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Really Big Telescopes are Coming

S

SirUlli

Senior member
Summary - (Apr 8, 2005) If you think current telescopes are powerful, just you wait. A new class of observatories are in the works that could sport mirrors as large as 100 metres (328 feet) across, and have 40 times the observing power of the Hubble Space Telescope. A new study developed by a commission of European astronomers proposes that instruments this large could be built for approximately 1 billion Euros and take 10-15 years to construct.

Full Story - The largest ground-based optical telescopes in use today use mirrors that are 10 m (33 ft) across. But the prospects for future Extremely Large Telescopes (ELTs) are looking up. According to recent studies by international teams of astronomers and leading astronomical organisations, the next generation of optical telescopes could be 50-100 metres (165 330 ft) in diameter - big enough to fill a sports stadium.

This quantum leap in size has important implications, since astronomers want to capture every photon of light that comes their way, and a 100 m mirror has a collecting area up to 100 times greater than existing instruments. Furthermore, a 100 m telescope would have extremely sharp vision, with the ability to see objects at up to 40 times the spatial resolution of the Hubble Space Telescope.

more Info

http://www.universetoday.com/am/publish/big_observatories_coming.html?842005

and

http://news.bbc.co.uk/1/hi/sci/tech/4426535.stm

Sir Ulli
 
Thanks SirUlli!

Even with the size I wonder how the images will be affected by our atmosphere. The Hubble is off in space and does not have that issue. Or, does the size of the new telescope overcome that? I still thought that our atmosphere and graviety distorted what a telescope can see.
 
Originally posted by: JWMiddleton
Thanks SirUlli!

Even with the size I wonder how the images will be affected by our atmosphere. The Hubble is off in space and does not have that issue. Or, does the size of the new telescope overcome that? I still thought that our atmosphere and graviety distorted what a telescope can see.
Click to expand...

Yea same here ,you'd think the atmosphere would blurr the picture ,at least that's what they said before.
Also wouldn't multiple linked 'scopes be more cost effiecient & practical?

Thanks Ulli 🙂
 
This answers one of our questions

ELTs would incorporate adaptive optics, a computer controlled system that deforms the mirror to adjust for the atmospheric turbulence that distorts light waves coming into the telescope.
 
Originally posted by: Assimilator1
Also wouldn't multiple linked 'scopes be more cost effiecient & practical?
Click to expand...

Apparently they think with a new mirror design that these large telescope mirrors will be cost effective. Whether more cost effective than the smaller designs of today i don't know.

There are already several "arrays" working today, including the pair of 10-meter Keck telescopes, the VLT(4 8-meter scopes) & some others.

Here's another link to the proposed OWL(OverWhelmingly Large telescope)

 
Originally posted by: Assimilator1
Originally posted by: JWMiddleton
Thanks SirUlli!

Even with the size I wonder how the images will be affected by our atmosphere. The Hubble is off in space and does not have that issue. Or, does the size of the new telescope overcome that? I still thought that our atmosphere and graviety distorted what a telescope can see.
Click to expand...

Yea same here ,you'd think the atmosphere would blurr the picture ,at least that's what they said before.
Also wouldn't multiple linked 'scopes be more cost effiecient & practical?

Thanks Ulli 🙂
Click to expand...

Observatories in Chile using adaptive optics already get as good and on rare occasions, slightly better resolution than Hubble can get. It's getting to the point where space telescopse are almost not needed unless you want to do some extremely sensitive measurements (extrasolar planets), or do something that the atmosphere prevents you from doing (UV measurements).

The smaller linked telescopes are very very difficult to set up as for a 100m optical array of more than 1 telescope (2 telescopes placed 100m apart) you have to match up the light PERFECTLY to get an image. That means the path length from the star, through the atmosphere along the two paths (which changes due to wind currents etc), through the telescopes, off all the mirrors, down the combining tubes and into the interferometer must be precise down to the fraction of a nanometer. Furthermore, just 2 telescopes will only give you enhanced resolution in the direction along their baseline (ie, in the x-direction, but you'll still be blurry in the y-). The best way would be to have a ring of small telescopes that was filled in with others... but then you're practically making a big telescope anyways. And you're still losing information in the spatial structure, as well as light with a smaller reflecting surface. It's not so simple a matter as just setting up two telescopes and pressing "click" on two cameras.

Radio interferometry is much easier as radio waves aren't affected nearly as much by path length differences as their wavelengths are so long. Also, because they are relatively very low frequency as compared to optical frequencies, you can record the incoming signal at each telescope overlayed with the ticks of an atomic clock. To do the interferometry you can just play back the tapes and sync up the clocks. No optical path length tubes to worry about, no vibrational worries, no temperature change variables, no realtime constraints...
 
I'm almost done an astrophysics degree. Last term I took a telescope and detector design course (not really a design course, we didn't design anything, but just learned about the designs of all the systems and what they're good for etc), and this term I got to do some observing with the university's telescope. I got a few pics of saturn that I'll still have to clean up but will post when I get some free time from exams. You can see about 5 of Saturn's moons and can clearly see the rings, but I have to play with some light values because the contrast difference between Saturn and the moons is so great that if you make Saturn dim enough to see its rings and features, the moons are too dim to see. It'll just take some fine tuning 🙂
 
Originally posted by: superkdogg
With these, there won't be a need for SETI, we'll be able to see those little buggers flying around!
Click to expand...

LOL

Actually, I think we'd have to come up with an OALT(Obscenely Agile and Large Telescope) that will be able to quickly move around on it's axis to follow zooming little buggers.

edit:misspelled axis
 
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