The Future of Astronomy: NASA's James Webb Space Telescope 117
An anonymous reader writes: In 1990, the Hubble Space Telescope was launched and deployed, becoming the first space-based observatory. In the years since, many others have followed, covering the entire electromagnetic spectrum, but with nothing superseding Hubble over the wavelengths it covers. That will all change with the James Webb Space Telescope, currently on schedule and almost ready for its October 2018 launch date. The science instruments are all complete, the final mirrors are being inserted into the optical assembly, the sunshield (a new, innovative component) is almost complete, and then it just needs assembly and launch. When it's all said and done, JWST will be orders of magnitude greater than all the other observatories that came before, and will finally allow us to truly see the first stars, galaxies and quasars in the Universe, not limited by the obscuring neutral gas that currently blocks our view with other observatories.
Finally be able to really see our own galaxy (Score:4, Insightful)
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This conversation is becoming quite mercurial.
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This Ceres of puns really Mars my enjoyment of this story.
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Check the Focus! (Score:3)
Did anyone think to point this thing at something on the ground and check the focus?
Because they didn't think to do that for the Hubble.
Re: Check the Focus! (Score:1)
You'd have to check the telescope's focus in free fall: surface telescopes are designed for 1g of gravitational force distorting the lenses - while space telescopes have to have perfect focus in zero gee.
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If the JWST can focus on something on the ground a few meters from it then I'm not sure that the focus is set correctly for when it's in space.
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What, point it at the ground and check focus before you send it into space? How do you propose doing that??
For Hubble someone forgot to account for change in shape of the lens due to gravity, because, you know, it's a complicated thing to make.
Why does everybody act like the stuff NASA does any moron can do? These are hard things to do, with complex engineering involved ... and often being done for the first time.
Holy Hell (Score:4, Insightful)
Alright, for all you Pedants out there...
"Check that the mistake made with the Hubble wasn't made with this one"
Better?
Now get a Margarita or something.
Re:Holy Hell (Score:5, Funny)
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Margarita is the cleaning lady who sweeps up after hours. He's recommending we all get one for ourselves. Capitalization is perfectly appropriate here. I think Pedants may be a brand of shoes.
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Now you're making sense.
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"Check that the mistake made with the Hubble wasn't made with this one"
We won't make the mistake we made with the Hubble. And we also won't make the mistake we made with the last big telescope, which was to try to build it in the US.
Re:Check the Focus! (Score:5, Informative)
For Hubble someone forgot to account for change in shape of the lens due to gravity
No, the problem was caused by one of Perkin-Elmer's testing devices having been assembled incorrectly.
https://en.wikipedia.org/wiki/... [wikipedia.org]
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Correct.
It's a well know fact for everyone who has had any curiosity in this regard and bothered to look it up.
Yet, people still say whatever nonsense comes up in their mind and then proclaim it as a fact.
Ah, well, that's slashdot for ya.
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No, they measured it with a fancy new laser-device, and based themselves on that to sharpen the mirror. And not on the two measurements of the old focus-determining device, which showed a discrepancy with it.
Alas, turned out tit was their fancy new toy that was calibrated wrongly, and not the other ones they always used. And THAT was why it went wrong.
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The problem with the Hubble mirror had nothing to do with gravity.
The custom precision null corrector used during the figuring step was assembled incorrectly. When the standard null correctors used for the initial grinding showed spherical aberration during final testing, they were ignored as being too inaccurate compared to the custom precision null corrector.
Re:Check the Focus! (Score:5, Interesting)
Quite a lot of speculative fiction in this thread. In point of fact the US (and Russia and ... probably others) had extensive experience with big telescopes in space pointed at the Earth by the time Hubble was launched. Heck Google maps satellite view can resolve cars in our driveway an a barbeque on our deck. It's a safe bet that the intelligence folk, now and then, could/can do better. Most likely lots better
(BTW, my understanding is that you need very complex adaptive optics to get clear views of small stuff on the surface from space. The optics correct for minor atmospheric issues. Same issues that make stars appear to twinkle.)
