Surviving the Extremes: A Doctor's Journey to the Limits of Human Endurance (40 page)

Were your space suit inflated to the same sea-level pressure as your space capsule, you would float out looking something like the Michelin tire man. Shoulders and hips might be able to move against the high pressure, but the small muscles in the hands would have no chance. Tightening a bolt, much less fixing a telescope or even opening a door, would be hard if you couldn’t move your fingers. Cosmonaut Aleksei Leonov made his first space walk outside
Voskhod 2
in a fully pressurized suit. When he tried to get back inside, he found the suit was so cumbersome that he could hardly grab the door handle, and had to perform an emergency depressurization before he could fit through the opening. So suit pressure needs to be reduced. One-third sea-level pressure is a good compromise: low enough to provide some flexibility yet still high enough to hold back the space vacuum. But then slipping into a space suit from a fully pressurized cabin would be like going from sea level to the summit of Mount Everest with no acclimatization. And we’ve learned how the body reacts to that.

To acclimatize safely, your decompression—or reduction to space suit pressure—should take at least four hours, and that’s far too long to wait around for each space walk. Astronauts cut preparation time to forty minutes by modifying the environment in the cabin and space suit to narrow their differences. Less difference means quicker adaptation.

Cabin pressure was dropped to two-thirds of an atmosphere just after docking, so your body is already starting to adjust while you’re performing other tasks. Hours later you get into your suit, at one-third atmospheric pressure, and start breathing pure oxygen. Though there’s less air, there is enough oxygen in it to keep your lungs working to capacity. The miniacclimatization and the supplemental oxygen work in space as well as they do on Everest.

The moment arrives. Standing in the open hatchway, you launch yourself into the void by pushing off on your toes. The feeling is eerie and overwhelming and you need to adjust to the sensation of being in slow motion. You float over to do some maintenance work. All workstations feature a handhold or foothold for stability. If they didn’t, pushing a button would propel you backward off the rocket, and tightening a bolt would spin you counterclockwise into space. Both of these things you manage to do, and many other things as well, but the work is strenuous, and doing them in a space suit is like exercising inside a thermos. The problem of heat buildup is addressed by water-cooled underwear. Interwoven into its fabric are hundreds of yards of tubing through which water is pumped before being passed over an ice pack. Water-cooled long underwear is available for especially hard work.

Modular units that need servicing or that are most likely to need repair work are designed with round corners and easy access. Still, sometimes unanticipated repairs have to be made. Astronaut Jeff Hoffman related to me how fixing the Hubble Space Telescope (whose myopia was the biggest blunder in the history of optics) required his team to work at some very awkward angles and to squeeze into compartment corners that were never meant to be entered by astronauts. Sharp edges and pointy instruments can puncture a space suit more easily than a micrometeorite. Should something happen, however, sensors will note a pressure drop and automatically inject high-pressure oxygen from a backup canister, which can feed a quarter-inch leak for half an hour. That should be enough time to get back inside. If not, the rapid depressurization would theoretically cause the bends. Should it ever happen, the treatment would be to put the astronaut into a functioning space suit, block the relief valve, and then pump the suit up to twice normal pressure. The suit would act like a recompression chamber. Better not to get bent, though. Besides being very painful, the treatment ruins the suit.

Attaching fuel tanks, solar panels, cameras, antennas, and other assorted equipment and then visually or manually verifying each system takes several sorties of teams from the spacecraft and the space station, and in various combinations. Finally, though, your work at the space
station is done. It took either three days or forty-eight days, depending on where you were standing. On Earth, the planet made three spins past the sun. On the station, orbiting at 18,000 miles per hour, the sun rose and set and rose again every ninety minutes. This rhythm is hopelessly confusing to your pineal gland. Located at the base of your brain, the gland had been accustomed to gently secreting the sleep-inducing hormone melatonin in response to the gradual onset of darkness. In space your sleep pattern is interrupted—in fact, you’re not sure you’ve slept at all since launch.

