New telescope could reveal secrets of the universe
When Douglas Adams wanted the answer to life, the universe and everything, he arrived at the number 42. Now, a few decades later, astronomers have caught up, choosing that number as the diameter -- in metres -- of a proposed new telescope that will uncover how the universe evolved in its earliest years and could reveal whether life exists anywhere else in the cosmos.
The Extremely Large Telescope (ELT) being proposed by scientists from a consortium of European countries based at the Cerro Paranal observatory in Chile's Atacama desert will dwarf anything astronomers use today. It could be used to address mysteries such as what the first objects in the universe were, how many types of matter exist and whether there are any other Earth-like planets in our galaxy.
"There are two questions: how did the universe begin and how did life begin?" said Andreas Kaufer, director of the European Southern Observatory's (ESO) telescopes at Cerro Paranal. To answer these questions, astronomers need bigger telescopes. Last month, ESO set up an expert group to deliver a design for the ELT by the end of the year.
"We have to go for the next step that is technologically possible and that is what 42m seems to be," said Dr Kaufer. The telescope, which could cost up to €1-billion and be located in Antarctica, would be operational within a decade.
The sharpest eye that astronomers have on the universe today is ESO's Very Large Telescope (VLT), a €500-million array of four 8m-diameter telescopes that sit on the 2 500m-high peak of Cerro Paranal. These telescopes have produced the first direct images of planets outside our solar system, weighed distant stars and made important observations of black holes.
But the VLT cannot see small planets. The faintest objects at the edge of the universe, which give astronomers clues about how the universe began, are barely detectable.
Bigger telescopes can gather more light and, therefore, produce much more information. The ELT will be able to image faint, previously unseen objects such as cold stars, baby galaxies and small planets, while collecting far more detail on the more familiar ones.
"We will start to see the chemical composition of the very early galaxies, which will tell us about how the first generation of stars evolved and when they were formed," said Kaufer.
The ELT will also be able to take pictures of individual stars in faraway galaxies for the first time. "All galaxies are composed of stars and we understand stars very well, so we can use them to understand galaxies. That's interesting if you want to know how the first galaxies developed," said Kaufer.
Another driver for the ELT has been to take pictures of planets around other stars. Because the light from stars drowns out any light reflecting off the planets orbiting them, spotting planets is rare. As a result, astronomers have only ever photographed three extrasolar planets directly. Because the ELT would be more sensitive, it could regularly image these faint objects, raising the chances that astronomers could find another Earth-like planet, which may harbour life.
The concept for the ELT came from a long-discussed dream by astronomers to build a 100m-wide telescope called OWL -- the Overwhelmingly Large Telescope. A study published earlier this year, however, suggested that there were too many hurdles: the mirror would need an amount of steel equivalent to the Eiffel tower to support it, the whole structure had to be moveable, and it would probably cost €1,5-billion.
But the study opened astronomers' minds to the idea of large telescopes. Kaufer said that ESO's expert team is considering options for a telescope somewhere between 30m and 60m in diameter, partly driven by competition with the Americans, who are planning a 30m telescope.
"We want to do something a bit bigger -- the working area at the moment is 42m, the average area between 30m and 60m," said Kaufer. "We want to present the full concept by the end of this year."
The ESO team is canvassing opinions from astronomers around the world and scouting potential locations -- the shortlist includes Chile, Morocco, Tibet, South Africa, Greenland or a place called Dome C, a 3 000m plateau in Antarctica -- before designing the ELT. Kaufer said, if all went well, construction could begin by 2010 with the first science results coming as early as 2016.
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