]THE DEEP-SPACE SUIT
THE MATERIALS ISSUE
Astronauts can only travel so far in existing space suits. What will it take to see the universe?
BY THE TIME the alarms go off, he’s back on his feet, hoping the rover wasn’t filming, but knowing that it was— that his face-first sprawl on the surface of Phobos has been recorded for posterity. The visor’s fiber-optic display flashes ominously: suit breach. His body, or some small sliver of it, has been exposed to the raw, airless vacuum of a Martian moon.
An astronaut can die many ways, but decompression is one of the more gruesome. A punctured space suit means a race to sanctuary, before the envelope of pure oxygen surrounding the body bleeds away and hypoxia causes the person to black out. Rapid pressure loss isn’t explosive, but it’s ugly: Water in the body begins to vaporize and tries to escape, the lungs collapse, and circulation shuts down.
No one’s dying today, though, at least not on Phobos. The suit he’s wearing isn’t a pressurized balloon. It’s the reverse, really—a squeeze suit, with a lattice of smart-memory alloys that binds it to the body, replacing an oxygen cushion with direct, mechanical counterpressure. The result is formfitting and nimble; it requires less energy to move and increases an astronaut’s range on foot. And in the event of a rupture, the suit remains viable: It can be patched on the spot with a space explorer’s equivalent of an Ace bandage, its own shape-memory alloys pulling tight to seal the breach.
By the time the patch is in place, the alarms have stopped. Epidermal biosensors and path-planning algorithms have shortened the astronaut’s trek across the surface, from six miles out to just over four. He’ll call mission control to argue against this shortcut when his heart rate settles. A nasty bruise isn’t going to kill him. And he didn’t travel 100 million miles from home to turn back now.
FOR HUMAN BEINGS to push farther into the solar system—to an asteroid, to a Martian moon, or even to Mars itself— they will need a new space suit: one that will allow them to travel through deep space, move easily across alien surfaces, and survive a wide range of potentially lethal hazards. “If a small hole appeared in a gas-pressurized suit, it’s a major emergency. Mission over; get back to your safe haven ASAP,” says Dava Newman, an aerospace biomedical engineer and director of MIT’s Technology and Policy Program.
Even today’s most sophisticated suits are limited to low-Earth orbit—and one was never designed to leave the spacecraft. NASA began using the Advanced Crew Escape Suit (ACES) after the 1986 Challenger disaster to protect shuttle astronauts during launch and reentry. But it was barely fit for duty. Since the shuttle’s controls weren’t built for suited operation, pilots routinely flew without their bulky gloves, leaving them vulnerable to a rapid pressure leak. The suit’s life-support system was ad hoc, with hoses taped down throughout the cabin. Now that the shuttle program has ended, astronauts wear the Russian equivalent of the ACES, introduced in 1973.
NASA’s other suit, the Extravehicular Mobility Unit (EMU), is less of a garment than a multimillion-dollar spaceship packed with liquid-cooled plumbing. Worn during space walks, it first touched the void in 1983; the majority of its fabrics were cutting-edge during the Cold War. Though the suit’s manufacturer, ILC Dover, has been experimenting with self-healing polymers, and though NASA has promoted the development of
In its initial contract with a suit maker, SpaceX stipulated that the pressure garment must look "badass."
advanced materials such as aerogels for ultrathin thermal insulation, those technologies haven’t yet migrated into the EMU.
The next era of spaceflight shouldn’t have to make do with handme-downs, not with the wealth of materials and designs incubating in labs around the world. With the impending private takeover of orbital and suborbital launches, and the first echoes of a mandate to land humans on Mars, there will be many more people going to space, some of them traveling vast distances. They deserve suits that not only keep them safe, but also live up to their ambitions.
The Launch Suit
The first new suits will be streamlined successors to ACES, only they won’t be designed for steely-eyed missile men, but for a new cohort of pilots and passengers who paid hundreds of thousands of dollars to be whisked into space. Called intravehicular activity or launch-entry suits, these are the drop-down oxygen masks of the space industry, devices whose true functionality—which includes pressurization and some measure of life support—kicks in during emergencies.
As designers deal for the first time with clients other than NASA, they are being forced to take on new challenges. In an initial contract with suit-maker Orbital Outfitters, SpaceX stipulated that the pressure garment must look “badass.” “You don’t get that sort of verbiage in government contracts,” says Chris Gilman, chief designer at Orbital Outfitters. “I love it.” There are obstacles, however, to badass space suit design. A launch-entry suit is ungainly, an oversize one-piece embedded with rigid interfaces for the helmet and gloves, and enough room to inflate, basketball-like, when pressurized—especially in the seat, so an astronaut isn’t forced to stand up. Gilman plans to counter this “baggy butt” with tactical stitching. Ted Southern, cofounder of Final Frontier Design, which secured initial funding for its 3 G Suit through the Kickstarter crowd-funding platform, hopes to use patterning as fash-
ion designers always have—to improve fit. “I honestly think that’s the key,” he says. “The more anthropomorphic it is, the cooler it looks.”
