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Project Ozma: The Birth of Observational
SETI
H. Paul Shuch,
Executive Director Emeritus, The SETI League, Inc.
It was an idea whose time had come, but nobody dared admit that out loud.
Frank Drake, in particular, was keeping silent. Like many of his generation,
he had long speculated about the existence of extraterrestrial life, and
pondered how we humans might probe for direct evidence of our cosmic
companions. Now, in 1959, the young astronomer was nally in a position
to do more than ponder. At 29, he had just completed graduate school, the
ink on his Harvard diploma as wet as he was behind the ears. As the new kid
on the block at the National Radio Astronomy Observatory, he had access to
the tools necessary to mount a credible search for radio evidence of distant
technological civilizations. Drake knew enough to tread lightly; a publicly
announced hunt for Little Green Men would be tantamount to professional
suicide, so he approached his superior with understandable trepidation.
Fortunately, NRAO director Otto Struve was sympathetic, even as he
counseled caution. Having theorized that the slowed rotation rate of certain
stars suggested that their angular momentum had been dissipated in the
formation of planets, Struve himself speculated on the probable existence
of extraterrestrial civilizations. So, he authorized Drake to use the 85 foot
diameter Howard Tatel telescope (Figure 2.1) in his off-duty time, to conduct
what was to become the world’s rst observational SETI experiment. Only,
do so quietly, Struve warned; we don’t want the word getting out that we’re
using a government facility to hunt for aliens.
Drake had already run the numbers. He knew the most likely frequency
on which to search, and the best receiver circuitry to employ. He had picked
H. Paul Shuch, Searching for Extraterrestrial Intelligence, The Frontiers Collection,
DOI 10.1007/978-3-642-13196-7_2, © Springer-Verlag Berlin Heidelberg 2011
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his candidate stars, two nearby sunlike ones which he reasoned were likely
to harbor habitable planets. He had selected his research methodology, and
proceeded (very quietly) to assemble his listening station.
And then, the Nature article hit the newsstands. “Searching for Interstellar
Communications” was written by two Cornell University professors,
Giuseppe Cocconi and Philip Morrison, and it proposed, in brief but clear
detail, the very experiment which Drake was preparing to conduct! This very
rst scientic article in the not-yet-named discipline of SETI was complete,
down to the selection of frequencies and target stars – and it paralleled
Drake’s work exactly. Neither the team of Morrison and Cocconi, nor that
of Drake and Struve, knew anything about the others’ interest in this esoteric
study. Both groups had arrived at the same crossroads in history, completely
independently, in an elegant example of what I like to call the Parenthood
Principle: when a great idea is ready to be born, it goes out in search of a
parent. Sometimes, it nds more than one.
Now Schrodinger’s Cat was out of the bag, and Drake had no choice
but to go public. The publicity he received was widespread, and generally
enthusiastic; the scientic community, it appeared, was ready to embrace the
Fig. 2.1 The 85-foot diameter Howard Tatel Telescope at the National Radio Astronomy
Observatory, Green Bank WV, used by Frank Drake for his Project Ozma observations in
April and May of 1960.
Project Ozma
15
notion of SETI. Struve began writing about the possibility of extraterrestrial
life: “An intrinsically improbable event may become highly probable if the
number of events is very great… it is probable that a good many of the
billions of planets in the Milky Way support intelligent forms of life. To me
this conclusion is of great philosophical interest. I believe that science has
reached the point where it is necessary to take into account the action of
intelligent beings, in addition to the classical laws of physics.”
His cover now blown, Drake soon found himself in the company of
other open-minded scientists and technologists, who collectively found
themselves unwitting parents to a newly-emerging scientic discipline.
Among those contacting Drake after reading about his nascent experiment
were: microwave communications expert Bernard M. Oliver, then vice-
president of engineering at Hewlett-Packard (and, later, president of the
Institute of Electrical and Electronic Engineering); Dana Atchley, president
of Microwave Associates in Massachusetts; and a young planetary scientist,
Berkeley post-doctoral researcher Carl Sagan. These individuals, as well as
Struve, Morrison, and a handful of others, were ultimately to become SETI’s
patriarchs. (Cocconi, though having co-authored the seminal SETI article
with Morrison, went on to distinguish himself in particle physics research at
CERN, never to return to the SETI fold.)
Drake named his search Project Ozma, after the princess of Oz in the
L. Frank Baum books, as he saw his efforts leading humans to a far-off
and exotic land. Launched in April 1960, and running only through May
of that year, Ozma searched only two stars, on a single frequency, for mere
dozens of hours, but established the protocols and laid the groundwork for
all subsequent SETI experiments. It was a paradigm-shifting endeavor,
successful for its audacity, if not for its discoveries.
And yet, for one brief moment early on, Frank Drake thought he had hit
paydirt. As he slewed his antenna off Tau Ceti and onto Epsilon Eridani,
he was greeted with a strong, periodic, pulsed signal on 1420 MHz, the
hyperne transition emission line of interstellar hydrogen atoms proposed
by Cocconi and Morrison, and still favored as a promising hailing frequency
for interstellar communications. “My god,” Frank mused, “can it really be
this easy?”
