Planetary Society's SETI@home Takes New Step in Search for ET:

After nearly four years of searching for extraterrestrial intelligence, the SETI@home project will now take a closer look at its most promising candidate radio sources. The "Stellar Countdown" will use Puerto Rico's Arecibo radio telescope on March 18-20, 2003 to re-observe up to 150 of the most interesting radio sources found out of the billions detected since the distributed computing project began in May 1999.

The Planetary Society is the founding and principal sponsor of SETI@home, which is based at the University of California, Berkeley. SETI@home harnesses the computing power of four million volunteers to analyze data from the Arecibo telescope. Designed as an innovative screensaver program, SETI@home parcels out packets of raw data from Arecibo to be processed in the personal computers of volunteers around the world.

David Anderson, SETI@home's Project Director, said, "After the re-observations of our Stellar Countdown help us eliminate candidates that are random noise or terrestrial radio interference, we will be very curious to see what candidates remain."

On-the-spot analysis of data during the Arecibo observing run will allow the team to re-target any especially promising signals. A more detailed analysis of the Stellar Countdown results will be conducted after the SETI@home team returns to UC Berkeley.

Candidate radio sources were chosen on the basis of several criteria:

• number of times the radio source was detected
• how closely different observations resemble each other
• strength of radio source
• proximity to known stars
• type of star (main sequence stars given preference)
• the presence of known planets

Dan Werthimer, Chief Scientist of SETI@home, will lead the team conducting re-observations at Arecibo. The researchers will observe the sky eight hours each day, staggering the time of day for each session to cover as much sky as possible.

Werthimer, who will head for the Arecibo observatory on March 16, said, "I believe that we will likely discover extraterrestrial civilizations in the next hundred years. Even if we don't find a signal from ET this time, I'm optimistic in the long run, since our search capabilities are doubling every year."

SETI@home is the largest computation in human history, logging a staggering 1.3 million years of computer time. The screensaver program runs on computers in homes, offices and schools worldwide, and volunteers range in age from school children to retirees.

"Whether or not SETI@home succeeds in finding evidence of extraterrestrial intelligence at this early date," said Bruce Murray, Chairman of the Society's Board of Directors, "this project has already made history. SETI@home has performed the most sensitive and detailed SETI sky survey to date, has demonstrated the power of the Internet for doing scientific distributed computing, and has allowed the general public to participate directly in an exciting research project."

The Planetary Society has provided privately raised funds for more than a dozen searches for ET around the world since 1983. Currently, it is supporting searches in both optical and radio frequencies.

Read daily updates from the Arecibo research team during the Stellar Countdown. The Planetary Society's website will also features maps of the candidate targets and articles about the re-observations, SETI@home, and the search for extraterrestrial intelligence. Dan Werthimer will be the guest on the Society's Planetary Radio program, Monday, March 17.