Your biggest impediment to sleep, however, isn’t the pineal gland’s confusion; it is you. Like all astronauts, even veterans, you’re so excited about being in space that you don’t feel tired and don’t want to waste time sleeping. This is your last day (or last sixteen days) in Earth’s orbit, and though you’re scheduled for a few orbits of sleep, you would rather look out the window. Being exhausted, however, you are unable to resist visual cues. Each time the spacecraft goes into darkness, you fall instantly and soundly asleep. You awaken bright and full of energy when it comes back into sunlight. You go through an entire sleep-wake cycle every ninety minutes. To get some solid sleep, all you have to do is pull down the shade—except that out the window, rolling under you, is a gorgeous aqua-blue planet. Soon it will disappear from view as you head toward Mars. These few remaining orbits may be the last you will ever see of your home.

The main engines power up for the trans-Mars propulsion. Thrusters fire, reorienting the rocket toward outer space. You feel the pull of gravity once again; orbital equilibrium has been broken. This time it’s a gentle pull as Earth slowly releases you from its final hug. You turn away from the window, now filled by the blackness of space, and look around the cabin: your home for the next three years.

Through a combination of complex machinery and clever contraptions, life in the spacecraft can feel almost like home. Cabin pressure is the same as at sea level, and the air is cleaner than on Earth. The temperature remains a constant and pleasant 70°F; your clothes are appropriately casual. A refrigerator keeps drinks cool. Food is preserved by dehydration. The menu consists of 120 choices. A day’s meal might include scrambled eggs for breakfast, a ham-and-cheese
sandwich for lunch, and shrimp cocktail, steak, and broccoli au gratin for dinner. There are thirty beverages to choose from. Hot and cold tap water is plentiful because, conveniently enough, the fuel cells that combine hydrogen and oxygen to produce electricity give off water as a by-product. There is no dining table, but with adhesive straps you can attach a serving tray to your legs. Despite zero gravity you can eat your food with ordinary silverware, so long as there are no sudden starts and stops. There’s a watertight shower stall for periodic, and mandatory, use, though sponge baths are more practical. Every two days you put on fresh socks and underwear, sealing the dirty laundry in airtight bags until you put it through the washing machine. The toilet is very similar to earthbound ones except that air current rather than gravity draws the waste into sealed containers. To prevent hair pollution, the men have power shavers with vacuum attachments. The women keep their hair in nets so it won’t get caught in machinery, though for photos and videos they’re allowed to let it flow freely, thereby creating the ultimate “big hair” picture.

You have all the comforts of home, except that your survival depends entirely on an artificial environment maintained by an array of machinery too complex for any one person to understand or maintain. This home is a tiny oasis encased in a metal shell sailing through the vast and deadly realm of outer space. Lingering as it does in the back of your mind, this thought never lets you fully relax. A sudden noise gets your immediate attention, like the loud bang astronauts Jim Lovell, Jack Sweigert, and Fred Haise heard in
Apollo 13
as it was on its way to the moon. They very quickly determined that two of the three fuel tanks had exploded. Lovell looked out the window and saw gas escaping from a hole blown out the side of the command module. Most of the supply of power, oxygen, and water was gone. Two hundred thousand miles from home and headed in the wrong direction, they would need four days to circle the moon and return to Earth. “Houston,” Sweigert famously radioed to Mission Control, “we have a problem.”

A body can survive a few days without water but only a few minutes without oxygen. The supplies in the
Apollo 13
command module were lost, but luckily the lunar landing module contained
more than enough oxygen and just enough power and water to get them back. Had the fuel tank been the tiniest bit stronger and exploded on the return flight, the lunar lander would have been depleted, leaving the astronauts with no lifeboat.

The most sinister threat to the three astronauts’ survival was their own breath. They had enough oxygen, barely, but soon they had too much carbon dioxide. The natural by-product of respiration, carbon dioxide is poisonous in high concentrations. The problem is neatly taken care of on Earth, where plants take it in and produce oxygen as their by-product. But a space capsule is not an ecosystem. Canisters of lithium hydroxide are needed to “wash” the carbon dioxide out of the air. There were only two in the lunar lander—not nearly enough to absorb the exhalations of three astronauts for four days.

