Extreme Medicine (22 page)

But Soyeon knew that they hadn't separated from their orbital module correctly. Whatever it was that still remained attached could throw things off, leaving the capsule in the wrong orientation as reentry began. If an unshielded part of the capsule was facing forward as they pushed through the dense atmosphere, the heat would very quickly destroy them and their vehicle. If this had happened, then the first indications would be a sudden increase in the G load followed by heat building up inside the capsule.

Inside the capsule, the G meter, measuring the severity of their deceleration, peaked at 8.2 G—more than twice the normal value—and Soyeon struggled to remain composed.

—

I
T IS AN OLD ADAGE THAT
the two hardest feats in all of rocket science are starting and stopping. These are the so-called dynamic phases of flight, when the vehicle and crew are gaining or losing huge amounts of energy over a short period of time. It was a failure of an O-ring seal at launch that had killed the crew of
Challenger
in 1986 and a damaged heat shield in one of
Columbia
's wings that had destroyed it and its crew during reentry in 2003.

Just as the heat assaulting Soyuz from the outside was at its fiercest, a red lamp began to flash on the control panel. It was a warning light, telling them that something in their systems had failed and that the vehicle was switching to an emergency backup procedure: ballistic reentry. It meant that they were plunging inelegantly through the atmosphere—like the cricket ball rather than the Frisbee. But Soyeon found this strangely reassuring. The Soyuz capsule was designed for this. The ride would be rough, but they should still arrive safely.

After what seemed like an eternity to Soyeon, the violent buffeting stopped, and she felt a jerk as the parachutes opened above them. Unsure of what had happened, they checked their systems. It was at this time that they noticed something that looked like smoke coming from beneath one of the panels. In the cramped space of the Soyuz capsule, nobody could be sure of what they were seeing, but the cloud seemed to hang around Soyeon. With minutes left to go in the descent, the crew's fears turned to the possibility of fire.

Fire in the confines of the Soyuz capsule would be devastating. The crew decided to power down the electrical systems. The reentry had, after all, been hotter and harder than expected; perhaps something had overheated and caught fire.

Soyeon, however, wasn't convinced. As part of her PhD, she had worked daily with liquid nitrogen and liquid oxygen. To her this “smoke” looked like the vapors from a cryogenic system. Yuri asked her if she was absolutely certain. “Yes,” she insisted. Reassured, the crew turned their systems back on a short time before landing, but by then they were more than two hundred miles off course.

The capsule hit the ground hard, bouncing before it came to rest on its side in the Kazakh steppe, far from the intended landing site. The crew unbuckled their straps and crawled out, where they were met by a small group of nomadic tribesmen, who initially couldn't understand where Soyeon and her colleagues had appeared from or how they had arrived. Yuri flicked on a satellite phone and called in their position. It was cold—cold enough for their breath to frost in the air—and they would have to wait more than an hour before their rescuers reached them. But Soyeon was once again back on Earth and safe.

—

F
OR ORBITAL FLIGHT, IT IS ENGINEERING
and not clever adaptations or augmentation of physiology that saves lives. The nature of spaceflight is such that in its most dynamic phases, the resilience of our physiology and its ability to adapt to the physical extremes of the Earth are utterly irrelevant. The reliance upon artifice is so complete that any significant failure is met with the death of the entire crew. There has never been a mishap in spaceflight in which only part of a crew has been injured or killed. For every accident, the same has been true. Either everything works and everyone lives, or it doesn't and everyone dies. The first consideration on the way to the final frontier is not about our ability to adapt physiologically. It is about the safety of the evolved engineering solutions.

This recognition of our increasing reliance upon artificial systems to preserve and protect life is not limited to the endeavor of human spaceflight. We push at the edge of the envelope of survival in space exploration in the same way that we take our bodies to extremes in medicine. Evolution has finely crafted the balance between our physiology and the limits of the natural world in which we live. That solution leaves us complex and capable but at the same time fragile. The challenges that we face in future exploration and the limits we would like to probe in medicine far outstrip the spirited but limited resilience of the human body. We no longer explore in the way that Scott and his forebears explored, when determination and self-reliance were the key prerequisites. In this century, exploration will rely almost entirely upon artifice.

