- Scoles, Sarah.
Making Contact.
New York: Pegasus Books, 2017.
ISBN 978-1-68177-441-1.
-
There are few questions in our scientific inquiry into the universe and
our place within it more profound than “are we alone?” As we have learned
more about our world and the larger universe in which it exists, this
question has become ever more fascinating. We now know that our planet,
once thought the centre of the universe, is but one of what may be
hundreds of billions of planets in our own galaxy, which is one of hundreds
of billions of galaxies in the observable universe. Not long ago, we knew
only of the planets in our own solar system, and some astronomers
believed planetary systems were rare, perhaps formed by freak
encounters between two stars following their orbits around the galaxy.
But now, thanks to exoplanet hunters and, especially, the
Kepler spacecraft,
we know that it's “planets, planets, everywhere”—most stars
have planets, and many stars have planets where conditions may be
suitable for the origin of life.
If this be the case, then when we gaze upward at the myriad stars in the
heavens, might there be other eyes (or whatever sense organs they use
for the optical spectrum) looking back from planets of those stars toward our
Sun, wondering if they are alone? Many are the children, and
adults, who have asked themselves that question when standing under a
pristine sky. For the ten year old Jill Tarter, it set her on a path
toward a career which has been almost
coterminous with humanity's efforts to discover communications from
extraterrestrial civilisations—an effort which continues today,
benefitting from advances in technology unimagined when she undertook
the quest.
World War II had seen tremendous advancements in radio communications,
in particular the short wavelengths (“microwaves”) used
by radar to detect enemy aircraft and submarines. After the war,
this technology provided the foundation for the new field of
radio astronomy, which expanded astronomers' window on the
universe from the traditional optical spectrum into wavelengths
that revealed phenomena never before observed nor, indeed, imagined,
and hinted at a universe which was much larger, complicated, and
violent than previously envisioned.
In 1959, Philip Morrison and Guiseppe Cocconi published a paper in
Nature in which they calculated that using only
technologies and instruments already existing on the Earth, intelligent
extraterrestrials could send radio messages across the distances to the
nearby stars, and that these messages could be received, detected, and
decoded by terrestrial observers. This was the origin of SETI—the Search
for Extraterrestrial Intelligence. In 1960, Frank Drake used a radio
telescope to
search for signals
from two nearby star systems; he heard nothing.
As they say, absence of evidence is not evidence of absence, and this
is acutely the case in SETI. First of all, consider that you must first
decide what kind of signal aliens might send. If it's something which
can't be distinguished from natural sources, there's little hope you'll be
able to tease it out of the cacophony which is the radio spectrum. So we
must assume they're sending something that doesn't appear natural. But
what is the variety of natural sources? There's a dozen or so Ph.D. projects
just answering that question, including some surprising discoveries of
natural sources nobody imagined, such as
pulsars, which were sufficiently
strange that when first observed they were called “LGM” sources
for “Little Green Men”. On what frequency are they sending (in
other words, where do we have to turn our dial to receive them, for those
geezers who remember radios with dials)? The most efficient signals
will be those with a very narrow frequency range, and there are billions of
possible frequencies the aliens might choose. We could be pointed in the
right place, at the right time, and simply be tuned to the wrong station.
Then there's that question of “the right time”. It would be
absurdly costly to broadcast a beacon signal in all directions at all times:
that would require energy comparable to that emitted by a star (which, if
you think about it, does precisely that). So it's likely that any civilisation
with energy resources comparable to our own would transmit in a narrow beam to
specific targets, switching among them over time. If we didn't happen to
be listening when they were sending, we'd never know they were calling.
If you put all of these constraints together, you come up with what's called
an “observational
phase space”—a
multidimensional space of frequency, intensity, duration of
transmission, angular extent of transmission, bandwidth, and
other parameters which determine whether you'll detect the
signal. And that assumes you're listening at all, which depends
upon people coming up with the money to fund the effort and pursue
it over the years.
It's beyond daunting. The space to be searched is so large, and our ability to
search it so limited, that negative results, even after decades of observation,
are equivalent to walking down to the seashore, sampling a glass of ocean
water, and concluding that based on the absence of fish, the ocean contained
no higher life forms. But suppose you find a fish? That would change
everything.
Jill Tarter began her career in the mainstream of astronomy. Her
Ph.D. research at the University of California, Berkeley was on
brown dwarfs
(bodies more massive than gas giant planets but too small to
sustain the nuclear fusion reactions which cause stars to
shine—a brown dwarf emits weakly in the infrared as it
slowly radiates away the heat from the gravitational contraction
which formed it). Her work was supported by a federal grant, which
made her uncomfortable—what relevance did brown dwarfs
have to those compelled to pay taxes to fund investigating them? During her Ph.D.
work, she was asked by a professor in the department to help
with an aged computer she'd used in an earlier project. To acquaint
her with the project, the professor asked her to read the
Project Cyclops
report. It was a conversion experience.
