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James Webb is fully deployed

nasa.gov

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Re: James Webb is fully deployed

#281

Post by porsupah »

ThinkBeat wrote: post #189
WalterBright wrote: post #72

What puzzles me is the maneuvering fuel. When that fuel runs out, the telescope can no longer orient itself. This ended the life of the Kepler telescope. But aren't there other ways to orient in space? 1. use pressure from the solar wind 2. have 3 electric motors on 3 axis. Wouldn't spinning those motors rotate the craft? Electric power to do it would come from solar panels, giving it plenty of fuel.

They should have made a port for refueling it. An internal fuel tank and a high-capacity tank externally Once the fuel is getting low, launch a refuel. when the new supply gets closed, eject the previous tank, dock the new one. Easy. When they managed to du an in air refuel of a SR71 in 1970s . Surely we can dock a fuel tank in 2022?

They did:

"Unlike Hubble, Webb isn't designed to be fixed by astronauts. But it can be refueled robotically. Zurbuchen says that 'once this telescope is deployed, I'm going to put all the effort towards developing that technology, and so within the 10-year lifespan, we can go refuel it'"

https://nitter.42l.fr/marinakoren/status/1474367236244750345...

https://nitter.42l.fr/Dr_ThomasZ/status/1474398711505580032#...

Re: James Webb is fully deployed

#282

Post by jrockway »

wolverine876 wrote: post #255

Something I am wondering about the L2 orbit ... per NASA: > Webb's orbit [~ around L2] ... is actually similar in size to the Moon's orbit around the Earth! This orbit (which takes Webb about 6 months to complete once) keeps the telescope out of the shadows of both the Earth and Moon. Unlike Hubble, which goes in and out of Earth shadow every 90 minutes, Webb will have an unimpeded view that will allow science operat…

I think it needs to get some sun to power the solar panels, right? No sun = no electricity = no science.

Re: James Webb is fully deployed

#284

Post by sailingparrot »

BurningFrog wrote: post #264
sailingparrot wrote: post #242

Earlier quoted context omitted.

> be able to observe anything in the sky, and get the most detailed pictures ever seen of them That's just not true. JWST is primarily infrared, with some limited ability to observe in visible light (essentially half of the spectrum, no blue or green). It has no capability in ultraviolet, x-rays, gamma-rays, microwaves or radio. You just can't build a single instrument to "observe anything". JWST can't do what Hubble…

You seem to argue against something I didn't say. I understand it observes a different frequency range than Hubble, but it can still "observe anything in the sky, and get the most detailed pictures ever seen of them".

> but it can still "observe anything in the sky, and get the most detailed pictures ever seen of them".

That's my point: it cannot!

Not all objects are visible at all wavelengths. Some extremely old and far-away objects are not emitting anything in the shortest wavelengths because of red-shifting, and you need infrared capabilities to see them (hence JWST).

Dust clouds are also blocking certain frequencies of light from reaching us, so you need instrument detecting certain frequencies to see through them. But if you want to study dust clouds, well you obviously need a different instrument that will not see through them.

If you care about observing very energetic objects like neutron star, you need x-ray capabilities.

If you care about studying atmosphere of exoplanet your best bet is UV light, and this is why NASA is working on LUVOIR.

It's like saying you can observe anything with an iPhone camera. You can't, if you care about imaging a brain tumor or a broken bone, you need x-ray, your iPhone just won't see through the skin. And if you care about taking a picture of the skin, you can't do that in x-ray.

Re: James Webb is fully deployed

#285

Post by behnamoh »

JohnBooty wrote: post #208
daveslash wrote: post #204

Earlier quoted context omitted.

RE>> "I understand the reasons for not putting a camera on or near the JWST" What are the reasons? I'm sorry ~ I'm ignorant on the topic, but I'd love to learn more. Why/what are the reasons?

Great blog post from NASA themselves explaining it: https://blogs.nasa.gov/webb/2022/01/06/why-doesnt-webb-have-... the post is really not very long and I would suggest getting it straight from the horse's mouth, but for those not willing to devote a click here are arguably the most relevant bits! "deployment surveillance cameras would not add significant information of value for engineering teams commanding the spac…

they could have sent a temporary camera along with the craft to take a picture of it at the final position and send back to earth.

Re: James Webb is fully deployed

#286

Post by [deleted] »

bichiliad wrote: post #250
JohnBooty wrote: post #208

Earlier quoted context omitted.

Great blog post from NASA themselves explaining it: https://blogs.nasa.gov/webb/2022/01/06/why-doesnt-webb-have-... the post is really not very long and I would suggest getting it straight from the horse's mouth, but for those not willing to devote a click here are arguably the most relevant bits! "deployment surveillance cameras would not add significant information of value for engineering teams commanding the spac…

One thing they mentioned that kinda sends it home to me is that the telescope is aimed at the dark and away from the sun, and the other side is especially reflective[0]. In other words, one side is too dark to see, and the other is too bright to see. [0]: https://twitter.com/NASAWebb/status/1479161991252131841

[deleted]

Re: James Webb is fully deployed

#287

Post by frosted-flakes »

idealmedtech wrote: post #266
frosted-flakes wrote: post #234

Earlier quoted context omitted.

With Hubbles's highest resolution optics, the JWST will be about one-tenth the size of a pixel.

How can it make out galaxies at billions of light years away, but not a truck sized craft at a few million miles? I haven't done the math myself, so I'm certain one side of that equation is wrong, but that seems hard to believe!

Here's the math[1]. Seems believable to me. The Web telescope is miniscule conpared to faraway galaxies, and it doesn't emit much light.

[1]: https://mobile.twitter.com/gfish/status/1479339620785524736

Re: James Webb is fully deployed

#289

Post by stolsvik »

BurningFrog wrote: post #236
ducktective wrote: post #26

Earlier quoted context omitted.

>344 single points of failure How can a system have more that one single point of failure?

In your body, the brain, heart and lungs are all single points of failure. If either one fails, you die.

You have two lungs, though. One can fail and you will still live. As with kidneys. Strange that there is only one heart.

Re: James Webb is fully deployed

#290

Post by behnamoh »

frosted-flakes wrote: post #230
surfsvammel wrote: post #209

Earlier quoted context omitted.

Won't it be pretty close to earth in its final position at L2? If so, is there no chance that there will be future missions to do service to it? If so, maybe we can get a photo of if then?

L2 is 1.5 million km away. For perspective, the moon is 384 000 km away. That's nearly 4x the distance. It took Apollo astronauts 3 days to reach the moon.

So it will take almost 2 weeks to get to JSWT, and two weeks to come back.
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