on the surface of an average planet
circling an ordinary yellow star an
advanced intelligence searches the skies
for evidence of life directed by even
higher intelligence machines with brains
of silicon patiently sift through faith
shards of radio data for the
unmistakable signal that will indicate
the first sign of life beyond Earth in
1959 physicist Philip Morrison was
co-author of the first scientific paper
to suggest a strategy for such a search
no is an answer to a very simple
question are we alone as conscious
beings in this entire buzzing four
hundred billion star galaxy one of ten
to the tenth other galaxies it seems
pretty implausible it's an enormous task
to search the skies for intelligent life
looking for a golden needle in a huge
cosmic haystack but steady the search
for extraterrestrial intelligence has
come a long way since early experiments
by young radio astronomer Frank Drake in
1960 Drake made the first radio search
from Green Bank West Virginia he called
it Ozma after a princess from the
fictional Land of Oz now plans for the
most sophisticated SETI search ever
focus on the goldstone deep space
communication complex in California's
Mojave Desert it is the site of tests
for a possible future NASA project one
not yet funded the full-scale NASA
system when operational in the next
decade would be billions of times more
powerful than the sum of all previous
searches
for carl sagan a proponent of Seti for
many years this technical progress has
made the present unique for the first
time we're mustering substantial
sophisticated serious scientific
searches for for extraterrestrial
intelligence has never been a time like
that perform so there is some chance
that in the next few decades we will get
a signal from some spectacularly distant
spectacularly exotic civilization and
everything on earth will as a
consequence change that is possible
how why when and whether to search for
life beyond Earth has been debated for
centuries deciding what sort of signal
to look for in the skies is no easy task
NASA's proposed search focuses on radio
a portion of the electromagnetic
spectrum where nature produces the least
interference for any intelligent signal
the plan is to use existing radio
antennas and combine them with advanced
computer hardware and software
specifically designed for the task
signal processing equipment suitable for
SETI is constantly becoming more
powerful and more efficient but also
cheaper and smaller than ever before in
the mid 1990s NASA hopes to deploy it
systems in a relatively low cost ten
years search that will for the first
time systematically explore all the
radio frequencies and directions on the
sky that researchers think might reveal
a signal my name is Jill tarter I'm an
astronomer from the University of
California at Berkeley and I work with
colleagues from NASA's Ames Research
Center the Jet Propulsion Laboratory and
the SETI Institute to help design the
special purpose tools needed to do SETI
properly over the years I've worked at
many radio telescopes like this one at
knole say in france trying to adapt
existing equipment to this difficult
task these efforts I hope will soon be
eclipsed by the planned NASA system some
parts of which may eventually be placed
here at Nelson
contemporary city is a science a
discipline which transforms humanity's
age-old speculations about life and
universe into experimental reality
steady pioneer Frank Drake came up with
a way to organize our developing
knowledge and current ignorance SETI
scientists often use what's called the
Drake Equation to illuminate the
necessary conditions for contact and to
provide a rough estimate of the number
of other civilizations the existence of
other technical civilizations depends
upon astronomy how planets form
comparative planetology biochemistry the
role of intelligence in evolution
technology and the fate of technical
civilizations so SETI becomes a way to
test our theories of the origin and
evolution of the universe and the place
of life within it some factors in the
Drake Equation are well determined
others are not we're pretty sure our
galaxy has about 400 billion stars and
maybe ten percent of them will shine
long enough for life to evolve and we
understand something of a life cycle of
those stars we know that it required
colossal supernova explosions to
transform the simple elements produced
in the Big Bang into the heavy elements
that form rocky planets and we ourselves
and we have taken the first steps in
understanding the chemical origin of
life and the principles of evolution but
as yet we found no definitive proof of
solar systems beyond our own though
recent observations of the disk of
matter around the nearby star beta
Pictoris suggests the planets they
become in our own solar system we have
found no signs of advanced life though
planets like Mars from the large moons
like Europa and Titan may have provided
suitable environments for life in the
past or may do in the future and seem
worth further exploratory missions so
far we have detected no signals from
other civilizations around other stars
using technologies which could make them
visible across the light-years and we
cannot predict whether civilizations
