Hubble versus Webb

By Phil Plait | June 15, 2010 2:24 pm

Hubble is an awesome ‘scope, but its life is limited. Heavy and huge, there’s no way to bring it back, and with the Shuttle retiring there’s no easy way to get to it. Eventually its gyros will fail, it won’t be able to be pointed, and then that’s that.

For the past few years, NASA has been working on the James Webb Space Telescope, what some people call Hubble’s "replacement", which is a misnomer: it’s actually Hubble’s successor. It will do amazing astronomy too, but it has different capabilities than its predecessor.

How different, you ask? I’m glad you did, and so is NASA: they’ve put together a side-by-side comparison of the two observatories (warning huge Flash animation stuff).

Just how different are they? Check out the comparison of their mirrors:

hst_vs_jwst

Hmmm, the woman in the diagram is pretty tall, 1.8 meters — 6 feet! Of course, she’s in heels. But should she really have her hand on that priceless (if incorrectly ground) mirror?

Anyway, check out the comparison. I’ll miss Hubble when it goes, but I’m very excited about what JWST will do for astronomy, for science, and for humanity’s search for understanding. It will be a powerful, powerful tool.

CATEGORIZED UNDER: Astronomy, Cool stuff, NASA

Comments (68)

Links to this Post

  1. Looking back… « Communion Of Dreams | June 17, 2010
  1. Adrian Lopez

    “Heavy and huge, there’s no way to bring it back…”

    Will Hubble remain in orbit forever, even after it’s stopped working?

    I remember the Hubble being offered for a huge chunk of change by telescopes.com, with ownership to be transferred after the end of its service. I don’t think anybody ever bought it.

  2. Doesnt the mirror on the JWST fold out to full size once in space?

  3. AFAIK, Hubble is in low earth orbit so it should be subject to SOME minimal drag and thus it won’t be orbiting forever, literally speaking. But how “fast” it’s orbit will decay, I cannot say. My personal guess is it will take ages before it hits the atmosphere (can a guess be more vague than that?). Of course, the Kessler syndrome might be a reality (heaven forbid though) and if that happens, it would come down a little sooner.

    Regarding James Webb telescope, YES I’m looking forward to view the pictures it takes of our solar system, the galaxy and the rest of the universe.

    Imagine the images of the center of the Milky way that will be brought to us!

  4. Craig

    Am I the only one who thinks that this telescope is not the best suited tribute to James Webb and vice versa?

    Webb was an excellent administrator during the pioneer days of human spaceflight. He wasn’t particularly notable for his scientific contribution. I would think that the tools we use to learn more about the Cosmos should be named after astronomers that have pioneered that effort.

    I’d have thought it a much more appropriate tribute to name a future lander/rover after Webb than after a device which ‘only’ stares at the heavens.

    It’s sort of the difference between Astronautics/Astronomy. The two overlap, and both tell us about our universe, but they are different.

  5. Mchl

    AFAIR Webb will be orbiting one of Earth-Sun lagrangian points (I forgot the actual number, so I’ll spare myself embarassment) which is also pretty cool in itself (pun not intended).

    Do we already know what booster will be used to place it there? Ares V was rumored, but since it won’t be, a Delta IV is likely I think…

  6. Kevin F.

    HUBBLE VS WEBB IN TELESCOPE SMACKDOWN ON SUNDAY-SUNDAY-SUNDAY!!!!!!!

  7. crf

    The Americans decided to name it after Webb, even though they are not the only nation paying for the telescope, and afaik, didn’t ask anybody else when they did so.

    Who it is named for shouldn’t affect how it works … but it doesn’t help. It certainly can’t do anything to help cooperation on future projects though.

  8. Since we are on the topic of space telescopes, Dennis Overbye of the NYT, most recent column discusses the witholding release of data by NASA, In the Hunt for Planets, Who Owns the Data?. I am curious to know what your take on this subject is Phil.

    I myself have some ethical concerns about the witholding of raw data on publicly funded space astronomy missions simply to preserve the reputations of a few scientists. Seems to me the more people looking at the data, the better the opportunities for discoveries and the better the science.

