Scientists at the 30th Lunar and Planetary Science Conference held March 15-19, 1999 in Houston, Texas, have presented support for the theory that the "bulk of the Moon was ripped away from the early Earth when an object the size of Mars collided with the Earth." Analysis of data collected from the National Aeronautics and Space Administration's (NASA) Lunar Prospector spacecraft has supported this theory. The first site is a press release from NASA.