This is the new business of space suit design: to satisfy the needs of commercial customers, whether that means cramming survivability into a svelter package, or coming up with novel, costsaving innovations in structure and materials selection. The 3 G suit—the first of which is slated for delivery as early as January to the Spanish aerospace start-up zero2infinity—eliminates some metal components. Final Frontier is considering replacing others with highperformance plastic. For the IS3 suit that Orbital Outfitters is providing to XCOR Aerospace for use in its suborbital twoseater, the Lynx, the company is exploring disposable elements. Components such as the bladder layer that seals the suit could be swapped out before each launch.
The Exploration Suit
To go beyond low-Earth orbit, astronauts will need more than a new launch-entry suit. They’ll need an all-purpose suit for exploration. NASA recently unveiled its Z-l suit, the first in a series of testbed designs. The Z-l contains bearings in the joints that make it far more mobile than the current extravehicular activity (EVA) model, the EMU. It also has a rear-entry port that can turn the suit into its own air lock, allowing it to be docked to the side of a habitat to avoid tracking in abrasive lunar regolith or corrosive Martian soil. Next, the agency will begin work on the Z-2, and the best features of both of these suits will be folded into the Z-3. If all goes according to plan, the Z-3 will make its inaugural space walk from the International Space Station by 2017.
The Future Suit
For astronauts to explore deep space, suits must be sleeker, smarter, and far more maneuverable. Many of the materials that could make this happen are in labs right now. -ELBERT CHU
Rather than gas pressurization, future suits may use shape-memory alloys, such as a weave of Nitinol wire made by Boston-based Midé Technology, to apply steady mechanical counterpressure. The alloy would be treated with heat to tightly fit astronauts after they don their suits, but also conform to movement.
Concave areas of the body might require another shape-memory material to regulate the suit’s counterpressure. Syracuse Biomaterials Institute has developed the basis for this technology: carbon nanofibers that produce heat when activated by electricity, which could cause foam to expand to a preset shape.
One wrong squeeze from mechanical counterpressure could injure vital organs. A rigid, fully pressurized shell would provide protection without restricting an astronaut's movement. To minimize bulk and keep the contact points between hard and soft materials comfortable, each shell would be 3-D-printed to fit its user.
Silica aerogels, consisting of about 95 percent air, could insulate against severe temperature swings. By coating a silica nanoskeleton with a flexible polymer, a team at the University of Akron made aerogels durable and flexible enough for space. Embedded hydrogen could also block dangerous levels of radiation.
A dry adhesive created at the University of Massachusetts, strategically placed on space suits, could help astronauts hold fast to surfaces and tools. Its weave of carbon fiber and Kevlar mimics the skin and tendon structure of gecko feet, giving it unprecedented strength—yet it easily peels away from surfaces.
Astronauts today peer through plastic; future visors could be made of a clear ceramic called ALON, which is thinner than bulletproof glass and three times as strong. A heads-up display by Lumus Optical, used by F-16 pilots, could migrate to space helmets as a full-color display that guides light to the eyes with optical prisms.
Current suits circulate water through 300 feet of tubing to draw away body heat. Purdue University engineers created a technology that could insulate the tubes and also produce power: glass fibers (in the future, polymers) coated with thermoelectric nanocrystals that absorb heat and discharge electricity.
So far, the best defense against a torn suit or glove is to fortify it with stronger layers. Engineers at ILC Dover investigated a better approach: Integrate self-healing materials, such as polymers embedded with microencapsulated chemicals. When the capsules rupture, the chemicals foam and heal the torn suit.
Prolonged exposure to low gravity causes bone loss and muscle atrophy, which astronauts fend off by exercising 2.5 hours each day. Devices developed at Draper Laboratory could build fitness into space suits. Gyroscopes attached to the arms and legs could provide resistance similar to the force of gravity on Earth.
The batteries that power life-support systems must be repeatedly charged. Zinc-oxide nanowires being developed at Michigan Technological University can convert movement into electricity. Embedding such piezoelectric wires into the fabric over knees and elbows could provide valuable redundancy in space.
Astronauts need a suit that can face the pocked surface of a hurtling asteroid and a dust storm on the Red Planet.
