Printer Friendly

New telescope for old.

New telescope for old

When the Multiple Mirror Telescope (MMT) was completednine years ago, astronomers waited eagerly to see whether this most innovative of telescopes would really work. The MMT consists of six mirrors set on a single mount; among the questions were whether such a seemingly unwieldy thing could track and point accurately, and whether six mirrors could be made to throw their reflections into a single image.

The MMT's managers believe it has fulfilled all those expectationsvery well. But Frederick H. Chaffee Jr. of the MMT Observatory in Amado, Ariz., told the meeting that this does not deter them from planning to replace its six mirrors with a more conventional single one. The MMT can point to within 0.3 second of a arc, it can track objects across the sky to an accuracy of 0.1 second of arc, and after a great deal of work, its images can be coaligned and made to coincide as well as astronomers would like. Indeed, experience with the MMT has led the designers of the National New Technology Telescope to choose a multiple mirror design for that project.

In spite of the success, the six 1.8-meter mirrors of the MMThave the total light-gathering power of a single mirror of 4.5 meters diameter. When the MMT was planned, that was a large power; today, with people planning 8-, 10- and even 16-meter equivalents, it is rather ordinary. So the MMT's managers have decided to upgrade their capacity by replacing their six mirrors with a single 6.5-meter mirror to be mounted in the same frame that now holds the six.

Casting single mirrors of this size was technologically impractical when the MMT was planned. Now, thanks to development of a method of casting very light, large, single mirrors in a spinning furnace, pioneered by Roger Angel of the University of Arizona, single mirrors up to 8 meters across are possible. The MMT people expect Angel to cast their mirror in 1988, and they hope to complete the conversion by 1922.
COPYRIGHT 1987 Science Service, Inc.
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 1987, Gale Group. All rights reserved. Gale Group is a Thomson Corporation Company.

Article Details
Printer friendly Cite/link Email Feedback
Title Annotation:Multiple Mirror Telescope to cast single mirror
Author:Thomsen, Dietrick E.
Publication:Science News
Date:Jan 17, 1987
Previous Article:Feeding pigeons serial chunks.
Next Article:Spectroscopic survey telescope.

Related Articles
Large telescopes, low prices; astronomers do it with mirrors - by leaving out most of the glass.
NNTT's next generation: harmonizing a quartet of large telescopes.
Spinning mirrors of mercury; a Canadian astronomer tries an age-old idea for making large telescope reflectors.
Big telescopes on a roll: the world has a number of projects for telescopes in a size range thought to be impossible not many years ago.
First telescope with active optics.
Small foam-mirror telescope built.
Dawn of a big telescope: astronomers await the debut of Keck's tiled mirror.
Back off veto threat.
Bed liner maker picks up.

Terms of use | Copyright © 2017 Farlex, Inc. | Feedback | For webmasters