Surviving the Extremes: A Doctor's Journey to the Limits of Human Endurance (41 page)

Emboldened once again, you and your small group of earthlings are ready to encounter your most formidable interplanetary enemy: the nuclear army waiting in ambush as soon as you venture beyond Earth’s protective fortress of atmosphere and magnetic field. Deadly radioactive particles and waves come from two sources—cosmic rays and solar radiation.

Cosmic rays originate outside the solar system, generated by the explosions of supernovas and other giant stars, ripping apart atoms of hydrogen, helium, and iron—the primary constituents of the stars—and releasing protons and alpha rays, highly energetic subatomic particles that radiate outward at nearly the speed of light. Coming from every direction in the galaxy, they weave a thick fabric that penetrates all of “empty” space. The other source of deadly radiation is closer to home—the sun. Sunshine is the result of an ongoing thermonuclear reaction, one by-product of which is the release of protons and electrons that stream outward in a steady flow called the solar wind. Once in a while a sun storm erupts, creating a solar flare that can rise 1,000 miles above the surface and release protons at 10 billion times the rate of the solar wind. The blast is unidirectional, can last for hours or days, and its timing is unpredictable. Traveling close to the speed of
light and aimed toward a rocket traveling from Earth to Mars, it would take about two days to arrive.

Cosmic rays and solar flares are two galactic villains to which earthbound creatures have never been exposed. The menagerie of deadly particles and rays that they produce is kept at bay by our planet’s environmental shield. Earth is surrounded by a gas-filled atmosphere and ringed by a two-part magnetic field called the inner and outer Van Allen Belts, both of which originate and terminate at the North and South magnetic poles. Many space particles carry electric charges, and as they approach the frontiers of Earth, some are drawn into, and captured by, one of the two magnetic belts, creating two rings of intense radiation. Some of the trapped particles ride the magnetic field to the North Pole, where they descend through the atmosphere, reacting with oxygen to create a fluorescent green glow known as the aurora borealis, or northern lights. The atmosphere promptly absorbs particles that somehow manage to filter through the Van Allen Belts. As these particles collide with atoms of oxygen, nitrogen, and, especially, water vapor, they lose energy and eventually fizzle out before they reach the ground. The only waves that make it through this obstacle course are the visible spectrums that light up our planet, and the ultraviolet rays that give us our suntans.

Inside the space capsule, radioactivity can’t be seen or felt, but the reading on the radiation gauge indicates a sharp rise. At 500 miles above Earth you enter the inner Van Allen Belt; 6,000 miles later, the reading drops, only to rise again at 15,000 miles and then slowly taper off over the next 10,000 miles. You’ve exited the outer Van Allen Belt. Now you are outside the bars of Earth’s protective cage, vulnerable to the relentless bombardment of cosmic rays and the unpredictable bursts of solar flares. Every particle that collides with your body will trigger a nuclear reaction. A high dose will generate enough explosive energy to break down molecular bonds in your cells and kill you outright. Smaller doses will alter strands of DNA, the highly sensitive and complex genetic molecule present in all cells that controls cell duplication. Loss of that control in reproductive cells will lead to
genetic malformation. In the rest of the body, it will lead to the chaotic proliferation of abnormal cells known as cancer.

How much radiation damage you will incur on this mission is unknown, but it will be far higher than on any previous flights. Only the moon landings took astronauts outside the Van Allen Belt, and those missions were of relatively short duration. Space shuttle flights and space station operations happen below the Van Allen Belt, so the radiation level remains low. An exception was the mission to repair the Hubble telescope, which had been placed in a high orbit so that it would be free of as much atmospheric interference as possible. The astronauts were exposed to radiation in the Van Allen Belt, roughly the equivalent of two chest X rays per day, a high dose. Nonetheless, until this mission, flight times for astronauts had been short enough so that total exposure to radiation was less of an occupational hazard than for airline attendants, who work at a lower altitude but spend much more time in the air. As for solar flares, they are easily visible to an astronomer, who can give a two-day warning to deorbit a spacecraft or evacuate a space station. Plenty of time.

