For astronauts, however, it quickly becomes as hassle. If not for Velcro, foil-packed dinners, and special toilets, the space shuttle would be an even dirtier, more dangerous habitat than it already is. Even the neatest astronaut inadvertently contributes crud to cabin air, where it stays suspended, affecting eyes, lungs and delicate interments. Zero-G causes other problems as well, including calcium loss from bones, atrophy of muscles, and visual disorientation. What a mess that would be.
Gravity is our most basic human assumption.
The force of gravity is part of every terrestrial activity, it is a given from the time we first drop into the world. But all humans need their feet on the ground for reasons of health, safety, and convenience. Even small annoyances are compounded in Zero-G. Losing the keys to your spacecraft, for instance, would force you to look not just on tables, sofa cushions, or the floor. You would have to search the space above you, too. For many years, scientists have planned on generating centrifugal force as replacement for Earth's gravity on long space flights.