Telescope Ready to Listen for Cosmic 'Howdy-Do'
(From the March/April 2006 issue of StarDate magazine)
If any extraterrestrial civilizations are beaming greetings
into the galaxy, a new listening post in California is ready
to hear them. Called the Allen Telescope Array (ATA) for benefactor
Paul Allen, it will begin monitoring stars toward the center
of the Milky Way galaxy in April.
The dishes of the Allen Array prepare to scan for radio signals.
ATA will continue a search started
in the 1990s by the SETI Institute, says Peter Backus, observing
programs manager for the institute’s
Center for SETI Research. The earlier search, Project Phoenix,
used several radio telescopes, including the 300-meter (1,000-foot)
Arecibo telescope in Puerto Rico, to scan several hundred stars
for signals produced by other civilizations. It found none.
When it begins, ATA will use 42 small radio telescopes linked
by computers to provide the sensitivity of a single radio telescope
40 meters (130 feet) in diameter. The smaller collecting area
means that “we’re basically looking for signals that
are intentional,” Backus says. “With Phoenix, we
could detect the equivalent of an airport radar out to 150 light-years.
But when you use smaller antennas, you put the burden on the
[extraterrestrial] transmitter to be loud and intentional.”
The initial search program will scan a region toward the center
of the Milky Way galaxy. “There are a lot of stars in that
direction,” Backus notes.
At the same time it hunts for ET, the array will conduct conventional
radio astronomy, with up to four observing programs in progress
at the same time. Radio astronomers will determine where the
array points, with SETI scientists scanning target stars in that
direction. Astronomers may search for pulsars, for example, study
stellar nurseries, or measure outbursts from some binary systems.
ATA will expand to 98 antennas next year, and eventually grow
to 350 at its site at Hat Creek Observatory near Reading, California,
greatly increasing its sensitivity. That will allow SETI scientists
to study more than one million target stars. Some of these stars
are similar to the Sun, while others are red dwarfs — much
smaller, fainter stars that may be good candidates for habitable
planets — prime locations for civilizations that are trying
to say “howdy” to their galactic neighbors. — Damond
Benningfield
» More information about extrasolar planets
|
Contact | About | Friends of McDonald | Sign up for Sky Tips
