For nearly 70 years, astronomers have made some of their most
significant discoveries by tuning in to the universe with telescopes
that gather radio waves instead of light.
Through these sensitive receivers, scientists have detected the
big bang's afterglow, improved their ability to measure the
universe's expansion, and rigorously tested Albert Einstein's theory
of general relativity. Three of the five Nobel Prizes given to
astrophysicists have been awarded for cosmic discoveries made at
Now, a new generation of radio telescopes is moving from design
sketches to construction sites, with the first scheduled to be
dedicated this month.
The devices are engineering marvels - some using thousands of
tiny pistons to keep football-field-size dishes from warping in heat
and wind, and others using complex computer programs to link
hundreds of smaller dishes. And they are expected to open a fresh
round of discoveries as scientists probe the farthest reaches of
space and search for extraterrestrial life.
*In Green Bank, W.Va., the National Radio Astronomy Observatory
(NRAO) is slated to dedicate a new, 100-yard-wide dish this month.
It is the largest fully steerable radio telescope in the world,
observatory officials say.
*High in Chile's Atacama Desert, the NRAO and the European
Southern Observatory are building an array of as many as 64 dishes,
each 12 yards wide. They can be spread over an area more than six
*In California, the University of California at Berkeley and the
Search for Extraterrestrial Intelligence (SETI) Institute are
building an array of 500 to 1,000 small radio telescopes, scheduled
to begin operating in 2005. The primary goal is to search for
signals from alien civilizations.
*Astronomers from five countries and a consortium of European
nations last week signed a pact to begin planning the mother of all
radio telescopes - a connected array of dishes that, taken together,
would yield a combined area of 1 square kilometer.
"It's a new age for radio astronomy," says Alyssa Goodman, who
studies the cosmos in radio wavelengths at the Harvard- Smithsonian
Center For Astrophysics in Cambridge, Mass.
Much of the groundwork for these new instruments has been laid
during the past two decades. During that time, astronomers have
solved a number of technical puzzles that prevented them from
observing the full spectrum of electromagnetic waves that penetrate
"Now what we're doing is building the facilities that allow us to
go beyond the preliminary observations we've been able to make,"
says Lincoln Greenhill of the Center for Astrophysics.
Frontiers of exploration
Those preliminary observations have given astronomers much to
For example, astronomers had once thought that molecules couldn't
exist in interstellar space, because the radiation from stars would
break them apart. …