Humans want to go to Mars. Too bad the journey turns our bodies into mush. NASA's solution: strap down a few civilians and spin them around really fast.
"Medical team ready?"
The author gets set for a tolerance run at NASA Ames Research Center.
I'm strapped into a modified fighter jet seat, my head encased in a blue helmet bolted to the top of the chair. The chair is inside a windowless box at one end of a 58-foot platform at the human centrifuge facility in Building N-221A of the NASA Ames Research Center in Moffett Field, California. At the other end, there's a 6- by 71/2-foot chamber – about the size of a minivan – where I'll be spending the next 22 hours. But first, a tolerance run in the chair to see how much gravitational force I can bear. A 300-horsepower engine causes the entire apparatus – the chamber on one end, the chair on the other – to spin on an axis inside a 62-foot-wide circular bunker.
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The voices of a team of NASA technicians and doctors are piped in through a speaker in the chamber's ceiling. Electrodes on my chest, neck, and left wrist feed my vital signs into wires laced through the skintight singlet I'm wearing under a canvas harness. The wires converge in a white umbilical cord a little thicker than a standard coaxial cable, which relays the data into a rack of 1970s-era computers behind the chair.
"Data acquisition ready?"
A Doppler sensor, taped to a freshly shaved patch of skin above my right temple, measures the velocity of blood flow to my brain. Each time my heart squeezes blood past the sensor, a control-room speaker emits a noisy slurp, like someone abruptly finishing off a milk shake through a straw.
About an arm's length from my eyes is a metal halo known as a light bar. Two rows of red dots on either side of my head march inward, starting from just beyond my peripheral vision and meeting directly in front of me. I've been told to focus on the center for the duration of the run. In my right hand I'm holding a bike handlebar grip with a button on top and a hinged switch like a hand brake. To reset the lights, I click the button on top of the grip as soon as I see them. If I fail to do this quickly enough, the centrifuge operator will know that the g forces have radically narrowed my field of vision and will stop the run. If I want to terminate the run, I release the hand brake, which will set off an alarm.
"Light bar ready?"
"Light bar ready."
"For the record: 20-g centrifuge study HR1-213. Principal investigator: Cohen; medical monitor: Pelligra; test subject: McHugh. Tolerance run. Begin run in five, four, three, two, one."
With me in the chair, the box shudders into motion. Its plywood walls, spray-painted black and studded with leftover bolts and brackets from experiments past, creak as the centrifuge picks up speed.
"Extensive research has been conducted using human subjects exposed to increased g-forces, although not for the duration of exposure to which you will be subjected." – Human Research Consent Form, NASA Feasibility Study HR1-213
The 20-g centrifuge at rest.
NASA has chosen four civilian test subjects to help tackle a problem that's been holding back the space program: In the zero gravity of outer space, the human body slowly turns to mush. We have evolved in an environment about 4,000 miles from the center of Earth with a steady pull of 9.8 meters per second squared, a pull defined as 1 g. The cells that make up our bodies expect that pull and build up their walls with support structures, called cytoskeletons, accordingly. In space, the pull doesn't exist, and so the cells' cytoskeletons collapse. Muscles atrophy and bones decalcify. The heart shrinks.
This is a large part of why we're nowhere near deploying a manned Mars mission. After traveling in zero gravity for 18 months, the first human to step down onto the Red Planet would probably snap an anklebone and collapse into a small pile of goo. NASA has nearly completed the prototype of a spacecraft that would cut travel time to three months each way, but even in that reduced timeframe, zero gravity would have a debilitating effect on the body. NASA astronaut Jerry Linenger remembers how the absence of gravity caused extreme back pain for some passengers on the Russian space station Mir. In his book, Off the Planet, which recounts five months on Mir, Linenger says he experienced a 13 percent bone loss in his hips and lower spine. Two years later, he still hadn't recovered fully. Translation: Human physiology remains the primary stumbling block to a prolonged space journey. "On a long-duration trip to Mars, there's going to be significant bone loss," Linenger said on NPR's Fresh Air. "That could be a show-stopper."
