Space Interferometry Mission
The Space Interferometry Mission (SIM), also called "SIM PlanetQuest," is a NASA instrument originally expected to be launched in 2011; however due to budget cuts it will now launch no sooner than 2013. Once in orbit, scientists expect SIM to be able to make very accurate astrometric observations of distant stars.
NASA hopes the SIM's ability to very accurately measure the distances and positions of stars will help astronomers probe for Earth-like planets in other solar systems, and possibly answer fundamental questions about the universe, such as its age and size. Additionally, SIM will measure the masses of stars, including exotic neutron stars, and stellar-size black holes.
SIM works through optical interferometry, a technique pioneered by Albert Michelson and developed specifically for use with SIM. Interferometry combines light from two or more telescopes as if they were pieces of a single, gigantic telescope mirror.
NASA hopes that SIM's new technology will eventually lead to the development of telescopes powerful enough to take images of Earth-like extrasolar planets orbiting distant stars and to determine whether those planets are able to sustain life — in fact, NASA has already begun developing future missions that will build on SIM's technological legacy.
SIM is being developed by the Jet Propulsion Laboratory under contract with Northrop Grumman in Redondo Beach, California.