But whatever features the Z-3 takes into orbit, it’s not likely to include today’s most pioneering materials, or resolve the biggest drawback of EVA suits: They are person-shaped blimps, filled with enough oxygen to maintain a survivable pressure. When moving, astronauts burn 75 percent of their energy struggling against their own garments, muscling their giant balloon-animal limbs into flexion and extension, and only 25 percent on the actual business of exploration.
MIT’s Newman wants to flip that ratio. Since 1999, she has been developing the BioSuit, a space suit that replaces gasfilled pressurization with a different system: mechanical counterpressure (MCP).
Instead of pumping in a protective buffer of air, MCP exerts a uniform, full-body squeeze, reproducing sufficient atmospheric pressure through mechanical force. The resulting suit would move more easily, using only 25 percent of an astronaut’s energy. It would also be far more durable, since mechanical counterpressure could be restored easily in the event of a breach.
To make MCP a reality, Newman needs a new material—one that binds tightly, conforming to the intricate curves of human physiology, while also yielding to motion. “In the last couple of years, we were looking at 14 candidate technologies,” she says. “Now, we’ve got it down to three.” One option is dielectric elastomers, which expand or contract through electrical current, acting as low-power actuators. Another is shape-memory alloys, a catchall term for flexible metals that can resume their original shape and properties. Newman’s team is focusing on braiding mul-
tiple alloys, including the nickel-titanium blend, Nitinol, which deforms and reforms based on shifts in temperature.
“I think we’ve proven the technical feasibility,” Newman says. She estimates that, with even a few million dollars per year, she could scale the technology up to produce a real suit in three to five years.
The Dream Suit
The hurdles standing in the way of a manned deep-space mission are daunting: propulsion capable of economically making a round-trip to Mars, a spacecraft that can shield its crew from lethal galactic cosmic rays during the yearlong flight. It won’t be next year, or probably even next decade, but when the day for far-ranging space exploration comes, astronauts will need a suit that can face a range of environments, from the pocked surface of a hurtling asteroid to a dust storm on the Red Planet. To build it, designers will need an arsenal of new materials, each imparting a new capability.
Conductive nanowires and electroactive polymers laced throughout the suit could harvest energy from the astronaut’s movements, turning the pressurized helmet’s visor into a translucent fiber-optic heads-up display. Local maps and preset routes CONTINUED ON PACE 96
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superimposed on the visor could toggle on and off with voice commands. Other data might come from epidermal biosensors, filtered through algorithms that recommend a slower pace to optimize energy and air supply. Even engineers skeptical of realizing full-body MCP anytime soon envision limited applications, such as gas-free gloves.
Depending on the destination, designers could swap in other components. A suit headed to an asteroid might have boot soles that leverage the same dry adhesion effect of gecko skin, allowing them to attach to surfaces in nearly any condition, including near-zero gravity on a quickly rotating celestial body. Stabilizers under development at Draper Laboratory could be mounted on a suit’s arms and legs: Miniaturized gyroscopes that have tiny spinning discs, they would provide resistance to create the impression of Earth gravity and potentially reduce disorientation in zero-G.
Mars presents its own challenges, including temperatures that swing from 70°F to -225°F. “On Mars, there are seasons,” says Amy Ross, a space suit engineer at NASA involved in the Z-l. “You might actually need your light spring jacket and heavy winter coat.” While Ross imagines supplying removable, full-body coveralls of various weights, Newman is pushing for an actual coat— an aerogel-layered garment that would be just a few millimeters thick, with enough gas-impregnated insulation to withstand the worst Martian temperature drops. A lotus-leaf-inspired coating developed by ILC Dover—it mimics the plant’s slippery, self-cleaning properties—could limit the amount of dust tracked into vehicles and facilities.
Final Frontier is pursuing nanostructured or powdered compounds for lightweight, flexible shielding from radiationone of the greatest challenges for future suits. Extravehicular suits currently have no radiation protection, forcing NASA to simply limit the number of space walks during an astronaut’s career.
As Gilman from Orbital Outfitters points out, “Space suits are filled with invisible subtleties.” Every ounce of mass, and every potential interaction between materials, adds complexity to a system that’s already mind-bogglingly intricate. Still, this is what the future of the space suit could be—not an incremental upgrade to Apollo-era gear, but the best that multiple research fronts have to offer. Astronauts’ ability to truly explore the solar system will be defined by the materials engineers have at their disposal. Some of those materials may never work in space. But those that do might mean the difference between a few shuffling, symbolic steps and a walking tour worth the 100-million-mile flight. 7$
ErikSofge wri tes about science, technology, and culture from Massachusetts.