  9. John Baxter

    I seem to remember that the last shuttle mission to Hubble attached one or more fittings such that an orbiting remotely operated vehicle could attach and do a planned deorbit when the time comes. Am I dreaming?

  10. JohnK

    John Baxter you are NOT dreaming. Here’s a NASA link, with a nice photo, explaining what’s going on.

    http://www.nasa.gov/mission_pages/hubble/servicing/SM4/main/SCRS_FS_HTML.html

  11. Jamey

    The primary reason to call it a “successor”, and not a “replacement”, would be that it doesn’t even look in the same region of the spectrum. It’s like saying a heat lamp is a good replacement for that blacklight you were using to light up your rave.

  12. Astrofiend

    “1. Adrian Lopez Says:
    June 15th, 2010 at 2:31 pm

    “Will Hubble remain in orbit forever, even after it’s stopped working?”

    Nope – the Hubble will be intentionally de-orbited once it can no longer be pointed, and will burn up in the atmosphere over the ocean. As part of the previous service operations, the astronauts attached a de-orbiting grapple point that a robotic or other craft could latch onto to maneuver it for this purpose.

    The main reason that NASA need to do this is that without attitude control or the ability to boost Hubble into higher orbits, atmosphereic drag (there is a still an exceedingly thin atmosphere at the altitude of Hubble’s orbit) will eventually bring Hubble crashing down to Earth, but not in a way NASA can control. Since modeling suggests that at least part of Hubble’s large primary will survive re-entry intact, the risk of a completely uncontrolled reentry is unacceptable since there is a small chance that it could occur over a densely populated area. Far better to be able to guide it into a re-entry over the pacific or something. Hubble’s failure should be at least 7-10 years away though.

    Bring on JWST!

  13. So let’s keep a couple of Shuttles in good repair and when the time comes, go get Hubble and bring it home. It deserves better than to burn up like a used booster stage.

  14. Chief

    re: bring hubble back home in shuttle.

    Sounds good but why not spend the billion or so it would take to get it on a better space telescope to aid the ones already planed and in use. There are a lot of frequencies that we still would like to cover to get answers that the current research presents.

  15. Josh

    Wow not only a tall girl but without the disclaimer on the NASA site I don’t know that I’d understand the the HST is not as big as the moon

  16. Astrofiend

    13. Comrade E.B. Misfit Says:
    June 15th, 2010 at 5:52 pm

    I too agree that it would be very nice to have Hubble sitting in a museum – it does seem a shame that the greatest scientific instrument of all time burns up, and that such an important primary mirror ends up sitting on the bottom of the ocean somewhere.

    However, as Chief said, in the end I think that the money is better spent on new instruments to show us more. In the end, Hubble’s greatness lies in the science it has provided us with; it would be a shame to forgo further opportunity to extend that legacy due to sentimentality…

  17. AJKamper

    Okay, so here’s what I don’t understand: if the Webbscope is primarily an infrared scope, what capabilities will we be losing by not actually replacing our visual-light scope? SHouldn’t we have some sort of replacement for Hubble as well?

    Or do the new ground-based telescopes in the ATacama do that job adequately now?

  18. Trebuchet

    I’m with Comrade E.B –I’d gladly pay a bit more in taxes to keep a couple of shuttles going, just to service the Hubble. It’s done a lot for mankind — we can spend a few more bucks to keep it going. Not that there aren’t other uses for a couple of shuttles, as well.

  19. Wikipedia describes the L2 point as:

    On the side of the Earth away from the Sun, the orbital period of an object would normally be greater than that of the Earth. The extra pull of the Earth’s gravity decreases the orbital period of the object, and at the L2 point that orbital period becomes equal to the Earth’s.

    My question is: is this also the point, similar to geosynchronous orbit, but instead where it “orbits” the Earth with an orbital period equal to 1 Earth year?

  20. You could store a lot of movies on that DVD.

    Anyway, please excuse me while I go satisfy my sudden honey craving.

  21. Charon

    JWST has no UV capabilities, which makes me very, very sad. When HST goes, so does UV astronomy, for 10-20 years. (Oh, maybe WSO-UV will launch. Possibly in 2007, according to what one project website still says, although inventing a time machine will really jack up the cost. But it might not launch. And it’s small. And the US isn’t participating.)

