ET, phone SETI@home - In only one week since the release of free SETI@home software nearly 300,000 computers have contributed 1100 years of CPU time to the search for extraterrestrial life. Read this article to find out how you can join the search, to discover how SETI@home works, and to learn more about the giant radio telescope that collects the data for your home computer.
University of California-Berkeley
BERKELEY -- One hundred lucky pioneers will get the chance of a lifetime this month -- the opportunity to participate in a unique search for extraterrestrial intelligence from their desktop computer.
These one hundred will test a one-of-a-kind computer program called SETI@home that allows a desktop PC to analyze radio data from space in search of intelligent signals. If all goes well, the finished product will roll out next April for 100,000-plus people who have already signed up to participate.
The computer program is essentially a screen saver that kicks in when your desktop computer is idle, and crunches data collected from a radio dish in Puerto Rico.
"SETI@home is a way of harnessing all the idle computers to increase our computing capacity and our chance of finding extraterrestrials," said SETI@home project scientist Dan Werthimer, a research physicist at UC Berkeley's Space Sciences Laboratory.
SETI@home -- named after the acronym for the search for extraterrestrial intelligence, SETI -- is a way for UC Berkeley's SETI physicists to more thoroughly analyze the data they receive daily from their ongoing survey of the sky using the large radio dish at Arecibo, Puerto Rico. This 20-year-old search, which piggybacks on the Arecibo telescope, is called SERENDIP IV -- the fourth incarnation of an instrument designed to Search for Extraterrestrial Radio Emissions from Nearby Developed Intelligent Populations.
Unfortunately, the computer capacity available to SERENDIP is sufficient to look for only the most obvious signals from extraterrestrial civilizations, Werthimer said.
"In terms of science, SERENDIP is very powerful, but it looks for a very restricted class of signal," said Werthimer. "SETI@home does an exceptionally good job of analyzing a small band of signals very thoroughly."
The radio data is broken down into small chunks -- typically a range of wavelengths -- through which the screen saver program can search for patterns that may indicate a deliberate broadcast from a distant civilization.
"You can download enough data through the internet in five minutes to keep the computer analyzing for several days," said computer scientist David Anderson, project director and a long-time volunteer with the project. "The computer then sends back a summary of the interesting stuff it found, and gets another chunk of data."
As the computer works away at the data, the computer screen displays a three-dimensional graph charting the signal analysis.
Anderson developed the screen saver program that crunches the data, now available only for PCs. He currently is developing versions for Macintosh, Unix, Linux and other systems.
"The point is to get the bugs out of the software so we are ready to go for 100,000 people in April," Werthimer said.
The SETI@home project is the first "distributed computing" project to offer the general public the opportunity to participate in important research. Distributed computing is a way of breaking down a problem requiring lots of computation into small chunks that can be done by many small computers distributed anywhere in the world.
"Ours is the first that actually does a useful computation and sends data both ways through the pipe," Anderson said.
The type of data coming from SERENDIP is particularly suitable for distributed computing, Anderson said, though other major scientific projects -- drug discovery, for example -- might also be candidates. The main requirement is number crunching, or in computer jargon, CPU (computer processing unit) time.
"Projects suitable for distributed computing are those that are very CPU intensive with not a lot of data to transfer," Anderson said. "But there are many such projects, which may create a future market in CPUs."
SETI@home has been building to this point for several years, mostly with the help of volunteers. What finally got it off the ground, however, was an infusion of money from the Planetary Society, which donated $50,000, and Paramount Studies, which donated another $50,000 and is tying the project to the launch of its new movie, "Star Trek: Insurrection," December 11. Sun Microsystems also has donated computer equipment to SETI@home.
With the publicity generated by these two donors, the project is getting a thousand new sign-ups each day, Werthimer said.
The SERENDIP IV instrument on the 1,000-foot diameter Arecibo dish looks at radio signals in the "water hole," an area of the spectrum identified as a possible region where advanced civilizations might broadcast a signal. It is located to either side of the 21 centimeter wavelength, the wavelength of light absorbed by water molecules in space.
SERENDIP records signals in a band around the water hole and stores them on magnetic tape, which is expressed to UC Berkeley for analysis. The more detailed analysis that can be done by the SETI@home screen saver will look for unusual patterns that are too complex and time consuming for the SERENDIP project to attempt.
Whatever interesting signals may turn up from SETI@home must be checked by people like Werthimer to make sure they are not due to radio interference from Earth or orbiting satellites.
"We're not asking people to call the press when they see a spike on the screen," Werthimer said. "We get strong signals all the time and have to sift through them."