—

T
EN DAYS AFTER THE LAUNCH,
I stood in darkness at the shuttle landing facility, swatting mosquitoes and straining my eyes in vain to try to catch sight of
Atlantis
. The last mission of the space-shuttle era would land at night, cruelly close to daybreak. We'd be lucky to see anything at all, but we had to come anyway. Somewhere above, the crew of STS-135 was on its way home.

A double sonic boom overhead heralded
Atlantis
's arrival. She was circling now, on final approach to Kennedy Space Center, falling unpowered back to Earth, her fuel gone, nearly all of her energy spent. We caught a glimpse of her as she flew through searchlights near the end of the runway, before she touched down out of sight. It's not how I had imagined it. I thought that the last space shuttle would land in a blaze of illumination and trundle triumphantly across the tarmac, trumpeting the end of an era. Instead
Atlantis
darted furtively from cover to cover in the half light, gone almost as soon as she'd appeared, vanishing into what remained of the night like a mythical creature.

It had been half a century since Yuri Gagarin first ventured into orbit aboard
Vostok 1,
in a mission lasting an hour and a half. In those fifty years, the Russians and their American counterparts had learned to work together in low Earth orbit, transforming it into a staging post for still more ambitious feats of exploration. People now permanently lived and worked in space. Low Earth orbit could be visited not just by trained astronauts like Soyeon, but by paying customers. It was time to set sights on new destinations.

W
hen I first arrived at NASA in 1997 as a student, it was all about Mars. The human spaceflight division buzzed with excitement; there was a sense that the agency might really be about to embark on a new chapter of exploration—the next small step.

There was a kind of Mars underground at NASA, a cadre of folk who had long held dear the hope of sending a human crew to the Red Planet. For them, low Earth orbit and the Moon were pedestrian destinations. Mars was where the action was at; exploring it would be the defining feat of their generation: a long overdue return to the sort of barefaced ambition that had first made NASA famous. A badge had appeared on the lapels of the faithful: a cheap tin badge about the size of a quarter with the words M
ARS OR
B
UST
! in bold red lettering.

We've imagined sending people to Mars since well before Gagarin's first spaceflight. Wernher von Braun, principal architect of the Saturn V launcher that delivered Neil Armstrong and Buzz Aldrin to the Moon, laid out his dreams in the 1953 publication
Das Marsprojekt
(
The Mars Project
), the first mature study of what it would take to send humans across the huge void of space that lay between Earth and Mars.

It was a design of startling ambition. In it von Braun envisaged an armada of ten spacecraft plowing on toward their destination, crewed by no less than seventy astronauts. In this plan, he foresaw the need to place nearly forty thousand tons of payload in low Earth orbit, providing a platform of booster stages with which to launch his Martian flotilla.

Von Braun's plan was, of course, too fantastic in scale to ever be realized, but the kernel of these designs underpinned much of what would follow. The idea that future explorers of Mars would be hurled away from Earth by a brief but violent explosion at the start of their journey and then left to fall freely through space toward their target became the accepted template for human missions to Mars.

Throughout the
twentieth century, Mars continued to drift in and out of our thoughts, appearing almost within reach and yet somehow tantalizingly beyond our grasp. Von Braun's designs envisaged 1965 as the date on which the first humans might arrive at Mars. And since
Das Marsprojekt,
more than a thousand different technical studies have been conducted, most of them making the assumption that Mars lay little more than twenty years in the future. But that is where Mars has remained: always in our future.

Space is not a single destination. Earth orbit, the Moon, and Mars are as different in character as the continents of the Earth. So too are the voyages and challenges involved in reaching these locations. Low Earth orbit is about negotiating the violence of launch and the terror of reentry, about understanding how we should climb out of the well of gravity in which we live, breaking the bonds of attraction created by the mass of the Earth.

Orbital spaceflight is a furious sprint, with the energies involved barely controlled, an endeavor in which the frailties of human physiology are swamped by the physicality of the propulsive systems. For the pioneers of this age, the ability of the human body to adapt to the extremes of terrestrial environments was largely irrelevant. Dangers were more immediate and dramatic—catastrophic explosions that no one could hope to survive.

Mars presents a challenge of a different scale and character; it's more a marathon than a sprint. The Moon hangs around a quarter of a million miles away from the surface of the Earth. It is a distance we can easily conceptualize: the number of miles the odometer in your car might clock up before the vehicle seizes and fails. The Moon, the farthest point from the Earth any human in the history of our species has ever traveled, lies close enough to inspect with little more than the naked eye, reachable within four days of spaceflight.

