Comments on: Adventures in ELT Wonderland http://sarahaskew.net/2009/08/26/adventures-in-elt-wonderland/ sarahaskew.net Mon, 16 Jan 2012 21:47:33 +0000 hourly 1 http://wordpress.org/?v=3.3.1 By: Stephen http://sarahaskew.net/2009/08/26/adventures-in-elt-wonderland/comment-page-1/#comment-618 Stephen Thu, 27 Aug 2009 16:16:05 +0000 http://sarahaskew.wordpress.com/?p=1025#comment-618 I thought i'd written it up on a blog, but can't find it. A couple years ago, i computed the Moore's Law for telescopes. For end points, i used the 1609 1.5 cm Galileo telescope, and the 1992 10 meter Keck telescope (first light with all the segments). Telescopes increased in diameter by a factor of 666x (do the math) and doubled in size only about 8.58 times over 383 years, giving a telescope doubling period of about 44.6 years. Has the pace increased lately? http://en.wikipedia.org/wiki/List_of_largest_optical_telescopes_historically That compares to the doubling of 'parts' on a computer chip every 1.5 years. Which will go on until, first, the 'parts' are too small for the physics to work, and then the chips are too big. Of course, diameter gives resolving power, whereas area gives light collecting. And interferometry should be taken into account for resolving power. The Kecks have 100 meter separation, and the light collecting area of a 14 meter scope. Interferometry started there in 2001, giving a very quick jump for 'diameter'. Size matters, but what size matters to you? http://www2.keck.hawaii.edu/library/milestones.html I can hardly wait for space based interferometers at optic wavelengths. In space, you can pretty much always take a longer exposure. And, you could have kilometers or megameters of separation. With radio, VLBI has achieved something like 10-15 microarcseconds resolving power, and with patience determined proper motion for M33. What could you do with a 2 AU optical interferometer? Parallax for any star in the Milky Way? Parallax to M31? I thought i’d written it up on a blog, but can’t find it. A couple years ago, i computed the Moore’s Law for telescopes. For end points, i used the 1609 1.5 cm Galileo telescope, and the 1992 10 meter Keck telescope (first light with all the segments). Telescopes increased in diameter by a factor of 666x (do the math) and doubled in size only about 8.58 times over 383 years, giving a telescope doubling period of about 44.6 years. Has the pace increased lately?

http://en.wikipedia.org/wiki/List_of_largest_optical_telescopes_historically

That compares to the doubling of ‘parts’ on a computer chip every 1.5 years. Which will go on until, first, the ‘parts’ are too small for the physics to work, and then the chips are too big.

Of course, diameter gives resolving power, whereas area gives light collecting. And interferometry should be taken into account for resolving power. The Kecks have 100 meter separation, and the light collecting area of a 14 meter scope. Interferometry started there in 2001, giving a very quick jump for ‘diameter’. Size matters, but what size matters to you?

http://www2.keck.hawaii.edu/library/milestones.html

I can hardly wait for space based interferometers at optic wavelengths. In space, you can pretty much always take a longer exposure. And, you could have kilometers or megameters of separation. With radio, VLBI has achieved something like 10-15 microarcseconds resolving power, and with patience determined proper motion for M33. What could you do with a 2 AU optical interferometer? Parallax for any star in the Milky Way? Parallax to M31?

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