The case for adding new ground-based telescopes is compelling,
astronomy experts say. But they cost $700 million to $1 billion
apiece just to build.
In a lab beneath the University of Arizona's football field,
scientists are painstakingly polishing a glass disk nearly 28 feet
across - the first of seven mirrors that, when combined to form an
enormous optical telescope, would help revolutionize ground-based
The telescope would reveal the universe's youngest stars and
galaxies. It would analyze atmospheres surrounding planets orbiting
other stars. In our own solar system, it would allow astronomers to
explore frozen orbs far beyond the orbits of Neptune or Pluto in the
so-called Kuiper Belt.
Nor is the Giant Magellan Telescope (GMT), supported by a US-led
international group, alone. Another US-led, international consortium
is moving forward this month on an even larger optical telescope,
the Thirty Meter Telescope (TMT), atop Hawaii's Mauna Kea.
IN PICTURES: Images from the Hubble telescope
And both groups are looking over their shoulders at the
Europeans, who in April approved a site for the European Southern
Observatory's Extremely Large Telescope (ELT), whose 40-meter light-
gathering mirror would make it the largest of the three projects.
Even in an era of space-based telescopes, the case for more glass
on the ground is compelling, astronomers say. The light-gathering
mirrors on space telescopes tend to be relatively small compared
with their ground-based counterparts. So they can't perform the
detailed studies of distant objects as efficiently as the larger,
But these new telescopes are expected to cost between $700
million and $1 billion just to build. Operating costs are likely to
range from $70 million to $100 million a year, several researchers
With all of the projects bidding for government money, "there may
be some hard choices ahead," says David Silva, director of the
National Optical Astronomy Observatories in Tucson, Ariz.
In the United States, the choices revolve not only around which,
if either, of the two projects to support.
A third, more modest US project, called the Large Synoptic Survey
Telescope (LSST), also is vying for construction funds and has been
on the astronomical community's priority list for the past decade.
And astronomers are concerned that these big projects could siphon
funds from other facilities used for important exploration that
doesn't require telescopes whose light-gathering mirrors would fill
nearly half a football field. …