Long-term exposure to microgravity makes humans weak, so hypergravity should have the opposite effect, right? In a 2001 study, 10 Australian fighter pilots routinely exposed to 2 to 6 gs while flying experienced an average 11 percent increase in the density of their spinal vertebrae over a 12-month period. NASA figures that astronauts could use a solar-powered, onboard centrifuge to stave off muscle and bone deterioration in space. Thanks to the hypergravity chamber, they'd be completely healthy upon arrival. To find out if this might work, I and my fellow test subjects – all of whom needed to be 5-foot-9 or shorter, because of the chamber's cramped quarters – will participate in seven daylong hypergravity sessions. Malcolm Cohen, a ruddy psychologist with thick, busy hands and a booming voice, is supervising the experiment. Each session will increase in intensity, ending with a 22-hour whirl at 2 gs. Before and after each spin, NASA will measure our adaptation to hypergravity with "tolerance runs" in the fighter chair. Compared with the marathon chamber spins, the tolerance runs – accelerating 1 g every 15 seconds – are manic, full-on sprints.
In hypergravity research, passing out and blacking out are not the same thing. Passing out is known as G-LOC, for gravity-induced loss of consciousness. Blackout, preceded by grayout, is the point at which g force keeps blood from getting into the eyeballs. Ralph Pelligra, the experiment's white-goateed chief medical monitor, will be watching out for the exact timing of such effects. If the hypergravity training sessions have the desired effect, the subjects will black out (or gray out) at ever-higher g levels as the experiment progresses. At no point will we be subjected to more than 7 gs.
"Relax," Pelligra says. "Don't hold your breath. Breathe normally."
The chair gradually tilts to horizontal, keeping my spine aligned with the prevailing gravitational force. I try to relax. The onset of hypergravity feels like a truckload of sand pouring over me.
The light bar's red dots march inward. "You're doing well."
Forty-five seconds into the spin, at 4 gs, I weigh about 720 pounds. It's like being at the bottom of a pig pile. I click away at the thumb button, trying to focus on the center light. The white lights in the top corners of the chamber turn brown. The centrifuge accelerates. Everything goes dark.
"Bring him down. Bring him down," Pelligra barks.
Prepping the autogenic feedback vest.
The centrifuge slows. After a few long seconds, I finally remember to let go of the handle. The chamber squeaks to a stop. The houselights come up. The chair remains locked in the upward position. The back door swings open. Two burly technicians burst in, unlatch the chair, and lower it. Pelligra scampers in. He's agitated and wants to know why I didn't let go of the handle sooner. I was so surprised by how it felt to weigh nearly half a ton, I tell him, that I plumb forgot.
Later, I ask how many gs I pulled. I'm told that to preserve the purity of the data, it won't be revealed until after the experiment.
"If you strain, you can elevate your tolerance by 2.5 or 3 gs. We want the data to be accurate. Do not fight the g."
– Malcolm Cohen
When not protected by a g suit like fighter pilots wear, most people have a tolerance between 3 and 5 gs. The last time NASA tried this experiment, in 2000, all the subjects bailed. One made it to the 1.5-g habitation run but called it quits after became violently ill. The experiment was, in NASA terminology, scrubbed. As was the chamber. This time, NASA went in search of a hardier crop of test subjects.
The position of hypergravity guinea pig pays $8 an hour – a quarter less than Starbucks offers new hires in San Francisco – and is no cinch to land. Two weeks after I attended an initial briefing session with 16 other short men between the ages of 18 and 35, Cohen asked me to come back to Ames Research Center. He wanted to know why I was choosing to do this experiment, aside from the fact that I had a contract with a magazine to write about it. He was worried that I would stay only long enough to gather material for my story, then take off when things got a little uncomfortable. He said that if I had any doubts, I could still write about it as an observer.