  22. Charon

    @18 KenB: no, it’s not really orbiting the Earth at all. It’s orbiting the Sun. The change in period comes from the pull of both the Sun and the Earth, whereas geosynchronous orbits just come from the pull of one body (the Earth) and match the Earth’s rotation simply because the orbital speed falls off with distance.

  23. Messier Tidy Upper

    Hmmm, the woman in the diagram is pretty tall, 1.8 meters — 6 feet! Of course, she’s in heels. But should she really have her hand on that priceless (if incorrectly ground) mirror?

    She’s pretty strong too holding that big mirror up all by herself! ;-)

    Did NASA hire a female basketballer for that portrait I wonder? ;-)

    @ 13. Comrade E.B. Misfit Says:

    So let’s keep a couple of Shuttles in good repair and when the time comes, go get Hubble and bring it home. It deserves better than to burn up like a used booster stage.

    I’ll second that suggestion – even thought I know it probably isn’t possible and certainly is very unlikely to happen. :-(

    @18. Trebuchet Says:

    I’m with Comrade E.B –I’d gladly pay a bit more in taxes to keep a couple of shuttles going, just to service the Hubble.

    Not an American but an Aussie so my taxes will never help here but if there was a legitimate “Save Hubble” fund I’d gladly donate. ;-)

    That is a cause I believe in – destroying it seems like a travesty to me. :-(

    The Hubble Space observatory does deserve better – even if we just boost the Hubble into a higher orbit where it can stay up for centuries out of the way.

    I’ll miss Hubble & I’ll miss the shuttles, I wish we could keep both going forever. We can’t but I wish we could.

    I’m sure the Webb telescope will do well & be great too. Personally, I think they named it just for the puns that will no doubt ensue! ;-)

    @ 20. Naked Bunny with a Whip : No worries. You’re excused! ;-)

  24. jcm

    “Hubble is an awesome ’scope, but its life is limited. Heavy and huge, there’s no way to bring it back, and with the Shuttle retiring there’s no easy way to get to it. Eventually its gyros will fail, it won’t be able to be pointed, and then that’s that.”

    I suppose that Hubble (HST) will eventually just become part of the space junk.

  25. Dave

    HST is not an American treasure; it’s an international and historically timeless treasure. And as such — impractical and costly as it may be — it would be nice to save it. Humans have built museums honoring people who play games for a living, yet an instrument that gives us the Universe and reveals the Universe’s truth will perish, largely with societal apathy.

    Such inaction only adds to the unfolding tragedy that is humanity.

    But life goes on. Can’t wait for the Webb.

  26. DaveS

    Think about the 20 year mission history of the Hubble. Big mistake, discovered after launch, fixed by manned mission. Fix after fix, improvements, new experiments, refurbishments, always keeping it relevant. All because it is in low earth orbit, and reachable by the Shuttle.

    Now think about the JWST. Once it launches, that’s it. No fixes, no new experiments. No manned fix-it missions. Maybe robotic fix-it missions, less capable than manned missions, but then, probably not, unless there’s a real disaster.

    Think about what the HST is doing now, that the original designers never thought of, or didn’t have technology to implement. No wonder the JWST only has a mission profile of 5 to 10 years. It’ll be obsolete and irreparably broken after that.

  27. reidh

    Hope they don’t crash it like they do every other one they launch

  28. To be pedantic: in a true astronomical view, the JWST is actually quite a bit smaller than the JST. Hubble works at wavelengths of about 5*10^-7 meters whereas Webb works at around 10^-5 metres. That is a factor of 20 longer with a mirror less than 3 times the diameter. So the resolution is 8 times worse.

  29. greg

    Can’t wait to see what kind of pics this thing will produce, I wonder if it has the necessary resolution to see the lunar landing sites of the Apollo missions so it can shut up those annoying deniers.
    On a side note, I understood the figures about the wavelength, but how big is the telescope again, because all I got was some feet, yards, cubits and hogshead. No even the school-bus comparison wasn’t enough, since I’m not familiar with American school-buses. Maybe they should have used Texas for comparison, I already thought it was a standard measure unit as all those movies have taught me.

