- Oliver, Bernard M., John Billingham, et al.
Project Cyclops.
Stanford, CA: Stanford/NASA Ames Research Center, 1971.
NASA-CR-114445 N73-18822.
-
There are few questions in science as simple to state and
profound in their implications as “are we
alone?”—are humans the only species with a
technological civilisation in the galaxy, or in the universe?
This has been a matter of speculation by philosophers,
theologians, authors of fiction, and innumerable people gazing
at the stars since antiquity, but it was only in the years
after World War II, which had seen the development of
high-power microwave transmitters and low-noise receivers for
radar, that it dawned upon a few visionaries that this had now
become a question which could be scientifically investigated.
The propagation of radio waves through the atmosphere and the
interstellar medium is governed by basic laws of physics, and
the advent of
radio astronomy
demonstrated that many objects in
the sky, some very distant, could be detected in the microwave
spectrum. But if we were able to detect these natural sources,
suppose we connected a powerful transmitter to our radio
telescope and sent a signal to a nearby star? It was easy to
calculate that, given the technology of the time (around 1960),
existing microwave transmitters and radio telescopes could
transmit messages across interstellar distances.
But, it's one thing to calculate that intelligent aliens with
access to microwave communication technology equal or better
than our own could communicate over the void between the stars,
and entirely another to listen for those communications. The
problems are simple to understand but forbidding to face: where
do you point your antenna, and where do you tune your dial?
There are on the order of a hundred billion stars in our
galaxy. We now know, as early researchers suspected without
evidence, that most of these stars have planets, some of which
may have conditions suitable for the evolution of intelligent
life. Suppose aliens on one of these planets reach a level of
technological development where they decide to join the
“Galactic Club” and transmit a beacon which simply
says “Yo! Anybody out there?” (The beacon would
probably announce a signal with more information which would be
easy to detect once you knew where to look.) But for the
beacon to work, it would have to be aimed at candidate stars
where others might be listening (a beacon which broadcasted in
all directions—an “omnidirectional
beacon”—would require so much energy or be limited
to such a short range as to be impractical for civilisations
with technology comparable to our own).
Then there's the question of how many technological
communicating civilisations there are in the galaxy. Note that
it isn't enough that a civilisation have the technology which
enables it to establish a beacon: it has to do so. And
it is a sobering thought that more than six decades after we had
the ability to send such a signal, we haven't yet done so. The
galaxy may be full of civilisations with our level of
technology and above which have the same funding priorities we
do and choose to spend their research budget on intersectional
autoethnography of transgender marine frobdobs rather than
communicating with nerdy pocket-protector types around other
stars who tediously ask Big Questions.
And suppose a civilisation decides it can find the spare change
to set up and operate a beacon, inviting others to contact it.
How long will it continue to transmit, especially since it's
unlikely, given the finite speed of light and the vast
distances between the stars, there will be a response in the
near term? Before long, scruffy professors will be marching in
the streets wearing frobdob hats and rainbow tentacle capes,
and funding will be called into question. This is termed the
“lifetime” of a communicating civilisation, or
L, which is how long that civilisation transmits and
listens to establish contact with others. If you make
plausible assumptions for the other parameters in the
Drake
equation (which estimates how many communicating
civilisations there are in the galaxy), a numerical coincidence
results in the estimate of the number of communicating
civilisations in the galaxy being roughly equal to their
communicating life in years, L. So, if a typical
civilisation is open to communication for, say, 10,000 years
before it gives up and diverts its funds to frobdob research,
there will be around 10,000 such civilisations in the galaxy.
With 100 billion stars (and around as many planets which may be
hosts to life), that's a 0.00001% chance that any given star
where you point your antenna may be transmitting, and that has
to be multiplied by the same probability they are transmitting
their beacon in your direction while you happen to be
listening. It gets worse. The galaxy is
huge—around 150 million light years in diameter,
and our technology can only communicate with comparable
civilisations out to a tiny fraction of this, say 1000 light
years for high-power omnidirectional beacons, maybe ten to a
hundred times that for directed beacons, but then you have the
constraint that you have to be listening in their direction when
they happen to be sending.
It seems hopeless. It may be. But the 1960s were a time very
different from our constrained age. Back then, if you had a
problem, like going to the Moon in eight years, you said,
“Wow! That's a really big nail. How big a hammer do I
need to get the job done?” Toward the end of that era
when everything seemed possible, NASA convened a summer seminar
at Stanford University to investigate what it would take to
seriously investigate the question of whether we are alone. The
result was
Project
Cyclops: A Design Study of a System for
Detecting Extraterrestrial Intelligent Life, prepared in 1971
and issued as a NASA report (no Library of Congress catalogue
number or ISBN was assigned) in 1973; the link will take you to
a NASA PDF scan of the original document, which is in the
public domain. The project assembled leading experts in all
aspects of the technologies involved: antennas, receivers,
signal processing and analysis, transmission and control, and
system design and costing.
