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NASA Space Science

How To Build a Telescope That Trumps Hubble 185

Posted by samzenpus
from the bigger-and-badder dept.
An anonymous reader writes "In cleanrooms around the country NASA and its contractors are building the James Webb Space Telescope, a marvel of engineering scheduled to launch in 2014. This gallery shows the features that will allow Webb to take the universe's baby pictures in infrared — most notably an 18-segment mirror and a 5-layer sunshield. I can't wait until Webb settles into its Lagrangian point way out beyond the moon and gets to work."
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How To Build a Telescope That Trumps Hubble

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  • So why do they thing that the universe isn't infinite? It seems that every time they get a bigger telescope the size of the universe gets bigger :\ Did they ever think that that big bang thing could have just been a localized event?

    • by dkleinsc (563838) on Wednesday February 16, 2011 @05:18PM (#35225016) Homepage

      Why do you think it is infinite, without any proof whatsoever? All evidence we have is that the observable universe is finite, and observations of the early universe (thanks to the finite speed of light) match what the Big Bang Theory predicted. Ergo, it's the best answer we've got right now, and the burden of proof is on those who have evidence to the contrary to produce it.

      Is it possible there's an unobservable universe outside of the observable universe? Of course. But you can't do science with it because it is simply impossible to observe.

      • Re: (Score:2, Insightful)

        by ubergeek65536 (862868)

        I have just as much proof that the universe is infinite as they do that it's not. That is to say exactly none. We will never be able to prove that it is infinite by measurement just and we will never be able to prove that it is finite. Like I said a hunch isn't exactly proof with either argument. A year ago the "universe" was about ten times smaller than it is now. Once the new telescope is functional I'm going to make the wild speculation that to will get bigger yet.

        • by bunratty (545641)
          I don't understand this idea you have that the amount of the universe we can observe is getting bigger. Since the 1960s, we've observed the cosmic background radiation. It's the thing farthest away we can observe, because before the cosmic background radiation became visible the universe was opaque. We have been able to resolve galaxies that are farther and farther away, but we knew that there was universe there. We just weren't able to see physical, gravitationally bound objects there before.
        • There is a *lot* of evidence the universe is finite. The further back/away we look we see younger and younger galaxies at a different stage of their evolution. They *look* different and match predictions.
      • by hedwards (940851)

        Actually, you're confounding the problem. The observable universe is always going to be finite until such a time as the observable universe and the universe are the same and the universe itself proves to have some sort of a limit in dimension.

        I don't personally like the idea of confusing mass and energy with the dimension of the universe as you don't measure mass or energy with meters. If you're able to do that without any other units of measure, then you might have a point, but as it is there isn't any goo

      • by msauve (701917)

        Why do you think it is infinite, without any proof whatsoever?

        It all boils down to definition. What is the size of the universe? Is it the extent of space which contains matter? light? That is finite, according to our current knowledge, but is usually called "the observable universe." Is there something which prevents it from growing infinitely (aside from gravity and the potential "big crash")? Observations show the observable universe is still expanding, and there is legitimate argument that growth can co

        • by Nemyst (1383049)

          You can count to infinity (though it would take an infinite amount of time). That doesn't mean you are infinite or the number you are counting is. In the same manner, the universe can be expanding forever without ever being infinite.

      • by lpq (583377)

        Then that is the fault of science.

        In all the infinity that that is -- whether that be endless nothing beyond our 'universe bubble' (but why it wouldn't be equally likely to be an endless series of self-contained universe bubbles, is beyond me).

        And that's where 'faith' can enter into science. Thinking that 'science' does anything other than predict conditions in the little speck of universe that we know about -- and nothing about the volumes beyond -- and that some people lean toward believing that our uni

    • by fishbowl (7759) on Wednesday February 16, 2011 @05:25PM (#35225080)

      Was space created by the Big Bang, or did the Big Bang happen inside of space that already existed?

      Observe something that is more distant in space-time than the big bang, and settle the matter!

      It is fine to speculate, but if you want coherent scientific models of the universe, you need to either assume the 13.7 billion light-year horizon or else show by observation or by theory that the horizon does not exist.

