The most severe symptoms of space motion sickness occur during the first few days of space flight and disappear as the body and brain adapt to the new environment. And after landing, there is some vestibular disturbance as the astronauts return to Earth's gravity. NASA wants to improve crew efficiency and comfort by eliminating space sickness. Although astronauts have used some motion sickness drugs successfully to reduce nausea, no treatment has been found to completely eliminate the symptoms. Experiments have focused on identifying the underlying causes of this problem, on ways to treat it, and on studying how the nervous system adapts to microgravity.
Drugs have unfortunate side effects, including drowsiness and nausea.
Pre-flight adaptation by exposing the astronauts to unusual motions before the flight have not proven effective yet. The best countermeasure so far is preventing head motion by sitting still, but this seriously impacts crew work schedules. You can go back to where you came from, or jump back to the beginning. The next section contains the frequently asked questions about humans in space.