The next day, when the signal reappeared, Drake was ready with a second,
low-gain antenna. The pulses were there as well, sadly disproving their
extraterrestrial origin. But they were not exactly terrestrial interference,
either. The rate at which the phantom signal traversed the sky suggested
that it was emanating from an aircraft cruising at unprecedented altitude
– perhaps 80,000 feet! Of course, in April 1960, no known aircraft could
reach the stratosphere. Such an aircraft, as it happened, didn’t “come into
existence” until the following month, when Francis Gary Powers was shot
down over the Soviet Union. (Frank wisely decided to withhold publication
The Birth of Observational SETI
16
of this positive result, so he never did receive proper credit for “discovering”
the U-2.)
A year after Project Ozma’s brief tenure, Drake convened at Green Bank
the rst scientic conference devoted to modern SETI. He gathered together
10 scientists from disparate disciplines to spend a week contemplating areas
from the physical, biological, and social sciences which had relevance to
the question of extraterrestrial technological civilizations, and how to
communicate with them. The assembly included the six SETI patriarchs
already mentioned, along with J. Peter Pearman of the National Academy
of Sciences’ space science board, Su Shu Huang of NASA, University of
California chemist Melvin Calvin (whose Nobel prize was to be announced
during the Green Bank meeting), and neuroscientist John C. Lilly, who was
then studying the language of dolphins, and attempting to communicate with
these intelligent Earth mammals. The group called themselves the Order of
the Dolphin, a tribute to Lilly’s studies into human -dolphin communication,
which they deemed a worthy metaphor for the challenge of interspecies
communications on a grander, cosmic scale.
Drake chalked on a blackboard seven topics for discussion, which would
comprise the agenda for the week-long meeting. They included stellar
formation, planetary formation, the existence of planets within habitable
zones, the emergence of life, the evolution of intelligence, communications
technology, and the longevity of technological civilizations.
Having established that the emerging discipline of SETI was to encompass
elds as diverse as stellar evolution, planetary astronomy, environmental
science, biology, anthropology, engineering, and sociology, Drake next did
something almost whimsical, which assured his lasting fame: he strung these
seven factors together into an equation (Figure 2.2).
Fig. 2.2 The seven agenda items for the Order of the Dolphin meeting. Strung together,
they form the famous Drake Equation. This plaque graces the very wall on which the
equation was originally scrawled on a chalkboard at NRAO Green Bank in 1961.
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The idea was to multiply seven unknowns together and, in so doing, to
estimate N, the number of communicative civilizations in our Milky Way
galaxy. The Drake Equation, as it is now called, appears in every modern
astronomy textbook. It is a marvelous tool for quantifying our ignorance:
never intended for quantication, but quite useful in narrowing the search
parameters. We still use it, not to seek a numerical solution, but rather to
help us to focus our thinking in designing our searches for life.
Drake’s seven factors are cleverly ordered, from solid to speculative.
Today’s astrobiology meetings are similarly structured. When the equation
was rst published, only the rst factor (the rate of stellar formation) was
known to any degree of certainty.In the intervening decades, Drake’s
equation has guided our research in an orderly manner, from left to right,
so that today we have a pretty good handle on Drake factors two and three
(planetary formation, and habitable zones). The remaining four factors are
still anybody’s guess, and it may well take decades more before our research
begins to quantify those areas of our ignorance. But the Drake Equation
is most valuable in guiding our research, because it asks the important
questions. It is still up to us to answer them.
The lessons learned during the brief course of Project Ozma, amplied
and expanded at the Order of the Dolphin meeting, have informed and
enriched every subsequent SETI experiment. The interdisciplinary nature
of the science now known as SETI was articulated at the outset. Drake’s
work clearly showed that Earth’s technology was at last approaching the
level at which a disciplined search for extraterrestrial microwave emissions
was becoming feasible. The quietest part of the electromagnetic spectrum
was explored then, as now. Highly directional, high gain parabolic antennas,
coupled to very low noise microwave preampliers, remain our preferred
observational tools. Although the advent of multi-channel spectrum
analyzers means we no longer have to select a single channel to scan, SETI
scientists continue to speculate as to universal calling frequencies that alien
civilizations might employ to make their presence known. Concentrating
our efforts on known, nearby sun-like stars remains an accepted technique
for planning targeted searches, one of the two primary search modalities still
practiced. (The other popular SETI research strategy, the all-sky survey, was
long employed at the Ohio State University “Big Ear” radio telescope, and
more recently forms the basis of The SETI League’s Project Argus search,
as discussed in subsequent chapters of this book.)
Most important, Frank Drake’s early efforts began to lend legitimacy to
an endeavor previously considered fringe science. Today, the preponderance
of informed opinion holds that we inhabit a universe teeming with life.
The only matter for speculation is whether we yet possess the technology
necessary to detect it. The emphasis here is on yet. Most of us contemplating
such a detection no longer argue “if” but rather “when.”
The Birth of Observational SETI
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Drake subsequently distinguished himself as Director of the famed
Arecibo Observatory, from which he orchestrated the Arecibo Message,
humankind’s rst deliberate microwave transmission to the stars, as detailed
elsewhere in this volume. His astronomical research has led to important
discoveries about pulsars and Jovian radio emissions. Now retired, he is
today recognized as the godfather of observational SETI. Much in demand
as a speaker at scientic meetings (Figure 2.3), Frank remains deeply
involved in SETI science fully half a century after Project Ozma, serving as
a Director of the SETI Institute in California and on the scientic advisory
board of the nonprot SETI League.
This, then, is Project Ozma’s legacy: it, and Frank Drake, have turned
science ction into credible, respectable science.
Fig. 2.3 In his rightful role as SETI Elder Statesman, Frank Drake still serves as keynote
speaker at SETI conferences all over the world.
Project Ozma
