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?
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pb Reply or e-mail; don't vaguely moderate.

Re:Terrestrial Optical Telescopes

[chgreer]

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)?

Think about trying to blast an 8.4m mirror into space -- imagine how much fuel you'd have to expend and how much it would cost. I once read that one space shuttle mission costs up around a billion dollars per launch, the cost of the payload not withstanding.

The dual Gemini telescopes that NOAO and a group of others are putting together are nearly 4 times the size of HST. NGST, or the next generation space telescope is years away from being launched (2010, maybe?) and will only be 6.4m.

(For those who don't know, a bigger mirror means more light gathering power (ie, fainter objects.) and higher spatial resolution (things are less fuzzy), so it is in effect, possible to build ground telescopes that are big enough to out resolve HST, even after dealing with atmosphereic corrections.

(Also, fwiw, spain will be building a 15m on the canary isles soon.) There is also the Large Binocular Telescope in AZ that will be going on line in 5 years or so that will have 2 8m mirrors that have the resolution of 1 18m mirror, and will allow astronomers even higher resolution.

So, the say it in a line: space is not the end all and be all of optical astronomy, no matter what STScI wants you to believe.

BHT (Big Honkin' Telescopes)

[Golias]

With so many "purdy pictures" coming in from the Hubble, and more orbital telescopes planned, it seems that we might approaching the point of diminishing returns for bigger ground-based telescopes.

Other than cost savings and easy access for changes, are there many advantages to staying on the ground?

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.

Re:Why on the ground

[lennon]

It is cheaper to control light pollution than build something in space. http://www.darksky.org is just one of the places where a little money go a long way to fight light pollution.

Atmospheric Turbulence Correction?

[exploder]

I've read a little bit about mechanisms to correct for atmospheric distortion using adaptive optics. To what degree can these systems reduce the distortion that an earth-based telescope suffers? Will advances in this area make it less attractive to put an optical telescope in space, given that the cost of lifting it into orbit can instead be used for corrective systems, and to build a larger instrument?

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

CCD or what?

[paRcat]

What kind of imaging does a telescope of this scale use? Is it an OWLCCD or something else? What kind of resolution? And how far away would an object need to be before the resolution becomes a shortcoming?

Moon closeup

[russiste]

I've always wondered: "now" that we have incredibly powerful telescopes, wouldn't be possible to take closeup pictures of the moon, for example where people have landed (and/or left some stuff)? (it has been already asked if it would be possible to track the moon considering its relative fast speed).

It sure would put an end to all of those conspiracy theories... or maybe confirm them. ;-)

Greg

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?

GAC's future and Hacking Consciousness

[Animol]

From a look around the MindPixels site, I must say I'm fairly impressed with the idea of training an AI-consciousness through not just interaction, but through large-scale, longer-term communication with Real Live Human Beings. The question this leads me to, though, is two-part:
1. When GAC is online, working, and trained to a certain extent, what purpose will he/she/it serve aside from a learning experience in the AI consciousness field?
2. Do you think there's a large place for non-human "presences" on the internet at large?

Technology

[rw2]

I know that SDSS (www.sdss.org) uses Linux in it's effort to map the sky. Can you tell us about the hardware, OS and software used for your kind of control and DAQ work and what considerations were particularly relevant in the selection process?

Distributed Computing Problems

[Aravaipa]

Recently, SETI@HOME has received much attention for their distributed project, which allows non-astronomers to participate in the search for ET. Can you think of any other astronomy projects that could benefit from this approach utilizing the data from these new telescopes?

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.

How do you guys do it?

[pc486]

With exptreemly high magnification, how in heck do you keep the telescope still enough to take photos?

The slightest movement ought to mean millions of miles so thoes pesky little earthquakes should be a problem. Not to mention how you guys move the telescope accuratly.

Adaptive Optics and Inferometers

[wazzzup]

Has adaptive optics foregone the need to deploy space-based telescopes? For those who don't know about adaptive optics, the primary mirror continuously makes small variations in its figure to compensate for atmospheric distortions, thus giving very crisp resolution like we see from the Hubble (which operates free from atmospheric distortions). To launch or construct a 100m scope in space would seem to be exceedingly expensive both in initial construction costs and the inevitable component replacements and upgrades. Given the cost of launching and constructing objects in space, recent advances in the field of adaptive optics and placing several smaller telescopes in an array to simulate larger apertures (what, if I recall correctly, is called an inferometer), do space-based scopes still offer any advantages to earthbound scopes?

GAC

[Dungeon Dweller]

I have an active interest in artificial intelligence. I study it as part of my major, and hope to do research in it in the future. As a young man coming up in the world, I am hoping to enter into research eventually, am entering into research at my university (WVU).

Your project reminds me of several projects/theories that have been discussed before. In the psychological debate, your system depends entirely upon nurture, it would seem. I like that kind of system and research. I do have a few questions.

1) What separates this from other projects in the field?
2) Where did you draw your inspiration for this project?
3) What kind of support staff do you recommend to an individual who has never led research before, but would like to? (I ask this of many of my professors who conduct research)
4) Where are you getting the bulk of your input for this project?
5) What do you hope to learn from this project?
6) At what time will you consider this project a success?

I know that I posed a lot of questions, but several could be answered in combination, I just didn't want to ask 2 questions at the same time.