What I told Malcolm Cohen:
A) I am excited about participating in an experiment this important to the space program.
B) I consider it a physical challenge, like training for a marathon.
C) I recently learned to surf, a three-year process that entailed spending hours at a time being repeatedly dunked, tumbled, and held under 55-degree water. I know I can do this.
D) Since I'm writing a story about the experiment, I don't want to look foolish by wimping out early.
What I didn't tell him:
A) I was born six months and six days after a man first walked on the moon and, like lots of other kids my age, put "astronaut" on the top of my list of what I wanted to be when I grew up.
B) In grade school, I frequently wore a shiny blue tracksuit with a NASA patch on the sleeve. I spent a lot of time thinking about interplanetary travel and drawing outer-space combat scenes.
C) These ruminations led to my belief, for most of the first grade, that I was, in fact, originally from Mars.
D) I no longer believe that. But the prospect of participating in the experiment has stoked my fascination with the Red Planet.
G-LOC be damned – what could be cooler than being partially responsible for putting people on Mars?
After a physical and a round of blood tests, I filled out a form making me an employee of the Raytheon Company, which handles staffing for NASA, and was cleared to spin.
"Each session will last for up to 22 hours, and you will conduct normal daily activities such as eating, sleeping, viewing television, voiding, reading, and performing specific tasks at various intervals during this period." – Human Research Consent Form, Nasa Feasibility Study HR1-213
I'm looking at a small, outhouse-style seat in the chamber with an 8-inch-wide hole in it, pondering the dark matter of "voiding" in hypergravity. Should 22 hours turn out to be too long to go without going, I will drape a heavy-duty plastic bag over the seat and down into the hole, void into the bag, seal it, and spend the remainder of the run trying to ignore it. All this in full view of the video camera. I'm told that the medical team and anyone else in the control room will avert their eyes. As for urination, eight 16-ounce plastic bottles, numbered 1 through 8, are provided, and I am to fill them (in numerical order) in a corner of the chamber just beyond the camera's coverage, then pack them in ice for later analysis. My food is stashed in a pair of coolers stored in a wall cabinet. Test subjects are advised to stick to a "low-bulk" diet of low-fiber and processed foods the day before and day of the habitation run. My order: two turkey sandwiches, potato chips, Twinkies, a few Slim-Fast shakes.
The interior of the habitation chamber is covered in 4-inch blue padding, in case I get tossed around. My data umbilicus runs up to the ceiling and across to a computer. A canvas strap hangs from the ceiling to help me with my balance. I'll be able to watch movies on the monitor in the top corner. Every four hours during each habitation run, I'll take a "stand test," which entails putting on an inflating cuff that measures my blood pressure and pulse, lying on my back for three readings, sitting upright for three, and standing for three more. I wear a skateboard helmet with a thumbnail-sized triaxial accelerometer attached to the top to keep track of my head movements.
"Do you believe in God?"
The disembodied voice asking me the Big Question belongs to a NASA medical staff member named Ann Timbers. Timbers and I have not been properly introduced. Is this a psychological stress test?
Her question was prompted by Contact, which I'm watching on the monitor. In the movie, the character played by Jodie Foster, an atheist astrophysicist, gets religion after she travels through a hypergravitational space-time portal known as a wormhole and is reunited with her long-dead father in a distant galaxy. I'm halfway through the first habitation run, 22 hours at 1 g, during which the centrifuge doesn't move. This numbingly boring session lets NASA collect a set of baseline data to compare against upcoming spins.
Mission chief Malcolm Cohen makes adjustments.
When locked in a windowless padded chamber for 22 hours and hooked up to a bunch of electrodes, you'd think the safest answer to the God question would be yes. But NASA is hardcore science country. A lot of people around here probably think they still have a score to settle on behalf of Galileo. An infrared camera, a half-dozen electrodes, electrocardiogram machines, and Timbers await my response.
"Um, do you believe in God?" I say.