      The ideas of an infinite theoretical universe aren't incompatible with a finite observable universe, but people who build telescopes are going to be concerned exclusively with the practical aspects of the latter, even if they believe in the former.

      • by hedwards (940851)

        Precisely, it's pretty well established that we can't view all of the universe. Given the speed of light and that we're using light or various waves that travel at or near the speed of light, I think it's pretty inescapable that we aren't seeing everything. For all we know just outside our range of observation is a giant window in some sort of even larger department store display case. Sure it's incredibly unlikely, but beyond the range of what we can sense all sorts of weird things could be happening.

      • by pclminion (145572)

        Was space created by the Big Bang, or did the Big Bang happen inside of space that already existed?

        You ask it like it's some kind of unanswered question. Yes, space and time were created at the moment of the Big Bang. The question is HOW that happened.

      • by jandersen (462034)

        There's a lot of unclear and contentious issues at work here, I think; and unfortunately I don't know enough to gve an informed opinion on it all, but ...

        Was space created by the Big Bang, or did the Big Bang happen inside of space that already existed?

        Observe something that is more distant in space-time than the big bang, and settle the matter!

        "Space" is only a convenient mathematical model of reality - mathematically a space is loosely speaking a set with some topological structure. In all our current models "space" is assumed to be a pseudo-Riemannian manifold - more or less - and as far as I know, any such thing can be embedded in an Euclidean space of higher dimension; don't ask me about det

    • by Zorpheus (857617)
      We can not see further than 13.75 billion light years because this is the distance that the light has travelled since the universe has become transparent. This happened 300,000 years after the big bang.
      It does not really matter if it is infinite or not.
    • by bobs666 (146801)
      IMHO, Astronomers forget to use the word visible, when they say universe. Given the Universe is expanding stuff we can see is exiting the Visible Universe all the time. So the result is the Visible Universe is shrinking. And one day there will be noting to see when you look up into the night sky. So I an told on Astronomy.fm

      So if there another big bang overlapped our Visible Universe we might see a big corner of space blue shift. You can bet a lot of papers would get written about that.

      To defend Astro
      • by peragrin (659227)

        I actually want both. The hubble is awesome because it has multiple camera's and can view objects in multiple wave lengths.

        Infrared is good, ultraviolet is good, but you can't get some of the stunning images the Hubble has produced without some visible wavelengths as well.

        What was that comet? Levy 9 that hit jupiter years ago?? only the hubble got good images off of that. James webb won't be able to do such things. So we need both or even better, both in a binocular fashion. So we can see the same image

      • IMHO, Astronomers forget to use the word visible, when they say universe.

        I don't think they forget, I think they know it's redundant since traditionally "the Universe" (uppercase 'U') is everything, and "the universe" (lowercase 'u') is the visible universe.

    • by melikamp (631205)

      Did they ever think that that big bang thing could have just been a localized event?

      I am willing to bet money that they do (I am assuming you mean professional physicists). This guy [wikipedia.org], for example, thinks that bangs may be happening inside black holes, and new universes are created all the time, with parameters "inherited" from parent universes. This is almost an evolutionary interpretation of the largest-scale cosmology, with the parameters of our own universe being this way because other sets of parameters caused premature death (say, a big freeze) before new universes could be created. Th

    • by Chris Burke (6130)

      So why do they thing that the universe isn't infinite?

      Do you mean infinite in size, or infinite in age? Because the only implication of the summary or article is that the universe is finite in age. And there are pretty good theories with lots of observational support that suggest that the universe-as-we-know-it has a finite age.

      It seems that every time they get a bigger telescope the size of the universe gets bigger :\

      No, actually, that's not the case at all. Bigger telescopes have allowed us to see to points asymptotically approaching the theorized age of the universe, but it's been a long time since a bigger telescope has actually meant we had t

  • by Anonymous Coward on Wednesday February 16, 2011 @05:07PM (#35224918)

    Put a bad toupee on a telescope.