Project Cyclops was a NASA study conducted in 1971 on how to perform
a definitive search for radio communications from intelligent
extraterrestrials. Its
report
[18.2 Mb PDF], issued in 1972, remains the “bible”
for radio SETI, although advances in technology, particularly in computing,
have rendered some of its recommendations obsolete. The product of a NASA
which was still conducting missions to the Moon, it was grandiose in
scale, envisioning a large array of radio telescope dishes able to search
for signals from stars up to 1000 light years in distance (note that this is
still a tiny fraction of the stars in the galaxy, which is around 150,000
light years in diameter). The estimated budget for the project was between
6 and 10 billion dollars (multiply those numbers by around six to get
present-day funny money) spent over a period of ten to fifteen years.
The report cautioned that there was no guarantee of success during that
period, and that the project should be viewed as a long-term endeavour
with ongoing funding to operate the system and continue the search.
The Cyclops report arrived at a time when NASA was downsizing
and scaling back its ambitions: the final three planned lunar landing
missions had been cancelled in 1970, and production of additional Saturn V
launch vehicles had been terminated the previous year. The budget
climate wasn't hospitable to Apollo-scale projects of any description,
especially those which wouldn't support lots of civil service and
contractor jobs in the districts and states of NASA's patrons in
congress. Unsurprisingly, Project Cyclops simply landed on the pile
of ambitious NASA studies that went nowhere. But to some who read it,
it was an inspiration. Tarter thought, “This is the first time
in history when we don't just have to believe or not believe. Instead
of just asking the priests and philosophers, we can try to find an
answer. This is an old and important question, and I have the
opportunity to change how we try to answer it.” While some
might consider searching the sky for “little green men”
frivolous and/or absurd, to Tarter this, not the arcana of
brown dwarfs, was something worthy of support, and of her time and
intellectual effort, “something that could impact people's
lives profoundly in a short period of time.”
The project to which Tarter had been asked to contribute,
Project SERENDIP
(a painful acronym of Search for Extraterrestrial Radio
Emissions from Nearby Developed Intelligent Populations)
was extremely modest compared to Cyclops. It had no dedicated
radio telescopes at all, nor even dedicated time on existing
observatories. Instead, it would “piggyback” on
observations made for other purposes, listening to the feed from
the telescope with an instrument designed to detect the kind of
narrow-band beacons envisioned by Cyclops. To cope with the
problem of not knowing the frequency on which to listen, the
receiver would monitor 100 channels simultaneously. Tarter's
job was programming the
PDP 8/S
computer to monitor the receiver's output and
search for candidate signals. (Project SERENDIP is still in
operation today, employing hardware able to simultaneously
monitor 128 million channels.)
From this humble start, Tarter's career direction was set. All
of her subsequent work was in SETI. It would be a roller-coaster
ride all the way. In 1975, NASA had started a modest study to
research (but not build) technologies for microwave SETI searches.
In 1978, the program came into the sights of senator William
Proxmire, who bestowed upon it his “Golden Fleece”
award. The program initially survived his ridicule, but in 1982, the
budget zeroed out the project. Carl Sagan personally intervened
with Proxmire, and in 1983 the funding was reinstated, continuing
work on a more capable spectral analyser which could be used with
existing radio telescopes.
Buffeted by the start-stop support from NASA and encouraged by
Hewlett-Packard executive
Bernard
Oliver, a supporter of SETI from its inception, Tarter
decided that SETI needed its own institutional home, one dedicated
to the mission and able to seek its own funding independent of the
whims of congressmen and bureaucrats. In 1984,
the SETI Institute
was incorporated in California. Initially funded by Oliver, over
the years major contributions have been made by technology moguls
including William Hewlett, David Packard, Paul Allen, Gordon Moore,
and Nathan Myhrvold. The SETI Institute receives no government
funding whatsoever, although some researchers in its employ, mostly
those working on astrobiology, exoplanets, and other topics not
directly related to SETI, are supported by research grants from
NASA and the National Science Foundation. Fund raising was a
skill which did not come naturally to Tarter, but it was mission
critical, and so she mastered the art. Today, the SETI Institute
is considered one of the most savvy privately-funded research
institutions, both in seeking large donations and in grass-roots
fundraising.
By the early 1990s, it appeared the pendulum had swung once
again, and NASA was back in the SETI game. In 1992, a program was
funded to conduct a two-pronged effort: a targeted search of 800
nearby stars, and an all-sky survey looking for stronger beacons.
Both would employ what were then state-of-the-art spectrum analysers
able to monitor 15 million channels simultaneously. After
just a year of observations, congress once again pulled the plug.
