Is this an issue?mfb said:
Looking at this "top" view, my understanding is that the telescope tilts to get pointing in one axis (equivalent to altitude in an Earth-bound alt-az telescope), and that the entire telescope+sunscreen rotates around the axis pointing at the sun to get pointing in the other axis (equivalent to azimuth).KurtLudwig said:
The opening sentence in the linked article says "Taking advantage of its flexible commissioning schedule" That doesn't sound like an issue to me.pinball1970 said:
Where's Webb and links not working for me. A few things on YT mentioned the same thing but I prefer to get it from the horses mouth. At least from someone who understands the horse.anorlunda said:
I just checked, and it's working for me...pinball1970 said:
Nothing Wrong with link, it's my deviceberkeman said:
It probably means some sensor reading was different from the expectation and they spent another day understanding this. Not unusual with such a complex device.pinball1970 said:
That's a relief. They can now, at least use it for something to justify its existence. Things can only get better.mfb said:
So it can still work/semi work like this? If the Primary mirror fails?sophiecentaur said:
Indeed.phyzguy said:
So that's pretty good use of all the resources. No Earth-bound telescope can do that; they're all limited by their horizon and JW has (hopefully) many years to do the job. I hope all those Duracells will hold out.phyzguy said:
Well, it goes all the way from cold comets to stars.. That's pretty wide. It says "dust warmed by starlight", so I presume that dust not warmed is too cold to detect.Grinkle said:
Truly a marvel of science, technology, and engineering. It's basically 3/4 the way there in distance, half way in time, and fully deployed. I'm excited but it sucks that we're going to wait for the next 5 months.websterling said:
websterling said:
Still a long way to go before we are taking images. I agree it is great news so far, but as @sophiecentaur said, there is still a ways to go. I won't celebrate until we get some good images. Remember Hubble?websterling said:
When you throw a stone up in the air, it goes slower and slower as it approaches the high point. That experiment on Earth is very nearly under constant gravitational force and the variation of the g field near L2 is a bit more complicated but the same principle applies; Kinetic Energy turns into Gravitational Potential Energy and, at L2, the GPE changes are very small so KE has to be low.RandyD123 said:
I would normally respond with something about the lower cost of unmanned stuff but JWST costa packet.anorlunda said:
This calibration capability was built specifically because of the previous Hubble mirror flaw. There can't reasonably be a manned mission to fix any optical problems so JWST is designed to be able to overcome optical flaws on its own using this capability.JLowe said:
Also, remember that the problem with Hubble was that the mirror was fabricated incorrectly, and the problem wasn't caught because it was never completely tested on the ground. That's one of the reasons Webb was delayed so long, because they did extensive testing on the ground.JLowe said:
Well it would have been considerably more expensive to put a crew on the JWSTsophiecentaur said:
No - see my post above. There may be a robotic mission someday to replenish fuel but that would be more than 10 years from now.BWV said:
Apparently, they used up less fuel than anticipated and the latest estimate is a 20 year lifespan. Fab or what?Borg said:
I believe it was required because of the nature of the novel segmented berylium miorror. Do you have a reference for this particular assertion?Borg said:
It's from the video that I referred to in my earlier post. It depends on how you interpret that. Saying that it was specifically built because of the Hubble mirror flaw was my wording and may be a bit over-stated. However, the video goes into great detail about the issue with Hubble and how the engineers did not want a repeat of that since they wouldn't be able to repair this one with a mission.hutchphd said:
Yes, and I'm glad they did. I'm only saying, that's a lot of moving parts that have to work.phyzguy said:
It's quite comparable to rolling a ball up a hill, only we don't want to hit the peak at L2. If it drifts past, it will just continue to drift further out. The propellent will be used now and again to roll Webb back close to the peak from time to time (among other things) as it falls back toward earth. Perhaps we should call it Sisyphus (this is pretty standard for the many other observatories at L2).sophiecentaur said:
Or the old pub game of shove ha'penny; just one go to get the coin up to the line and not a nanometre over it.valenumr said:
