Monday, January 22, 2001
Tapping lasers to search for life in universe
A new telescope will use powerful beams of light to discover if E.T. really
does exist.
By Peter N. Spotts Staff writer of The Christian Science Monitor
E.T. hasn't phoned yet, but perhaps he's left a light on in the window.
Figuring an advanced civilization would hand out its galactic calling cards
on powerful laser beams instead of microwave signals, astronomers in the
United States are building the country's first telescope dedicated to
looking for E.T.'s optical beacon.
The 72-inch scope, under construction at the Harvard-Smithsonian Oak Ridge
Observatory in Harvard, Mass., is one of several new efforts that hope to
answer the age-old question: Are we alone in the universe?
"We've got organic molecules in space, we've got planetary systems, we have
life right away on Earth," and microbial life in extreme environments on our
planet, says Harvard University astrophysicist Paul Horowitz, who heads the
new telescope project. "What do you need to convince yourself that this is a
normal phenomenon?"
While no one is trying to communicate with molecules or microbes, the galaxy
has been around long enough for life to have emerged and evolved to
technological levels exceeding our own - at least in principle.
For years, scientists searching for extraterrestrial intelligence (SETI)
have used radio telescopes to search for signals from alien civilizations.
So far, they've come up dry. While those efforts will continue, Dr. Horowitz
says, many in the SETI community have come to appreciate the promise light
may hold for making first contact.
"Optical wavelengths have a lot of advantages that would make lasers the
method of choice," Horowitz says.
A laser beam, for example, can pack more information than radio. Although
galactic dust would block long-haul communications, he adds, visible light
"works well for regional and local calling" - out to about 1,000 light
years.
Easy to build for E.T.
If technological neophytes such as humans can figure out how to build them,
laser transmitters would be a snap for more advanced cultures.
Horowitz figures that if scientists used the 10-meter Keck scopes in Hawaii
to send billionth-of-a-second laser pulses, the beam blasting from the scope
would shine 1,000 times brighter than our sun.
Those pulses would be easy pickings for another 10-meter telescope 1,000
light years away. Within that distance, astronomers estimate the sky holds
roughly a million sun-like stars.
The concept of optical communications between solar systems is hardly new.
In 1961, three years after Arthur Shawlow and Charles Townes announced their
invention of the laser, the duo published a paper in the journal Nature
describing how lasers could be used for SETI work. But the concept failed to
catch fire in the US as a means of searching for other civilizations.
The reasons have less to do with technology than with technological
prejudices in the SETI community in the 1960s and '70s, according to Stuart
Kingsley, an electronics engineer who has long championed optical SETI
efforts.
From radios to lasers
He notes that during those two decades, the Russians were using telescopes
to look for optical signals from beyond our solar system. But in the US,
SETI efforts focused on using large radio telescopes.
In the past four years, however, a growing number of researchers at
institutions such as Harvard, Columbia, and the University of California at
Berkeley, have been developing optical approaches to SETI projects.
Nor are such projects limited to PhDs. Dr. Kingsley has spent nearly 11
years developing a backyard optical SETI observatory, using a 10-inch
amateur telescope.
He and Monte Ross, who heads a laser-communications company in St. Louis,
hope to pull together a relatively inexpensive package of detectors and
software that would allow amateur astronomers to take part in a coordinated,
Internet-linked optical-SETI project.
As with radio searches, optical-SETI projects remain privately funded.
Congress banned the use of federal funds for SETI work in 1993.
The Planetary Society, for example, is paying $350,000 to finance Horowitz's
project. It plans to announce its sponsorship today in San Jose, Calif.,
where optical-SETI aficionados are holding their third annual conference.
Other projects under way
The Harvard project is just one outcome of meetings held in the late 1990s
by the SETI Institute, a nonprofit organization in Mountain View, Calif., to
chart the future course of SETI efforts.
Another key project under way is the construction of a $26 million
1,000-dish array of radio telescopes at Berkeley's Hat Cree Observatory in
northern California.
The observatory, whose individual dishes aren't much larger than backyard
satellite-TV dishes, is designed to allow SETI researchers to conduct their
own searches while radio astronomers use the facility for more mainstream
studies.
In addition, Berkeley's two-year-old SETI@home project is moving into a new
phase that will use personal computers, in homes and offices around the
world, to sift through radio-telescope data from the Southern Hemisphere for
E.T.'s signals.
Until now, the program has drawn its data from the Arecibo Radio Telescope
in Puerto Rico. The project, which tied home PCs into the world's largest
supercomputer, has logged more than 500,000 years of cumulative computing
time since it began in the spring of 1999. More than 2.7 million people are
taking part.
For all the effort, it's no surprise that searchers have found nothing so
far, says Louis Friedman, executive director of the Planetary Society in
Pasadena, Calif. Humans have been looking for only about 40 years. Over the
longterm, he says, he gives search efforts a 50-50 chance of success.
The payback, however, would be enormous. "The discovery that we're not
alone, that there are other beings close enough to us to have communications
technology? There would be few moments like it in human history," he says.
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