They approached the problem from what might be called the
“Apollo perspective”: what will it cost, given the
technology we have in hand right now, to address this question
and get an answer within a reasonable time? What they came up
with was breathtaking, although no more so than Apollo. If you
want to listen for beacons from communicating civilisations as
distant as 1000 light years and incidental transmissions
(“leakage”, like our own television and radar
emissions) within 100 light years, you're going to need a really
big bucket to collect the signal, so they settled on 1000
dishes, each 100 metres in diameter. Putting this into
perspective, 100 metres is about the largest steerable dish
anybody envisioned at the time, and they wanted to build a
thousand of them, densely packed.
But wait, there's more. These 1000 dishes were not just a huge
bucket for radio waves, but a
phased array,
where signals from all of the dishes (or a subset, used to
observe multiple targets) were combined to provide the angular
resolution of a single dish the size of the entire array. This
required breathtaking precision of electronic design at the time
which is commonplace today (although an array of 1000 dishes
spread over 16 km would still give most designers pause). The
signals that might be received would not be fixed in frequency,
but would drift due to
Doppler shifts
resulting from relative motion of the transmitter and receiver.
With today's computing hardware, digging such a signal out of
the raw data is something you can do on a laptop or mobile
phone, but in 1971 the best solution was an optical data
processor involving exposing, developing, and scanning film. It
was exquisitely clever, although obsolete only a few years
later, but recall the team had agreed to use only technologies
which existed at the time of their design. Even more amazing
(and today, almost bizarre) was the scheme to use the array as
an imaging telescope. Again, with modern computers, this is a
simple matter of programming, but in 1971 the designers
envisioned a vast hall in which the signals from the antennas
would be re-emitted by radio transmitters which would interfere
in free space and produce an intensity image on an image
surface where it would be measured by an array of receiver
antennæ.
What would all of this cost? Lots—depending upon the
assumptions used in the design (the cost was mostly driven by
the antenna specifications, where extending the search to
shorter wavelengths could double the cost, since antennas had
to be built to greater precision) total system capital cost was
estimated as between 6 and 10 billion dollars (1971).
Converting this cost into 2018 dollars gives a cost between 37
and 61 billion dollars. (By comparison, the Apollo project
cost around 110 billion 2018 dollars.) But since the search for
a signal may “almost certainly take years, perhaps
decades and possibly centuries”, that initial investment
must be backed by a long-term funding commitment to continue
the search, maintain the capital equipment, and upgrade it as
technology matures. Given governments' record in sustaining
long-term efforts in projects which do not line politicians' or
donors' pockets with taxpayer funds, such perseverance is not
the way to bet. Perhaps participants in the study should have
pondered how to incorporate sufficient opportunities for graft
into the project, but even the early 1970s were still an
idealistic time when we didn't yet think that way.
This study is the founding document of much of the work in the
Search for Extraterrestrial Intelligence (SETI) conducted in
subsequent decades. Many researchers first realised that
answering this question, “Are we alone?”, was
within our technological grasp when chewing through this
difficult but inspiring document. (If you have an equation or
chart phobia, it's not for you; they figure on the majority of
pages.) The study has held up very well over the decades.
There are a number of assumptions we might wish to revise today
(for example, higher frequencies may be better for interstellar
communication than were assumed at the time, and spread
spectrum transmissions may be more energy efficient than the
extreme narrowband beacons assumed in the Cyclops study).
Despite disposing of wealth, technological capability, and
computing power of which authors of the Project Cyclops report
never dreamed, we only make little plans today. Most readers
of this post, in their lifetimes, have experienced the
expansion of their access to knowledge in the transition from
being isolated to gaining connectivity to a global,
high-bandwidth network. Imagine what it means to make the step
from being confined to our single planet of origin to being
plugged in to the Galactic Web, exchanging what we've learned
with a multitude of others looking at things from entirely
different perspectives. Heck, you could retire the entire
capital and operating cost of Project Cyclops in the first
three years just from advertising revenue on frobdob videos!
(Did I mention they have very large eyes which are almost all
pupil? Never mind the tentacles.)
This document has been subjected to intense scrutiny over the
years. The
SETI League
maintains a comprehensive
errata list
for the publication.
June 2018 