Ask Chris McKinstry About Giant Telescopes, Etc.

Have you ever heard of Chris McKinstry? If not (I hadn't until a few weeks ago), it's probably because he's been moving too quickly in the background for you to apprehend with human vision. In addition to operating the world's largest optical telescope -- the ESO Very Large Telescope (VLT) at Paramal Observatory (Atacama, Chile) -- he writes and reviews books, hacks consciousness, creates art, and enjoys his family. Chris has agreed to field questions about the VLT, as well as about the upcoming OWL (OverWhelmingly Large) telescope project -- a 100-meter filled-aperture device which would put all current terrestrial telescopes to shame. Please read through the linked sites, then post your questions (one per comment, please) for Chris below; we'll pass along the best ones for his reply.

Comments

might as well ask it now..

[Blue Lang]

i noticed in your 'fave books' section that you have the blind watchmaker, et al.

so, with an eye towards dawkins' views on evolution, what's your personal take on the probability (not the possibility) of humans locating extraterrestrial life without going outside the solar system?

Terrestrial Optical Telescopes

[pb]

What are the benefits of having an Earth-bound, optical telescope?

Or rather, what can a larger optical telescope find better from Earth that we can't already find on other wavelengths and from other venues (i.e. The Hubble)?

If there are no advantages here, is it more cost-effective, or what?
---
pb Reply or e-mail; don't vaguely moderate.

funding

[jmayes]

What's the biggest hurdle to hop over in getting funding for projects like OWL?
And how did you pull it off?

Why single-mirror?

[jd]

I could have been mis-reading the article, but it seemed to me as though the idea was to build a single-mirror system. On the other hand, in radio astronomy, and in the insect world, arrays are considered the norm.

Is there some advantage that a single mirror gives that cannot be duplicated using multiple smaller mirrors? (Simpler optics is an obvious one, paradoxically. :) Or is this (at least in part) NerdTrek III: The Search for Sponsors, where a record-setting single telescope is going to get more interest than a comparable array?

(A supplementary question, to go along with this. Let's say, for the sake of argument, that optical arrays are practical. Do you see any possibility of optical astronomers adopting the same line as radio astronomers, in trying to build an effective 1Km+ optical telescope, using an array?)

Re:Why single-mirror?

[pq]

This is deep, so I won't do a good job of explaining this, but let me take a stab at it anyways... The fundamental difference is that quanta of light (photons) have more energy than quanta of radio waves (also photons, but ever hear them called that?): E = hf, as Planck tells us. So for a given signal strength, there are far more radio photons than there are optical photons - this implies that optical telescopes are in a quantum regime (shot noise limited), while radio telescopes work in a classical regime (thermal noise limited). So what? So: radio signals can be received and amplified and replicated "perfectly" - each telescope output can be split into N identical copies to be correlated against the other N telescopes in the array. But optical photons cannot be received and amplified without destroying coherence - so the light form one mirror has to be split N ways to be combind with the other N telescopes. That's why optical interferometry is only possible with huge mirrors like the VLT, where for 4 mirrors, 1/3 the light from each telescope is still enough photons to work with. For radio telescopes: add more scopes? Sure, just boost the amplifier some more. Optically, to add another scope, you need to increase collecting area by (N+1)/N. This is a fundamental limit, sadly - so it keeps us radio astronomers in business and makes optical interferometry very very hard... - pq: I can't login today, for some reason.

How parellelizable?

[Omnifarious]

How parallelizable is the problem of micro-adjusting small portions of a large deformable mirror to correct for atmospheric distortion?

I remember a Scientific American article stating that you'd have to devote a top-of-the-line Cray to continuously recalculate the deformations needed given data from the guide star, or laser simulated guide star. If this problem is highly parallelizable, you may be able to get away with _much_ cheaper hardware.

I'm sure the idea has occured to you, but I want to know what your thoughts are on it.

Yeah, they're big...

[viper21]

But what do you do with them?

What kind of work do the telescopes at your facility generally do? Do local astronomers get to come in and do research or are the scopes reserved for some large project?

Thanks,

-S

Scott Ruttencutter

Division between Science and Spirituality

[ParticleGirl]

I am continuously frustrated that people's general perception seems to be that science and art, spirituality, and so forth are divided by an uncrossable schism. People feel the need to pit science against spirituality; logic against intuition. It is a rare thing that people accept the idea that these are different ways of approaching the same reality. As a dreamer and artist as well as a respected scientist, what do you say to people who doubt that scientists can be spiritual and artistic people?

How can we help?

[Mignon]

You probably know about SETI At Home, which lets people volunteer spare CPU time to processing radio-telescope data, in a (so far vain) attempt to find extra-terrestrial intelligence. Is there a similar way that we can help process some of the data that you gather?

As a simple example, one could compute the differences between a sequence of pictures of the same portion of the sky, looking for anomalies like giant asterioids on their way to wiping us all out.