I didn't work on Hubble's optics (no one in their right mind would put me to work on optics) and it's not unlikely that I wouldn't be able to talk about exactly what went wrong even if I knew because of the probable overlap with highly classified stuff that is probably still classified. But I suspect it was probably a simple screwup. If you're interested in the official story -- which surely could be true -- see http://www.cio.com.au/article/... [cio.com.au] (Bottom line; a small procedural error during calibration resulted in the optical elements in Hubble being ever so slightly misaligned.)
Here's a link to two decade old intelligence photos leaked in 1997. http://fas.org/irp/imint/kh-12... [fas.org]
BTW since no one else is likely to mention it, the Webb observatory is about a decade late and 400% or so over budget. Moreover, it's not clear that its imaging in the visual spectrum will be much if any better than the big ground based telescopes like this one https://en.wikipedia.org/wiki/... [wikipedia.org] scheduled for about a decade from now. If nothing else the EELT is likely to be a good deal easier to tweak/repair/improve than a telescope meandering around hundreds of thousands of km from earth.
(The IR portion of the Webb device is clearly worthwhile although one might question if it is eight billion dollars worth of worthwhile).
I apologize for being grumpy. But I'm kind of tired of listening to hype, fiction and misrepresentation, and of folks continuing to buy into it.
I appear to be surrounded by slow learners.
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(BTW, my understanding is that you need very complex adaptive optics to get clear views of small stuff on the surface from space. The optics correct for minor atmospheric issues. Same issues that make stars appear to twinkle.)
Actually, the problem of atmospheric turbulence causing blur is not as bad looking at the Earth from space as it is the other way around. The biggest problem is rotating the large telescope required quickly enough to track what you're looking at. There's a great discussion of the problem here. [xkcd.com]
Re:Check the Focus! (Score:4, Insightful)
Their calibration involved a reference point for one of the lasers that had to be precisely positioned. This was done by having a rigid metal bar with a polished end, covered by a very black cap with a pinhole in it. The point on the end of the bar visible through the pinhole was meant to be the reference.
Unfortunately someone scratched the end of the cap a little and no one noticed. The shiny metal in one of the scratches got picked up as the reference instead of the pinhole. As a result it was too close to the mirror by the thickness of the cap (a millimeter or so). That was enough to lead them to carefully polish the mirror to slightly the wrong shape.
They did, I believe, ignore contradictory results from another basically much less accurate method of testing the mirror, since the laser was giving consistent results and was the superior method.
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Or at least point it at the Earth so we can disabuse rapper B.o.B. about the Earth being flat. Young man is struggling right now. Maybe a visual aid would help.
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Done:
http://www.ustream.tv/channel/... [ustream.tv]
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So the Earth IS flat?
I knew it.
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Peering billions of years into the visual past is more accurate. It's a huge assumption that we will " finally allow us to truly see the first stars, galaxies and quasars in the Universe".
* Makes a calendar event to buy Popcorn for the first imaging. *
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We can see our own galaxy, but not the article. Any alternatives out there?
fRO0ST MALAW1WARE (Score:5, Insightful)
Don't click the link. It's forbes. it won't work uunless you disable adblock, and if you do it'll install malware.
(It's Ethan, the goatblower with the shaved head and the beard, if you hadn't guessed)
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(It's Ethan, the goatblower with the shaved head and the beard, if you hadn't guessed)
I thought that was Brian "Booda" Cavalier. Which goatblower are we talking about?
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I am using adblock and it works fine for me.
StartsWithABang (Score:5, Informative)
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The introductory quotation in my physics thesis was the song's first verse... quite different from your "run of the mill" Goethe or Schiller quote that most folks used back in the day. ;-)
Site blocked - Forbes (Score:5, Insightful)
Why would you post a link to Forbes? It gives me some crap about disabling my ad-blocker (yeah, right) and not letting me see the content unless I do so. As far as I'm concerned it is the same as paywalled. Either find another source or don't post it. Oh, right, it's Timmy.
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Why do the editors allow Forbes links?
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It is StartsWithABang posting links to his blog at Forbes. He should be banned from Slashdot for the money grab.
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I mentioned this yesterday, but in case you didn't see the post: Chrome with AdBlock. Forbes lets you right on through.
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I guess they figure that all your private information already belongs to Google so they'll give you a pass.