  • by Petersko (564140) on Wednesday February 16, 2011 @05:09PM (#35224952)
    The budget cuts announced by Obama include cutting $64 million from the James Webb Telescope program, "which an indendent group of experts "found to have a fundamentally broken estimate of cost and schedule". [cnn.com]

    While I recognize the U.S. is totally fucked, economically, this is a mistake. Throwing a minor budget item with huge potential like this under the bus in the name of pretending to become fiscally responsible is beyond short-sighted.
    • Re: (Score:3, Interesting)

      by DisownedSky (905171)
      A 64 million dollar cut isn't much at JWST's burn rate. It's not being thrown under the bus at all. In fact, it's eaten all the money intended for other, equally worthy space science mission. Realistically, it isn't going to launch until 2015 at the earliest (my money's on 2016) and will cost much more than it's current massive overrun.
    • Re: (Score:3, Funny)

      by dkleinsc (563838)

      While I recognize the U.S. is totally fucked, economically, this is a mistake. Throwing a minor budget item with huge potential like this under the bus in the name of pretending to become fiscally responsible is beyond short-sighted.

      The reason that's happened is that the US is totally fucked politically as well as economically.

    • by Big Smirk (692056)

      No problem. They'll just save that money by skipping a few focal length tests on the mirror.... Oh wait...

    • by hedwards (940851)

      That's what we call being "fiscally conservative." You sign off on massive debt for wars and other pointless silliness even as you cut funding to tiny projects that are likely to lead to prosperity in the future. To put it into perspective, anything that costs less than about $15b isn't worth obsessing a lot over. That's about $1 a week per person for the year, sure it adds up but we're not going broke on that. We're going broke on big budget items like the overspending on the DoD and welfare for billionair

      • You sign off on massive debt for wars and other pointless silliness even as you cut funding to tiny projects that are likely to lead to prosperity in the future.

        I'm really curious as to how the JWT is expected to "lead to prosperity in the future". Off the top of my head, I can't foresee anything meaningful to our standard of living coming from IR pictures of the early universe.

    • While I recognize the U.S. is totally fucked, economically

      The Federal government is kinda fucked fiscally (though not irrecoverably so), but the U.S. itself is pretty well-off economically. Our unemployment rate is "only" 9% and we have one of the highest median household incomes in the world. Parts of Asia may have lower unemployment at present, but you really need to have everyone working when you make $2000/year on a full-time income.

  • I think just having "one" Hubble space telescope was a mistake. I hope they're building more than one of these new 'scopes.

    I mean, it'd be a shame if a launch incident destroyed a unique capability. And it shouldn't cost anything like N times as much to build N of these at the same time, right?

    --PM

    • by Anonymous Coward on Wednesday February 16, 2011 @05:23PM (#35225058)

      Of course not - the thing is a few billion Dollars to build and not exactly cheap to launch either.

      In fact - if it does break, even if just in a minor way (e.g. the solar panels don't unfold because a space flea is jamming a gear), it's likely going to be a multi-billion dollar piece of space junk.
      Why? Because it's going to sit at the Lagrange 2 point when it goes operational. That's far, far further than we've put humans (way beyond the Moon), which so far have been the only instruments adapt enough to do repairs on satellites (such as the ones for Hubble).

      As it is, the James Webb Space Telescope is awesome - in infrared and -only- infrared. People suggesting it's a -replacement- for Hubble (IR, Visible, UV) are completely and utterly deluded.. or looking for additional grant money. They might as well claim it's a replacement for Chandra (X-Ray) as it's almost equally as idiotic.

    • by spacemandave (1231398) on Wednesday February 16, 2011 @05:48PM (#35225324)
      Actually, more than a dozen "Hubble space telescopes" were built and launched into orbit. The biggest differences are that they point at the Earth instead of away from it, and they are called KH-11 instead of HST. Oh, and their imagery data is mostly classified.
    • it shouldn't cost anything like N times as much to build N of these at the same time, right?

      It depends on how you calculate N.

      If you look at the total cost of the satellite (cost to procure the bird + the birds amortized share of the R&D program), then yes - N drops considerably. But that's not really an accurate method of accounting in this instance because you're performing the R&D no matter how many you build.

      If you define N as the opportunity cost (just the direct costs to procu

      • by mhajicek (1582795)
        But you have to develop the testing methodology and devices to inspect one, why not just run another unit through? Speaking as a manufacturer of medical device components I know from experience that the first part is where a huge percentage of the cost resides. Time and materials to machine a duplicate part once the programming, tooling, and inspection systems are set up and proven would be cheap. You can bet that they make spares (and certify them) for most components just in case something goes wrong a
        • I know from experience that the first part is where a huge percentage of the cost resides. Time and materials to machine a duplicate part once the programming, tooling, and inspection systems are set up and proven would be cheap.