with advanced technology will perish
quickly or learn to use it to explore
the universe and thrive for the lifetime
of their star some people look at the
seven conditions Drake proposed and see
a weak chain that could easily be broken
Drake himself thinks there could be many
thousands of civilizations with whom we
could communicate in the Milky Way alone
we take the solar system which we know
has happened and the life on Earth is
typical and as far as we know it is
typical we know of nothing no freakish
event that was required for us with our
motorcycles and our video tape recorders
to exist SETI researchers such as
Harvard's Paul Horowitz doubt that the
question of other life in the universe
will ever be answered in the abstract
people have argued for a long time about
the odds what are the probabilities that
there's life elsewhere in the universe
and lacking any data they're nothing but
arguments and you can argue yourself
blue in the face but if you want to
answer this question you're gonna have
to do the experiment but how can you do
the experiment what is the right
experiment over interstellar distances
there's little sign of Earth the Sun
outshines the planet by more than a
billion to one
that's one reason we've not yet seen
planets around other stars with even the
largest optical telescopes it's rather
like trying to see a firefly perched on
the rim of a searchlight but at radio
wavelengths at certain times and certain
frequencies Earth's technology outshines
all other sources in the solar system by
nearly a million to one the carrier
waves of Earth's radio and television
broadcasts leak outward in a spherical
shell and could be detected by distant
civilizations radio signals travel at
the speed of light the fastest velocity
possible in contrast pioneer 10 has been
traveling for nine years to cover some 4
billion miles but its signal arrives
back here on earth in just five hours
that's one reason NASA researchers think
it is communication not physical travel
that makes most sense for all species
everywhere in the universe earth's most
sensitive antennas could detect strong
signals from halfway across the galaxy
traveling for just five light-hours
pioneer tens very weak signal is being
used to test NASA's prototype detectors
back here on earth Barney Oliver chief
up NASA's SETI office looking for a
signal now it's coming from the Pioneer
spacecraft which is now outside the
solar system that's beyond the orbit of
Neptune its carrier is a 1 watt signal
and that is about the fun what one
twentieth of the energy of a candle
burning so we're picking up a really
small signal indeed we succeed the Naza
effort has united Barney Oliver and
other longtime City proponents with the
younger generation of computer builders
and programmers including Kent colors
who despite being blind has worked on
the statistics of pattern recognition
pioneer 10 is simply a very good example
of the kind of signal that we might
detect first of all although it's kind
of close in interstellar terms it's a
very weak one would expect that a
civilization would be farther away and
hunger it's near the limit of our
detection it's also a good example of a
signal that might be used as beacon I'm
gonna go upper hurts just let's see what
happens here the test was successful
even though the rotation of the earth
and its motion through the galaxy
continuously changes the frequency of
Pioneer signal over time there's a
promising candidate right here laughs a
wait for a few more spectra to see if it
does yes I think that's it this right
line do you see going slanting down the
screen is the signal from the pioneer 10
spacecraft now if you look at other
means of communication or making contact
you have to send something you can't
just think about it you have to send
something and we've investigated all the
known particles and it's certainly true
that electromagnetic waves or photons
are hands down the best medium to use so
it might seem that we have solved the
problem of how to do the SETI experiment
look for artificial signals at radio
frequencies unfortunately it's not that
simple consider a terrestrial FM radio
dial on earth we recognize the channels
of our favorite radio stations defined
in mega birds and can tone from one to
the other each station has an assigned
place on the dial there it broadcasts a
carrier wave that's always present you
no matter the program content the
stations are separated from each other
so that they do not interfere on the
cosmic radio dial we're also looking for
signals artificially concentrated in
frequency but we don't know what
frequencies the extraterrestrials may be
using on earth between 90 and 92
megahertz there are just ten frequencies
in use on the cosmic dial there are 20
million potentially usable frequencies
in space the entire electromagnetic
spectrum could be used for communication
but in practice some portions of the
cosmic radio dial are harder to use
lower frequencies that we use for FM and
TV broadcasts are overwhelmed by
interference from natural sources in our
galaxy so we think it makes sense to
listen in the microwave region between
1,000 and 100,000 megahertz there is a