It turns out that Timbers is more of a spiritual agnostic than an atheist, and she goes on at length about why. When she finishes, I say, "That's pretty much what I believe, too," a true statement – which it might as well be, since I am attached to a 300-horsepower lie detector.
As the experiment progresses, my pulse rate becomes a bit of a joke among the crew. A Krispy Kreme cholesterol count of 214 and a set of burgeoning love handles aptly reflect my sporadic exercise routine, but for some reason I have a Tour de France pulse rate in the low 40s (the normal at-rest rate for a man my age runs in the 70s) and low blood pressure. Before one tolerance run, as I sit strapped in the chair, Ralph Pelligra asks whether I'm having a nervous breakdown: My pulse had briefly rocketed to 51. Laughter in the control room. I come to take the ribbing as a compliment and begin to think of myself as something of a specimen.
I also develop a bit of hypochondria. Every twinge comes with the thought: "Is it from the centrifuge?" One morning not long after my second tolerance run, I feel a dull ache at the base of my skull. An aneurysm waiting to blow? I picture my heart, suddenly free from the crush of the g force as the centrifuge stops, firing a torrent of pent-up blood into my brain, stretching blood vessels to the breaking point. It turns out to be just a hangover, but researching the subject doesn't help my paranoia. According to "Spinal Shrinkage Due to +Gz Forces," an article in the journal Aviation, Space, and Environmental Medicine, a 1996 experiment showed that 40 minutes of hypergravity exposure caused a 5-millimeter decrease, on average, in aviators' height. And any hopes I may have had for someday populating Jupiter are crushed by "Floating Fertility," an article on NASA's Web site that says sperm motility begins to fall at 1.3 g and fertilization rates drop 50 percent in hypergravity. The experiment is making me shorter – and sterile.
"Wow. Mr. Consistency," says project coordinator Abigail Bautista as I climb down from the chair after my fourth tolerance run. I'm graying out at the same level every time.
At this point I have a notion. NASA, looking to drum up a little buzz before budget-allocation season, decides to send a journalist up on a space shuttle mission. Having made it through the whole hypergravity experiment, I'm the obvious choice.
Following the session, Pelligra offers me a ride to San Francisco. I've been taking the train in light of the warning against operating heavy machinery after a spin. Inside his red Volkswagen Bug, we dart through the early-afternoon traffic. I ask if NASA has ever sent a reporter into space. His answer: not quite. Tom Brokaw, among others, once jockeyed for a spot on a shuttle mission. NASA denied the request.
"It's a different world in there. If you move your head quickly, you're going to pay a penalty." – Malcolm Cohen
The floor and bench in the chamber slant up toward the center of the rig at a 37-degree angle. I lean back and wait for my first 22-hour hypergravity run to begin. The centrifuge hums and lurches into action. As the gravitational field shifts planes, the canvas strap hanging from the ceiling slowly swings toward me. In about 60 seconds I go from 180 pounds to 225 pounds as gravity settles in at 1.25 g, pressing me into the bench.
I sit "up," moving very slowly. The scuttlebutt in the prep room this morning: The chamber's previous inhabitant, who completed a 1.5-g run the day before, threw up during a stand test. I note with relief that the air carries no trace of his distress.
I learn why head movement is such a big deal when I have to hunt for a roll of tape to fix the microphone on my harness. When I move my head, my field of vision rotates. With my back to the right wall of the chamber, turning my head to the left makes the interior twist counterclockwise. A right turn twists it clockwise. With my back to the left wall, a right turn tips it counterclockwise, while a left turn tips it clockwise. Moving my head up or down gives me the sensation that my stomach is attempting to leave my body.