But you’re on your way to Mars. The cosmic rays will add up, and you won’t be able to outrun solar flares. Putting full shielding on the spacecraft would have made it too heavy to lift off. Partial shielding would have been far worse than nothing at all, for when cosmic rays penetrate shields, they interact with the metal, forming highly radioactive neutrons. Because neutrons have no electric charge, their energy is not easily deflected. They have a high affinity for hydrogen, one of the two elements in water, and water is the primary ingredient of human beings. This is the reason why neutron bombs would kill people so effectively yet would not disturb buildings.

The cumulative effect of long-term exposure to cosmic rays may be unknown, but the effect of a solar flare is easy to calculate: one dose is fatal. So intense is the burst of radiation that you would die within a few hours. You need a safe haven when a solar flare is moving toward you, and your spacecraft provides one—a small, well-shielded shelter into which you and the crew can retreat for the hours or days it takes for the intense radiation to pass by. As for the cosmic rays, space contains no water to absorb them like Earth’s atmosphere does, but your spacecraft boasts a plentiful supply, stored in hollow tanks
surrounding the sleeping quarters and workstations and affording at least some protection from the steady bombardment. How effectively this works you won’t know for years. If you do return from space, you will only be able to say, “I survived the trip to Mars . . . so far.”

Months pass. Radiation may be the biggest environmental threat to your mission, but the greatest danger of all may come from within. Echoing the words of the cartoon character Pogo, you may one day radio back to Earth, “We have met the enemy, and he is us.”

Powerful human forces are put in play when you seal six people into a container for three years. The enormous blue globe that was turning outside your window a few months ago is now but a speck in a black void. Everyone you’ve ever known intimately, everyone who truly understands you lives on that speck, moving 25,000 miles farther away every hour. Your family wanted you and needed you at home, but they stood behind your decision to depart on mankind’s greatest adventure. You left them, some would say forsook them, to adopt a family you need to get along with for the next three years.

That family consists of a highly select group of pilots and scientists whose qualifications for inclusion were not what you had first imagined—otherwise you might not have been selected yourself. Six hard-charging test pilots with alpha male personalities would have been a recipe for disaster. Nor can the group have six leaders. Members were picked to blend commanders with conciliators, introverts with extroverts, talkers with listeners. The group is multinational, coed, and ethnically mixed, as befits any enterprise of this historic magnitude, not merely for geopolitical expediency but because different perspectives create a stronger team. Besides, six people with the same cultural and social background on a claustrophobic three-year voyage would be incredibly boring—and therefore very dangerous.

Boredom may be the most deadly disease you will face. Its symptoms begin slowly and subtly, the first signs being a loss of energy and motivation. Soon you’re fatigued and irritable, and gradually you lose your tolerance for others. You may withdraw and sink into depression or become aggressive and, at the extreme, hostile. Much has been done
to prevent, diagnose, and treat boredom. Potential crew members were analyzed and evaluated through endless interviews and personality tests, then mixed and matched until, like a patchwork quilt, the pieces seemed to fit together to form a harmonious pattern. The interior of the living quarters was humanized. Sharp edges and exposed metal were kept to a minimum. Illumination was subdued, except for reading lamps and the brightly lit multicolored instrument panels. Walls were painted in soft hues, and large windows were placed in positions easy to look through, though other than the background of stars, there’s nothing out there to look at.

You have far less contact with the outside world than a prisoner. Stimulation has to come from within, but by this point, systems maintenance and experimental protocols no longer take up much time or inspire much interest. You have the very latest in entertainment and educational technology—exciting at first, but it all got stale pretty quickly. You were encouraged to bring along hobbies, but how many times can you look at your, or somebody else’s, stamp collection?

The key to treating boredom is to keep stimulation dynamic and personal. With an up to forty-minute delay in communication, you might be able to play a chess game with someone on Earth, but you can’t hold a meaningful conversation. Though you can occasionally receive video broadcasts of your family and hear their voices live over the radio, dialogue is mainly limited to e-mails; these take days to complete. You try to take part in family life, even help manage family affairs, but the frustrating delays make it harder and harder to stay in the loop. Events on Earth are passing you by, decisions are being made without you. You feel more and more irrelevant and isolated.

