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Thinking space<br />

Ano<strong>the</strong>r way to encourage gifted individuals might be to reform <strong>the</strong> way time on telescopes is allocated.<br />

The IAU’s new president, Robert Williams of <strong>the</strong> Space Telescope Science Institute in Baltimore, Maryland,<br />

is a supporter of this idea. He reckons decisions about who gets what observing time should be made by<br />

<strong>the</strong> directors of observatories, answerable to a governing body, ra<strong>the</strong>r than by groups of <strong>the</strong> great and<br />

good, as tends to happen now.<br />

“High-risk, high-reward projects require hard decisions that are best made by individuals, not<br />

committees,” he says. And he should know. As director of <strong>the</strong> Space Telescope Science Institute he was,<br />

in 1995, allocated ten days on Hubble (pictured above), America’s most famous eye in <strong>the</strong> sky. Instead of<br />

using that time on a project with a preordained objective, he asked, in what might be seen as an act of<br />

ei<strong>the</strong>r modesty or bravura, that <strong>the</strong> telescope be pointed at a typical patch of sky and left <strong>the</strong>re for <strong>the</strong><br />

whole period, to see what it could see.<br />

The result was <strong>the</strong> Hubble Deep Field, a fantastically detailed image of a small region in a constellation<br />

called Ursa Major. The field of view is so narrow that only about 20 stars from <strong>the</strong> Milky Way, <strong>the</strong> galaxy<br />

in which <strong>the</strong> Earth resides, lie within it. What it shows instead is almost 3,000 galaxies, some of which are<br />

<strong>the</strong> most distant (and hence <strong>the</strong> youngest) ever observed. The image demonstrates that <strong>the</strong> universe is,<br />

indeed, uniform over large scales and that <strong>the</strong> Earth occupies a typical region of it. It is unlikely that a<br />

committee would have had <strong>the</strong> guts to allocate so much time to what was a speculative punt.<br />

Yet despite <strong>the</strong> professed desire of some to do so, astronomers cannot turn <strong>the</strong>ir backs on big science. In<br />

particular, to see faint, distant objects at <strong>the</strong> dawn of time, as Dr Williams did with Hubble, you need to<br />

collect a lot of light. That means your telescopes need big mirrors. And big mirrors do not come cheap.<br />

Back on Earth, <strong>the</strong> biggest mirrors in prospect belong to three telescopic<br />

projects that will, by coincidence, all come to fruition in 2018, if <strong>the</strong>ir<br />

backers get <strong>the</strong>ir way. The Giant Magellan Telescope, a joint effort by<br />

America, Australia and South Korea that is to be built in <strong>the</strong> Atacama<br />

Desert in Chile, would have seven mirrors, each 8.4 metres across, giving<br />

an effective diameter of 25 metres. An even larger beast, dubbed <strong>the</strong><br />

Thirty Metre Telescope, for obvious reasons, is a collaboration between<br />

American and Canadian universities. It has been on <strong>the</strong> drawing board<br />

since 1990. Last month its project board announced that, if funding were<br />

forthcoming, it would be built on Mauna Kea in Hawaii.<br />

The third, <strong>the</strong> European Extremely Large Telescope, is <strong>the</strong> suggested<br />

replacement for <strong>the</strong> Overwhelmingly Large Telescope, a proposal rejected<br />

by <strong>the</strong> European Sou<strong>the</strong>rn Observatory three years ago when it discovered<br />

that <strong>the</strong> bill would also be overwhelmingly large. Its mirror would be 42<br />

metres across, and it would probably be built ei<strong>the</strong>r on one of <strong>the</strong> Canary<br />

Islands or in Chile.<br />

Science Photo Library<br />

Galileo moved <strong>the</strong> Earth<br />

Besides <strong>the</strong>se new conventional telescopes, completely novel ways of doing Big Astronomy are likely to<br />

emerge to tempt astronomers back into its clutches. Several projects are already under way to detect<br />

gravitational waves—ripples in <strong>the</strong> fabric of spacetime itself—although none has yet caught its quarry.<br />

Should <strong>the</strong>y, or <strong>the</strong>ir successors, eventually do so, it would open up a new window on <strong>the</strong> universe,<br />

allowing astronomers to study massive objects such as colliding black holes in unprecedented detail.<br />

Astrophysicists have also begun to be able to detect <strong>the</strong> directions from which streams of subatomic<br />

particles called neutrinos arrive, and progress is being made as well on interpreting cosmic rays. Once<br />

<strong>the</strong>se are better understood, astronomers could use <strong>the</strong>m to study <strong>the</strong> universe in <strong>the</strong> way <strong>the</strong>y now use<br />

light and radio waves.<br />

Yet astronomers are still right to want space for <strong>the</strong> small. The two most exciting recent findings—<strong>the</strong><br />

discovery of “dark energy”, which pushes space itself apart, and of planets beyond <strong>the</strong> solar system—were<br />

made using modest equipment. It is <strong>the</strong> very success of <strong>the</strong> small that promotes <strong>the</strong> growth of <strong>the</strong> big.<br />

Copyright © 2009 The Economist Newspaper and The Economist Group. All rights reserved.<br />

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