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Antarctic Telescope?
angkor pastes "'A novel Antarctic telescope with 16-m diameter mirrors would far outperform the Hubble Space Telescope, and could be built at a tiny fraction of its cost, says a scientist from the Anglo-Australian Observatory in Sydney, Australia.'"
Would this telescope be as beneficial as the Hubble considering the Hubble isn't attached to any surface and can freely move in space... This Antartic version would have limited viewing capabilities, so which would you rather have?
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The scientist is even quoted as saying so ... FTFA:
"... It's nearly as good as being in space."
Nearly as good, perhaps, but while you may have minimized light pollution by using the Antartic you still have the atmosphere diffusing incoming light. It's like a being a photojournalist with a sheet of fine tissue paper over your lens.
Built it on top of K2 or some other super-high peak if you want to keep it on earth, and only image things that are relatively perpindicular to minimize atmospheric distortion.
'Software' algorithms could compensate for the effects of the atmosphere. (probably by using data gather by Hubble)
No, you use Adaptive optics. Antarctica is particolarly good because the atmosphere effects are small, so the adaptive optics works very well.
When the sun is up (summertime) you can observe in the infrared and submillimeter. Hubble's observing efficiency is about 50% due to the requirement to avoid the Earth, the South Atlantic Anomaly, slew time, etc.
The limitation is sky coverage is not important for many astronomical programs. Important regions such as the Galactic Center, the Magellanic Clouds, and the South Galactic Pole, are all visible.
Does Antartica get that much snow - I always thought it was more of a desert. It doesn't snow much, but what's there doesn't melt.
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I'm an ex-astronomer, so I'll comment on this.
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The optical arangement is unlike any I've seen before or heard of. I don't have the expertise or the information to comment on whether it will really work. I'll just comment that making optically flat mirrors was very hard (much harder than the normal curved mirrors) last time I heard, but there might be new technology to help here.
There are basically three competing locations: space, Antarctica, somewhere else on Earth. There is an order of magnitude or more in accessibility and cost between each option.
Space:
Pro:
Access to the full range of wavelengths - no atmospheric absorption or emission. (Particularly useful in UV and IR.)
No atmospheric bluring - diffraction limited resolution at all wavelengths
Can observe almost any part of the sky at any time.
Con:
Hugely expensive
Very inaccessible - service missions are either impossible or cost hundreds of millions or more
Size limitations on launch - either the telescope is smallish (Hubble) or needs even more expense to 'unfold' in orbit (new generation space telescope).
Very hostile environment: cold on one side, hot on another, radiation belts,
Antarctica:
Pro:
Access to wavelengths difficult or impossible to access elsewhere on Earth (mostly mid to far IR. The ozone hole presumably helps out in UV also.)
Best seeing on the planet: very little atmospheric blur much of the time.
Con:
Can only ever view half the sky
Unusable during summer
Very expensive
Poor accesibility: Only during summer, only at great expense.
Hostile environment: extreme cold. Possible build up of ice by sublimation deposition.
Anywhere else:
Pro:
Cheapest
Daily access, can drive a truck up to the telescope
Can have astronomers on site, e.g. debugging new detectors
Can see the northern hemisphere
Con:
Poor seeing
Many interesting wavelengths inaccessible or hard to observe
Unusable during the day
We need all three - space for what we can't do on Earth, Antarctica for what we can't do elsewhere (except space, which costs more). Whether the telescope described (very briefly...) in the article is sensible I couldn't say, nor could I say whether it makes sense to use Dome C rather than the more accessible, and manned, south pole base.
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The article from a few days ago about seeing at Dome C explains this: they get very, very little snowfall there. However, they do get blown ice crystals, but not very many at the proposed location. The linked article makes great reading.
The site at Paranal have 4 8.5 meter telescopes and interferometry can can equate their imaging to the distance they stand apart.
yes, but there are also problems with laser guide stars. Like they're hard to get working. Also, when you start adding multiple guide stars, as in Multi-conjugate AO (MCAO), you decrease the field-of-view (which on a large telescope is already pretty small) with every laser guide you use. There are trade-offs. You get excellent images, but only over a tiny area.
Laser systems are also extremely complex (and hence expensive). You'd need to make a pretty good science case for why they're necessary, especially given that the *median* seeing in the antarctic (dome C) is already as low as 0.27" (and less than 0.15" for 25% of the time). Compare this to mauna kea (the current best site in the world) which gets to 0.4-0.5" on a good night.
Also, I think you might have missed the point with CCDs. without closing the shutter, you can't just discard photons from a ccd one they're detected. since there's no time-tagging (as in, say, the FUSE UV detectors) you can't exclude photons after the fact - "discarding those timeslots" is a bit harder than it sounds.
A couple of people have mentioned that you can't work in the ultraviolet part of the spectrum without going to space. True, and critically important to some science. Also, from Antarctica, you can only see the southern sky, not the north, so this is another limitation.
These are not good reasons not to build this proposed telescope, just ways in which Hubble is still uniquely qualified.
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