Will this satellite need 'glasses' too? (Score:1)
Will this satellite need 'glasses' too? https://news.google.com/newspa... [google.com]
Not superseding Hubble (Score:5, Informative)
This is not entirely accurate. JWST is primarily infrared- it won't cover the full visible spectrum. Hubble will still be required to see anything below yellow/green wavelengths, including blue down through ultraviolet, where JWST can't see at all. It will certainly let us see farther, and through the dust, but it's not the be all end all of space telescopes.
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Considering that Hubble starts to get a bit aged now but still is very useful for visible spectrum imaging it would be sad if it was taken down. Unfortunately there are no shuttles operational anymore so a new vessel is needed if it's going to be serviced.
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A bit aged?
I googled "Hubble replacement" and found that the scientists themselves have apparently taken to naming their proposal for a next-gen optical spectrum telescope the Advanced Technology Large-Aperture Space Telescope, ATLAST.
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That's the information I was wondering about also (I can't read the article though, because it's hosted on Forbes and I'm not turning off ad blocking for them). But, Wikipedia says this:
The JWST will offer unprecedented resolution and sensitivity from long-wavelength (orange-red) visible light, through near-infrared to the mid-infrared
So it's orange and "longer", right? Isn't that one of the more useful ranges for looking at objects in space, though? I realize that the very small wavelengths are good for looking at specific things like neutron stars, but isn't infrared more useful for looking at some of the larger structures? What about planets, if we
the word oversight is its own opposite (Score:4, Funny)
The Future of Astronomy: NASA's James Webb Space Telescope
You know what they say: The James Webb Space Telescope is the future of astronomy, and it always will be.
Don't worry, natives will block it (Score:2)
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I think that will be the Lunites.
No, it will be the Luddites.
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The next news: "Hawaiian natives block the James Webb telescope because it desecrates the heavens".
But in space nobody can hear you protest.
In any case, by then Hawaii will have legalized pot and the anti-astronomy protests will have vanished. Trump won't even have to send tanks.
Help is Far (Score:1)
When I first saw an illustration of this thing, I thought, "WTF: it's a satellite dish on raft; those rocket scientists are projecting their vacation dreams". A lot of things have to go right in its deployment.
I wonder what happens if something goes wrong such as a jammed deployment? It's not in low-Earth-orbit like Hubble is, but further than even Apollo went.
Would they give up on it under that scenario? Scramble-rush the launch of a fix-it bot? They should start the planning now, because there's probably
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If anything happens to it then it's gone. We have no way to get to it to fix the telescope. Heck we can't even get to Hubble to fix that even if we wanted to.
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If it costs $1 billion to fix a new $10 billion machine, it seems worth it. Better to spend 11b and have it working than 10b with nothing.
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It's not a matter of money on whether or not to fix JWST (or even to repair the Hubble). We don't have the technology to any repairs. If the James Webb goes up an doesn't work then we can't go up there and fix it. We would have to create a new method to transport people, have them live for a mission, and provide a lock in order to transfer in and out of space. We are a long way from that.
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It depends on the nature of the problem. If a boom gets snagged, for example, it may just need a little nudge from the right angle.
I will agree that if say a system board or lens had to be replaced, then the R&D to prepare a bot for that would take a good while.
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They should start the planning now, because there's probably at least a 10% chance of deployment issues.
I highly doubt that. On their first try, NASA gently placed a chunk the size of a car on the surface of Mars after dangling it from a crane floating in the sky via rockets. I'm sure they can unfold the telescope.
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I'm frankly surprised the sky-crane thing worked as planned. It had a whole lotta critical steps. But, perhaps luck was also involved. Bleep happens.
You cannot test the entire thing under 100% real conditions.
Re: Help is Far (Score:2)
Skycranes are actually in many ways simpler than other landers. The engineering is easier and since you are not setting the weight of the fueltanks down the force on the payload is less so you need less shock absorbtion. Also any object that has tge bulk of its mass below its rest point will have perfect ballance. Skycranes at least partially gain that so you need less powerful reaction wheels and monopropellants so that saves weight and power. Thats just a few of the numerous ways they are a much easier te
on schedule? (Score:2)
I guess you could call it on schedule at the moment since they've slipped at least nine times since the project was announced in 1997. According to the initial schedule it should already have been in orbit almost nine years!
