Actually, it is entirely possible that they have joined forces. They do interact in strange ways. Europa’s repeated torques on Io’s orbit help
keep the tidal heat flowing and the Ionian volcanoes pumping. A steady
rain of sulfur from Io’s volcanoes falls on the frozen surface of Europa
and eventually diffuses into the ocean below. For microbial (or other)
life, sulfur can be just as good an energy source as oxygen, so there
could be a biosphere within Europa powered by volcanoes on Io!
Perhaps Io started out more like Europa, with a watery shell, but
became desiccated by the greater energy flow that goes with the terri-
tory deeper in Jupiter’s tidal hot zone. In much the same way, Venus
started life more like Earth, but eventually dried out from living closer
to the flame. What happened to the life on these worlds when most of
the water went away? Did it disappear or change with the times?
A relentless stream of hyperenergetic charged particles would rip into
anything trying to make a living on or near the surface of Io, like bulls
in the organic china shop, smashing up the delicate molecules that
make up living cells. But could something evolve to harness these reck-
less bulls, getting them to plow their fields and grow their food?
Imagine an organic creature that evolves to secrete or deposit some
shell or substance, let’s call it “special sauce,” that surrounds it and
shields it from this radiation. What if this special sauce absorbs the
radiation through chemical reactions that turn its energy into food?
Or what about life deep inside Io? A huge flow of energy from
Jupiter’s tidal heating extends throughout the entire orb. I am not will-
ing to rule out life in such a thermodynamically fertile environment just
because we can’t think of how it would work. At some depth there is
almost surely an “aquifer” of liquid SO2. Could such a liquid support a
biosphere? I have often wondered about sulfur’s biochemical potential
in the context of Venus and its active sulfur cycle. I think sulfur might
have some surprises for us in different environments. If we want to pro-
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pose a chemical basis for life in hell, how about sulfur, the stuff of
brimstone, fool’s gold, and rotten eggs? Maybe sulfur is the magic elixir
on Venus and /or Io, in the way carbon is here. On Io, sulfur drools,
dribbles, flows, explodes, and snows all over the surface. We don’t yet
know much about the sulfur cycle on Io, but certainly there is one and
it is energetic and complex.
In its elemental state (bonded only to itself) sulfur takes on many
poorly understood forms in every phase (gas, liquid, and solid). Sulfur
reacts in interesting ways with carbon, oxygen, nitrogen, phosphorous,
fluorine, and chlorine, all common elements in the universe, all present
on Venus and Io. Even in our supreme state of ignorance about how
sulfur may act and react in the conditions found on other planets, we
do know that sulfur compounds can store large amounts of energy and
make complex and unusual structures. In certain conditions sulfur
forms polymers, the long chains of repeating structures that give car-
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bon an edge in the life game. What can sulfur do that we don’t know
about? A lot, I bet.
Admittedly, life on Io, as on Venus, is a long shot. But I think when it
comes to astrobiology, we should not discount the long shots until we
have good reason to do so, regarding them instead as additional rea-
sons to keep exploring.
These ideas are not quite science, because they do not make precise
predictions. But they do suggest an approach to exploration. Look in a
wide range of environments for possible signs of life. Any unexplained
phenomena—particularly those that involve disequilibrium, physical
shapes that seem biological, and unexpected activity confined to nar-
row thermodynamic conditions—should be considered possible signs of
life, and thus worthy targets for further exploration. Life itself should
be doubted until the evidence is extremely compelling. Currently, cer-
tain unproven assumptions have became axioms that threaten to rail-
road our exploration program. Yet, a narrow search is not mandated
by the state of our knowledge.
These are my current thoughts about the nature of life in the uni-
verse, based as much on scientific intuition as on established facts. I
have presented these ideas in the science section, but I know that by
now I’ve crossed the line and I’m talking about my own beliefs. Natural
philosophy recognizes that these sections (“History,” “Science,”
“Belief”) are really one and the same. There are no known facts about
life in the universe, except that it has happened at least once.
P A R T I I I
Belief
SETI: The Sounds of Silence
18
I got the radio on
I feel in love with the modern world
Image unavailable for
I like the power, got the magic
electronic edition
I feel in touch, I feel alive
With 50,000 watts of power
going faster miles an hour
And I got the radio on.
