There is something unsettling about an astronaut in his underpants. Here is the American hero, the icon. He inhabits the rarefied realm of popes and kings. You expect to see him in parades and CNN feed. You do not expect to see him in his Thermal Comfort Undergarment.
The ungarbed astronaut is Chris Hadfield, a 38-year-old former engineer and fighter pilot from Canada. He is standing around in his underwear because he needs help getting dressed. You would, too, were you about to don a 250-pound space suit. The suit will be worn for an underwater training session in NASA's neutral buoyancy tank, part of the Sonny Carter Training Facility at Johnson Space Center in Houston. (It contains 6.2 million gallons, so "tank" is something of an understatement. The public affairs office waxes biblical: "It took three days and three nights to fill.")
The tank, formally known as the Neutral Buoyancy Laboratory, or NBL, is NASA's gravitational approximation of outer space. Floating around fully suited in a pool is one of the ways astronauts train for floating around fully suited in space, which they will be doing in unprecedented amounts during the upcoming construction of the International Space Station (ISS). The station is too big to launch fully assembled and in one piece. Instead over 100 pieces will be launched and put together in space, one at a time, like an extremely complicated Erector set. ISS astronauts will spend an estimated 1,100 hours in open space assembling the craft. (NASA's term for a space walk is Extravehicular Activity, or EVA.) That is more than twice the total EVA hours of all U.S. space mISSions to date.
The tank must be huge so that mock-ups of ISS piecesoupon which astronauts rehearse their outer space construction tasksocan be completely submerged. Before the first NBL was built, in the 1970s (the current tank dates to 1996), EVA rehearsals were done in the ocean, in a lagoon in the Bahamas, a situation wistfully recalled by NASA personnel. This morning's session takes place on a full-size model of a section of the space station's truss, a 350-foot cat's cradle of crISScrossing I beams that will serve as the station's main support structure.
Hadfield's primary task in space will be to unfold and install the ISS's 60-foot-long robotic armoa remote-control helper designed to inch its way around the station exterior, moving bulky items and carrying out simple hookups. Anything complex or detailed will still have to be done by spacewalking astronauts. As Hadfield puts it, "It's like here on Earth. There are some things you can do with a backhoe and some things you need a wrench for."
Or, more likely, a Torque Multiplier with Anti-Backdrive and a Bayonet Probe. In zero gravity, even the simplest task becomes complicated. Hadfield gives the example of changing a fuse. On Earth, if you run too much electricity through a fuse, it gets hot and melts, and gravity pulls the little molten bit out, breaking the current. "In space, it melts but the droplet doesn't go anywhere, so electricity continues to flow till it actually boils the fuse."
In space, simply getting dressed for work is an hour-long undertaking. You've got your Thermal Comfort Undergarment, your Liquid Cooling and Ventilation Garment, your Boot Sizing Inserts, your Lower Torso Assembly, your Arm Assemblies and Hard Upper Torso, your gloves with individual finger adjustments, your bioinstrumentation system, your communications assembly, and your helmet. Hadfield has made it as far as his Lower Torso Assembly, which is lying poolside on a towel. Poufed and white, it does not lie flat like an ordinary pair of pants but appears to have legs already in it: the Pillsbury Doughboy run through by a sawmill blade.
The top half of the suit, the Hard Upper Torso, holds the life support system, emergency jet propulsion unit, and computerized display and control module. It is more like donning a small building than an article of clothing. Imagine a turtle that has somehow come out of its shell and must now get back in. Hadfield squats below the thing, lunges upward, effects a brief hula-hoop maneuver, and eventually his head and fingers pop through the appropriate openings.
It takes two people to pull up an astronaut's pants. They attach Donning Handles, a pair of L-shaped sartorial grappling hooks, to either side of the waist ring and heave with the grimacing might of linemen against a blocking sled. The metal rims of the suit's two halves click together like a FabergE egg.
And so they will remain for the next seven hours. Everything Hadfield needs is either on or in his suit. Buckled on his front is a small workstation of tools and tethers, what Hadfield calls his Bat Utility Belt. A plastic tube near his lips is attached to an IDB, In-suit Drink Bag, available in 21-ounce or 32-ounce (Big Gulp) models. If they care to, the astronauts can take a Food Stick with them, but the logistics of eating in a space suit have prompted many to give it a mISS. "The helmet is like an enclosed room," says Hadfield, "and the only tools you have are your lips and teeth." The fruit bar is mounted right up beside the astronaut's face so he can just turn his head and take a bite. Unfortunately, when the water tube leaks, which is almost always, the fruit bar disintegrates. "You end up with this gooey mass all over your face and visor, and there's nothing you can do about it."