  30. Jess Tauber

    If it comes down on land ebay will have auctions for the mirror shards- some bright boy will melt these together and fashion his own ATM’ed optics. I’ve thought of doing this myself for tektite glass and for olivine crystals from meteors (but the latter have caught on as ‘space jewels’ and former junk from cutting is now too expensive…drats!).

    You know, the Hubble mirror DOES have a big hole (not ho…) in the center, big enough for the lovely lady to pop through. We could knot a long rope through it and tie the other end around the moon’s circumference. That should keep it from falling. Diamond cables!

    Graphene mirrors are going to make these chunky clunkers look like dinosaurs someday- you could fold up one as big as a US state into a package a few meters on a side.

  31. Grand Lunar

    I can only imagine what the Webb might see at the galactic center. I say make THAT the prime target area first. Should be cool!

    Does anyone know if Webb might also be turned toward one of the planets in our solar system? Like how Hubble does once in a while?

  32. #17 AJKamper:
    Yes, in visible light, many ground-based telescopes can now do a better job than Hubble. 20+ years ago, the primary reason for putting a visible light telescope in orbit was to enable it to operate at the theoretical limit of its mirror’s resolving power; for a ground-based telescope, this was never possible, due to the blurring effect of the atmosphere. So even telescopes far bigger than Hubble couldn’t match its resolution.
    Today, we have adaptive optics – systems which measure atmospheric blurring every few milliseconds, and induce opposite tiny distortions in the optics to compensate. This enables telescopes to achieve a resolution close to their theoretical limit. So they can now equal, and far exceed, the resolution of Hubble, at a fraction of the cost.
    That’s all for visible light; unfortunately, we’ll lose Hubble’s capabilities in the ultraviolet.
    For infrared wavelengths which are blocked by the atmosphere, we still need telescopes in space – hence the JWST.

  33. Nigel Depledge

    So, to bring NASA into the 21st century…

    Hubble’s mirror has a diameter of about 2.4 m, with a collecting area of approx 4.5 m2.

    JWST will have a mirror with a diameter of approx 6.4 m and a collecting area in the vicinity of 31 m2.

  34. Nigel Depledge

    The BA said:

    Hmmm, the woman in the diagram is pretty tall, 1.8 meters — 6 feet! Of course, she’s in heels. But should she really have her hand on that priceless (if incorrectly ground) mirror?

    Never mind that. What the frak is she breathing?!?

  35. Just me

    @6 Kevin F.

    I was thinking “Celebrity Deathmatch”. :D

  36. Jasper

    Actually in the Netherlands the average height of young women is about 1.7 m, so that 1.8 m is not that uncommen here..

  37. Ray

    Wouldn’t the “de-orbit grappler” be equally capable of being used as a “get back to higher orbit grappler” if we attahced a booster rocket to the Hubble?

    I get that Hubblle’s orbit will decay, but why don’t we just boost the silly thing higher? Don’t we have the smarts to do that?

    What is Hubble’s useful lifespan? If its 5 years longer than its orbit will last, why not try to boost it higher?

  38. Gary Miles #8: Phil has addressed this issue before, although I can’t find the exact post. Astronomers work very hard to get time on Kepler, the HST, or any other platform. They have to submit multiple proposals and so forth, and when they finally get their data, they get exclusive use of it for a year so that other astronomers with, say, more computer time to process the data more quickly can’t “scoop” them. A year of exclusivity is perfectly reasonable, and if they need a little more time due to unforseen delays, so be it.

    I see where you’re coming from though. I am highly critical of the government withholding information from its employers (us) in the guise of so-called “national security”. I think permanent or semi-permanent government secrecy is antithetical to democracy. But in any case, I think a year is a reasonable amount of time to hold research data obtained through a public platform before it is made public.

