Space Interferometry Mission

The Space Interferometry Mission (SIM) flight system will be launched in June of 2005 into a nearly circular orbit around the Earth. A Delta II 7920 launch vehicle will boost the SIM flight system from the Vandenberg Air Force Base into Earth orbit. Over the next three months, the flight system will be calibrated and prepared for the science observation phase. During the science observation phase, data will be collected and returned from a precision optical interferometer on-board the spacecraft for five years and will enable fundamental new discoveries in both Galactic and extragalactic astronomy. SIM will perform unparalleled wide-angle astrometry with an angular accuracy of at least 4 microarcsecs (μas), roughly a factor of 250 over the current state of the art, and narrow-angle astrometry with an angular accuracy of 0.6-1 μas. This precision enables the measurement of distances to sufficiently bright objects in the Galaxy by direct parallax with no more than 10% error and makes possible highly accurate proper motion measurements of objects. As a consequence, SIM will allow studies of the kinematics of both isolated stars and composite systems over a large fraction of the Galaxy and of large-scale transverse motions out to 100 Mpc