[tt] NYT: Stretching the Search for Signs of Life

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Stretching the Search for Signs of Life
http://www.nytimes.com/2007/10/11/science/11seti.html

By DENNIS OVERBYE

Call it a small step for E.T., a leap for radio astronomy.

Astronomers in Hat Creek, Calif., are planning today to switch on
the first elements of a giant new array of radio telescopes that
they say will greatly extend the investigation of natural and
unnatural phenomena in the universe.

When the Allen Telescope Array, as it is known, is complete, it
will consist of 350 antennas, each 20 feet in diameter. Using the
separate antennas as if they were one giant dish, radio astronomers
will be able to map vast swaths of the sky cheaply and efficiently.

The array will help search for new phenomena like black holes
eating each other and so-called dark galaxies without stars, as
well as extend the search for extraterrestrial radio signals a
thousandfold, to include a million nearby stars over the next two
decades.

Today, 42 of the antennas, mass-produced from molds and employing
inexpensive telecommunications technology, will go into operation.
Its like cutting the ribbon on the Nina, the Pinta and the Santa
Maria, said Seth Shostak, an astronomer at the Seti Institute, in
Mountain View, Calif., who pointed out that this was the first
radio telescope ever designed specifically for the extraterrestrial
quest.

The telescope, named for Paul G. Allen, who provided $25 million in
seed money, is a joint project of the Radio Astronomy Laboratory of
the University of California, Berkeley, and the Seti Institute. If
they do find something, theyre going to call me up first and say we
have a signal, Mr. Allen said in an interview, adding, So far the
phone hasnt rung.

Describing himself as a child of the 50s, the golden age of space
exploration and science fiction, Mr. Allen, a founder of Microsoft,
said he first got interested in supporting the search for
extraterrestrial intelligence after a conversation 12 years ago
with Carl Sagan, the Cornell astronomer and exuberant proponent of
cosmic wonder.

When the idea later arose to build a telescope array on the cheap,
using off-the-shelf satellite dish technology and advanced digital
signal processing, Mr. Allen was intrigued. If you know anything
about me, he said, you know Im a real enthusiast for new
unconventional approaches to things.

Telescopes, including radio telescopes, have traditionally been
custom-built one-of-a-kind items. The antennas for the Allen array
are stamped from a mold. Mr. Allens family foundation put up the
money to get the first part of the array built, with other
contributions from Nathan Myhrvold, formerly of Microsoft and the
chief executive of Intellectual Ventures in Bellevue, Wash., among
others.

Leo Blitz, director of the Radio Astronomy Laboratory, estimated
that it would take three years and $41 million more, depending on
the price of aluminum, to complete the array. The full array,
astronomers say, will be useful not just for science, but also as
practice for a truly giant telescope known as the Square Kilometer
Array, which would have a combined receiving area of a square
kilometer and which astronomers hope to build in Australia or South
Africa in 10 or 20 years.

Dr. Blitz said the main advantage of the Allen array for regular
radio astronomy was the ability to obtain images of large swaths of
the sky, several times the size of the full moon, in a single
pointing. At low frequencies, he said, the full array could map the
entire sky in a day and night and do it again the next night.

This has not been possible before, he said.

In its partial form, Dr. Blitz said, the array is already almost as
fast, and much cheaper to run, than larger telescopes.

The speed should make it possible to catch transient events, like
radio bursts from colliding black holes, that might last only a few
hours, while the mapping ability should enable astronomers to
search for lumps of gas without stars, the so-called dark galaxies
predicted by the prevailing models of cosmology.

The search for extraterrestrial intelligence has lived on the
kindness of strangers since Congress canceled a NASA-sponsored
search using existing radio telescopes in 1993, only a year after
it had begun. The Seti Institute, which was to have conducted a
search of nearby stars under contract to NASA, raised money from
Silicon Valley and revived the search as Project Phoenix, using
existing radio telescopes.

Project Phoenix was finished three years ago, having checked some
750 stars for signals, Dr. Shostak said. While that might sound
like a lot, he said, it doesnt impress anybody who knows how many
stars there are in the galaxy.

There are some 200 billion stars in the galaxy, and a significant
fraction of them have planets. Estimates of the number of
intelligent civilizations in the galaxy have ranged from one (or
none, if you are particularly discouraged about human affairs) into
the millions.

Dr. Shostak calculated that the full Allen array would be able to
detect a signal from as far as 500 light years that is only a few
times more powerful than what can now be sent by the Arecibo radio
telescope, a 1,000-foot-diameter dish in Puerto Rico that is the
worlds largest (although it is in danger of being shut down to save
money). That translates to about a million stars, which he said was
getting into a promising number. Dr. Shostak described the expanded
search as looking for the needle in the proverbial haystack with a
shovel instead of a spoon.

Anyone out there and broadcasting, for whatever wacky alien reason,
would also have to be broadcasting right at Earth. But advanced
civilizations, Dr. Shostak said, would be able to tell there was
life on Earth because of the oxygen in our atmosphere.

Weve been broadcasting that for 2.5 billion years, he said.

The first thing Dr. Shostak and his colleagues plan to do with the
newly operational 42-antenna array is to survey a strip across the
center of the galaxy. There will be several billion stars in the
field of view, but they will be very far away, 10,000 to 50,000
light years, so any signal would have to be huge to be detected.
But who is to say that among galactic civilizations there are not a
rare few with tremendous capabilities?

Ive never begrudged aliens any power in their transmitter, Dr.
Shostak said.