Tuesday, February 05, 2008

Run Down on New Astronomical Observatories

Space.com has the rundown on the latest astronomical telescope projects being planned or built over the next decade. Despite all the recent progress in such matters, we're still actually very early in the process of building our knowledge of our system, other solar systems and the beginnings of the universe. All of the proposed projects would result in imagery that makes those gathered from the Hubble look like black and white TV.

"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.

With these proposed giant telescopes, astronomers hope to get the first pictures of planets outside our solar system, watch stars and planets being born, and catch a glimpse of what was happening near the birth of the universe."

Current telescopes are limited into how far in the past they can peer to about 1 billion years. The new projects will be so powerful they will be able to study the early formative years of the universe only a couple of hundred million years after the Big Bang, 13.7 billion years ago.

Two technical breakthroughs have completely redefined how such telescopes are designed and built. The first is adaptive optics, which allows astronomers to "tune" telescopes to adjust for atmospheric distortion created by the Earth's atmosphere -something which would have been impossible before the advent of economical high speed computing, which provides the capability of making the hundreds of adjustments per second necessary. The second is in how the actual mirrors are built. Instead of building a single large mirror, many small mirrors are built and pieced together. Astronomer Jerry Nelson of Hawaii's Keck observatory got the idea from seeing the tiled mosaics of ancient Greek and Roman baths.

The current single mirror Keck telescope is the world's largest at 10 meters. All of the new projects will dwarf it. The bigger the mirror, the more light that can be gathered and further back in time we can examine. The American/Australian Magellan project is planning an 80 foot telescope in 2016 to be located at Las Campanas, Chile at a cost of $800 million. Another joint project, this one American/Canadian , the 30 Meter Telescope, (Nelson is working on this one) is planning a 98 foot observatory with 492 mirror segments (some of the best current segmented Earth telescopes have 36) costing $780 million for 2018 but has not yet decided on a site. Not to be outdone, a European project destined for Chile (exact location to be determined) is planning a monster 138 foot (reduced from 328 feet!) for 2018 as well with a price tag around $1.17 billion.

Then there is the Hubble replacement.

This is the $4.5 billion James Webb Telescope, an 18 mirror segmented telescope 2 1/2times the size of its predecessor. Planned for launch into deep space 900,000+ miles from Earth in 2013 by NASA, the Webb will carry four different scientific instruments. Interestingly enough, it too will utilize adaptive optics due to the extreme temperature variations in the cold of space. The Webb's mirror will face the cold of space and be shielded from the sun by the remainder of the spacecraft, called the bus, where the control mechanisms will reside. (Images courtesy of NASA)

We are almost certainly going to learn more about the universe in the next decade or two than we have in all of human history.

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