Gerard K. O'Neill

Gerard Kitchen “Gerry” O’Neill (February 6, 1927–April 27, 1992) was an American scientist. He taught physics at Princeton University. He invented a machine for holding subatomic particles. He also invented the mass driver, a machine used to launch things into outer space. He wrote about building cities in space.
His space station design is known as the "O’Neill cylinder". He started the Space Studies Institute (SSI). SSI is a group focused on learning about space manufacturing and colonization.
In 1954 O'Neill finished school at Cornell University. Then he began his work on particle physics at Princeton.
Two years later he wrote about a device to hold very fast moving subatomic particles. In 1965 he used his device to shoot two beams of particles at each other for the first time. This experiment was done at Stanford University. Scientists used the experiment to discover the size of the electron.
While he was teaching, O’Neill became excited about humans living in outer space. He wrote about the O’Neill cylinder in “The Colonization of Space”. This was his first paper about people living in space. He met with other scientists at Princeton in 1975. There he talked with them about manufacturing in outer space. O’Neill built his first mass driver with help from scientist Henry Kolm in 1976. Mass drivers were part of his plan to mine the Moon and asteroids. His book "" won an award and got people excited about outer space. He died in 1992 after a seven year fight against leukemia.