The Space Interferometry Mission (SIM) would hunt for Earth-sized planets around other stars and provide new insights into the origin and evolution of our galaxy.
SIM would be placed into orbit around the Sun on a path that follows Earth's orbit. Light gathered by its multiple telescopes will be combined and processed to yield information that could normally be obtained only with a much larger telescope.
The mission would also measure the locations and distances of stars throughout our Milky Way Galaxy, and study other celestial objects.