—JONATHAN RICHMAN AND THE
MODERN LOVERS, “ROADRUNNER”
L I S T E N U P
I’ve been waiting for a signal all my life. The news might come any day:
a manic phone call late at night or a solemn announcement on NPR as
I’m driving to work one morning. I’d swerve and spill coffee down my
pants, but it would be worth it. What would your reaction be if you
turned on CNN to a head talking about an alien message that had just
been picked up by scientists at the Arecibo Radio Observatory? How
would the masses respond as the news spread? Pandemonium? Dancing
in the streets? Disbelief? Indifference?
Once large masses of people thought there had been such an
announcement. It was Halloween, 1938. Orson Welles’s fictional radio
broadcast of a landing in Grovers Mill, New Jersey, by an invading
Martian army was taken seriously by millions of people who didn’t
hear, or at least didn’t heed, the disclaimers.* Panic ensued. People fled
*This drama was based on H. G. Wells’s War of the Worlds, but in the radio version the location of the invasion was moved from London to New Jersey. By the time the movie version was released in 1953, the Martians had apparently learned more about us and figured out that they should really destroy Los Angeles.
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their homes, flooded police phone lines, and did their best to prepare
for a gas attack from the marauding Martians. In its lead story the fol-
lowing morning, the New York Times reported that the broadcast had
“disrupted households, interrupted religious services, created traffic
jams and clogged communications systems,” and that “at least a score
of adults required medical treatment for shock and hysteria.”
This example can hardly be considered instructive, because first co
ntact
won’t come in the form of an invading army. If creatures able to travel
interstellar distances wanted our planet, it would not resemble a war as
much as an extermination or a wildlife relocation program. And why
would they even want our Earth? Aliens will surely be better adapted to
their own planets. It is highly unlikely that they will be able to breathe our
air, infect us, or eat us without a lot of expensive and messy food process-
ing. “War of the worlds,” while entertaining (except for those needing
treatment for shock and hysteria), is not a likely scenario.
If first contact comes in the form of a radio message, then we may at
first know nothing about the senders except for the simple, startling fact
that they are out there, broadcasting a signal that seems incontrovertibly
the product of some kind of mind. It might be frightening, liberating,
uplifting, disturbing, or all of the above, but I say, “Bring it on.”
As long as we are still the one “intelligent species,” alone in a uni-
verse swimming with bugs and scum, we are still the big-brained lords
of all we see. Even finding microbes on Mars wouldn’t dethrone us,
rather it would enlarge our kingdom. The most enticing aspect of such
a discovery might be the implication that intelligent life is also relatively
close by, because in a universe that is teeming, someone else must be
dreaming and scheming.
What we most want to know is whether anyone is out there whom
we can talk to and learn from. We want to know what they look like,
how they think, what they know, whether they’ve had the same prob-
lems we have, and how they’ve solved them.
So we search the skies.
F I R S T A T T E M P T S
The modern era of SETI (the search for extraterrestrial intelligence)
began in September 1959 when the Cornell University astrophysicists
Guiseppe Cocconi and Philip Morrison published a seminal paper in
Nature entitled “Searching for Interstellar Communications.”
SETI: The Sounds of Silence
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The idea of trying to communicate with beings on other worlds was
not new. In the nineteenth century, several schemes were proposed for
contacting inhabitants of the Moon or Mars by drawing huge diagrams
on Earth’s surface for the aliens to read. German mathematician Carl
Friedrich Gauss proposed that massive areas of Siberian forest be clear-
cut in the shape of a triangle with adjoining squares, showing the
Martians that we know the Pythagorean theorem. Viennese astronomer
Joseph von Littrow suggested that a giant circular trench be built in the
Sahara desert, filled with kerosene, and ignited when Mars was close to
Earth.* In 1909, in the wake of the “Mars mania” caused by Percival
Lowell’s sensational claims of a canal-building civilization, Harvard
astronomer W. H. Pickering advocated the construction of a huge mir-
ror to signal the Martians, and in the 1920s several astronomers imag-
ined flashing huge searchlights in the direction of Mars using a kind of
“Morse code” to convey various pictorial images.
Even radio communication had been attempted, decades before mod-
ern SETI. In 1899, the Croatian-born American physicist, electricity
pioneer (and New Age cult figure) Nikola Tesla declared that he had
received electrical communications from extraterrestrials, most likely
residents of Mars or Venus. Describing the experience in the February
1901 issue of Collier’s Weekly, he wrote:
I felt as though I were present at the revelation of a great truth. My
first observations terrified me, as there was present in them some-
thing mysterious, not to say supernatural, and I was alone in my
laboratory at night. . . . The changes I noted were taking place
periodically, and with such a clear suggestion of number and
order. . . . The feeling is constantly growing on me that I had been
the first to hear the greeting of one planet to another.
