Astronaut

Moon dust is razor-sharp. Earth's sand is worn smooth by water and wind, but lunar dust has never been weathered, leaving it jagged like broken glass. Apollo astronauts' suits were visibly abraded within days. Dust control is now a key engineering challenge for Artemis.

Aboard the International Space Station, tears don't stream down a face. In microgravity, surface tension makes them cling around the eye as a growing blob, blocking vision and causing pain if unwiped. Astronaut Chris Hadfield demonstrated it on the ISS in 2013.

The International Space Station orbits Earth every 92 minutes, so its crew sees 16 sunrises and sunsets daily. A 45-minute day-night cycle would wreck their sleep — so astronauts keep window shades closed and run the station on Greenwich time, regardless of the light outside.

Astronauts grow up to 3% taller in space. Without gravity pressing down, the discs between the spinal vertebrae swell as they stop being squeezed. For someone 180 cm tall that's about 5 cm—but gravity restores it within months back on Earth.

You can't directly smell anything in space. But astronauts report a distinctive odor when returning to the spacecraft after spacewalks—described as 'gunpowder,' 'brake pads,' 'seared steak,' 'ozone,' and 'walnuts.'