James Webb Telescope

3point14 said:
Forgive my ignorance. And this is probably in the thread somewhere.

How long does it take to get on station and then start working? When can we expect pictures of little green men?
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We already have them. Had them for years. But there is a big government conspiracy to keep them from the general public, don't you know. (and they are actually sort of a greenish-grey color)
 
Don't worry about what might be in the thread earlier. It might be wrong by now. June-ish is when the first real images are expected to show up. Possible other calibration images might get released before then. It takes a month just to get to where it's going to deploy.

ETA: Sneaky 4th page.
 
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3point14 said:
Forgive my ignorance. And this is probably in the thread somewhere.

How long does it take to get on station and then start working? When can we expect pictures of little green men?
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ohms said:
Looks like 6 months+ until deployment and testing is complete and the mission begins:

https://webbtelescope.org/contents/media/images/4180-Image
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Cool info.
An Ariane-5 rocket will throw the telescope out to an observing position about 1.5 million km from Earth.
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That's farther away than the moon, by the way, which is only 384,400 km away.

Presumably if there are any serious problems, we would learn about them before six months into the mission.
 
a_unique_person said:
IIRC once it's in its way there is nothing we can do to fix it.
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It would be far-fetched. Maybe not impossible, but certainly not easy.

It will be about 4 times farther away from earth than the moon. No human has ever gone out that far from earth, have they? The far side of the moon is the farthest away we've been, unless I'm mistaken. Just getting out that far would take nearly a month.
 
No human has ever been to the far side of the Moon.

ETA: Wait. You probably mean just distance? Yeah, just the other side of the Moon. No manned mission landed on the far side.
 
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Puppycow said:
It would be far-fetched. Maybe not impossible, but certainly not easy.

It will be about 4 times farther away from earth than the moon. No human has ever gone out that far from earth, have they? The far side of the moon is the farthest away we've been, unless I'm mistaken. Just getting out that far would take nearly a month.
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You could get there a lot faster if you wanted to. The problem, though, is that you would be going faster, which means you'd have to spend a lot of energy to STOP there. So it's actually better to get there slower.
 
RecoveringYuppy said:
No human has ever been to the far side of the Moon.

ETA: Wait. You probably mean just distance? Yeah, just the other side of the Moon. No manned mission landed on the far side.
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I just meant in orbit around the moon, which meant going around the far side.

Ziggurat said:
You could get there a lot faster if you wanted to. The problem, though, is that you would be going faster, which means you'd have to spend a lot of energy to STOP there. So it's actually better to get there slower.
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Also there's no moon there to help you change directions. Then you of course need to match speeds with the telescope, and then come back home again. All of which require more fuel.
 
If you're heading to the telescope, your braking burns would have to be pointed more or less at the telescope. I wonder if the outgassing would cause problems for the telescope.
 
theprestige said:
If you're heading to the telescope, your braking burns would have to be pointed more or less at the telescope. I wonder if the outgassing would cause problems for the telescope.
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You can use sets of angled jets, so the jets don't point directly at the target you approach, but a bit to the side. I think that's already the case for the capsules that dock with the ISS.
 
I suspect the manned rescue mission would cost more than just building and launching another telescope.
 
Let's just hope this one works. If it doesn't, they'll probably go back to the drawing boards. There won't be a rescue mission, and they won't build another one just like it.
 
BowlOfRed said:
I wonder if you could get odds from someone on the possibility that Hubble is still doing science when JWT is done.
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Sure. Not me, but it's absolutely within the realm of possibility. If for no other reason than that it's not a sure thing that the JWST will ever work in the first place. But if everything goes according to plan, and it does work, I don't see why it shouldn't keep working for a long time.
 
To me, it seems like the biggest risk is the deployment process. All those moving parts. If that goes well, the next biggest risk is miscalculation of the heat load and heat dumping. If those numbers are even a little bit wrong, JWST is probably doomed.

So I guess we'll see.
 
BowlOfRed said:
I wonder if you could get odds from someone on the possibility that Hubble is still doing science when JWT is done.
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JWT's initial mission is for five years, and might last ten. Eventually it will run out of fuel for station-keeping.

Now keep in mind that Hubble was designed to be serviced using the Space Shuttle; it's one of the reasons it's lasted so long. Now that the shuttles are no longer flying, as things on Hubble break they won't get fixed. Eventually something critical will go and NASA will have to de-orbit the telescope.

In my opinion, I think the Hubble will fail before the James Webb telescope does, provided of course the JWST deploys as expected. I'd be happy to be wrong, though. :) (See: Voyager)
 
Puppycow said:
Sure. Not me, but it's absolutely within the realm of possibility. If for no other reason than that it's not a sure thing that the JWST will ever work in the first place. But if everything goes according to plan, and it does work, I don't see why it shouldn't keep working for a long time.
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Because JWST requires fuel for stationkeeping. It requires consumables to be useful, and the design lifetime for them is 10 years.

Admittedly, they would be long odds (Hubble has had several issues and eventually one of the failures will kill it). But the long tail of survivability for HST does reach to around 2040. I suspect that JWST fuel usage will end up being below the estimates, but reaching 2040 would be a stretch as well.
 
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