The SETI Institute would have to go it alone.
Tarter launched
Project Phoenix,
to continue the NASA targeted search program using the orphaned
NASA spectrometer hardware and whatever telescope time could be
purchased from donations to the SETI Institute. In 1995,
observations resumed at the Parkes radio telescope in Australia,
and subsequently a telescope at the National Radio Astronomy
Observatory in Green Bank, West Virginia, and the 300 metre dish
at Arecibo Observatory in Puerto Rico. The project continued
through 2004.
What should SETI look like in the 21st century? Much had changed since
the early days in the 1960s and 1970s. Digital electronics and
computers had increased in power a billionfold, not only making it
possible to scan a billion channels simultaneously and automatically
search for candidate signals, but to combine the signals from a
large number of independent, inexpensive antennas (essentially,
glorified satellite television dishes), synthesising the aperture of
a huge, budget-busting radio telescope. With progress in electronics
expected to continue in the coming decades, any capital investment in
antenna hardware would yield an exponentially growing science harvest
as the ability to analyse its output grew over time. But to take
advantage of this technological revolution, SETI could no longer rely
on piggyback observations, purchased telescope time, or allocations
at the whim of research institutions: “SETI needs its own
telescope”—one optimised for the mission and designed to
benefit from advances in electronics over its lifetime.
In a series of meetings from 1998 to 2000, the specifications of such an
instrument were drawn up: 350 small antennas, each 6 metres in diameter,
independently steerable (and thus able to be used all together, or in
segments to simultaneously observe different targets), with electronics
to combine the signals, providing an effective aperture of 900 metres
with all dishes operating. With initial funding from Microsoft
co-founder Paul Allen (and with his name on the project, the
Allen Telescope
Array), the project began construction in 2004. In 2007, observations
began with the first 42 dishes. By that time, Paul Allen had lost
interest in the project, and construction of additional dishes was placed
on hold until a new benefactor could be found. In 2011, a funding crisis
caused the facility to be placed in hibernation, and the
observatory was sold to SRI International for US$ 1. Following
a crowdfunding effort led by the SETI Institute, the observatory was
re-opened later that year, and continues operations to this date. No
additional dishes have been installed: current work concentrates on
upgrading the electronics of the existing antennas to increase
sensitivity.
Jill Tarter retired as co-director of the SETI Institute in 2012,
but remains active in its scientific, fundraising, and outreach
programs. There has never been more work in SETI underway than
at the present. In addition to observations with the Allen
Telescope Array, the
Breakthrough
Listen project, funded at US$ 100 million over ten years by
Russian billionaire Yuri Milner, is using thousands of hours of
time on large radio telescopes, with a goal of observing a million
nearby stars and the centres of a hundred galaxies. All data are
available to the public for analysis. A new frontier, unimagined in
the early days of SETI, is optical SETI. A pulsed laser, focused
through a telescope of modest aperture, is able to easily outshine the
Sun in a detector sensitive to its wavelength and pulse duration.
In the optical spectrum, there's no need for fancy electronics to
monitor a wide variety of wavelengths: all you need is a prism or
diffraction grating. The SETI Institute has just successfully completed
a US$ 100,000 Indiegogo campaign to crowdfund the first phase of the
Laser
SETI project, which has as its ultimate goal an all-sky,
all-the-time search for short pulses of light which may be
signals from extraterrestrials or new natural phenomena to which
no existing astronomical instrument is sensitive.
People often ask Jill Tarter what it's like to spend your entire
career looking for something and not finding it. But she, and
everybody involved in SETI, always knew the search would not be
easy, nor likely to succeed in the short term. The reward for
engaging in it is being involved in founding a new field of
scientific inquiry and inventing and building the tools which allow
exploring this new domain. The search is vast, and to date we have
barely scratched the surface. About all we can rule out, after more
than half a century, is a Star Trek-like universe
where almost every star system is populated by aliens chattering
away on the radio. Today, the SETI enterprise, entirely privately
funded and minuscule by the standards of “big science”,
is strongly coupled to the exponential growth in computing power
and hence, roughly doubles its ability to search around every
two years.
The question “are we alone?” is one which has profound
implications either way it is answered. If we discover one or more
advanced technological civilisations (and they will almost certainly
be more advanced than we—we've only had radio for a little more
than a century, and there are stars and planets in the galaxy
billions of years older than ours), it will mean it's possible to
grow out of the daunting problems we face in the adolescence of our
species and look forward to an exciting and potentially unbounded future.
If, after exhaustive searches (which will take at least another
fifty years of continued progress in expanding the search space),
it looks like we're alone, then intelligent life is so rare that we
may be its only exemplar in the galaxy and, perhaps, the universe.
Then, it's up to us. Our destiny, and duty, is to ensure that
this spark, lit within us, will never be extinguished.