          That's true to some extent, but you still have to test, verify, and QA the new part - and that's where the real costs are in manufacturing a spacecraft. And not only do you do that to each individual part, you do it to assemblies as they are built up, and then to units built of th

    • by arisvega (1414195)

      These things are insured. Yup, there is insurance for space missions- lots of money, but it pays back to have one.

      In the unlucky event of an accident, a significant amount of the cost will be returned- sure, they won't launch again on the next day, but it's far better than loosing the craft and the money.

      • They are certainly not insured. Commercial spacecraft are usually insured, but not government.

    • by skoda (211470)

      They're not. Just the one.

    • For this level of instrumentation, there are no economies of scale. Its why good optics are expensive even for terrestrial applications and with lots of competition. making stuff accurate to +-50nm or so over a large area is expensive.
  • JWST is great and I'm glad their building it. Prior to canceling Constellation, NASA was investigating this:
    http://www.youtube.com/watch?v=2YsNvpVSzbI [youtube.com]

    It wasn't all about space cowboys. In terms of cosmology, if this had been only thing Ares V had ever accomplished it would have been worth every cent.

    Maybe China will get there.

  • by PineGreen (446635) on Wednesday February 16, 2011 @05:18PM (#35225018) Homepage

    As a professional astronomer I hoped this thing would never have happened. It costs 6 billion and at this price tag a 5% overrun is $300 million, about six times the cost of the entire SDSS project, which has undoubtedly gave us more science that James Webb ever will. True, Hubble and JWST make great pictures, function as amazing PR machines, but most science at the end of the day comes from survey imaging and spectroscopic observations.

    • by JoeMerchant (803320) on Wednesday February 16, 2011 @05:32PM (#35225180)

      SDSS was good science, making great use of relatively humble tools. But, it takes an ecosystem - and heavyweight instruments like the Webb, or the LHC, will illuminate things that can later be confirmed with the broader toolset of more pedestrian instruments, things that would just be considered a wild theory unless they came with backing from observations on an instrument like the Webb.

      You also need to face up to the reality that if the Webb were scrapped at inception, it wouldn't have meant $6B extra would have been supplied to general astronomy, only a small fraction of that money would have made its way around the community.

    • by melikamp (631205)
      I totally believe you when you say that surveys provide more and better scientific data, but as a tax-payer I am thrilled with HST's performance, and I could hardly be happier about this wealth of data [hubblesite.org], which is useful to everyone, professionals and amateurs alike. The only thing I dislike about JWST is that we cannot service it, as so we miss an opportunity to launch more people into space. You guys could turn the surveys into PR machines too, you know. In KStars, for example, there are shortcuts to downlo
    • $6.5B versus $3.5B. Much of that cost overrun is from being years late.
    • by DerekLyons (302214) <fairwater AT gmail DOT com> on Wednesday February 16, 2011 @07:59PM (#35226664) Homepage

      As a professional astronomer I hoped this thing would never have happened. It costs 6 billion and at this price tag a 5% overrun is $300 million, about six times the cost of the entire SDSS project, which has undoubtedly gave us more science that James Webb ever will.

      Science isn't something you can measure by how many buckets you collect. Not all buckets have the same value.
       

      True, Hubble and JWST make great pictures, function as amazing PR machines, but most science at the end of the day comes from survey imaging and spectroscopic observations.

      If you honestly believe that all Hubble and JWST are doing or will do is collect pretty pictures, you're either hopelessly ignorant or hopelessly biased. But ff you want to talk spectroscopy - consider that four of the Hubble five main instruments are dedicated to spectroscopy, and two of JWST's three main instruments are so dedicated. If you want to talk surveys... Check out Hubble's schedule from Feb 14, 2011 [stsci.edu], or January 29, 2011 [stsci.edu] for some recent survey campaigns that Hubble is participating in.

    • by skoda (211470)

      JWST has spectroscopy e.g. NIRSPec = Near Infra-Red Spectrophotometer.

