NeoCode writes: "It's been 11 years already and the stats are mind boggling. Hubble is celebrating its 11th birthday and it sent another beautiful image. Stories here (CNN) and here (Space). A lot of these images have been called "space-art". The image bank can be found here."
Re:Is Hubble So useful? Adaptive optics is cheaper
by
pavonis
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· Score: 4
Well, AO in optical wavelengths is still an immature technology, in the sense that every rigup is rather unique and experimental. It's only become really usable at all in the last year or so. And it's quite expensive too, though admittedly less so than Hubble.
It's a wonderful use of technology, and a terrific example of wholly separate fields of science aiding each other; but it's not the endall to telescopes, either. Space scopes have a number of advantages over even the best ground-based telescopes, like ESO and Keck-
You need to build a bigger scope on the ground to get the same amount of light, due to atmospheric lossage. Admittedly it's relatively easy to build big scopes on the ground.
Hubble can look at (almost) any target at any time, 24 hours a day, and it never rains up there. This means that in sheer amount of observing done, it needs to be compared to at least 3 telescopes, not just one.
Good sites for ground telescopes are in increasingly short supply, as cities spread around the world. Many, for instance, now take sites in the Chilean Andes that are about as hard to get to, and work from, as any place on Earth. That ends up costing quite a bit, too.
No ground-based scope can ever take an exposure lasting more than maybe eight hours. The Deep Field would be impossible to ever do on Earth. And the effectiveness of AO declines the longer your exposure, of course.
While, tragically, launch prices are not coming down much yet, we can at least imagine that eventually they will, and space telescopes will be cheaper.
It would be very hard, maybe impossible, to do long-baseline optical interferometry on Earth, because of things like ground tremors. It may be possible to use baselines miles long in space. This would utterly change the face of astronomy. The first test will be NASA's Terrestrial Planet Finder, sometime this decade. For optical interferometry, see Keck's web site- here.
Hubble's successor, the NGST, will actually be a near-infrared telescope. Light from very distant objects is red-shifted all the way into the infrared, so NGST will be optimized for this kind of large-scale, cosomological research. This is hard to do from the ground, as the atmosphere is a tremendous source of infrared noise even at night in cold places.
So while AO is extremely valuable, I don't think any astronomer is prepared to say "Okay, let's ditch the space telescopes now." And if you can launch them working right the first time, and don't have to foot the bill for shuttle repair missions, they are not so expensive as most folks here seem to think.
Slashdot Mirror
Well, AO in optical wavelengths is still an immature technology, in the sense that every rigup is rather unique and experimental. It's only become really usable at all in the last year or so. And it's quite expensive too, though admittedly less so than Hubble.
It's a wonderful use of technology, and a terrific example of wholly separate fields of science aiding each other; but it's not the endall to telescopes, either. Space scopes have a number of advantages over even the best ground-based telescopes, like ESO and Keck-
So while AO is extremely valuable, I don't think any astronomer is prepared to say "Okay, let's ditch the space telescopes now." And if you can launch them working right the first time, and don't have to foot the bill for shuttle repair missions, they are not so expensive as most folks here seem to think.