I guess that's "on schedule" for NASA.
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The future of slashdot (Score:5, Insightful)
There's only one article I'm interested in: How much is StartsWithABang paying Dice to constantly post every one of his damn blogs? We've got 2 in one day now. Is this a subscription service, or do you pay by the submission? Does it cost extra to hide the poster as an Anonymous Coward? Is the cost proportional to the amount of hate they get?
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by no means the first space-based observatory (Score:1)
Too much, too late? (Score:2)
For all it's worth - and I'm sure it will be a great telescope - one can not also look at the downside of it. It has been exorbitantly expensive. Originally estimated at 1 billion, and 5 years development, it will now clock at 8,8 billion (more than 8 TIMES as much, thus!) and 11 years later...
For sure, I do not agree with those who say to just scrap it, since it gobbles up all the money that other space-science projects could use - at least at this point. It has come this far, and we'd poured so much money
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You know, the logic behind your post sounds vaguely familiar [newsmax.com].
I wonder if Hanlon's Razor [wikipedia.org] is fundamentally wrong. Incompetence is the new malice.
Re: Too much, too late? (Score:2)
Yep. His post is pretty much a sunk cost fallacy. Which is perfectly sound logic for a business but not for science - and the reason why we need public funded science orgs like NASA where the budget is not the sole motivation.
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I'm not sure if you understood my post. It's meant to be a taken as indicating it has cost TOO much, and the money would well have been spend much better. If you're not agreeing to that, give arguments, not just some non-sequitur snapshot remarks and links that have nothing to do with the issue.
If, however, you are specifically taking out one element of my post, namely that I argue that one should have pulled the plug out long ago, and that now it's not a good idea anymore - feel free to argument why this w
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The argument that "we've spent too much not to finish now" is a sunk cost fallacy - it's a common thinking error that is generally terrible business. My argument was that it being terrible business is irrelevant, because the purpose of the excercise is not to make a profit - so the budget is not the primary concern, and that this is actually why public scientific organisations like NASA are so important.
Somebody has to do the science where we can't see any application - because much of that science ends up
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However, it's reasonable to ask oneself what the best bang for the bucks is. While the purpose might not be making a profit, budgets are never infinite, thus one can not deny cost IS important. The bang, in this case, is indeed not profit, but it is scientific return. But the same principle remains: couldn't one have gotten more scientific value out of the 8,8 billion that one poured into it? Since a lot is due to mismanagement, one can reasonably argue a lot of the budget was wasted. And whether that is a
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While there is some worth to that reasoning the problem is that we have no idea what the value of lost science may turn out to be. When Einstein wrote that obscure paper in 1929 he didn't win a nobel prize for it, it drew very little attention. Compared to relativity it was not exactly his best work... but the equation in that paper gave us the laser. How much technology has that made possible ? How many lives has that technology saved ? How much better to get lifesaving surgery from a modern laser scalpil
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Yes, I know what you're argumenting. But, on itself, that has little to do with wasting money on overhead and mismanagement. The problem with what you say is, that, even when taken at face value, it's indeterminable *in any case*. So, while it might be true, it has no argumentative value (in determining the best course of action).
Let me make this clear: you basically say, well, the 8 billion might be worth it, since you never know what you will get out off it. Very well, but for 2 billion you could have mad
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I'm not sure if you understood my post. It's meant to be a taken as indicating it has cost TOO much, and the money would well have been spend much better. If you're not agreeing to that, give arguments, not just some non-sequitur snapshot remarks and links that have nothing to do with the issue.
If, however, you are specifically taking out one element of my post, namely that I argue that one should have pulled the plug out long ago, and that now it's not a good idea anymore - feel free to argument why this w
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The *entire* spectrum???? (Score:2)
From 0 Hz to 6.2e34 Hz?
Somehow, I doubt that.
first launch date was 2007 (Score:2)
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No. How would they have built this without the experience from Hubble and its failures? This is a much more expensive and complex telescope, but it built on experience earned in the previous scopes.
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Yep, just like the world has pissed away TRILLIONS of dollars on all the lame, underpowered PCs made before 2000 or so, even though a cheap machine today is orders of magnitude faster. What a waste!