In a sealed room, carbon dioxide will kill you long before you run out of oxygen. Breathing is stimulated not, as might be expected, by too little oxygen in the blood but by too much carbon dioxide. The respiratory centers in the brain that monitor both gases are far more sensitive to carbon dioxide concentration. As its level rises, your breathing rate will increase, to blow off more of the gas. At toxic levels, your breathing becomes very rapid and shallow, too inefficient to get adequate air into the lungs.

To minimize their carbon dioxide output, the
Apollo 13
crew did their best to limit physical exertion. Nevertheless, the lithium hydroxide canisters, functioning on reduced power, were saturated after a day and a half. Warning lights flashed. There were extra canisters in the command module, but their square pegs wouldn’t fit into the round holes of the lunar module filtration system. Through trial and error, engineers and astronauts on the ground improvised an adapter, using only items that would be available on the spacecraft. Following step by step the instructions radioed up to them, the
Apollo 13
crew assembled a jury-rigged contraption of plastic bags, cardboard, parts scavenged from a spacesuit, and a lot of duct tape. An hour later they were breathing easy—and so was the ground-support team. Without that low-tech solution to a high-tech problem, the mission would have ended in tragedy. Instead,
Apollo 13
became “the most successful failure” in NASA’s history

NASA is justifiably proud of its performance, but that doesn’t provide much assurance to you and your fellow Mars travelers. Actually, the story is disquieting. A similar crisis on this mission would most likely not have a happy ending. The
Apollo 13
explosion occurred a mere 200,000 miles from Earth—a distance that can be traveled in four days by a spacecraft and one allowing almost instant communication with Earth by radio signal. An explosion on the way to or on Mars, depending on interplanetary alignment, could occur anywhere from 100 to 250 million miles from Earth, with a return transit time of six to eighteen months. Radio communication might have as much as a forty-minute delay. In an emergency, survival will be up to you.

A sobering thought as you head out into deep space. Right now you’ve got a cold and a backache and your bladder is full. Your stouthearted shipmates, equally puffy-faced, can’t seem to get comfortable and are getting up to pee a lot. Liberated from the bonds of gravity, the water within you no longer feels the need to stay in place. Since your body is more than 60 percent water, major shifts in fluid distribution are occurring. You’ve got “bird legs.” The half-gallon of water normally held down in your legs by gravity has floated upward, causing overload in the head, especially in the nose and sinuses. The congestion causes a loss of taste and smell, and this makes you feel as if you’ve caught a cold. Free of downward pressure, the stack of vertebral bones that make up your spine has drifted apart, allowing the fluid migrating through your body to enter and swell the cushions, or discs, that separate the bones. The hydraulic pressure cranks your spine out, making you two inches taller than you were on Earth. Sounds great, except that the sudden pull gives you a backache. No position feels comfortable. You feel as if you need to stretch your muscles, but generating the necessary counterforce is not so easy; pushing against something in a space capsule just moves you away from it. Inside the major blood vessel of the chest—the aorta—and of the neck—the carotid artery—receptors monitor the amount of blood in the body, relaying the information to the maintenance center in the hypothalamus. Not understanding the idea of weightlessness, your brain interprets the extra volume flooding the receptors as an overload. It signals for the release
of hormones that reduce whole body fluid by filtering out more through your kidneys and into your bladder.

So you’re an intrepid explorer with a stuffy nose and sore back who frequently needs to go to the bathroom. You’re also still suffering from bouts of space sickness. Yet incredibly, after several days in space, you adapt. Your body begins to function smoothly on reduced fluid volume, draining swollen tissues and relaxing stretched muscles. Sinuses clear, back pain vanishes. Having reached a new fluid equilibrium, you no longer have the urge to excrete excess water. Your nausea and dizziness have subsided as well. The vestibular system has a built-in ability to reset balance—otherwise we would be unable to adapt to our own growth or weight gains. But that kind of adjustment happens at a leisurely pace and is dependent upon feedback from gravity; it won’t happen fast enough for a space flight. Therefore the brain reprograms itself using visual cues. You have learned to play by a new set of rules.