within our own solar system.
M A D S C I E N C E
Say what you will about the seventies. Maybe you still think disco sucks,
but at least we were setting sail for the planets on a regular basis. After
the stunning successes of planetary probes launched between 1961 and
1978, planetary exploration lost momentum in the eighties. The Soviets’
winning streak at Venus continued into the early eighties, as they landed
more cameras and sent balloon-borne instruments below the clouds, but
no American planetary craft was launched toward any planet for an
entire decade. This was due in part to the aftermath of Viking. Though
the search for life on Mars was considered a long shot by most of the sci-
entists involved, they had overhyped this angle to sell the mission to
Congress and the public. As a result, the failure to find life was perceived
as a failure of the mission, and that added to the difficulty in getting new
missions funded.
But there was a larger problem. Whether we like it or not (and many
of us do not) Cold War competition gave planetary exploration its first
big push. Our fantastic voyages had largely been funded and supported
60
L o n e l y P l a n e t s
as part of an elaborate form of saber rattling. The technology needed to
launch a lunar or planetary probe is not dissimilar to that needed to
deliver an ICBM. What better way to inspire missile envy than by nail-
ing another planet? Our science had been enabled by the desire of gov-
ernments locked in the MAD embrace of the Cold War to show off
their destructive potential. By the late 1970s these demonstrations had
served their purpose, and Apollo was only a memory. The governments
that had supported our science to back up their threats were losing
interest.
The most dangerous competition on this planet provided the impetus
for our first liberating leaps beyond it. That these initial interplanetary
voyages were financed and driven, financially and technically, by a
potentially suicidal contest carries with it all of the moral contradic-
tions of modern science.
Yet, our first pictures of Earth from space fostered a powerful new
sense of the unity and rare beauty of our planet. Then the uniqueness of
Earth was brought home to us with our first photos of the other plan-
ets. It is almost impossible not to have a global perspective while doing
planetary science. Even during the height of the Cold War, Russian and
American planetary scientists cooperated on their exploration plans
and shared data across the geopolitical fault lines. It doesn’t make sense
for one planet to have two isolated space programs.
Along with the planetary perspective comes a realization that many
of our problems and opportunities are global. The Earth has many
lands but only one atmosphere, and we are all in it together. Shifts in
global consciousness must be impossible to perceive accurately while
they are in progress, but it is not inconceivable that a new planetary
identity, which might be decisive for long-term human survival, is
slowly dawning (painfully slowly). Certainly, efforts to communicate
with intelligent extraterrestrials do not make much sense unless they
are made on behalf of all humans. Merely contemplating the possibility
of finding other life makes obvious our deep identification with all
Earth’s inhabitants.
It’s ironic that the technology that enables you to beat gravity and see
your planet whole can also threaten global self-destruction. One won-
ders if elements of this same drama might not be playing out elsewhere
in the galaxy. If we are going to anthropocentrically worry about others
on distant planets hastening their own demise with newfound techno-
The Planets at Last
61
toys, we might also hope that the leap into space will have a similar lib-
erating and unifying effect on their alien souls.
W O R L D S B E Y O N D
Anyway, after a decade-long malaise, having kicked the monkey of
Cold War aggression off our backs, we’ve now demonstrated that, hot
or cold, we don’t need war to explore. Planetary exploration was resur-
rected in the 1990s. In 1989, Magellan and Galileo were both launched toward Venus, where Magellan went into orbit and started its radar
mapping. Galileo made a close flyby, getting a gravitational kick from
Venus for its long journey out toward Jupiter.
The heartbreaking loss of Mars Observer, launched in 1992 (it went
silent as it reached Mars in August 1993, probably due to a fuel-tank
explosion), was an inauspicious start to a new series of Mars missions.
But then, on July 4, 1997, Mars Pathfinder, swathed in air bags, made
its daring bouncedown to land safely in an ancient flood zone.
Pathfinder delivered the cute Sojourner rover, which was a scientific and public relations success, as it crawled around in the red dirt, snapping photos and sniffing rocks, showing the world that we were back.
This triumph was followed by Mars Global Surveyor (MGS), which
began its orbital mapping in 1998. With the MGS cameras we can see
surface details a couple of meters across,* and its laser altimeter has
provided us with fantastically detailed global topo maps that reveal the
possible sites of ancient Martian oceans.
In October 2001, Mars Odyssey, a new orbiter, reached the Red
Planet and detected vast fields of water ice mixed into the upper few
feet of rock and soil surrounding the polar caps. New infrared images
from orbit have revealed a complex layered structure in some areas,
suggesting new complexities to the planet’s past geologic history that
have not yet been puzzled out. The search for signs of life-supporting
environments, in the past or even present, is once again the primary
goal of our entire revamped Mars exploration program.
