I know several people who are breathing again, though they still are stressing over each phase of the deployment still. But with each milestone, they relax a bit more. Usually, these things are mostly over once they get into orbit, as that is the highest risk part, but this particular mission is very complex in its movements, so the stress just goes on and on.
It’s not going to stop until they get first light, and get back data that’s not corrupted or blurry or any of the other things that could go wrong with the optics and instruments.
Nearly a month of stress just to get to L2, then more time (2-3 months IIRC) to tweak everything and get it dialed in and aligned. Of course, a lot of the folks have been stressing about this for years now, especially with all the delays.
It would make sense to have some micro cameras on board so they can watch it unfold.
Well, there’s the military mini-me version. The X-37B
They should have launched a separate craft to fly alongside the telescope (at a suitable distance), with all the cameras.
There are various animations on-line, showing various stages of launch and deployment, as would be seen by an outside observer a short distance away. It would be neat if they had a parallel craft actually doing that.
That video is but one page of a much larger JWST web site, showing a timeline of all the deployment stages, current statistics, and other such stuff. It’s been linked and/or mentioned at least twice earlier in this thread that I counted. There are other pages givings drawings and details of each of the stages that you can explore. Here is the link again:
I was looking at the diagram of the Lagrange points (Post #38) and was curious about why the JWST is going to orbit around L2 rather than just being parked at the equilibrium point. From what I can gather, there are two reasons.
The first is that it can’t really be “parked”. From what I gather, it would very quickly slip off one side or the other of this “gravity hill”, and the further it slipped, the faster it would go. It would need constant thrust adjustments to stay in place.
The second is that, by the nature of an L2 Lagrange point, the earth will always be directly between the sun and L2. This means that the JWST would always be in the earth’s partial shadow, effectively seeing a permanent annular eclipse, so the solar cells wouldn’t be effective.
So it appears that for both those reasons, the JWST will be in a so-called halo orbit around L2, an orbit that will actually be very large and elliptical. The JWST not only won’t be “at” the L2, it won’t even be close - if my numbers are right, it will come no closer than about 350,000 kilometers, and will be about twice that far at apogee. So the status page for the JWST quite correctly describes the “Distance” figure as “Distance to L2 Orbit” – to the point of orbital insertion, not to L2 itself. It will still need occasional thrust corrections, but will be relatively stable in this configuration.
The concept of “orbiting” around nothing may seem peculiar, but if you think about the L2 equilibrium, it’s the combined gravity of the earth and the sun (in a straight line) against the centrifugal force acting on the JWST, which is in a higher solar orbit than the earth and yet is being pulled along with the same period. Its orbit around L2 is somewhat like a weight hanging from a string that can be made to go around in a circle, which is also “orbiting around nothing”. It’s orbiting around a balance of forces.
It should be noted that there’s quite a lot about the Lagrange points that is counterintuitive. For instance, the “obvious” way of determining the stability of a point is to find an effective potential, and then to see whether that effective potential has a minimum, maximum, or saddle point at the point in question. But trying to do that analysis for the Lagrange points (at least, in the naive way) will give you the opposite of the correct answers.
Here’s a nice little factoid: The JWST, which launched on Christmas Day, will reach the halfway point to its destination on this fine New Year’s Eve. In fact, according to my rough calculations, it will reach the halfway point sometime very close to midnight EST, as we transition to a new year of hopefully great scientific discovery.
Not to me. Consider the Trojan asteroids at the Sun-Jupiter L4/L5 points. There’s probably hundreds of thousands of them and virtually none of them are actually at the Lagrange points. They all orbit around those points, although the orbits are not circles or even ellipses. Instead, they’re kind of long kidneybean-shaped orbits, which means the asteroids will be a very long way away from the Lagrange points at times.
Have they revealed what the first target will be?
The 3rd graphic on the Wikipedia page provides a visual of this: Lagrange point - Wikipedia
It’s still a bit odd to have something orbiting nothing. I was fascinated by lagrange points as a child, having read a short story about a space station in the Earth-Moon L1 point. (That was also the first time I came across the term “botanist”, and I thought that was the person in the marching band with the baton, and thought it very odd that they were giving this person as much deference about their knowledge of plants as they were.)
Anyway, pre-google, pre-internet in general, I spent quite a bit of time at the library trying to find more information about orbital mechanics. Wasn’t until Everything 2 came along that I really found a good explanation for the phenomenon.
Still find the idea of these areas of space where gravitational and inertial forces cancel out to be a bit eerie.
The one on this page - though oriented to L4/5 rather than L2 - shows the kidney-bean orbit in a cool way:
Looks like the Trojan asteroids, then near Earth objects and a bunch of planetary observations in the solar system:
There’s some exciting stuff coming up in the first cycle, For example, JWST will be able to detect organics in the vapor plumes from Europa and Enceledus.
After the planetary observations, JWST will be looking at Kuiper Belt objects, then at nearby exoplanets, not only sampling their atmospheres but directly imaging them by blocking the light from the parent star with JWST’s coronagraph.
Of course, they’re only “orbiting around nothing” or “in kidney-bean-shaped orbits” if you look at them in a rotating reference frame. In an inertial reference frame, they’re orbiting perfectly ordinary objects like the Sun, in orbits that are very close to Keplerian ellipses.
That’s because just looking at the gravitational potential tells you what would happen if both the Earth and Webb were stationary, right? But both are orbiting the Sun.
So Webb’s “orbit around L2” really means a periodic wobble up-and-down and back-and-forth in Webb’s orbit around the Sun. (Or equivalently, the orbit around L2 is in a rotating frame.)
The “hot” side of the JWST (the two “a” sensors, specifically) are up to 97 F.
Strange, since it’s the middle of winter, and nearly nighttime! 
Not unexpected, though, and the cold side is fine, but I wonder what caused this? Possibly mini-deployment activities related to the sun shield? The temp readings were extremely stable over the past 24 hours or so.
I said “effective potential”, which includes the actual gravitational potential as well as a term to account for centrifugal force (since we are, after all, working in a rotating reference frame). An effective potential of that sort is quite a useful tool for a lot of problems in orbital dynamics. But it doesn’t work here.
It must be a newly-discovered tropical vacation spot.
I hear, though, that you have to bring your own supply of oxygen.