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Chief Engineer Scott
2002-Jan-08, 08:03 AM
I was watching a program last night where the commentator launched into an explanation about how they planned to link the double Kek mirrors to create a super "virtual" mirror, the hope was this would enable detection of small rocky planets.
Unfortunately I missed the full explanation as there was a corrupt section on the tape I had used, can someone explain the mechanics of the link? I am interested in the section dealing with the synchronising of the light from the dual telescopes.

PS HAPPY NEW YEAR !

GrapesOfWrath
2002-Jan-08, 08:26 AM
Funny you should ask. They're discussing this sort of thing, one door down (http://www.badastronomy.com/phpBB/viewtopic.php?topic=366&forum=2&7).

David Hall
2002-Jan-08, 12:30 PM
Actually GOW, that thread seems to be focusing more on adaptive optics right now.

I'm no expert, but here's my layman's explanation of what's going on. Others can come along and fill in the details.

What the Keck scopes are trying to do is create an interferometer. This is the same kind of thing that's been used in radio astronomy for years, where several smaller telescopes are combined to do the work of one larger one. The most famous example there is the Very Long Baseline Array (VLBA), which has been seen in many movies from 2010 to Contact. But it's only just now being perfected for optical wavelengths, and that's what they're doing with the Keck scopes.

The idea is simply to merge the images from two or more seperate telescopes to provide the same resolving power you would get from one larger mirror. An interferometer has only a fraction of the light-gathering power of a single mirror, but it makes up for it in it's ability to resolve the same amount of detail as a full mirror of the same diameter as their seperation.

But let's let Keck speak for itself. Here's the Keck Interferometer Page:

http://huey.jpl.nasa.gov/keck/

If you click on "overview" you get a nice rundown on what the interferometer is, and there you'll find a link with more details on the types of interferometers available. This is it here:

http://huey.jpl.nasa.gov/keck/publicWWW/overview/intro-interferometry.html

I hope this helps. I think it's cool, and I'm curious to see what the results are.

Donnie B.
2002-Jan-08, 08:54 PM
What the Keck scopes are trying to do is create an interferometer. This is the same kind of thing that's been used in radio astronomy for years, where several smaller telescopes are combined to do the work of one larger one. The most famous example there is the Very Long Baseline Array (VLBA), which has been seen in many movies from 2010 to Contact.


I think you mean the Very Large Array, which is a single installation in (I believe) New Mexico.

Very Long Baseline Interferometry is even trickier; it combines the data from radiotelescopes a whole world apart. This is done by recording the data along with a very accurate time base, and crunching the numbers later.

(Edited to fix the quote)

<font size=-1>[ This Message was edited by: Donnie B. on 2002-01-08 15:55 ]</font>

David Hall
2002-Jan-08, 09:17 PM
Yeah, I believe you're right. Somehow I thought there was another word in it. I must have gotten the name mixed up. Well, it's the one in the movies anyway.

Russ
2002-Jan-08, 10:00 PM
On 2002-01-08 16:17, David Hall wrote:
Yeah, I believe you're right. Somehow I thought there was another word in it. I must have gotten the name mixed up. Well, it's the one in the movies anyway.


You were correct, sorta. While the VLA in Soccoro N.M. is a radio interferometer unto itself it is also part of the VBLA which is a group of Radio Telescopes spread from Hawaii to VA. This is refered to in the book/movie "Contact" when they are trying to pinpoint the source of the message. Ellie says something to the effect that it'll take weeks to do if they only use the VLA but just hours if they can use the VLBA.

Chief Engineer Scott
2002-Jan-09, 11:41 AM
Thanks folks, it appears just about everybody is right, according to the site they are using a combination of both adaptive optics, and interferometery.

Hale_Bopp
2002-Jan-10, 01:15 AM
Actually, the VLBA extends from Hawaii to the Virgin Islands, not Viriginia. I was living on St. Croix when they built the radio telescope on the east end of the Island and even have some pictures of the construction /phpBB/images/smiles/icon_smile.gif

Rob

David Hall
2002-Jan-10, 12:21 PM
I just posted this in a new thread, but I think it should also be mentioned here. Looks like the Keck interferometer has succeeded in directly imaging a brown dwarf.

(At least I am assuming they used the interferometer, as they used Keck in the plural sense. At the very least they used the adaptive optics.)

http://www.cnn.com/2002/TECH/space/01/07/brown.dwarf/

David Hall
2002-Jan-10, 12:31 PM
Well, sorry folks. Looks like I was a little premature here. I looked around a bit more, and they don't seem to have used interferometry in this case. This'll teach me to jump the gun. /phpBB/images/smiles/icon_smile.gif

http://www.onlineschoolyard.com/channel/article.asp?lArticleID=7627&lChannelID=350