A spacewalk looks serene — an astronaut drifting above the blue Earth. Inside the suit it's a seven-hour athletic event in a personal spacecraft, where the enemy isn't the void but your own gloves.
The suit is a spacecraft
Call it what it is: the EMU spacesuit is a one-person spacecraft weighing about 145 kilograms, with its own oxygen supply, cooling system, radio, and battery. Water-filled tubes woven against the astronaut's skin carry away body heat; a backpack scrubs carbon dioxide and holds hours of reserves; over the visor, a gold-coated shield blocks a Sun with no atmosphere to soften it. The suit even carries a miniature jetpack — never yet needed — so an untethered astronaut could fly home. The first spacewalker, Alexei Leonov in 1965, learned the hard way what engineers now design against: his suit ballooned so stiff in vacuum that he had to bleed air out to squeeze back through the hatch.
The bends, 400 km up
The suit's sneakiest problem is pressure. Inflate it to cabin pressure and it becomes an unbendable statue, so it runs soft — about 4.3 psi of pure oxygen, less than a third of sea level. But stepping from station pressure to suit pressure risks exactly what surfacing divers face: nitrogen bubbling out of the blood — the bends. So spacewalkers pre-breathe pure oxygen for hours before the hatch opens, purging nitrogen from their tissues, sometimes after sleeping in an airlock at reduced pressure. Every spacewalk you've watched began the night before, with the crew already sealed away, breathing carefully.
Seven hours of forearm
Ask astronauts what hurts after an EVA and the answer is unanimous: hands. Every squeeze of a pressurized glove is work against a balloon, and a typical excursion runs six and a half hours of gripping rails, torquing bolts, and wrestling connectors — crews compare it to a full day of rock climbing done entirely with the forearms, wearing oven mitts. This is why the pool exists: for every hour outside, astronauts train roughly seven underwater on full-size mockups, choreographing each handhold. Watch the next EVA on the Live page with this in mind and the serenity reads differently — every graceful drift is a rehearsed move, paid for in advance, one aching handful at a time.