      The JWST is more about massive light gathering (seeing closer to the dawn of the universe than ever before) than pretty visible-light images.

  • by Just_Say_Duhhh (1318603) on Wednesday February 16, 2011 @05:22PM (#35225044)

    Not that I'm expecting some catastrophic screw-up on the scale of the Hubble, but if there is a problem with the JWST, once it is sitting out at the Earth-sun L2, we won't be able to go visit it and repair it. I haven't heard of any contingency to allow it to come back to earth, so they've really got one shot to get it right.

    I'm hoping everything is nominal.

    • Hubble didn't work out of the box. From the moment it was deployed there was a spacewalk to unfold one of it's solar panels. Then there was a famous 'set of glasses' fix to it's optics. There have been hardware upgrades and gyroscope fixes.

      It takes only one small glitch for this to be an expensive piece of space junk. It would kill any future space telescope in the process.

      • Surely there's a progressive plan in place to test it out in low earth orbit before launching to L2? Make sure it works before sending it beyond our reach. Seems a bit of extra time and effort on that part would be good insurance on a $6B project.
        • by skoda (211470)

          No. Not in the sense that it would sit in Hubble-type orbit for a year while it's tested, and astronauts go to turn wrenches and adjust things that aren't right. And yes, I suspect that would much more than "a bit of extra time and effort." It's probably completely at odds to being launched to L2, and would be an incredible cost and complexity adder.

          But it has pre-flight testing and a lengthy in-space verification process as it reaches L2.

    • by skoda (211470)

      Actuated primary mirror segments, actuated secondary mirror, and a wavefront sensor system enable it to self-align. While it's much more complicated, and unreachable for servicing, it's also much more flexible for on-orbit self corrections.

    • by rcw-home (122017)
      Yes there is. Build and launch another one. It should be a heck of a lot cheaper the second time around - most of the money for these things does not pay for the parts.
  • by Hatta (162192)

    They've got a lot of nice telescopes out there. Haw haw haw haw.

  • The real future of telescopes will have no mirrors.

    I'm not sure why no one has made a big deal out of this, but superconducting cameras have the potential to completely replace mirrors in telescopes, making them more robust and essentially eliminating complex alignment.

    Why do I say this? Well, I reasoned this out myself, so maybe I'm wrong, but basically superconducting cameras are able to register every photon that sees them, sending off ~18000 electrons per photon hit. CCDs, on the other hand, send off 1

    • by blincoln (592401)

      Even with the most sensitive detector possible, you still need a lens to focus the image. Otherwise you've just got a very fancy flatbed scanner, and everything further away than a couple of inches will be a useless blur.

      The lens can be virtual, like in synthetic aperture systems, but building something like that for optical wavelengths with literally *no* physical lenses involved (whether those lenses are glass, mirrors, or whatever) on a football-field-sized scale would be challenging at best. Each photos

      • Even with the most sensitive detector possible, you still need a lens to focus the image. Otherwise you've just got a very fancy flatbed scanner, and everything further away than a couple of inches will be a useless blur.

        The lens can be virtual, like in synthetic aperture systems, but building something like that for optical wavelengths with literally *no* physical lenses involved (whether those lenses are glass, mirrors, or whatever) on a football-field-sized scale would be challenging at best. Each photosite on each of your supercooled sensors would need to capture phase information as well as amplitude. The system would also have to store timestamps for each pixel with atomic clock-level accuracy in order to use the phase information. I think some day, the human race will build something like that, but it's probably going to be awhile.

        Ah. Yeah, I was wondering about optics.

        Well, it would still allow much smaller mirrors to be used, right? So something like a (relatively cheap) 30" mirror with an S-CAM sensor would be able to outperform a much larger telescope with a CCD?

        Even if there are optics involved, making the sensor 18000 times more sensitive seems like it would be immensely more helpful than just making bigger optics.

        • by ogre7299 (229737)

          You still have to contend with the diffraction limit though, 100% efficiency be damned if you can't resolve anything. Also, CCDs are not as ineffecient as you are purporting them to be; they are as efficient as ~90% at some wavelengths (http://www.astronomy.ohio-state.edu/MDM/MDM4K/qe.jpg); therefore, getting 100% effeciency is not going to increase your signal as significantly as you seem to think.