  39. VJBinCT

    Back in 1968 or so, I was observing as a grad student at LIck on the 120 incher when Werner von Braun came to visit. He was a very likeable guy (Tom Lehrer’s song not withstanding), and we spent the night talking about telescopes and lunar insertion orbits, etc. He was there to look into the feasibility of orbiting a big telescope, and the kitchen folks there on Mt Hamilton were afraid he was going to cart the telescope away and tie it to a rocket. I remember one of the kitschy plaques inside the dining hall next to the door: ‘I’m not a fast cook. I’m not a slow cook. I’m a half-fast cook.’ It was a nice place to visit. BTW, does anybody else recall that the 120 inch mirror was a test blank for the 200 inch Palomar telescope? It was a bit thin so the focal length is on the high side. The spectrograph at the coude focus was absolutely awesome. I was told that a grad student some years before had put a fingerprint on one of the 12-inch original gratings, and subsequently was beheaded. Pour encourager des autres, I suppose. This may not actually be true. Halcyon days.

  40. A few weeks ago I took my family to the New York Science Festival. There was a mock-up of the JWST in Battery Park. One of the people from the STSI was answering questions, and, when I mentioned that I was a regular BA reader and rare commenter, she lit up like a solar flare. Seems I said the magic word or something. She is an old friend of Phil’s. One question that I neglected to asked was whether the JWST would become a new star at night, since it will be orbiting at the L2 LaGrange point, which is directly opposite of the Sun from earth.

  41. Carey #39 For typical ground based astronomy research where a university or organization is paying for the astronomer’s time or research, I would certainly agree that astronomer should be able to keep their data proprietary for at least a year to prevent others from scooping their research. However, the Kepler mission is funded by the American taxpayers through NASA and is not being paid for through private research or university funds. Also, unlike HST, the Kepler telescope is focused on a very specific area of the sky and nowhere else, so the data is being collected continously day and night on the same locations. So as the article points out, why should the Kepler mission astronomers have exclusive rights to this data? Especially since their sponsoring universities are not paying for it. And some of the astronomers are direct NASA employees. The status quo of university funded research should not apply here.

  42. Matt T

    So…. dumb question, but is there any reason HST can’t still be used, even though it’s not being maintained? Even after the gyros go, could it not still record images of whatever the heck it’s pointing at? ( IIRC, there have been some very nice “accidental” Hubble discoveries.) Or are the exposures too long that it just can’t get an image without the gyros?

    I’m probably just naive, but it seems like that would be a nice way for Hubble to rage against the dying of the light.

  43. #41 Gary: Maybe it’s different in astronomy and physics, but most biomedical research is funded by the federal government — NIH, NSF, etc. — not university grants.

  44. Blake

    @5 The plan is to launch it on an Ariane V ECA , IIRC.

  45. Amadan

    The best memorial to HST is the data it has collected. The money it would cost to salvage or maintain it would be much better used for further and better research.

    It’s a machine, fercryinoutloud. It’ll make a cool meteor.

  46. T_U_T

    Wouldn’t the “de-orbit grappler” be equally capable of being used as a “get back to higher orbit grappler” if we attahced a booster rocket to the Hubble?

    What about an attach-an-ion-thruster-and-drag-it-all-the-way-to-ISS grappler ?

  47. J.J.

    @43. Martin, most research grants in the U.S. are provided by federal agencies, astronomy and physics included.

  48. Chris A.

    FWIW, shortly after HST was launched in 1990 (near solar maximum, which causes the Earth’s atmosphere to swell a bit), it was falling out of orbit at a rate of approximately 1 km/month.

    When the astronauts for the first servicing mission came to STScI, one of the staff asked them if it wouldn’t be possible to boost the telescope a bit higher than they were planning to. Their response was: “Yes, but we’d like to come home.” (Hubble’s orbit is the highest the shuttle has ever flown.)

    @42 Matt T.:
    “…is there any reason HST can’t still be used…after the gyros go…still record(ing) images of whatever the heck it’s pointing at?”

    Without pointing control, you might drift too close to pointing at the Moon, Earth, or Sun, all of which can damage/destroy instruments. And that’s not an improbable thing–each has a pretty large avoidance angle. Keeping the high gain antennae pointed at TDRS satellites to relay data’s going to be tough, too. Plus, you can’t keep the solar panels pointed at the Sun, and there goes your electrical power.

