Full disclosure -- I work for NASA, on HST.
Servicing Mission 4 is going to be pretty busy: In addition to the three things mentioned in the summary (installing COS and WFC3, and repairing ACS), we're also going to be repairing STIS, replacing some thermal blankets, installing new batteries, etc. It's going to be a busy 5 days up there.
As for some of the other comments on here: John Mather (the PI for COBE) is a friend of mine, and even he wouldn't claim that COBE did better science than Hubble. They're different things, and both have done fantastic science. Further, I would point out that NASA has had a vast array of scientific successes, including the rovers on Mars, Deep Impact, the Spitzer Space Telescope, Chandra, etc. etc. Just because the media gets more interested when something goes "boom"... sheesh.
Oh, and those of you inclined to give advice to NASA about how to engineer... Talk to me after you've put a telescope in space (no, seriously, after you've done that, I want to talk to you!)
Ok, while the facts here are stated accurately, it's sort of misleading. If I have a telescope that is twice as large (in collecting area), I collect twice as many photons, and my signal to noise goes up by a factor of sqrt(2). In an ideal world, adding together two frames from the smaller of the telescope gives an identical improvement in the signal-to-noise. That being said, there are practical issues in adding multiple pictures together, especially when you're looking through the atmosphere. Images have to be registered to align properly, the individual frames have to be well-calibrated (and calibrated in the same way), etc. Otherwise, you get junk out. Now, try doing this with different telescopes and/or different detectors and you've got a world of hurt. Trust me on this one. It's difficult enough coadding data from a single telescope, but trying it with different instrument characteristics? Nightmare time.
The second part of the rub here is one that I haven't seen anyone mention yet, and that's what's called the "confusion limit". There's a fairly thorough explanation of this at http://sirtf.caltech.edu/SSC/documents/compendium/ resolution/confusion.html
but the basic gist of it is that when there resolution and light collection go together. If i take enough pictures of somethign faint and add them together, i can eventually "see" what's there. However, if my telescope doesn't have the resolution for me to see that there's actually 3 sources really close together, my final picture of it may be horribly misleading.
So, the solution to this stuff is interferometry (and this is being worked on for a bunch of different space missions, including Darwin, Terrestrial Planet Finder, The Submillimeter Probe of the Evolution of Cosmic Structure, the Fourier-Kelvin Stellar Interferometer, Stellar Imager, etc. and for a number of ground facilities including Keck, VLT, CHARA, COAST, PTI, NPOI, etc., pardon my TLAs). The way that radio telescopes (and submm telescopes) do this stuff is by using phase sensitive detectors to observe; they are, in effect, watching the wave nature of photons instead of counting photons as particles (gotta' love the duality of quantum). For heterodyne detectors (i'm not explaining that here), this works great and gives electronic signals which can be added as if they were the EM waves (photons) coming into multiple telescopes. Such detectors don't work (well) in the optical or infrared, so the solution is to add the optical beams directly. This is the hard part, and there are a lot of people (like me) who get paid to work on solving this problem. Amateur astronomers *could* do radio wave interferometry, but keep in mind that they'd have to get even longer baselines to do anything useful (that whole lambda/D rule).
Where amateur astronomers have been traditionally of great value is in spotting solar system objects; comets, asteroids, etc. These objects are comparatively bright on the sky, and they move around, so the professional astrogeeks don't tend to spot them as easily. Amateur astronomers also ahve been good at spotting things like stellar nova, or other things which cause changes to the night sky. As for doing sky surveys, check out the Sloan Survey and 2MASS, a couple of major sky surveys that covered the entire sky with pretty good depth and with bigger telescopes than amateurs typically have.
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Full disclosure -- I work for NASA, on HST. Servicing Mission 4 is going to be pretty busy: In addition to the three things mentioned in the summary (installing COS and WFC3, and repairing ACS), we're also going to be repairing STIS, replacing some thermal blankets, installing new batteries, etc. It's going to be a busy 5 days up there. As for some of the other comments on here: John Mather (the PI for COBE) is a friend of mine, and even he wouldn't claim that COBE did better science than Hubble. They're different things, and both have done fantastic science. Further, I would point out that NASA has had a vast array of scientific successes, including the rovers on Mars, Deep Impact, the Spitzer Space Telescope, Chandra, etc. etc. Just because the media gets more interested when something goes "boom"... sheesh. Oh, and those of you inclined to give advice to NASA about how to engineer... Talk to me after you've put a telescope in space (no, seriously, after you've done that, I want to talk to you!)
Ok, while the facts here are stated accurately, it's sort of misleading. If I have a telescope that is twice as large (in collecting area), I collect twice as many photons, and my signal to noise goes up by a factor of sqrt(2). In an ideal world, adding together two frames from the smaller of the telescope gives an identical improvement in the signal-to-noise. That being said, there are practical issues in adding multiple pictures together, especially when you're looking through the atmosphere. Images have to be registered to align properly, the individual frames have to be well-calibrated (and calibrated in the same way), etc. Otherwise, you get junk out. Now, try doing this with different telescopes and/or different detectors and you've got a world of hurt. Trust me on this one. It's difficult enough coadding data from a single telescope, but trying it with different instrument characteristics? Nightmare time. The second part of the rub here is one that I haven't seen anyone mention yet, and that's what's called the "confusion limit". There's a fairly thorough explanation of this at http://sirtf.caltech.edu/SSC/documents/compendium/ resolution/confusion.html
but the basic gist of it is that when there resolution and light collection go together. If i take enough pictures of somethign faint and add them together, i can eventually "see" what's there. However, if my telescope doesn't have the resolution for me to see that there's actually 3 sources really close together, my final picture of it may be horribly misleading.
So, the solution to this stuff is interferometry (and this is being worked on for a bunch of different space missions, including Darwin, Terrestrial Planet Finder, The Submillimeter Probe of the Evolution of Cosmic Structure, the Fourier-Kelvin Stellar Interferometer, Stellar Imager, etc. and for a number of ground facilities including Keck, VLT, CHARA, COAST, PTI, NPOI, etc., pardon my TLAs). The way that radio telescopes (and submm telescopes) do this stuff is by using phase sensitive detectors to observe; they are, in effect, watching the wave nature of photons instead of counting photons as particles (gotta' love the duality of quantum). For heterodyne detectors (i'm not explaining that here), this works great and gives electronic signals which can be added as if they were the EM waves (photons) coming into multiple telescopes. Such detectors don't work (well) in the optical or infrared, so the solution is to add the optical beams directly. This is the hard part, and there are a lot of people (like me) who get paid to work on solving this problem. Amateur astronomers *could* do radio wave interferometry, but keep in mind that they'd have to get even longer baselines to do anything useful (that whole lambda/D rule).
Where amateur astronomers have been traditionally of great value is in spotting solar system objects; comets, asteroids, etc. These objects are comparatively bright on the sky, and they move around, so the professional astrogeeks don't tend to spot them as easily. Amateur astronomers also ahve been good at spotting things like stellar nova, or other things which cause changes to the night sky. As for doing sky surveys, check out the Sloan Survey and 2MASS, a couple of major sky surveys that covered the entire sky with pretty good depth and with bigger telescopes than amateurs typically have.