The source of all this weirdness is the vestibular system, headquartered in grape-sized apparatuses at the rear of each inner ear. Three semicircular canals, filled with a fluid that helps us maintain balance, combine with a pair of oblong chambers – the utricle and the saccule – to detect changes in momentum and gravitational pull. The vestibular system doesn't know what to make of hypergravity. The centrifuge's rotational force speeds up the normal flow of fluid through the canals, increasing the system's sensitivity. Quick head movements cause the fluid to interfere with stimuli receptors, resulting in dizziness and, very often, pronounced motion sickness.
I eventually get used to the twisting and am able to write, eat chips, drink Slim-Fasts, and watch movies, all in relative comfort while keeping head movement to a minimum. The first feature of the 1.25-g spin is 12 Monkeys, the time-travel bioterror film with a plot as disorienting as hypergravity.
I play more than a hundred games of computer solitaire and win none, which seems statistically significant. I urinate in the plastic bottles, try not to overfill, and place them in a cooler. Mundane stuff, but the novelty of hypergravity – one false move and you're sick! – makes the time pass quickly.
About 10 pm, Yvonne Cagle, an astronaut scheduled to be the flight surgeon on a 2004 shuttle mission, takes a turn as medical monitor. She asks how I'm feeling, if I've been drinking fluids, whether I'm hungry. I grab my notebook and start peppering her with questions. I ask what she thinks of Lance Bass. Considering that she has spent 20 years earning her wings, I expect nothing but scorn for the boy-band astronaut-wannabe.
Medical monitor Ralph Pelligra stands by.
"If I were in his shoes and I had $20 million," she says, "I'd do it in a heartbeat."
Why is NASA using civilians for this experiment instead of astronauts-in-training or military personnel? "One of NASA's objectives is opening the space station up to scientists and regular folks," she says. "They didn't want to inflate this data by using highly conditioned astronauts or aviators, then open it up to the public and find out that the results didn't apply." Then she adds something that grabs my attention. "You're a bit different. Your cardio profile is more like an astronaut's than an average person's."
On some level, I'm aware that all Cagle actually said was that my pulse rate is pretty low. And yet my mind distills only three words from her answer, and they float around the padded interior of the chamber long after the half-hour interview is over: You're… an… astronaut.
My notion of becoming the first journalist in space suddenly seems feasible. I ask the control room for Tomorrow Never Dies and am soon snoozing happily beneath a blanket.
"In a vasovagal state, you look like you're dead. it's a last-ditch survival method." – Ralph Pelligra
The cardiovascular system's number-one task is to keep the brain supplied with oxygen. If you are standing, your heart pumps away with enough vigor to push a supply of fresh blood upward to your brain. But if your brain decides that your cardiovascular system is slacking off, it interrupts whatever regularly scheduled programming your body's other systems are running to make an important announcement: It's time to lie down. First, your brain tricks you into thinking the ground beneath your feet is heaving. If it turns out you can't take a hint, the brain pulls the plug on your nerves and muscles, and you go into G-LOC. Your legs buckle, you topple, and, most often, your head comes to rest at an altitude much closer to that of your heart. Blood flows into your brain, which drinks its fill of oxygen before switching the systems back on. This process, known as vasovagal syncope, can result from many things, such as shock, hypothermia, hemorrhaging, or – in the case of G-LOC – spending too much time in an unusually strong gravity field.
"Look. His pulse is in the 30s again."
The movie has been turned off, and with faint feedback echoes trickling between the video monitor, my microphone, and the speaker, I feel as though I'm listening to Pelligra's voice from the bottom of a well.
"Josh, the next stand test is going to be in about five minutes."
I want to stay under the blanket. Pelligra has mentioned that I can elect to skip any test if I don't feel up to it. I'm sleepy and cold. But I slide the cuff over my elbow.
"We're going to need you to take the blanket off for the stand test."
After three readings lying down and three sitting up, I grasp the strap and slowly pull myself to a standing position. I yawn. The cuff inflates but fails to get a reading. It inflates again. The air seeps out, and finally, over the intercom, I hear a beep, signifying a reading. Two more to go. I yawn again.
"Inflation in 30 seconds."
