The Atlantic reports on 5,200 Days in Space "An exploration of life aboard the International Space Station, and the surprising reasons the mission is still worthwhile."
"We’ve got a permanent space colony, inaugurated a year before the setting of the iconic movie 2001: A Space Odyssey. It’s a stunning achievement, and it’s completely ignored." I learned a few things in the article, but this was the most unexpected:
We don’t yet understand all the implications of long-duration spaceflight. “Five years ago,” says John Charles, of NASA’s Human Research Program, “we had an astronaut on station all of a sudden say, ‘Hey, my eyesight has changed. I’m three months into this flight, and I can’t read the checklists anymore.’ ” It turns out, Charles says, that all that fluid shifting upward in zero‑G increases intracranial pressure. “Fluid pushes on the eyeball from behind and flattens it,” says Charles. “Many astronauts slowly get farsighted in orbit.”
In fact, the station is now stocked with adjustable eyeglasses, so astronauts who don’t normally wear glasses will have them if they need them. Those who already wear glasses bring along extra pairs with stronger prescriptions.
Astronauts need precise, reliable vision, so its deterioration during spaceflight is hardly a minor problem. And it’s a particularly humbling one. NASA has known about the eyesight issue for decades. “We saw this on Skylab”—the first U.S. space station, which intermittently housed astronauts for up to three months at a time from 1973 to 1974—“and on the shuttle,” Charles says. The importance of it just wasn’t clear until astronauts were regularly spending months in orbit. And at the moment, NASA doesn’t know how to fix it back on Earth. Bone mass, muscle mass, blood volume, aerobic fitness all return to normal, for the most part. But astronauts’ eyes do not completely recover. Nor do doctors know exactly what would happen to eyesight over the course of a mission four or five times longer than those of today.
I also learned, "As it happens, the cost to run and sustain the Space Station is about the same as the cost to run a single U.S. Navy aircraft-carrier battle group." And okay, one more:
But station residents have to be careful about staying in one place too long. Without gravity to help circulate air, the carbon dioxide you exhale has a tendency to form an invisible cloud around your head. You can end up with what astronauts call a carbon-dioxide headache. (The station is equipped with fans to help with this problem.)