Mars gets no closer than thirty-five million miles away. Its position relative to the Earth is always changing, stretching that separation to as much as four hundred million miles. To cross that gulf, astronaut crews will have to endure missions drawn out over months and years, spanning hundreds of millions of interplanetary miles, traveling thousands of times farther than Armstrong and the Apollo pioneers.

These crews, too, will have to survive the energies of launch and those involved in rocketing them away from Earth and toward Mars. But as they fall across the void that separates the two planets, they will also have to contend with the silent threat of space and its environment. Here the absence of gravitational load takes on a new dimension, transforming from a novelty into a creeping threat.

—

T
HE TERM ZERO-G IS A MISNOMER.
Weightlessness in low Earth orbit does not arise because there is no gravity. The gravitational attraction of the Earth doesn't suddenly melt away to nothing just because we venture 250 miles away from its surface. At that altitude, the force of gravity is only modestly diminished, to around 90 percent of its value at sea level. If you were somehow able to build a house on the end of a pole 250 miles long and live in it, you might have trouble noticing the change. A dropped glass would still break; climbing stairs would still require effort. There might be something of a spring in your step—you and everything around you would be around 10 percent lighter—but you wouldn't find yourself floating around from room to room. The weightlessness of orbit is experienced not because of the astronauts' separation from the Earth but because of the way they fall around it.

Weightlessness is something we have all experienced; it's only that our experience of it is generally so brief as to be barely noticed. If you jump up as hard as you can, you might stay in the air for a little over a second. For that time, you are weightless.

You could prolong the experience simply by falling farther. Imagine standing in a lift on the thirtieth floor of a skyscraper at the moment the supporting cable snaps. From the moment of release until the moment of impact you'd be weightless—a ride of around three hundred feet that would last a little over four seconds.

In the same way, astronauts in low Earth orbit find themselves floating because they are inside a spacecraft that is permanently in free fall around the Earth.

—

S
TRAPPED INTO MY SEAT
aboard a modified Airbus, I'm waiting to watch how the French do weightlessness. This is a specialized flight under the auspices of the European Space Agency's DGA (Direction générale de l'Armement) Essais en vol (literally, “tests in flight”), conducted by pilots who specialize in flying aircraft high into the sky in a parabolic arc and then plunging them into a steep dive, pulling out just in time to avoid disaster. At least, that's the theory.

There is a flurry of activity before the start of the parabolas. In place of air stewards, we have frequent flyers in tangerine jumpsuits, there to lend a hand if things get rough: the “orange angels.” People get ready, tweak experiments, and position themselves, preparing for the next stomach-lurching maneuver. “One minute,” comes the Gallic voice over the intercom, starting the countdown. The scurrying becomes more frantic.

“Twenty seconds . . . ten seconds . . . pull up!” comes the same disembodied voice. The words are spoken levelly, with no hint of excitement. The person uttering them is at the controls of the plane.

For the next ten to twelve seconds, we are pushed into the foam covering the floor of the aircraft. We experience close to twice the normal gravitational load. The burden of my 168-pound frame is suddenly doubled. I feel as though I'm made of lead.

This is nothing compared to the loads that fighter pilots experience during fast turns, but it's more than enough to create discomfort. It's not just toughing out the extra weight; this maneuver is perfect for confusing the hell out of the delicate system of accelerometry in your inner ear.

“Thirty,” calls the pilot in the same level tone of voice, narrating the angle of climb now instead of time. We are on our way up to the top of the roller coaster. That's exactly how it feels—the nervousness, the anticipation, the excitement—and that's not far off what it is. Only this ride is 25,000 feet high and will repeat itself thirty times in the next couple of hours.

“Forty,” comes the voice. “Inject.” And then, in one of the most effective rapid weight-loss programs the world has ever known, I go from being 336 pounds to weighing nothing.

They refer to the point at which the plane begins to fall away from you as rapidly as you are falling toward it as injection. It does indeed feel as though you've been injected into an alternate reality, one in which the normal laws of physics have been briefly suspended. Around you people and things tumble weightlessly, with no respect for the concepts of up or down. The effects of gravity are suspended here. All those dreams you ever had of flying? Well this aircraft makes them come true for twenty-three seconds at a time.