preferred region in the electromagnetic
spectrum we believe to minimize as the
energy required to make contact and that
is the microwave region and the reason
for that is that the noise that would
interfere with our transmissions or
theirs is lowest there if you know lower
in frequency the noise increases noises
of the galaxy produces you go higher in
frequency quantum effects come in and
create noise and in this silent valley
between those two walls communication
can be accomplished with the least
energy of any region of the spectrum but
even if there are clues about frequency
you still must choose where when and
exactly how to listen it's really more
like looking for a needle inside a
haystack inside a haystack for
simplicity SETI researchers compared
their experiments using three parameters
in addition to frequency you have to
choose directions to survey the whole
sky or to target individual stars and
all experiments will have different
sensitivities determined primarily by
the size of the radio antenna and by how
long they listen are there any further
clues which can help limit places to
look for the needle many study
researchers think there may be at least
in the frequency dimension since
hydrogen is the most abundant element in
the universe they argue that all
intelligent species would think of
transmitting their signals close to the
frequency at which hydrogen atoms
naturally emit radio waves
1420 megahertz was the first so-called
magic frequency to be tried it was at
1420 megahertz that Frank trach searched
in 1960 the first targeted search he
looked at just two stars at this one
frequency in a search of moderate
sensitivity in 1973 Ohio State
University with its unusual antenna
began a continuing sky servic it listens
not to single stars but to the sky
passing overhead it covers 50 channels
but is low in sensitivity searches over
the last six years by myself and French
radio astronomer Francois Bureau at mal
say have looked at 350 stars in the
latest targeted search there has been
significant international interest in
setting with searches mounted in the
USSR Canada Holland Germany and
Australia as well as those in the United
States
friends I'd not say by adapting existing
radio astronomical equipment we've been
able to listen to thousands of channels
simultaneously we've achieved improved
frequency coverage and a modest gain in
sensitivity as computers advanced it
became possible to construct detectors
that were specially adapted to the needs
of Seti one of the first researchers to
take advantage of this capability was
Paul harvest a professor of physics at
Harvard University the key breakthrough
was the ability to scan many channels
and frequencies simultaneously the heart
of the system is a so-called
multi-channel spectrum analyzer or mcsa
the one Horowitz uses in his latest
system was designed in collaboration
with ivan lins gotten colleagues at
Stanford University as part of the R&D
for NASA's plan city systems Horowitz
puts this equipment to practical test in
a Sky Survey known as meta the mega
channel extraterrestrial asset Drake's
experiment could scan only one frequency
channel at a time meta can listen to 8.4
million frequency channels
simultaneously it can do in one second
which took Drake five years meta funded
by the Planetary Society is perhaps the
ultimate magic frequency machine but if
Horowitz has guessed wrong he may be
looking in the right direction with
excellent sensitivity but just the wrong
frequency
no search to date has found any evidence
of intelligent life but SETI researchers
feel that their equipment has not been
equal to the task NASA's goal is to
extend these previous efforts into a
truly comprehensive search successful
tests of hardware and software in
detecting signals like those coming back
from pioneer are but the first steps in
a planned 10-year project that will
combine the most promising strategies
from these earlier searches the NASA
approach that we're that we're
developing right now has two different
approaches to the search and they're
complementary one of them is called the
sky survey and another is called the
target search and the objective of the
sky survey is to search the entire sky
having making no guesses as to what are
the best directions to carry out that
search in a reasonable length of time we
have to do it quickly which means we
sacrifice sensitivity to signals we only
detect may be the strongest of the
signals it might be there to cover this
guy quickly the radio telescopes will be
driven very rapidly eventually scanning
each patch of the sky 30 times but it is
in frequency sampled rather than
directions covered that NASA's project
will dwarf all previous searches Drake's
loan frequency is gossamer thin in
comparison to the tens of billions of
usable frequencies in the naturally
quiet microwave window and even though
the ohio state survey covers lots of
directions and stars about sixty percent
of the sky overall its frequency range
is also limited mehta also scans the
northern skies but all of its 8.4
million channels cluster around a single
magic frequency though it will be tuned
to others in contrast on the frequency
dimension NASA Sky Survey will cover the