The rest room is also inside the suit. When it takes 45 minutes and two assistants to get your pants down, you do not get a bathroom break. You get a DACT, a Disposable Absorption Containment Trunk, with a 32-fluid-ounce capacity and directional wicking to disburse fluid to outer layers.
"Nuh-uh," says engineer Lou Carfagno. "They're using MAGs now. That means Maximum Absorbency Garment. They're similar to the DACT but . . ."
Hadfield catches my eye. "They're diapers."
The platform on which the space suit is mounted has been improperly adjusted for Hadfield's height. He hangs as though from a coatrack. Feet swinging, glove pointing skyward, he strikes a mock-heroic pose. "To infinity and beyond!"
As if in response to Hadfield's gesture, a crane swivels toward us. When you are wearing 250 pounds and $10 million dollars' worth of equipment, you do not leap merrily into the pool. You are bound to a platform and lowered by a craneoslowly, dramatically, like James Bond above the piranha tank. Inch by inch, Hadfield disappears into the Tidy Bowl blue, until all that remains above the water's surface is his helmet and right glove, waving "So long."
Joining Hadfield in the tank this morning are astronaut Robert Curbeam and several scuba-diving assistants. The divers cart the astronauts from the edge of the pool floor to the work site. They are 40 feet down now, dwarfed to tadpolelike dimensions by the pool's oversize scale. It occupies twice the area of an Olympic pool, and it's six or seven times deeper. (After-hours swimming is strictly prohibited. Poolside security has been especially tight since the evening in February when a liquored-up guest on a vip tour took a yee-ha plunge into the wet.)
Once at the truss, the astronauts are on their own. Getting used to maneuvering around the exterior of a spacecraft in zero-g is one of the key objectives of NBL work and has proved, over the years, to be one of the greatest challenges of EVAs. The more colorful examples appear in reports from the early days of spaceflight, before astronauts learned to cloak their anxiety in jargon:
March 18, 1965, Voskhod 2 Alexei Leonov then . . . got stuck sideways when he turned to close the outer hatch. Doctors reported that Leonov nearly suffered heatstroke, and Leonov stated that he was "up to his knees" in sweat, so that his suit sloshed when he moved.
June 5, 1966, Gemini 9 Handrails, Velcro pads, and loop-foot restraints failed to help [Eugene Cernan] control his movements. "I was devoting 50 percent of my workload just to maintain position." As he struggled, he broke off an experiment antenna . . . and tore the outer layers of his suit. His exertions exceeded the capacity of the (suit) to remove moisture, fogging his faceplate and blinding him.
July 20, 1966, Gemini 10 "I let go of the rail for an instant, recock the sleeve, and grab the rail again," wrote Michael Collins. "In the process, I swing wildly and bang up against the side of the spacecraft. . . . The Gemini's attitude control system . . . reacts to this unwanted motion by firing thrusters."
At the heart of the trouble is torque. Hadfield describes it this way: "Say you wanted to arm-wrestle me. You could generate the necessary torque because of the weight of your body on the chair and your feet on the floor. In space, your body would just pivot up into the air." Imagine trying to tighten a bolt. The astronaut is as likely to turn as is the bolt. NASA quickly learned the importance of handholds and restraining devices. The ISS has more handrails than a nursing home. Twenty-four inches is the maximum distance allowed from one to another on the station's exterior. Velcro has been replaced by body restraint torques; foot loops by APFRS, Articulating Portable Foot Restraints.
Portable is something of an overstatement. An apfr is portable in the way a jackhammer is. Once you've lugged it to your work site, you must then clamp it in place; set the pitch, yaw, and roll of your desired position; and wrestle your Michelin man feet into it. You're exhausted before you begin to work.