In 1997, Cassini, a sophisticated, schoolbus-size spacecraft, departed
for Saturn. Cassini began orbiting the ringed planet in July 2004 and
in January 2005 will drop off the Huygens probe at Saturn’s moon
*As opposed to about a kilometer with Mariner 9 and fifty meters with Viking.
62
L o n e l y P l a n e t s
Titan. Titan is of special interest for possible extraterrestrial life. Voyager
revealed abundant signs of interesting organic chemistry beneath Titan’s
thick, hazy, nitrogen-rich atmosphere. Studying this environment may
help us understand the origin of life on Earth or, just possibly, reveal a new
kind of cold-loving biology. Launches planned in the next few years
include several new Mars missions, new Mercury and Venus orbiters, the
first flyby of Pluto, and several new missions to study asteroids and
comets.
The real planets provided a rude awakening from our dreams of
Earth-like neighbors, but we’re now learning to love them as they truly
are. Just the fact that the planets were where we thought they’d be and
our traveling machines actually reached them and worked has got to be
the most solid confirmation of the scientific and technological revolu-
tions of the past four centuries.* The r
esurrection of planetary explo-
ration, in the decade after the Cold War ended, shows that human
curiosity and wonder can occasionally transcend the deadly conflicts
that have so often fueled our greatest bursts of innovation.
But what about worlds beyond our Sun and planets? Ever since
Bruno and Fontenelle, most thinkers have concluded that our universe
contains copious extrasolar planets. Throughout huge transformations
in knowledge and worldview, scientists have consistently believed,
without any direct evidence, that the Sun’s family of planets is not
unique among the overwhelming profusion of stars filling the night sky.
But people believe all kinds of things, and neither analogy nor consen-
sus makes it so.
In 1995 another cherished belief crossed the threshold from reason-
able conjecture to observed fact: we started to find actual planets
beyond the solar system. The first definitive detection of an extrasolar
planet was made around a star called 51 Peg. After the first detection,
planet hunters stalked their quarry with renewed vigor. Before you
knew it, distant planets were popping up all over the place. As of this
writing, in the eight years since the first detection, more than one hun-
dred extrasolar planets have been found.† This is truly something
new—a definitive, affirmative answer to an ancient question.
*Stuff that in your socially constructed pipe and smoke it!
†Such is the pace of current discovery that whatever number of planets I plugged in here in the final edit of galley proofs will be wonderfully obsolete by publication date.
The Planets at Last
63
Though in some ways the twentieth century saw the end of our astro-
nomical innocence, the recent confirmation that our galaxy is rich in
planets has granted us a reprieve. Cosmology and extragalactic astron-
omy have banished us to the periphery of the universe, and spacecraft
exploration has replaced naive fantasy with cruel fact for the nearby
planets of our own system. But these brand-new worlds provide an
enlarged landscape for our speculative dreams. Like the planets of our
own solar system after the Copernican revolution and before planetary
exploration, we know these worlds are there, but we know little about
them. We can let our imaginations run wild.
A S T R O B I O L O G Y : N E W H Y P E A N D N E W H O P E
We tend to think of extraterrestrial life as a modernistic or futuristic
idea that rests on the findings of twentieth-century science and may
find verification in twenty-first-century discoveries. We think of it as
something for which humanity has had to be slowly prepared, while
gradually getting used to the disorienting and humbling knowledge that
we are very small and may not be so special in the universe.
Yet, as I’ve described, it is an old idea. Our seventeenth- and
eighteenth-century scientific heroes, the people we name spacecraft
after today, were almost all confirmed believers in a fertile, densely
inhabited universe. They based this belief on empirical observations of
other planets combined with metaphysical extrapolations. Today, our
rationale for believing in life beyond the Earth still involves a mix of
observation and extrapolation by analogy and plenitude. What is dif-
ferent now is the data. We’ve pretty much ruled out life on the Moon.
At one point we had ruled out life on Mars, though it has recently—at
least temporarily—been ruled back in. The boundary between that
which we can directly observe and that which we must deduce has
receded. But we still have to take that leap beyond the top rung of the
ladder of the known to reach for our conclusions.
Belief in aliens, among scholars at least, actually suffered some of its
lowest moments during the twentieth century. The search for extra-
terrestrial life was a semi-taboo subject among scientists. The public never
lost interest, but for decades professional astronomers risked disapproval
or career repercussions if they pursued the question as a major research
topic. Twentieth-century biologists mostly ignored the question.
