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Thinking space
Another way to encourage gifted individuals might be to reform the way time on telescopes is allocated.
The IAU’s new president, Robert Williams of the Space Telescope Science Institute in Baltimore, Maryland,
is a supporter of this idea. He reckons decisions about who gets what observing time should be made by
the directors of observatories, answerable to a governing body, rather than by groups of the great and
good, as tends to happen now.
“High-risk, high-reward projects require hard decisions that are best made by individuals, not
committees,” he says. And he should know. As director of the Space Telescope Science Institute he was,
in 1995, allocated ten days on Hubble (pictured above), America’s most famous eye in the sky. Instead of
using that time on a project with a preordained objective, he asked, in what might be seen as an act of
either modesty or bravura, that the telescope be pointed at a typical patch of sky and left there for the
whole period, to see what it could see.
The result was the Hubble Deep Field, a fantastically detailed image of a small region in a constellation
called Ursa Major. The field of view is so narrow that only about 20 stars from the Milky Way, the galaxy
in which the Earth resides, lie within it. What it shows instead is almost 3,000 galaxies, some of which are
the most distant (and hence the youngest) ever observed. The image demonstrates that the universe is,
indeed, uniform over large scales and that the Earth occupies a typical region of it. It is unlikely that a
committee would have had the guts to allocate so much time to what was a speculative punt.
Yet despite the professed desire of some to do so, astronomers cannot turn their backs on big science. In
particular, to see faint, distant objects at the dawn of time, as Dr Williams did with Hubble, you need to
collect a lot of light. That means your telescopes need big mirrors. And big mirrors do not come cheap.
Back on Earth, the biggest mirrors in prospect belong to three telescopic
projects that will, by coincidence, all come to fruition in 2018, if their
backers get their way. The Giant Magellan Telescope, a joint effort by
America, Australia and South Korea that is to be built in the Atacama
Desert in Chile, would have seven mirrors, each 8.4 metres across, giving
an effective diameter of 25 metres. An even larger beast, dubbed the
Thirty Metre Telescope, for obvious reasons, is a collaboration between
American and Canadian universities. It has been on the drawing board
since 1990. Last month its project board announced that, if funding were
forthcoming, it would be built on Mauna Kea in Hawaii.
The third, the European Extremely Large Telescope, is the suggested
replacement for the Overwhelmingly Large Telescope, a proposal rejected
by the European Southern Observatory three years ago when it discovered
that the bill would also be overwhelmingly large. Its mirror would be 42
metres across, and it would probably be built either on one of the Canary
Islands or in Chile.
Science Photo Library
Galileo moved the Earth
Besides these new conventional telescopes, completely novel ways of doing Big Astronomy are likely to
emerge to tempt astronomers back into its clutches. Several projects are already under way to detect
gravitational waves—ripples in the fabric of spacetime itself—although none has yet caught its quarry.
Should they, or their successors, eventually do so, it would open up a new window on the universe,
allowing astronomers to study massive objects such as colliding black holes in unprecedented detail.
Astrophysicists have also begun to be able to detect the directions from which streams of subatomic
particles called neutrinos arrive, and progress is being made as well on interpreting cosmic rays. Once
these are better understood, astronomers could use them to study the universe in the way they now use
light and radio waves.
Yet astronomers are still right to want space for the small. The two most exciting recent findings—the
discovery of “dark energy”, which pushes space itself apart, and of planets beyond the solar system—were
made using modest equipment. It is the very success of the small that promotes the growth of the big.
Copyright © 2009 The Economist Newspaper and The Economist Group. All rights reserved.
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