Table Of ContentTo the next generation of space pioneers,
who will realize their dreams to
live off-Earth.
CONTENTS
PREFACE
PART I. PRELUDE
1. Dreaming of Beyond
2. Rockets and Bombs
3. Send In the Robots
PART II. PRESENT
4. Revolution Is Coming
5. Meet the Entrepreneurs
6. Beyond the Horizon
7. A Plethora of Planets
PART III. FUTURE
8. The Next Space Race
9. Our Next Home
10. Remote Sensing
11. Living Off-Earth
PART IV. BEYOND
12. Journey to the Stars
13. Cosmic Companionship
14. A Universe Made for Us
NOTES
CREDITS
INDEX
Preface
Space is inhuman. We can’t survive unprotected in a pure vacuum for more than a minute.
Going there involves being strapped to a barely controlled chemical explosion. Low Earth
orbit is equivalent to half an hour’s drive straight up, but it’s insanely expensive to get
there. The set of people who have experienced zero gravity is one of the most exclusive
clubs in history. Yet space travel is an expression of a fundamental human trait: the desire
to explore.
This book is an exploration of the past, present, and future of space travel. We’re on the
cusp of an important transition, where diverse technologies have matured to the point
where space travel could be routine. A cadre of innovators and entrepreneurs is about to
deliver space travel that’s not just for astronauts and the super-rich. It will happen sooner
than you think.
Each of the four parts of this book is preceded by a fictional vignette delivering us into
the world of a young pioneer about to undertake a journey to the stars. First, we look at the
“Past” to learn about our genetic proclivity for exploration and our progress with rocketry
that let us leave the Earth for the first time in the mid-twentieth century. We also learn
about the highs and the lows resulting from that landmark achievement. Then, in the
“Present,” we see that the malaise of the space program will be cured by a new generation
of entrepreneurs who are transforming our potential to leave the planet. We examine the
legal and regulatory barriers that stand in their way and consider the dangers faced by
space travelers. Peering into the “Future,” we look at how we can travel to the Moon and
Mars, and we investigate the technologies needed to establish colonies there. We meet the
robots that will be our partners in space and we visualize a time when off-Earth humans
become a new species. Finally, we speculate “Beyond” our current capabilities to the time
when we can travel to the stars and become citizens of the Milky Way. In a universe built
for life, our yearning for cosmic companionship is strong, and we may never realize our
full potential as a species if we stay Earthbound.
I’m grateful to Anna Ghosh for stalwart support of my writing career, and Tom Mayer
and Ryan Harrington at W. W. Norton for helping to forge a better book. I’ve benefited
from conversations with many colleagues over the years, but any errors or misstatements
that remain are my responsibility alone. My deepest gratitude goes to Dinah Jasensky for
her love and encouragement of all my writing endeavors.
PART I
PRELUDE
I
was four years old when I was chosen to be a Pilgrim. Too young to understand
what that meant, I heard my mother try to describe it, but her words made no sense,
so I fixated instead on the mixture of excitement and fear in her voice.
A few years later, the implications came into better focus. I suffered difficult years
in a normal school, where I was alternately ostracized and bullied, ignored and
humiliated, with a relentlessness seen only in children. To be a Pilgrim was an
extraordinary honor but it marked me as different, as other. It was a relief when I was
plucked from there at age eight and sent to a special school called the Academy, a
school for my kind.
The Academy was in Switzerland, on a mountain lake that sparkled aquamarine in
the sunlight, in a special compound where we were shielded from the media and
prying eyes. There were nearly 300 of us, from more than fifty countries. We got one
trip home every year but no family member could visit the school. Video chats with
outsiders were limited to an hour each week. It may sound harsh, but it was for our
own good.
We ranged in age from seven to twelve. I was one of the youngest. There were
equal numbers of boys and girls. With so many cultures and languages represented, it
could have been like Babel, so most of us wore our digital translators all the time.
The curriculum was also polyglot. We studied everything from engineering and
philosophy to medicine and fine arts. With as many tutors and counselors at the
Academy as students, we had plenty of help. Expectations were high and there was a
gentle but persistent pressure to excel. The staff was aloof, no doubt instructed not to
form emotional bonds with us. Some of them were psychologists and psychiatrists
who were clinical and often cold in their detachment.
I remember my dreams from that time.
Large shapes moving around in the darkness. An unrelenting pressure in my chest.
A door sliding up, an inch from my face, like the lid of a coffin. A window, and
beyond it, nothing, an absolute void. The images were both inchoate and sharply real.
I would always wake with a start and sit up, bathed in sweat, my breathing fast and
shallow.