Ground control does what it can to keep you in touch with the planet. They beam news at you, arrange continuing education courses, and even encourage you to vote with absentee ballots. But earthbound institutions seem increasingly less important. Your world is here, in this space capsule.

You don’t even have night and day. It is always dark outside the window. No diurnal rhythm to regulate your biological clock. This was a problem I experienced, though for the opposite reason, when I spent a month in Antarctica. There during the summer the sun remains
constantly overhead, like a naked lightbulb in a windowless room. With no daily light change, melatonin has no idea when to begin its nightly hormonal flow. I slept when I felt physically tired or when I had nothing else to do. I awoke when it was time to resume work or when I felt fully rested. I carefully recorded each day’s events in a log, yet when I returned home I found that my log consisted of only twenty-three entries; I had been gone thirty days. Deprived of any outside cues, my body had reverted to an average thirty-six-hour day—awake about twenty-four hours for each sleep of about twelve. It was responding to some inherent need for replenishment rather than to the exigencies of survival for a human, a light-adapted animal that hunts and gathers during the day and seeks safe shelter at night.

The environment inside the spacecraft doesn’t promote anything resembling a normal sleep pattern either. You’re zipped into a sleeping bag tied into the wall so you don’t float away. Without downward pressure, you don’t feel the reassuring contact you were accustomed to on Earth. Machinery noise is incessant. Crews work in shifts, so a light is almost always on somewhere, and somebody’s bound to be moving around. Dozing off as necessary may work for a month in Antarctica, but it won’t fly in space for extended periods of time. Here, sleep has to be carried out on schedule, like any other part of the mission, no matter how badly you may want to stay up past your bedtime. You use sleeping pills to restore order, but they don’t induce good-quality sleep, and there are unpleasant side effects. More than once you’ve awakened confused and disoriented, wondering where you are. Or were.

Your body is deteriorating. You’ve lost muscle tone, your bones are weak, and your blood volume has dropped. Muscles and bones designed to hold the body up against the force of gravity are unemployed. Without steady work, any muscle will atrophy, losing both substance and strength. Bones not subjected to continual stress will become osteoporotic, losing the calcium framework needed to bear weight. The excess calcium leaches into the blood, whose volume is already diminished by all that urinating you did to compensate for the fluid that sloshed up from your legs when you first became weightless.
The calcium gets concentrated when it passes through the kidneys, coalescing into hard balls. When a ball gets trapped in a filtering duct, you experience the sudden and excruciating pain of a kidney stone.

Other, less noticeable changes are also under way. Your decreased blood volume has concentrated the oxygen-carrying red cells in the blood that remains. Not programmed for this possibility, the body reads the increased concentration as an excess of cells rather than a lack of fluid. It resets the proper hematocrit by destroying red cells, making you anemic and tired. Your heart has less blood to move around, what it does pump has no weight, and the demand for output is greatly reduced given that you do heavy lifting with one finger and can cross the entire spacecraft by pushing off on a single toe. Your heart has it pretty easy, and like all other muscles, it weakens from lack of use.

Your immune system, your body’s protection against disease, also weakens. No one understands why this happens. The phenomenon, which occurs in Antarctic encampments as much as on space stations, seems, strangely, to be caused by any prolonged isolation in close quarters. Outer space, however, also introduces some unique infection risks. Germs from an unconfined sneeze, unimpeded by gravity, will spread out in three dimensions and hang suspended in the air. Transported from Earth in and on our bodies, our germs may no longer be relatively harmless. Like you, they have been subjected to space radiation and weightlessness. They have most likely undergone frequent mutations and evolved through thousands of generations, adapting rapidly in order to ensure their own survival—not yours. The once-benign bacteria and viruses may by now have been transformed into virulent carriers of unrecognizable diseases.