The UC Berkeley Search For Extraterrestrial Civilizations
The UC Berkeley SETI Program, SERENDIP (Search for Extraterrestrial
Radio Emissions from Nearby Developed Intelligent Populations)
is an ongoing scientific research effort aimed at detecting radio
signals from extraterrestrial civilizations. The project is the world's only
"piggyback" SETI system, operating alongside simultaneously conducted
conventional radio astronomy observations. SERENDIP is currently piggybacking
on the 1,000-foot dish at Arecibo Observatory
in Puerto Rico, the largest radio telescope in the world.
SERENDIP is dedicated to providing an answer to the age-old question "Are
we alone?"
SERENDIP IV
We installed SERENDIP IV, the latest SERENDIP instrument,
at the Arecibo Observatory
on June 11. During this initial checkout phase both hardware
and software
have been working perfectly!
The SERENDIP IV instrument consists of 40 spectrum analyzer boards
working in parallel to look at 168 million narrow (0.6Hz) channels every
1.7 seconds. It is essentially a 200 billion-instructions-per-second
supercomputer. The observatory will install a dedicated receiver for the
SERENDIP IV sky survey.
Additional information is available in a recent
press release
from the University of California.
SERENDIP Worldwide!
We are now building two 4 million channel versions of the SERENDIP IV system.
One is for the University of Western Sydney, Macarthur in Australia,
and the other is for the Institute of Radioastronomy in Bologna, Italy.
Both of these groups have access to major radio telescopes and
have innovative ideas as to how to utilize the SERENDIP system in their
search.
Ain De Horta, from the Australian group, has joined us for the summer to
work with us on the Australian system.
SETI@home
As announced at the 1996 Bioastronomy conference in Capri,
the SERENDIP team is working with the University of Washington and
Big Science
on a project that
will enable people with home computers to actively participate in SETI.
Called SETI@home, the project will use screen saver and Internet technology
to allow users to analyze SERENDIP data.
We hope to have this available in 9 to
12 months.
Rationale for radio SETI
Radio is believed by most scientists to be the best and perhaps only
chance we have at interstellar
communication, considering the distances involved. Radio waves, like all
electromagnetic radiation, travel at the speed of light, 300,000
kilometers per second. This is the fastest velocity possible, and yet even
Proxima Centauri, the closest star to our own sun, is far enough away that
light takes approximately four years to make the journey. Almost all
stars are much
further away.
In contrast to the speed of light, the fastest space vehicle we have with
current technology travels about 25,000 miles per hour, or about 4 kilometers
per second. At such speeds, it would take a rocket 300,000 years to reach our
nearest neighbor.
Radio waves are thought to be the the optimum band of the electromagnetic
spectrum for
interstellar communication because radio wavelengths are relatively free
of the absorption and noise that plagues other areas of the spectrum. Radio,
visible light, and the near infrared are the only electromagnetic frequencies
able to penetrate the earth's atmosphere, and of the three, radio is not as
easily absorbed by interstellar gas and dust. In addition, stars are generally
quiet (or dim) in the radio wavelengths. This makes radio a natural candidate
for a deliberate beacon by an advanced civilization, or for interstellar
communications between civilizations.
Besides deliberate interstellar transmissions, other civilizations may
well radiate radio "leakage," or unintentional transmissions beyond their own
planets. Nearly all of the artificial electromagnetic
radiation emitted from the earth is in the radio spectrum. Technological
civilizations within about a 50 light-year radius of the solar system could
now be watching first-run broadcasts of "I Love Lucy" and "The Honeymooners."
By the same token, SERENDIP researchers may one day serendipitously pick up
the Tau Ceti equivalent of terrestrial TV shows.
Description of the SERENDIP project
Arecibo Observatory plays host to the SERENDIP instrument
For the last five years we had our current spectrum analyzer, SERENDIP
III, at the
Arecibo Observatory in Puerto Rico. This is the world's largest telescope
and is equipped with state-of-the-art radio receivers. Our piggybacking
approach has allowed us to observe essentially full time.
With the SERENDIP III instrument, we examined 4.2 million channels
every 1.7 seconds in a
12 MHz-wide band centered at 429 MHz. This is only a small piece of the
electromagnetic
spectrum, but it is by far the largest segment ever examined so
comprehensively. SERENDIP IV, our recently installed next generation instrument,
will examine 168 million channels every 1.7
seconds in a 100 MHz band centered at 1.42 GHz. The SERENDIP instrument stores signals that peak
significantly above the background noise.
The data gathered by the instrument are transferred across the Internet to the
SERENDIP lab at Berkeley. There we run the data through a series of
algorithms designed to reject radio frequency interference and detect signals
that have some possibility of being both artificial and extraterrestrial.
Current results
The 4 year SERENDIP III sky survey at Arecibo Observatory has recently been
completed,
logging a total of 10,000 hours of observation time. The project has observed 93
percent of the sky visible from Arecibo at least once, and has searched
43 percent of the Arecibo sky at least 5 times. Along the way, SERENDIP
has probed more than 100 trillion radio channels at very high sensitivity.
Final SERENDIP III data analysis is currently under way.
So far, no signal has been so amazing that it has sent us
rushing to Arecibo seeking dedicated telescope time for reobservation,
but the entire run of
data is getting a fresh look. When all of the data are
considered together, some candidates, such as those in which strong signals
recur several times, become more interesting. We then run
these candidates through additional algorithms, such as one to determine if
there is a likely star in the vicinity of the signal. If the same point in the
sky shows up on several different algorithms, it of course becomes much more
interesting.
This page will be updated when the analysis is complete.
SERENDIP has been in operation for 18 years, beginning with SERENDIP I in
1979. The SERENDIP I instrument consisted of a 100-channel spectrum analyzer
which was located at UC Berkeley's Hat
Creek Observatory.
Since that time, SERENDIP has undergone a series of sequential improvements.
SERENDIP II, which ran from 1986 to 1988, was thousands of times more powerful
than its predecessor. The second-generation instrument was able to observe
65,000 channels per second and was primarily located at the 300-foot NRAO
radio telescope at Green Bank and to a
lesser extent on four other high-quality telescopes around the world.
SERENDIP III began operations at Arecibo in April 15, 1992. The end of its
4 year survey coincided with the beginning of a major upgrade at Arecibo.
The upgrade is now complete, and
SERENDIP IV was installed at Arecibo in June 1997.
It greatly enhances the SERENDIP search;
we will collect 168
million channels worth of data every 1.7 seconds. SERENDIP IV, like SERENDIP
III, is piggybacking on the Arecibo telescope. Dedicated
telescope time will be used to look back at the most interesting candidates
from this and previous searches.
In addition to the new SERENDIP IV systems under construction
for the groups in Australia and Italy,
other SETI groups have adopted all or part of the SERENDIP III system in their
search efforts. The SERENDIP III design is at the heart of the Harvard
BETA system.
BETA, or Billion-channel ExtraTerrestrial Assay, replaces the
system previously used by Harvard.
Ohio State University has been using a 4 million-channel version of
SERENDIP IV for conducting SETI observations at OSU radio observatory.
Project Phoenix, of the SETI Institute, used the SERENDIP II
instrument for radio frequency interference studies.