On my mother’s last visit before I left the Academy, a few months after I turned
seventeen, she told me how my father died. I never knew the details when I was
young, and information at the Academy was tightly controlled. He was on his second
tour of a mining station on Phobos. His crew was deep in a shaft looking for
inclusions of platinum and iridium. Miscommunication with the surface crew caused
them to set off a charge nearby. Sofa-sized slabs of rock were ejected from the face of
the shaft. At the center of a small asteroid there’s no gravity, so no way to be crushed
by falling rock as on Earth.
But Newton’s laws have their own implacable logic. A large rock hit him squarely
in the chest and carried him to the opposite wall, where its momentum was
transmitted into his body, crushing and killing him instantly.
That’s probably part of why I was chosen. My father was a space rat and my sister
an accomplished pilot; I had space in my genes. But at the Academy there were many
kids with no predisposition to technical subjects; their parents were musicians or
artists or diplomats. No two of us were alike. We seemed to form, as intended, a
miniature world.
At my graduation, my mother and my sister were in the auditorium, and they
grinned ear to ear when I waved to them. Later, as we shared a meal in the dining hall
overlooking the lake, I flashed back to the way my mother’s voice had sounded a
decade earlier. Her excitement and fear had morphed into quiet pride tinged with
sadness.
After graduation, we had two weeks to pack up and say our farewells. Visits and
video chats were unlimited. I remember that it was emotionally exhausting to spend
so much time with my family. Many of the other students felt the same way. We were
young adults and had grown up without them, with only each other for sustenance. I
felt relieved when the time came to travel to the launch site, though that relief was
followed swiftly by a wave of guilt.
The time had come to learn what it meant to be a Pilgrim.
To be an emissary of Earth in the late twenty-first century. To be in a small group
chosen for a unique experiment. The experiment was designed by sober scientists and
engineers but it had the trappings of madness. We were human seedlings, charged
with taking root in a new world.
1
Dreaming of Beyond
_______________________
Out of Africa
When we were just one million strong, did we dream about what lay beyond?
Two hundred thousand years ago, anatomically modern humans first emerged in
Northeast Africa.1 The cradle of our creation was the place now known as Ethiopia. Over
the next hundred thousand years, these humans spread across Africa. Our distant ancestors
kept no journals and, as far as we know, they had no written language. Only bones and
scattered artifacts survive. Those artifacts speak of a rugged, doughty species that
ceremonially buried their dead, hunted with sharpened flints made into spears and arrows,
and daubed paint on cave walls to record the iconography of their lives. Their evocative
images, which must have seemed kinetic in the flickering glow of an oil lamp or a fire,
speak to us across the millennia of their fears and dreams.
Modern genetic techniques have allowed us to reconstruct their journey out of Africa—
an epic migration as audacious as our first steps into space many millennia later.
Life on Earth is united by a single genetic code. A four-letter alphabet of base pairs
encodes the unique function and form of every organism. The four bases—A for adenine,
C for cytosine, G for guanine, and T for thymine—form the rungs of the twisted ladder
that is DNA. A pairs with T and C pairs with G across the ladder; when the ladder splits
down the middle, each side is the template for a new DNA molecule. The genetic code
specifies the sequence of twenty amino acids used by living cells to build proteins.
If the genetic code were perfectly transcribed and expressed, there would be no
evolution and life would be, well, boring. It would also be a dead end, since it couldn’t
adapt and survive over time. One type of variation occurs when the genetic blueprint, the
genotype, is expressed in a particular environment, the phenotype. Two cloned seedlings
will develop quite differently when one grows in loamy soil and the other grows on a
windswept mountain. A second type of variation occurs over time when the genetic
material is altered by mutation or imperfect copying. Biodiversity cascades as variations
grow over time and are culled by natural selection. As a result, the DNA of life has
developed a tangle of branches that emerge from the root, a “last common ancestor” four
billion years ago.2 This primitive cell was the precursor of all plants and animals and the
mother of all microbes. Creatures that reproduce sexually, like humans, mix their DNA in
a way that makes everyone unique from their parents. This accelerates genetic variation
and evolution, particularly in small populations.3
Genetic anthropology is the use of DNA and physical evidence to trace human
migration. We all contain DNA from our last common ancestor, which is how we know
when and where humans originated. DNA mixes due to sexual reproduction but some
special sequences of DNA pass unaltered from parent to child. For example, the Y
chromosome passes only from father to son and so allows men to trace paternal lineages,
while mitochondrial DNA passes only from mother to child and so allows both men and