whole one to ten gigahertz window and
the entire sky
to achieve this comprehensive coverage
of directions and stars NASA plans to
use several telescopes around the world
which are part of its spacecraft
tracking system each of these telescopes
can see two-thirds of the sky and NASA
will move its sky survey system between
them the complementary approach is to
say let's concentrate on detecting with
more sensitivity to be able to tech
weaker signals and to do that we look
and wonder in a few directions for
longer periods of time that's called the
targeted search and we pre select a set
of stars that we know Apriori are more
or less similar to our own Sun in age
and size and look in those directions
with more sensitivity and the ability to
tech many more complex signals the
targeted search will look repeatedly and
at different frequencies at nearly 800
year by stars like mal say NASA's
targeted search may start around 1420
megahertz that is 1.4 2 gigahertz but
then it will expand to cover all
frequencies between one and three goods
like the Sky Survey the targeted search
requires antennas around the world the
giant radio telescope at Arecibo is the
largest on the planet and because of its
unique size and sensitivity NASA hopes
to share time to search for the very
faintest signals the large dish can't be
moved so it can only see stars which
rotate overhead each day the antennas at
either Ohio State or null say could be
used to observe about 300 stars outside
the range of Eros ebo
more of the target stars can be seen
from the southern hemisphere so about
200 of them could be observed from the
large NASA antenna at Canberra or
perhaps the astronomical facility at
parks in Australia the last 50 or so
stars must be searched from a telescope
in the northern latitudes perhaps rather
appropriately and green deck where Frank
Drake began the search with project Ozma
with this unparalleled combination of
advanced hardware and sophisticated
software NASA's project will have the
capability to revolutionize city
the targeted search will look for faint
signals from what according to the
current understanding of cosmic
evolution seem to be the most
interesting sights and we'll look at
billions of frequencies the sky survey
will color an even wider range of
frequencies yet with sufficient
sensitivity to detect a very strong
signal from clear across the galaxy in
addition NASA system will have an
unprecedented ability to look for
different types of signals that vary
over time not just a continuous carrier
wave like that of pioneer 10 or Earth's
radio broadcasts for the first time we
will be able to detect regular pulses
that some researchers say will save
energy and so be the choice of the
transmitting civilization the
interesting thing about the citysearch
is that although we claim that we're
looking for extraterrestrial
intelligence we can't actually define
what an intelligent signal is and so a
starting point is to say we look for a
signal which nature will not produce by
any mechanism that we understand where
it becomes kent colors helped NASA
design the smart computer algorithms
needed to locate weak signals and in
many channels of noise figure but there
will be no human staring at
sophisticated graphics display no human
is any more cited than Kent when it
comes to recognizing an extraterrestrial
signal so the eye is not a good detector
first of all in sensitivity a thing that
you could look at virtually forever and
you would never know whether you were
seeing random noise or whether you were
seeing a real signal the computer can
find signals that are 10 times weaker
than that the amount of data processed
per second is the equivalent of the
entire Encyclopedia Britannica per
second of course that's filled with
random letters if that's analogous to
noise and what you have to do is find
that one pattern that says hi there in
all of those random letters that come in
every second and then decide whether
that pattern could have happened at
random because
your statistics of your process or
whether in fact that's the real thing
and a human being even if he could
perform the task as effectively as a
computer couldn't do it for very long
removing humans from the signal
detection process requires a very
special hardware which is what Ivan
Linscott and his colleagues at Stanford
University have been designing and
that's like having 10 million ears each
one listening to a particular tone and
where all of those are listening
simultaneously and so what we're doing
now is taking the technology that exists
in this prototype form and casting it in
sand we're building silicon versions of
our processors that that together with
the way we know how to use them will
convince both the scale and increase the
performance the process of
miniaturization is already underway 680
of the older large boards will soon be
replaced by just 24 smaller boards
filled with new chips that are cheaper
smarter and faster and can be more
easily transported around the world no
longer will require you to step in small
chunks across the frequency band you can
make a giant stride and and spend lots
of time on particular sources or or
sweep broad swath of the sky
