for National Geographic News
Astronomers searching for signs of intelligent extraterrestrial life wrapped up their mission in Puerto Rico Wednesday to home in on some of the more exciting radio transmission to reach Earth. They collected data on 166 sources, exceeding their original goal of 150.
The astronomers' quick, real-time analysis of the data revealed no evidence of an extraterrestrial civilization, but they will take a more thorough look at it over the next several weeks.
The trip was the culmination of four years of research conducted by SETI@home, a hugely popular distributed-computing project in which more than 4 million people in 226 countries have volunteered their computer's free time to the search for extraterrestrial intelligence (SETI).
"Millions of people around the world have helped get us to the point where we could identify potential targets and take a second look," Bruce Betts, Director of Projects at the The Planetary Society in Pasadena, California, said in a statement. The society is principal sponsor of the project.
"Now the new data will go back to the SETI@home volunteers for more help with this early but critical step in our continuing search for extraterrestrial intelligence," he said.
The volunteers download a screensaver program from the University of California at Berkeley (UC Berkeley) that kicks in when their computer sits idle. The program sorts through chunks of data received from the university via the Internet for unusual radio signals that might be from alien civilizations.
The chunks of data are bits of digitized noise collected by SETI@home researchers who have a special receiver on the National Science Foundation's Arecibo Radio Telescope in Puerto Rico that allows them to "piggyback" on other researchers' use of the telescope.
"We send our data out in what we call work units to the millions of people who use our screensaver program," said David Anderson, a computer scientist and director of the SETI@home project. "It does signal analysis, looking for signals that are not known to occur naturally."
The screensaver then sends back, via the Internet, the most interesting candidates for further analysis by researchers at UC Berkeley. Since the program was started in 1999, the screensavers have sent the university about 5 billion signals worthy of further analysis.
"We've been weeding through all this stuff," said Dan Werthimer, a physicist and chief scientist for the SETI@home project. "We go through and find what is really interesting."
Through a careful analysis of all this information, the SETI@home researchers narrowed the field of candidates to about 150. They scheduled 15 hours of dedicated telescope time beginning March 18 at Arecibo to re-examine these most interesting parts of the sky in the hopes that one of the signals is truly from alien life. The dedicated observing time was interrupted by a need to re-observe a giant solar flare, but resumed March 24.
SOURCES AND RELATED WEB SITES