From Diana J. Choyce
Mar 13 - 26, 2000
Mid February is the time for Astronomer Seth Shostak to do his
semi-annual hunt for extraterrestrials. He travels to Puerto Rico, and a rectangular,
100-mile slab of tilted limestone that holds the world's largest radio telescope. The
Arecibo radio telescope is 1000 feet wide, 167 feet deep and covers 20 acres. Mr. Shostak
is an astronomer for Project Phoenix, an extremely sensitive experiment that listens for
faint radio broadcasts from nearby star systems. Twice a year, Project Phoenix gets a few
weeks of valuable telescope time on the Arecibo antenna. Mr. Shostak will join a group of
colleagues who come form the SETI Institute's headquarters in California for this twice a
year listening session. The Phoenix strategy is to concentrate on specific patches of sky
in the direction of nearby stars. By excluding the idea of looking everywhere, this search
can spend more time checking out our nearest neighbors. More time means more sensitivity.
It is sometimes remarked that the Phoenix equipment could pick up a cell phone on Jupiter.
The scientists and engineers number about 6. Although the group is small, as are all such
SETI based groups, they are passionate and dedicated about their project.
There are only three such projects going on in the world today,
including Project Phoenix. Southern SERENDIP is an Australian experiment that involves a
58 million-channel receiver connected to the 210 foot diameter Parkes Radio Telescope,
based in the sheep country about a six hour drive west of Sydney. And finally, Project
SERENDIP is run by a small team at the University of California at Berkeley. SERENDIP
"piggybacks" on regular astronomical observations at the Arecibo Telescope and
examines random tracks of sky with a 168 million-channel receiver. SERENDIP is the focus
of our article this week because of a very interesting program they run via home PC users.
This program is called SETI@Home, and anyone with a PC based computer can help them in
their search for ET.
SETI@home is a scientific experiment that uses Internet-connected
computers in the Search for
Extraterrestrial Intelligence (SETI). One can participate by running a
free program that downloads and analyzes radio telescope data. The list of sponsors for
this project are companies and corporations such as The Planetary Society, the University
of California Digital Media Innovation Program, Sun Microsystems, FijuFilm, IBM, Quantum,
and Friends of SETI@Home, which are solitary individuals. David Gedye, along with Craig
Kasnoff, conceived the idea for SETI@home and formed the initial project team. A
scientific plan was developed that received widespread academic support at the 5th
International Conference in Bioastronomy in July 1996. In 1997 the signal analysis code
and prototypes of the client and server software were developed. 1998 was devoted to
finding funding and the beginning of recording data and testing the client software. Last
year, in April, the program was launched via a website which can be found at
http://setiathome.ssl.berkeley.edu/. The project will run for two years, and the goal is
to process as much information as possible in that time.
Most of the SETI programs in existence today, including those at UC
Berkeley, build large computers that analyze data from the telescope in real time. None of
these computers can look very deeply at the data for weak signals nor do they look for a
large class of signal types. The reason for this is because they are limited by the amount
of computer power available for data analysis. To find the weakest signals, a great amount
of computer power is necessary and would take a supercomputer to get the job done. And
with the small funding involved they cannot afford to build or buy a computer of that
size. Therein lies the idea of using everyday home computers to process the information
necessary. The data analysis task can be easily broken up into little pieces that can all
be worked on separately and in parallel. None of the pieces depends on the other pieces.
SETI "borrows" your computer by using a screen saver that can download a unit of
data over the internet, analyze that data, and then report the results back to them. When
one needs their computer back, the screen saver instantly closes down, and only continues
it's analysis when one is finished with their work. An average, current model home
computer should take between 10 and 50 hours to complete one work-unit. This assumes that
the computer only works on SETI@home.
And what does one get in return for turning their computer over to
SETI? The person(s) who found the signal with their screen saver would be named as one of
the co-discoverers along with the others on the SETI@home team. If a signal is confirmed,
the SETI@home team will request dedicated telescope time and will re-observe the most
interesting candidates. If a signal is observed two or more times, and it's not RFI (Radio
Frequency Interference) or a test signal, the SETI@home team will ask another group to
take a look. This other group will be using different telescopes, receivers, computers,
etc. This will hopefully rule out a bug in their equipment or computer code. If it is
confirmed that the signal is coming from interstellar distances, SETI will make an
announcement in the form of an IAU (International Astronomical Union) telegram. This is a
standard way of informing the astronomical community of important discoveries. At this
point, as one can imagine, all the world will stop and listen to see if indeed we have
finally made contact with ET.
Despite what one may think about the need for us to spend time doing
this, the idea itself is indeed splendid. Using thousands of computers, and saving money
while processing a great deal of information can indeed be very helpful. And the idea of
the world working together and pooling their resources is surely a noble idea. There are
many applications for this idea and one would hope that we start taking advantage of it.