Another giant telescope gets funding boost (Sen) — The race continues to build ever-bigger telescopes to help astronomers solve some of the great riddles of the Universe. Currently the world’s largest is Spain’s Gran Telescopio Canarias, also known as GranTeCan, or the GTC, which Sen visited in 2012 on the Canary Island of La Palma. But GranTeCan’s huge segmented 10.4-metre mirror will be dwarfed in the years ahead by new observatories that are under construction or on the drawing board. We have told you before about plans for the monster European Extremely Large Telescope (E-ELT) that will boast a primary segmented mirror 39.3-metre wide when it comes into operation in Chile in 2023. But before that, another telescope in Chile’s Atacama Desert will briefly hold the crown as the biggest in the world. Called the Giant Magellan Telescope (GMT) it will use seven separate complete main mirrors, 8.4 metres (27ft) wide, to act like a single mirror 24.5 metres (80ft) in diameter, observing in the visible and near-infrared part of the spectrum. That will offer more than six times the collecting area of the largest telescopes today. IF WE SUCCEED, I THINK THE DISCOVERY OF A SERIES OF HABITABLE PLANETS WOULD BE A LANDMARK IN HUMAN HISTORY The telescope’s designers say that it will give astronomers 10 times the resolving power of the Hubble Space Telescope. It is being backed by several institutions in the US, Australia and South Korea, and it got a boost this month when the University of Texas was authorised to spend $50 million towards its $1.05 billion cost, with the promise of a further $50 million to be produced through fundraising. The new observatory will be built on a peak in the desert called Cerro Las Campanas, at an altitude of 2,550 metres (8,500ft) and enjoying excellent clear dark skies for more than 300 nights a year. It will gather so much light that astronomers will be able to see back in time to the formation of the earliest galaxies to form in the Universe, 13 billion years ago, but also hopefully image planets orbiting some of our closer stellar neighbours. A daylight view of how the Giant Magellan Telescope will look. Credit: Giant Magellan Telescope - GMTO Corporation David Lambert, director of the McDonald Observatory in Texas, said: “If we succeed, I think the discovery of a series of habitable planets would be a landmark in human history.” Three of the primary mirrors are already being made at the Steward Observatory Mirror Lab (SOML) in Tucson, Arizona. Like all such mirrors in reflecting telescopes, they are concave, but polished to give a surface accuracy of about one millionth of an inch. They are lighter than traditional main mirrors too because they are made with a honeycomb centre rather than a solid one. Even so, each weighs 12.5 tons! Another touch is that the mirrors’ glass is cast in a rotating oven so that it cools with an already parabolic shape to its surface, reducing the amount of grinding required. When light that has travelled for billions of years from the furthest reaches of the Universe hits the seven primary mirrors, it will be reflected to seven smaller secondary mirrors which will again redirect them through a hole in the central main mirror to CCD cameras and instruments that will analyse it. As is common with giant telescopes nowadays, the telescope will use adaptive optics in order to provide the sharpest images possible and compensate for the turbulence, or “twinkle”, introduced by the Earth’s atmosphere. It will do so using hundreds of actuators beneath the surface of the flexible secondary mirrors. These will be controlled by advanced computers to change the surface shapes of the mirrors so that they show stars as steady points of light. Announcing the latest funding for the GMT, University of Texas Austin President Bill Powers said: “Not only will we be helping to answer the most basic questions about our Universe, but our involvement will underscore our status as a top world university. This is the leading edge of science, and it is where Texas must be.” sen/news/another-giant-telescope-gets-funding-boost
Posted on: Mon, 17 Mar 2014 08:42:20 +0000
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