Telescope May Find Light From Earliest Galaxies
Monday, April 24, 2006
Last November, a thousand people gathered in South Africa's Great Karoo desert to inaugurate the Southern Hemisphere's largest optical telescope. Champagne flowed under azure skies as mingling guests snapped photos of the gleaming white structure, perched starkly against the barren landscape. President Thabo Mbeki gave the keynote address, paying homage to the "Great Eye in the Karoo" and its power to "tackle fundamental questions about the universe."
To its creators, the fanfare was befitting the event: The Southern African Large Telescope, or SALT, can see 13 billion years back in time, nearly to the big bang.
With its 10-by-11-foot hexagonal mirror -- the largest of its type in the world -- SALT concentrates the faintest, most distant light in the universe. If a candle were to flicker on the moon, SALT could detect it.
"One of the hottest things going in astronomy right now is [studying] light remnants from the earliest galaxies, and SALT is very well set up to do that," said Steve Maran, spokesman for the American Astronomical Society.
More than a tool for astronomy, SALT also symbolizes the growing importance of science to South Africa's identity and economy. When the African National Congress won power in 1994, its leaders inherited a science infrastructure created by the apartheid government to sustain white minority rule. Isolated by economic sanctions, that government used science to promote self-sufficiency and defense, said Dhesigen Naidoo, deputy director general of South Africa's Department of Science and Technology: "We decided to build on that but also to change the objectives."
Instead of serving a ruling minority, science aims to serve all 45 million inhabitants, Naidoo said. South Africa spends nearly 1 percent of its gross domestic product on science -- about five times the African average. Reflecting its needs as a developing country, much of that goes toward research in agriculture, health and biotechnology. But astronomy also plays a crucial role in the national research and development strategy, said Derek Hanekom, deputy minister of science and technology, because it draws global collaborators and because it inspires the population, particularly the young.
"When you show young people the telescope, they really seem to get it," he said. "SALT makes them want to get into science. You can't underestimate that in a country where science and math education were systematically neglected."
From its perch in the Great Karoo, far from interfering light pollution, SALT's view of the southern sky is practically unbeatable. The telescope sits in the middle of nowhere -- the nearest town, a frontier outpost called Sutherland, is more than 10 miles away.
"At night with a new moon, you can't even see your feet," said Kenneth Nordsieck, an astronomy professor at the University of Wisconsin and a principal investigator at SALT. "But then you look up at the sky and see the Magellanic Clouds, and it's just awe-inspiring."
Other Southern Hemisphere telescopes, including those in Chile, have views of the same celestial regions. But SALT's enormous light-gathering capacity and innovative design features offer advantages for certain types of research, Nordsieck said.
To save money, SALT's view of the sky is fixed -- astronomers can't point the telescope at specific objects in space. Instead, they wait for Earth's rotation to bring the bodies they want to study past the telescope's eye.
As a result, astronomers will use SALT for large-scale surveys of thousands of stars and galaxies within the telescope's field of view.