64
L o n e l y P l a n e t s
Then in the late 1990s the field was revitalized, enjoying newfound
respect and funding. It even got a new name: what had previously been
referred to as exobiology, bioastronomy, cosmobiology, xenobiology,
or exobotany was now rechristened astrobiology. NASA administrator
Dan Goldin declared that the alien quest should now be the corner-
stone of our approach for studying the entire physical universe. A
NASA Astrobiology Institute was founded in Silicon Valley, and the
money began flowing. Researchers in diverse fields are suddenly discov-
ering that it pays to consider yourself an astrobiologist.
Why the official change of heart? Several recent discoveries have
rekindled hope for a living universe. In August 1996, a year after the
first extrasolar planet was discovered, President Clinton made a star-
tling announcement. American scientists had found fossils in an ancient
meteorite from Mars.* Even though many scientists soon challenged
this interpretation of the microscopic, wormlike structures, it got us all
thinking “Why not?” Worldwide front-page headlines gave the field a
boost that lasted long after serious doubts were raised about the biolog-
ical origins of the possible Martian microfossils.
That same year Galileo entered Jupiter orbit and returned sharp pic-
tures of Europa, providing new circumstantial evidence for a possible
life-giving underground ocean. Around the same time several new kinds
of bizarre life-forms were discovered on Earth, living under conditions
previously thought to be deadly. Our conceptual limits on life’s domain
widened. This harmonic convergence of discoveries was seized upon by
advisers and officials at NASA, who were also discovering that casting
our space research in terms of the search for cosmic company could
supply a much needed PR lift.
Thus was born the “astrobiology revolution,” which I will discuss in
more detail in the next section of this book.
A C R O S S T H E G R E A T D I V I D E
Dreams of alien life will not die. Almost as if we need to believe that we
are not alone in the universe, or even somehow know we are not alone,
this idea is resurrected in every era in new forms reflecting the attitudes
and convictions of the day. Today, beliefs about extraterrestrials are
polarized in a way that mirrors our culture’s divergent attitudes about
*Shades of the panspermia of Kelvin and Arrhenius.
The Planets at Last
65
science. We scientists view the question as part of our turf, as the proper
subject of astrobiology. In recent decades, however, another train of
belief has been gathering steam on a parallel track. Although science
has been on a roll of confidence and power since the Enlightenment,
antiscientific voices are increasingly audible on the cultural airwaves.
Creationism, faith healing, astrology, postmodern relativism, and New
Age spirituality are among those
beliefs that mainstream science regards
as dangerous superstitions threatening the rational basis of our society.
Many adherents of these beliefs view science as equally dangerous,
threatening our very survival with an amoral, materialistic, antispiritual
attitude and an out-of-control pursuit of new technology. Nowhere is
the gulf between expert scientific opinion and popular folk beliefs
greater than on the subject of aliens.
Millions of rational adults currently believe that UFOs are alien
spaceships that have come to Earth and occasionally abducted people,
perhaps to study us, perhaps to help us out. Astrobiologists and SETI
scientists are quick to dismiss such opinions, even while adhering to
their own strong faith in our ability to establish radio contact with like-
minded aliens. On both sides of this divide, many people nourish the
fantasy that advanced extraterrestrials with superior wisdom will lead
us beyond the threat of high-tech self-destruction to a safe and won-
drous future.
Ironically, widespread belief in UFO aliens may be partly responsible
for the strong public support enjoyed by NASA’s astrobiology program.
Certainly our regular stream of “Life on Mars” headlines has lent com-
fort to the UFO believers. People think there’s life out there, and they
want us to find it. Although the science/antiscience divide is wide, both
sides believe in aliens. Perhaps, deep down, our reasons for believing
are not so different.
P A R T I I
Science
The Greatest Story
5 Ever Told
I believe a leaf of grass is no less than the journey-
work of the stars.
Image unavailable for
—WALT WHITMAN, Song of Myself
electronic edition
To punish me for my contempt for
Image unavailable for
authority, fate made me an authority myself.
electronic edition
—ALBERT EINSTEIN
May you build a ladder to the stars. May you climb
on every rung.
Image unavailable for
—BOB DYLAN, “FOREVER YOUNG”
electronic edition
N E E D T O K N O W
To assess our universe’s potential to create other life and intelligence,
we need a framework for understanding our own arrival on Earth.
What is this place and how did we get here? We need to know, so we
Lonely Planets Page 12
