🛸 Generation ships and spin gravity

Even at 1% of light speed, the trip to the nearest star (4.2 light-years) takes about 420 years — around 17 generations. A ship that carries people for that long is called a generation ship.

• Spinning a ring makes artificial gravity: the floor keeps pushing you toward the centre. A ring 224 m in radius turning twice a minute feels like Earth's gravity.
• NASA's 1975 Stanford Torus design was a ring 1.8 km across, turning once a minute, home to 10,000 people.
• People can feel dizzy if a ring turns faster than about twice a minute, so big, slow rings are more comfortable.
• Project Hyperion (since 2011) studies how a crew, its food and its society could survive centuries between the stars.