Hadfield is setting up an apfr now, in preparation for today's main task, an R&R.; A NASA R&R; is nothing like the R&R; we know. The Rs in this case stand for removal and replacement. On the space station, everything is geared toward easy replacement. You can't bring the ailing part home and fix it, as with the shuttle. You have to deal with it in space. When you need to fix a part that sits on the outside of the ISS, the safest, most cost-effective way to do it is simply to replace it. NASA can't afford to do NBL rehearsals for every part on the station's exterior. Happily, as much as 70 percent of the R&Rs; can be done by the robotic arm. As for the other 30 percent, the astronauts rehearse what they can and keep their fingers crossed on the rest. "We could do nothing and hope for the best," says Hadfield, "or we could spend billions of dollars and try to nail down every last detail. Or we could do what we do, which is shoot for somewhere in the middle."
The goal is to eliminate unknowns. Things will inevitably go wrong, but it's hoped the astronauts will know what to do. Hadfield cites the example of the Apollo 13 explosion. "It sure wasn't something they expected, but they'd simulated it once. Someone had said, eIf this happens, what are we going to do?' And so they had something to draw on. That's why I'm spending 250 hours in the pool getting ready for this flight."
Talking to Hadfield, one quickly gets the sense that being an astronautoeven an astronaut who will spend more time in space than most astronauts before himois an earthbound endeavor. "I don't fly in space for a living," he says. "I've been an astronaut for six years and I've been in space for eight days. The space stuff at the end, it's like a comprehensive oral.
"It's the preparation that matters. We sit in meetings going, 'Okay, today we're going to look at the antenna system.' You picture in your head what can break, what effect it's going to have, where you're going to stow it, over and over and over. You go see the real hardware as often as you can. You go in the pool. You try everything you thought might work, and you find out why you were wrong. And hopefully at the end of it all, you end up with something like the last Hubble flight, where it looks dead simple."
Right about now, it doesn't look dead simple. It looks like a Houdini stunt. Curbeam is attempting to replace a strain gauge, a boxy metal unit that monitors tension on the truss. He is jackknifed and upside down, feet clamped in an apfr, a tethered power wrench banging against his helmet visor. "Can I just say something?" The astronauts communicate via headsets with test conductor Stephen Smith, who watches them on a bank of video monitors upstairs from the pool. "This is not a good position."
"Okay," says Smith. "Translate back up to handrail 22 Foxtrot." For no doubt the same reason that NASA calls a diaper a Maximum Absorbency Garment, moving is known as translating. "And dock that power tool on the toolbox." The toolbox, actually more of a trunk, sits on a portable work platform that the astronauts can pull back and forth along a track that runs the length of the truss.
Spacewalking is a little like rock climbing in that everything, including and especially oneself, must be tethered or docked at all times. If you forget to tether a tool, it's gone. Ditto yourself. Unlike early EVAs, the ISS space walks will be done without umbilicals linking astronaut to ship. The suits are self-contained. (Like scuba divers in underwater habitats, astronauts are outfitted with CO2 scrubbers that remove carbon dioxide from their air, ensuring a constant supply of oxygen.) If you forget to tether yourself to the craft and let go for a moment, you drift off into the great black beyond. Until you realize what's going on, that is, whereupon you activate your emergency SAFERoSimplified Aid for EVA Rescueoa jet propulsion Man-From-Glad backpack with enough power to get you back to the station.
The earliest EVAs had no such emergency provisions. If the umbilical somehow became severed, there was nothing to be done. Soviet cosmonaut Alexei Leonov, the first man in open space, recently revealed that he carried a suicide pill for just such an eventuality. (He did not reveal where he kept it or how he'd planned to get it into his mouth.)
Curbeam is still trying to dock his power wrench. "These hooks don't quite fit on this."
"Try the other end." "It won't go on at all." You can't see through Curbeam's visor, but you have a pretty good idea what's going on in there. "Forget it. I'm just going to let it dangle."
The next piece to be replaced is a box the size of an air conditioner, called an MBSU-0001. The acronym stands for Multi Bus Switching Unit. No one seems to know exactly what it is.
"Ask Dave Treat," says Stephen Smith, referring to one of the EVA test specialists. "Ask Leslie from Boeing," says Dave Treat.
"It's big and it's important," says Leslie from Boeing.
What makes this R&R; tricky is the coupling that attaches the unit to its cold-plate cooling system. Sharp edges make the coupling surface a "no-touch area," because it could easily tear the astronauts' pressurized gloves and suits.