    You might be able to do some crude station keeping with the reaction wheel assembly, but maintaining pointing on a target long enough for anything but the shortest of exposures is not going to be feasible.

  49. Marc

    To those wondering about the fate of the Hubble, and why it’s not planned to go to a museum:

    The original plan WAS for the Hubble to be brought back by one of the STS shuttles. A deal had been worked out with the Smithsonian to do just that. This was back in the naive days when the STS was going to be our one and only ‘national’ launch system, and launches were going to be so frequent (and therefore so inexpensive) that even commerical satellites would be sent aloft by shuttle orbiter. Which actually happened a few times, early on.

    Then two things happened:

    1) The real cost of a shuttle launch became apparent, and so the real cost of bringing the HST down became apparent. The Reagan era was waning, and the belt-tightening began. HST would only come down if the Smithsonian was willing to pay for the mission – something they’d never have the budget to do.

    2) Challenger. The loss of Challenger pretty much put an end to any thoughts of using the STS as the “space truck” it was originally envisioned to be. No more commercial launches – it’s not worth the risk to astronaut’s lives to put another comsat up. Once the commercial missions dropped out, any thought of enough flight rate to significantly affect the cost of launches went out the window, too, putting the final nail in the coffin for bringing the HST home.

    Which, frankly, is a huge shame from my perspective. Not only is the HST a simply monumental historical artifact, but it’s also the longest long-duration spaceflight experiment ever performed. It’s been up for years. The study of the impact of long-duration exposure to the LEO/MEO environment by looking at the parts of Hubble still original could move that research forward literally decades. I’m simply amazed (boggled, dumbfounded) that the last servicing mission didn’t change out some exposed hardware and bring the old stuff home for study. NASA seems to have forgotten about long-term exposure issues, which itself is boggling considering the expected (and now funded) life of the ISS.

  50. #39 VJBinCt asked

    Yes indeed. I have just been rereading “The Perfect Machine” by Ronald Florence which describes the conception and building of the 200″ Hale telescope. What an epic of engineering that was! Pouring and annealing a 200″ disc was really way beyond the technology of the time. Indeed the whole telescope from the mirror to the guidance system pushed the limits of the possible

  51. @44 Blake…At the NY Science Festival the mock-up of the JWST was accompanied by a mock up of the Ariane 5. One of the scientist/engineers told me that they chose it for several reasons including reliability and mating, but, had they visited the launch site, they would have almost changed their minds. Seems no one likes to visit there except for a short stay, since it is a miserable place in the jungle. You can check it out on GoogleEarth.

  52. Just me

    I remember when Hubble was launched, it was a big joke among most non-science people I knew—$2 billion for a telescope??? Are you freaking kidding me??? And then, to add injury to insult, the mirror was ground wrong. And non-science people were like, geez, these so-called “scientists” can’t get anything right!!! But then, the corrective optics were installed, and WOW. Hubble’s been a hit ever since. I think Hubble can be counted among space exploration’s success stories, despite its rocky start. Hooray for HST!!!

    Can’t wait to see what JWST brings to the game.

    Hubble’s a pretty big machine. I wonder if any of it will survive re-entry? (Admittedly a moot point, as I assume, it’ll be targeted towards one of the oceans)

  53. JohnDoe

    @49:

    There’s a third reason why the HST can’t be brought back: Columbia was the last shuttle that did not have the ISS docking hardware installed in the payload bay – with that installed, there’s not enough room for the HST.

  54. Panecito

    You are missing the main point: The JW will be for INFRARED !!!

    These telescopes should not be compared because the Hubble is for the VISUAL part of the spectrum.

  55. “Wouldn’t the “de-orbit grappler” be equally capable of being used as a “get back to higher orbit grappler” if we attahced a booster rocket to the Hubble?”

    If it is a money issue, why not attach something like a blueray disc, sell recording space to pay for the mission, so anyone could send a message to the stars. It would be very poetic.

  56. AJKamper

    Just wanted to say thanks to Neil Haggath, #32, for the great answer.

  57. Walter

    Why isn’t the Fermi Gamma-ray Space Telescope on the wavelength comparison?

  58. Robert Carnegie

    It’s OK, she’s holding it at the edge, it won’t get smudged or scratched.