"Inflation in five, four, three "
The cuff inflates, fails to get a reading, inflates, fails again, and on the third attempt gets a reading. I'm becoming irritated, I'm spinning at 1.25 g, and my arm feels like it's going to pop. Pelligra suggests I raise my arm over my head to drain the blood back out of it. I yawn, raise my arm, and wait.
My scalp begins to tingle. The tingling progresses down my neck and through my shoulders, arms, and chest. I rock backward slightly. I've been standing for more than four minutes. It feels as though someone is pouring a pitcher of cold water on my head.
"How are you feeling?" Pelligra asks.
"You'd better sit down right now."
I grab the strap and begin lowering myself, trying not to move too fast.
By the time my ass hits the bench, I'm unconscious. The videotape shows me keeling over and rolling onto my stomach. In the control room, Pelligra calls a Condition Red, and a technician punches a large red button. The centrifuge slows and simulated gravity gives way. My body slides off the bench, legs first. My chin snags the edge on the way down, snapping my head back. Various objects – a pillow, a Slim-Fast can, a notebook – rain down on me.
In the control room, I later learn, the line on my EKG monitor goes from a normal zigzag to this: ____________.
Fifteen seconds later, I come to, half-sitting on what used to be the front wall. I'm profoundly confused. I have no idea where I am. I get my knees under me. Outside the chamber, an alarm bell drones. I grope for the bench, remember where I am, and feel a keen sense of failure. I want to stand up and say "I'm fine, I just tripped, turn it back on." On the video, I look like a felled boxer, grasping at the ropes trying to get up before the ref counts him out.
Feet clatter toward me. The door swings open, fluorescent light floods in. Pelligra grabs my shoulders and tells me several times to lie down. The video camera catches the slogan on the back of a tech's T-shirt: EXTRA OXYGEN: DON'T GO DOWN WITHOUT IT. Pelligra holds a breathing apparatus against my face. I suck oxygen sullenly, my head resting on a six-pack of full urine bottles.
For the rest of the night, I sleep in a hospital bed in the prep room. Pelligra stays with me as a precaution. Over breakfast in the cafeteria the next morning, he and Cohen explain what happened: Low blood pressure made it hard to take a reading while my heart kept chugging away at a laid-back 42 beats per minute. Between beats, the blood was draining out of my head and pooling in my gut and legs. In short, the super-duper cardiovascular system I was so proud of turned out to be my fatal flaw.
"There's a name in aviation for someone with your kind of physiology," Cohen says.
"Yes," he says. "Cargo pilot."
Pushing the 4-g envelope.
Bautista calls the next week to say that the study has been scrubbed. Based on my swoon, the other subjects' motion sickness, and the similar results in 2000, NASA decided that a series of 22-hour hypergravity sessions will never be a practical way to protect space travelers against the ravages of microgravity. Which is not to say NASA's giving up on hypergravity. In the next round of the experiment, test subjects will power the centrifuge with a bike.
I go back to Ames for a debriefing with Cohen. At the end of the interview, he asks if I'd be interested in participating in other NASA experiments. I say that I would.
It isn't until later, during a photo shoot, that I find out I had flatlined – I actually died – in the centrifuge. Even though my heart stopped for only three or four seconds, a possibility that Pelligra had described at the prebriefing, the discovery shakes me. I have second thoughts about my willingness to do more experiments.
While flatlining is the most unsettling thing about my experience, it may not be the most profound. Watching Contact got me thinking about the time-warping effects of gravity predicted by Einstein. I email Kip Thorne, the Caltech astrophysicist who helped Carl Sagan conceive the movie's wormhole machine. I ask what effects he thinks the experiment may have had on me. His reply: The hypergravity took me forward in time, and I emerged from the centrifuge younger than I would have been otherwise, by a hundredth of a nanosecond.
I also traveled back: to 1977, when I was a kid sketching spaceships and planning a career as an astronaut.Go Back to Top. Skip To: Start of Article.