Space Studies Institute is a not-for-profit[2] organization that was founded in 1977 by Princeton University Professor Gerard K. O'Neill.

[3] SSI is involved in several initiatives, including a solar sail project that it is developing with Carnegie Mellon University and an effort to find asteroids that could be mined for valuable materials.

The use of extraterrestrial resources in space settlement has received increasing attention in recent years.

Other areas of research include a search for Earth-Sun Trojan asteroids, a design study of a Lunar Polar Probe to search for water and useful volatiles at the poles of the Moon, and studies of reuse of the Space Shuttle external tank.

O'Neill performed a study of a large space habitat named Island Three that could house 10,000,000 people.