Twenty years later Italian radio pioneer Guglielmo Marconi pro-
posed that radio could be used to communicate over interplanetary,
even interstellar, distances. In a front-page article in the New York
Times of January 20, 1919, Marconi suggested, “It may someday be
possible, and as many of the planets are much older than ours the
beings who live there ought to have information for us of enormous
value.”
*Today this sounds like a good idea for the Burning Man festival.
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After outfitting his luxury yacht, Electra, with radio receivers,
Marconi sailed to the middle of the Atlantic Ocean, where he could lis-
ten for alien signals free from local interference. He believed he heard
them. In response, the Times ran an editorial entitled “Let the Stars
Alone,” warning that through such efforts we might receive “knowledge
for which we are unprepared precipitated on us by superior intelli-
gences. . . . If Mars is a million years ahead of us, it is far from impossi-
ble that Mars . . . would regard argument with our mundane mathe-
maticians as no more serious an occupation than inciting a kitten to
chase its own tail.”
Real radio astronomy was born of the invention of radar in World
War II. Turned toward the heavens, the powerful new radio techniques
developed for spotting enemy aircraft revealed a universe humming
with noise and a vast, hidden landscape peppered with pulsars and
radiant with radio galaxies. Might there be a deliberate signal, or at
least some leaking chatter, hidden among all this radio clatter?
In their 1959 paper, Cocconi and Morrison reasoned persuasively
that with the technology of their day (late 1950s) we should be able to
detect a radio signal directed at us from elsewhere in our own galaxy.
They backed this up with convincing calculations, and they even told us
what frequency the aliens would be broadcasting on. Hydrogen, the
most abundant element in the universe, hums naturally at 1420 MHz
on your radio dial.* This region of the spectrum is generally pretty
quiet, so the hydrogen channel is not only useful for studying the struc-
ture of the universe, but also a good communication frequency. The
aliens would know that any species who had recently discovered radio
astronomy would build equipment designed to listen on the hydrogen
channel. The Nature paper concluded:
The reader may seek to consign these speculations wholly to the
domain of science-fiction. We submit, rather, that the foregoing line
of argument demonstrates that the presence of interstellar signals
is entirely consistent with all we now know, and that if signals are
present the means of detecting them is now at hand. Few will deny
the profound importance, practical and philosophical, which the
detection of interstellar communications would have. We therefore
*MHz means “megahertz” or “million cycles per second.” These are exactly the same as the numbers on your FM radio.
SETI: The Sounds of Silence
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feel that a discriminating search for signals deserves a conside
rable
effort. The probability of success is difficult to estimate; but if we
never search, the chance of success is zero.
Who could argue with that? After Cocconi and Morrison, it seemed
foolish not to listen for alien signals.
S W I T C H I N G O N
It was a time of great excitement and optimism about planetary explo-
ration and ET life.* At almost the last possible moment before reality
intruded, in the form of data from planetary probes, the golden age
planets were still filled with the busy cackle and buzz of life. Indeed, to
support their argument for life on the planets of distant stars, Cocconi
and Morrison pointed out that it exists on two planets in just our own
solar system, “Earth and very probably Mars.” This, they noted, was a
good thing, since a sample of one lacks statistical significance.
My earliest memory, or rather the earliest thing I can remember
remembering, is of lying in a crib with several large humanoids peering
down at me. These big heads were talking, and I was frustrated, trying
to figure out what it was they were saying. That must have been in
1960, around the time when Frank Drake, a brilliant and bold thirty-
year-old astronomer at the National Radio Astronomy Observatory in
Green Bank, West Virginia, was conducting the first modern search for
alien radio signals. He pointed his radio dish at the two nearest Sun-
like stars, Tau Ceti and Epsilon Eridani, and listened on the hydrogen
frequency suggested by Cocconi and Morrison. (Drake had decided
completely independently that this was the right frequency to search.
So, at least for smart human astronomers in 1960, it really was a uni-
versal frequency.) On the first day, Drake detected a strong signal. As
he later recalled, “My first thought was ‘Could it be this easy?’ My sec-
ond thought was ‘What do we do now?’ ” Fortunately, he did not alert
the media, because this first quick success turned out to be a false alarm
caused by local interference.
Drake named this first listening effort Project Ozma after the queen
*Recently my mother gave me a copy of the Life magazine issue published on the day I was born (three months after SETI was born with the Cocconi and Morrison Nature paper). Inside is an enticing article headlined “Target Venus: There May Be Life There.”
Lonely Planets Page 43