          • by ogre7299 (229737)

            I missed a point here, you seemed to be implying using these for optical interferometry. However, we cannot currently digitize an optical signal and current optical interferometers use analog methods to create interference fringes. At radio wavelengths we can simply downconvert the signal so something more manageable and then calculate the antenna-antenna the interference.

        • by Laser Dan (707106)

          Well, it would still allow much smaller mirrors to be used, right? So something like a (relatively cheap) 30" mirror with an S-CAM sensor would be able to outperform a much larger telescope with a CCD?

          Even if there are optics involved, making the sensor 18000 times more sensitive seems like it would be immensely more helpful than just making bigger optics.

          You need a lens/mirror to focus, but the reason they have to be so big is to collect more light. The problem is not so much that the CCD doesn't detect all of the photons, but that there aren't many photons to detect in the first place! A sensor 18000 times more sensitive can still only detect photons that arrive.

          The objects being imaged are reeeally far away, so you want to collect light from as large an area as possible to reduce the exposure time you need. A quick google says that some hubble exposures a

    • A camera needs the light to be focused. You either need a glass lens or a mirror. Without the focus you just get an omnidirectional light detector but no picture.
    • by skoda (211470)

      That's not how optics work. You need to image what you want to see onto your detector.

      To test this: remove the lens from your DSLR and take a photo. You'll get nothing but blur.

      • That's not how optics work. You need to image what you want to see onto your detector.

        To test this: remove the lens from your DSLR and take a photo. You'll get nothing but blur.

        Yeah I was wondering about that. Some of the other replies cleared that up earlier.

        I still imagine that investing in those sensors would have a great payoff.

  • Building one is the easy part, launching it into orbit is another matter entirely.

  • Seems like a natural gravity pit wouldn't be the best place to hang out.

    • by AikonMGB (1013995)

      L1, L2, and L3 are not stable (if you stick a rock there, it will fall away in "no time"). JWST is going to be placed at L2 (though it will move around a bit in a halo orbit). Only L4 and L5 are stable.

      Aikon-

    • It's my understanding that only L4 and L5 are actually gravitational minima. The other LaGrange points are actually saddles. This means that the point itself isn't stable, but stable orbits around the point do exist.

    • by codegen (103601)
      Its not going to be at the actual L2 point, it is going to orbit the L2 point. True, other objects may also be orbiting the L2 point, but its a little less crowded staying slightly away.
    • by rcw-home (122017)

      The L2 point (which is where JWST is headed) isn't a gravity pit - it's a gravity hill. It's a long-term unstable orbit, but it takes minimal delta-V to stay put there with active correction.

      L4 and L5 (60 degrees ahead and behind the orbit of the lighter-mass object) are the gravity pits, and lots of miscellaneous stuff does collect there. But even then, it's still nearly empty space and whatever has collected there isn't moving fast relative to you.

  • by Lemmy Caution (8378) on Wednesday February 16, 2011 @07:12PM (#35226184) Homepage

    OK, I have no productive contribution here, but the phrases "Hubble trumping" and "trouble humping" are now echoing through my head.

  • I've been lucky enough to have had a peek inside one of the cases (as it was being built and having the kinks ironed out) they're going to use to transport the reflector sail things from the manufacturer to the assembly plant, one case per sail. My friend is the shop's computer guy. The case was enormous and had to be perfectly air tight so it could be filled with nitrogen to protect the sail during transport. I saw it in July so I'm pretty sure they've finished and shipped them all by now.

    Granted, it wasn'

  • When astro images are made with reflecting telescopes, diffraction spikes [wikipedia.org] around bright stars can usually be seen at 0, 90, 180 and 270 degrees. Sometimes they are rotates a bit, but most of us are so used to seeing these little crosses, that artists often add them in their renditions of star fields.

    This won't be the case with the James Webb Space Telescope, however. Once it begins operations, we're going to have to get used to seeing diffraction spikes around stars in the images it sends back to us at s
  • If you want a comparaison with hubble go there : http://www.jwst.nasa.gov/comparison.html [nasa.gov]

  • That naming the telescope after a NASA administrator is possibly the lamest thing they could have done?

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