The ISS will be chockablock with cooling systems. This is because the ambient temperature up there on the sunny side of Earth will be 200 degrees. Even in the shade, at minus 200, things can overheat. Because there's no air, there are no convection currents; hot air doesn't rise to let cool air in underneath. The heat just sits there, and the equipment gets hotter and hotter until it blows. So you need a cooling systemoa coldplate, a fan, a water system. But water systems have problems of their own. Without gravity, it's hard to make water flow from place to place. Surface tension holds it to the pipe's interior walls, so you have a sort of water tube with air inside. You can pump it, but you have to remove all the air, or your pump will just pump air. Nothing is easy.
It's 1 p.m. The men have been in the tank since 8 a.m. Curbeam's concentration appears to be flagging. "I'm going to use a retractable tether here. Could someone pick up some sandwiches from the cafeteria?"
Hadfield breaks a half-hour silence. He's busy repositioning the work platform, all but obscured in an Alka-Seltzer whirl of bubbles. "Don't they have pizza over there?"
Curbeam is instructed to pretend to screw in the bolts on the MBSU. The power tool is actually a low-fidelity mock-up: same shape and buoyancy but as useless as a plastic Fisher-Price mallet. Curbeam dutifully screws his imaginary screws. "Hey, whatever they're getting for my sandwich, can I get tomato and mayo on it? Turkey with cheese, tomato, and mayo would be great."
Much as NASA might like it to be, outer space is not a great big swimming pool. Space is a vacuum; a tank of water is not. Water's viscosity creates drag. For this reason, the NBL doesn't impart a true sense of what it's like to move something heavy through space. Nor does it mimic zero gravity. The astronauts may float, but the blood still runs to their heads when they float upside down.
There are several ways to mimic weightlessness on Earth. Free-falling down an empty mine shaft is one. NASA actually employs this technique to test the effects of weightlessness on various pieces of equipment. For astronauts and other things you don't want to drop down a mine shaft, the preferred method is to fly them in a large airplane, round and round in enormous parabolic arcs.
You have perhaps heard of the Vomit Comet. The official name is the KC-135 Weightless Flight Simulator. The problem with the KC-135 is that the astronaut has barely 25 seconds of weightlessness at a stretch. The weightless condition exists only as the plane banks the head of the parabolaoan extended, magnified version of that moment in an elEVAtor when negative gravity forces cancel positive. There's not much you can do in 25 seconds. You can get a preview of weightlessness, and a preview of space-motion sickness. Snap a few pictures. Fill up a motion discomfort bag. You cannot practice unpacking a 60-foot robotic arm.
For this you make your way across the manicured paranoia of the jsc grounds (squirrels on the lawn; cameras on the rooftops) to Building Nine, home of NASA's Virtual Reality Simulation Facility. In a cluttered second-floor lab, VRsf manager David Homan has created outer space. It's over in the corner, in the form of a VR helmet and an odd, suspended box whose bulk and metallic finish call to mind a squared-off beer keg. The box is strung puppetlike on eight thin wires that lead from each of its eight corners to a large, spindly cubic frame. The box can be programmed to take on the mass characteristics of an object floating in space. When an astronaut pushes or pulls it, load cells and torque sensorsovia the computerocue the appropriate wires to reel in, moving the box exactly as much and as fast as would happen in zero gravity.
Astronauts who captured the Spartan satellite in 1997 practiced on this system (which is called KAMFR, Kinesthetic Application of Mechanical Force Reflection IYMK, If You Must Know). Today the box is pretending to be a 580-pound solar array, a virtual twin of the new, improved solar arrays that will be installed on the Hubble in 1999.
Homan hands me the VR helmet. The keg disappears from my visual field, replaced by a complicated orange rectangular thing the size of a pickup truck bed. I set it moving, Superman-like, with my index finger.
Stopping it is another story. Objects in space don't weigh anything, but they still have mass and inertia. Overcoming the latter can be dicey. I push too hard and the solar panel careers gracefully, implacably, to the right. "Whoa!" says Homan. "Easy," adds someone else. I see an astronaut in my field of vision, butoas no one's using the second VR helmetohe's just floating there, watching me struggle. Homan steps in to help wrestle the imaginary unit into submISSion.
"You learn quickly not to move things too fast," says Homan. Then he asks if I'd like a tour of the shuttle mock-up downstairs, where there are fewer multimillion-dollar virtual reality gizmos to break.