and I think there's where the
opportunity lies because it's a
prospectors art you know and you just
have to look and take your best bet in
normal operations the NASA systems will
rely very heavily on silicon
intelligence with limited human
involvement the computers will have to
have sufficient online intelligence to
analyze the vast amounts of data
arriving every second and weed out the
inevitable false alarms before involving
humans for the operational sky survey
the sky will automatically be divided
into blocks which will be searched in
turn NASA expects many suspicious
signals during each scan but they won't
be from extraterrestrials these events
will be compared to the online database
of radio frequency interference RFI to
identify man-made signals most of the
signals will be explained away until
someday maybe there might come something
more significant the characteristics of
the long hoped for signal will show some
clear sign of intelligence and the
computer will have made content then it
will call humans to come look and we
will know for sure about life elsewhere
in space but before that increasing RFI
poses the greatest obstacle to success
think of the haystack principle we're
looking for the needle in the haystack
as a gold needle same color as the hay
in the haystack but some Joker has
thrown an awful lot of bras needles in
the haystack too so not only do we have
to pick up every little straw and sort
of crinkle it our fingers to see if it
sell it or not but we also have to test
every solid one because it might be a
bronze one since the first SETI
experiments we have filled Earth's skies
with all manner of satellites and we use
them continuously for this reason said
he must get started soon or it will
become more and more difficult to sort
out man-made signals from possible
extraterrestrial intelligence
from the early theories of Philip
morrison and the Ozma experiment of
Frank Drake past searches have
tantalized as much as resolved now in
the proposed NASA search technology and
task are beginning to converge millions
of times we've in fact even billions of
times more comprehensive than the sum of
all previous searches but fall short by
about a million fold from what could be
done so we're kind of nicely positioned
in the middle and if we succeed we will
succeed with the cheap play searching
the cosmic haystack with the full NASA
system would cost just a few pennies per
american per year is it worth that price
when I take my paycheck home I certainly
pay my house bill and my medical bills
and I insurance premiums first and that
takes up most of my income but I always
save a little bit to buy a book or go to
a good movie or go to the Art Museum or
go to a football game and I think it's
that kind of activity that's necessary
for us as human beings to keep us human
I mean that's what that's what keeps our
curiosity stimulated our our our
intellect moving and I think we
collectively as a human race also need
to invest some of our resources into
exploration into trying to understand
nature as it is around us nature as it
is out there and the cosmos trying to
learn who we are and what we're like I
think we always need to climb that extra
mountain somehow I think that's very
important to us collectively I think
even if there's a plausible argument for
a few we got to keep looking I even go
further than that if there's a plausible
argument that there isn't anybody out
there bearing in mind that we can be
wrong we ought to keep looking because
the question is of the most supreme
importance it calibrates our place in
the universe it tells us who we are and
so it is worthwhile trying to find other
civilizations I would say no matter what
we've hardly searched all the various
frequencies the forms of signal the
places in the sky from which signals
might come and so the fact that we so
far have no evidence of extraterrestrial
life is not at all discouraging we
shouldn't have found it yet
we have hardly begun but i think this
enterprise can best be understood as a
kind of exercise in the archaeology of
the future we're well aware of the
archaeology of the past we find a site a
tumulus or a ruin and we take a spade
and we dig into the ground and if you're
lucky you discover or of the kaldi's or
something marvelous now we ever thought
that we could examine the same thing in
reverse time but in fact in a way we can
we know that it's possible that somebody
who wants to do it will bring us in of
course it is their past but our future
which we are investigating to some
degree even though they're made of
different chemistry even though they've
never seen our star even though they
have nothing biological in common with
us they have if they have got radio
astronomy if they have the Conn
technology were imagining have very much
income with us the manufacturer of a
culture the development of a culture
which is unmatched among in all the ten
billion species or more that have come
to the face of the earth so that's the
story and maybe the spag will turn up
luckily a good site one day we hope it
will it's just a question being patient
when you got the Spade and you know the
future is there it seems very wrong not
to dig
you