Then there’s the pressure difference. Space is nearly a vacuum. If an astronaut stepped into the void with lungs full of oxygen in ordinary clothes, the air would expand enough to rupture the lungs. The pressure is also so low that the boiling point of blood drops below human body temperature, a condition that can kill in an instant. Space is also full of micro-meteoroids, tiny projectiles that threaten to pierce an astronaut’s armor.
Spacesuits protect astronauts against all these challenges. They have multiple layers to provide insulation and prevent a puncture of the inner coating, which is filled with pure oxygen at a livable pressure. (The pressure difference between the suit and the external environment is daunting, though. Without the improvement in modern spacesuit joints, bending your knee in a spacesuit would be like trying to bend an inflated football.)
A layer of water circulates throughout the suit, interacting with a layer of ice near the outer surface, to moderate the temperature. A ventilation system removes excess body heat when the sun threatens to warm the astronaut too much. For the most part, the temperature remains fairly comfortable, although some space travelers have noted that their extremities — which aren’t covered by the water circulation system — can get chilly.
Modern suits have built-in life support systems, so the astronaut can function outside a spacecraft without being tethered to a much larger machine. (Earlier astronauts had to remain attached to their shuttles by large tubes.) The suits are so self-contained that some refer to them as the universe’s smallest space vehicles.
Until recently, an astronaut’s indoor outfit hasn’t had nearly the same sophistication. The international space station, which is still operating despite the end of the shuttle program, has regulated temperature and pressure, plus breathable air. It also protects astronauts from nasty space projectiles.
But this environment has its own challenges. Living in a small orbiting object requires astronauts to adjust to microgravity. It’s not just a matter of overcoming the initial clumsiness of movement as they float around the ISS. Since there’s very little to resist an astronaut’s motion, muscles become deconditioned over months of space life. Bone density also drops, and faces puff up as fluid that is normally pulled toward the feet floats into the head.
To deal with all this, engineers at Draper Labs, an MIT spinoff, are working on a spacesuit that creates the sensation of gravity.
To understand how it works, consider this experiment: If you sit still in a swivel chair holding an upright, spinning bicycle wheel by its axle, then tilt the wheel to the left or right, the chair begins to turn. (Watch the BBC’s “office chair fun” on YouTube to see the experiment in action.)
“A flywheel or spinning mass doesn’t like to change its orientation,” says Kevin Duda. He’s leading the Draper team that’s developing the spacesuit. “When you tilt the spinning wheel, it exerts a force against your body.”
The engineers at Draper think they can use this effect to create a suit that resists an astronaut’s attempts to move, in the same way gravity resists us on Earth.
Imagine that an astronaut working in the space station reaches for an instrument on a nearby shelf. As soon as he begins to lift his arm, a computer system inside the suit would order flywheels located along the suit’s forearm to begin spinning in a direction that would exert a force against the arm’s motion. The faster the flywheel spins, the more the suit would push back against the astronaut.
If it works, the suit would offer a number of benefits. It could ease the transition to life on the space station, and the return to living on Earth. The suit could reduce some of the muscle deconditioning that happens in space.
Beyond the space station, the suit could be used to prepare astronauts for the long, low-gravity trip to Mars and for maneuvering on the Martian surface, whose gravity is only about 40 percent as strong as Earth’s.
There may even be uses on Earth. Since the flywheels can make movement more difficult in any environment, Duda thinks the technology could be useful for rehabilitation.
“Some patients have trouble with repetitive movements, such as walking,” he says. “The flywheels could train the body to walk by making it difficult for the patient’s legs to stray from a proper gait.”
Duda hopes Draper Labs will have the spacesuits ready in five years. That should be several years before NASA’s first manned mission to Mars, which probably won’t come before 2025.