Is Bigger Better?

When it comes to astronomical telescopes, you betchya.

Us old timers remember when the 200″ Hale telescope (later re-christened the “5-meter”) at Mt. Palomar was the world’s premier instrument for space studies. It was surpassed in size (but perhaps not in quality) by the Soviet 6-meter in the mid 1970s. By 1985, Hubble was nearing readiness for launch, and I remember being told that the director at Palomar had no intention of letting the Hale be used as a mere service instrument for HST.

But it was too late. The race was on. The first Keck telescope, 10 meters in diameter, was completed in 1990. It’s then revolutionary segmented mirror design not only reduced costs, but made it physically possible to construct such a large instrument. It was the advent of small, inexpensive microprocessors that made it possible to tightly focus 36 separetely controlled mirrors to act as one.

The original Keck was so successful that construction of it’s twin was started almost immediately.

Increasing computer processing power performed another minor scientific miracle. The mirrors could be “flexed” quickly enough to compensate for atmospheric distortion. This is “adaptive optics”, and now most every major observatory can obtain resolutions that rival Hubble at a fraction of the cost.

All this was a good thing TM because the advent of cheap CCD cameras, coupled with cheap, powerful computers, was allowing amateurs to make astronomical photographs that were way beyond the capabilities of major observatories in the ’60s and ’70s. Even more amazing, it took smaller telescopes, with their correspondingly wider field of view, and the ability to stitch together a number of images into an even larger field, to expose intricate connections between objects that had previously been thought of as separate.

But bigger is still better, because with bigger you can see deeper into space. Today there are serious plans in the works, and serious searches for funding, for three telescopes that will dwarf even the Keck.

Just the names of many of the proposed observatories suggest an arms race: the Giant Magellan Telescope, the Thirty Meter Telescope and the European Extremely Large Telescope, which was downsized from the OverWhelmingly Large Telescope. Add to those three big ground observatories a new super eye in the sky, NASA’s James Webb Space Telescope, scheduled for launch in 2013.

The Giant Magellan Telescope will have a mirror that is 80 feet across. The Thiry Meter Telescope will be 98 feet across, and The Extremely Large Telescope is planned to span 138 feet.

I’m amused that the ELT is a scaled down version of the OverWhelmingly Large Telescope (OWL. Don’t you love it? Who said that astronomers don’t have a sense of humor?)

How good will they be? Count on them being very good.

If completed, ESO’s European Extremely Large Telescope would be the biggest of the new observatories and should be able to see 20 to 100 times more sharply than the current best land-based telescopes. The Hubble, which set the standard for stunning astronomical pictures, will seem less amazing.”Oh, you ain’t seen nothing yet,” said 2006 Nobel Prize-winning physicist John Mather, senior project scientist for NASA’s James Webb Space Telescope.

It is the biggest observatories in the works, however, that will provide the dramatic change in astronomical pictures. The pictures to come, Nelson said of the Thirty Meter project, will “knock your socks off, faint stuff that Hubble can’t see.”

Looking forward to it.

Explore posts in the same categories: Astronomy, Science

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