The Airbus drifts over the top of its parabolic arc, its lift balanced perfectly against its weight, thrust throttled to match drag.

“Thirty . . . twenty . . . pull out.”

After hanging effortlessly in midair one second, I'm smashed back into the deck. The phrase “back down to Earth with a thud” could have been invented for the experience of parabolic flight.

Glancing outside, I see the wingtips flexed two meters out of their normal position, like a tensioned bow. More alarming still, a steady trickle of fuel escapes along the wing edges. Swallowing hard, I turn back to the cabin.

The 1.8-G load pours on. People's faces appear to age visibly as gravity takes on the skin's elastin and wins. I'm lying on the deck, still managing a smile, when I catch sight of one of the other passengers, head buried in his arm, sweating beads.

One of the orange angels asks him if he's OK. He shakes his head vigorously. He's manhandled to the rear of the plane. There's a fumble for a sick bag and the familiar sound of retching. It's not for nothing that they call this the Vomit Comet.

—

I
N OUR DAILY LIVES,
gravity is that pedestrian physical force that keeps us glued to the ground. We don't think of it as something that shapes our lives. Our bodies are set up to allow us to move within its field of attraction without too much effort, so much so that we barely notice it. You have to go out of your way—climb a cliff face or jump out of a plane—before it starts demanding your attention. But we are constantly sensing the effects of gravity and working against them—largely unconsciously.

We are, for example, equipped with antigravity muscles—those groups that work against the Earth's force of attraction to keep you standing upright. To get an idea of which groups these are, imagine being on a parade ground with a sergeant major barking at you to stand to attention. Pretty much every muscle you would tense to avoid the prod of his baton is antigravity in function.

Of these the quadriceps, buttocks, and calves, along with a group of muscles—the erector spinae—that surround the spinal column and keep it standing tall, are the most important. Without them the pull of gravity would collapse the human body into a fetal ball and leave it curled close to the floor.

These muscle groups are sculpted by the force of gravity. They are in a state of constant exercise, perpetually loaded and unloaded as we go about our daily lives. It is because of this that the quadriceps, the mass of flesh that constitutes the bulk of your thighs and works to extend and straighten the knee, are the fastest-wasting group in the body.

Your bones, too, are shaped by the force of gravity. We tend to think of our skeleton as pretty inert—there to provide rigidity, little more than a scaffold on which to hang the flesh or a system of biological armor. But at the microscopic level, it is far more dynamic: constantly altering its structure to contend with the gravitational forces it experiences, weaving itself an architecture that best protects the bone from strain.

The biological adaptations to gravity don't stop there. When you're standing up, your heart, itself a muscle pump, has to work against gravity, pushing blood vertically in the carotid arteries that lead away from your heart toward your brain.

Even your system of balance and coordination appears to rely in a fundamental way upon the constant force of gravity, with the otoliths—the organs of the inner ear that sense linear acceleration—using it as a sort of calibrating input.

Life on Earth has evolved over the past three and a half billion years in an unchanging gravitational field. In that context, it shouldn't be a surprise that so much of our physiology appears to be defined by, or dependent upon, gravity. Take gravity away, and our bodies become virtual strangers to us.

—

A
S A MEDICAL STUDENT,
you don't take the contents of the inner ear very seriously. The organs within detect acceleration and audible stimuli, gathering information about motion and sound. But they are not considered “vital,” in the sense that they are not required to keep the human body alive. As a result, the essential role they play in delivering a finely calibrated sense of motion is often overlooked. However, like all of the best things in life, you don't really appreciate what you've got until you lose it.

The system of accelerometers in your inner ear, the otoliths and semicircular canals, are engineered to provide the finest detail about movement in the ever-changing world about you, creating the illusion that you are essentially a stable platform through which the world can be observed as though it were a film made with a Steadicam. It is a system that shares its inputs and outputs with the eyes, the heart, the joints, and the muscles.

Consider for a moment the act of looking at stuff. Hold a finger up in front of your eyes. Now shake your head left and right as though you are vigorously saying no. The image of your finger remains remarkably stable, doesn't it? Now try keeping your head still and waggling your finger back and forth at the same rate. This time the image is less stable; plenty of blur creeps in.