  59. Grand Lunar

    @48. Chris A.

    “Without pointing control, you might drift too close to pointing at the Moon, Earth, or Sun, all of which can damage/destroy instruments.”

    The sun will do this, but as the BA wrote in his book, Hubble has been pointed at the Moon and Earth. All they do is turn off certain sensitive instruments.

  60. Matt T

    @Chris A (48)
    Thanks! Good points — I didn’t think about the communication link or the solar panels.

    (also @ Grand Lunar, 59) Can some instruments (eg the main mirror maybe?) not be switched off? That is, will pointing HST at the sun fry something no matter what?

  61. Messier Tidy Upper

    @57. Walter Says:

    Why isn’t the Fermi Gamma-ray Space Telescope on the wavelength comparison?

    Well Fermi observes at Gamma ray wavelength & there are a *lot* of other space observatories up there eg. WISE, Solar Dynamics Observatory, Kepler SOHO (still I think) etc .. so I guess its simplestand easiets just tocpompare the JWST with Hubble – plus its supposed tobe the “replacement” / “successor” to the HST. Not that itreallycan be -different, sure, great, hopefully but “replacement” – never! :-(

    @ 46. T_U_T Says:

    What about an attach-an-ion-thruster-and-drag-it-all-the-way-to-ISS grappler ?

    This came before and was discussed on another BA blog thread which I’ll have to see if I can find – basically, its not a good idea because the vibrations and interference from the International Sapce Station *really* wouldn’t help. :-(

  62. T_U_T

    the vibrations and interference from the International Sapce Station *really* wouldn’t help

    This is as pathetic as excuses for doing nothing can get. The hubble does not need to be permanently attached to ISS. It can be just in a close orbit, so that repair crews from ISS can easily access it.

  63. DaveS

    @50. dave from manchester England Says:
    I have just been rereading “The Perfect Machine” by Ronald Florence which describes the conception and building of the 200″ Hale telescope. What an epic of engineering that was! Pouring and annealing a 200″ disc was really way beyond the technology of the time. Indeed the whole telescope from the mirror to the guidance system pushed the limits of the possible

    They had to design a paved road to the top of Mt. Palomar for the 200″ mirror to be driven up the mountain. The road had to zig-zag up the mountain with perfectly constant radius turns, based on the turning radius of the special truck used to haul it.

    Which today makes South Grade Road one of the most awesome motorcycle roads in the US.

  64. Kevin Graham

    Hi,

    I’m a professional astronomer grad student whose work is pretty much possible because of ACS’s fine visible-light capability. JWST is no successor to HST; it is much closer to a successor to Spitzer; tbh, JWST doesn’t excite me very much…

    HST needs a true successor in UV and vis, but nothing great is looming on the horizon… here’s to keeping it up and running as long as we can…

    – kev;

  65. Muzz

    Kevin; Last time I brought that up (sounding like the embarrasing drunken well wisher at Hubble’s birthday party at times) people said we don’t need another Hubble because you can do everything it can do on the ground now thanks to computer based noise/interference cancelling processes.
    What’s your take on that?

    In any case I think we should start a Bring Back Hubble campaign, doubly so if there’s no longer any need for anything like it. It then becomes a piece of human history unlikely to be repeated. It should be on display next to the Wright flyer and Apollo landers and so on.

  66. MadScientist

    Ah, Hubble’s not going just yet. Sure there won’t be any more service trips, but the power supply is very predictable and who knows what will fail next and when. Hubble may very well run for another decade.

    @Kev #65: JWST is just the next big space observatory; the instrumentation will be nothing like Hubble’s. I disagree about it being a replacement for Spitzer though – the Spitzer observatory is hardly comparable. It’s a bit like calling the fast trains a replacement for the horse carriage. JWST will be more comparable to Planck or Herschel.

  67. Jeroen

    The US government wants to cancel funding on the JWST, we can’t let this happen!

    Please sign the petition and join the FB group, and make as much noise about this as you possibly can!

    http://www.change.org/petitions/do-not-cancel-funding-for-the-james-webb-space-telescope

    http://www.facebook.com/SaveJWST

    Thanks!!

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