origami nature of the thing.I think I'm missing the intent of your question.

No, you got it. I was wondering about the sunshade's effects on electromagnetic radiation (radio waves), things like the material used, reflectivity, absorption, density, did it have to be placed at an angle, is it flat or does it have a very specific topography, did its presence affect choice of communication frequencies, etc.--Percy

I don't know about the comm effects of the shield. I can't find anything specific to sunshield design effects on comm.The Sunshield Webb/NASAHas the sunshield materials, construction, function, physics of layering, etc To me, the physics of the heat dissipation of the shield are fascinating. Pay attention to the spacing. Thermodynamics in all its glory.Sunshield Coatings Webb/NASAInfo on the coatings used in each layer and why.JWST Communications Subsystem - JWST User DocumentationHas info on the comm suite Webb will us.But I haven't found anything discussing the design impact one upon the other.Edited by AZPaul3, : No reason given.

Stable orbit at L2 achieved!!

So now we wait…

Oh no. We dream. We hold our breath at every test and we dream.

Five freaking months though!

No. 30 freaking years.