Some people like runway fashion. Not me. I’m much more interested in function than form. From that perspective, no one has a more interesting closet than an astronaut. While they look very much like painter’s smocks — their sloppy draping would probably make Michael Kors faint — spacesuits are fascinating, high-tech threads.
Astronaut clothes really boil down to indoor wear and outdoor wear. Let’s start with the outdoor ensemble. To state the obvious, space is an inhospitable environment. There’s no air. Astronauts are constantly bombarded by ultraviolet-C rays, the high-energy solar radiation that ozone blocks from the Earth. The weather is terrible. A spacewalker’s suit can confront freezing temperatures on the front and burning-hot conditions on the back, because the difference between sun and shade is around 275 degrees in space.
(NASA/NASA) - Astronaut B. Alvin Drew Jr., STS-118 mission specialist, dons a training version of his shuttle launch and entry suit in preparation for a training session in the Space Vehicle Mockup Facility at Johnson Space Center.
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.