Interferometry Program Experiment
IPEX is a NASA Jet Propulsion Laboratory flight experiment which investigates the microdynamic behavior of a representative deployable space truss, including the effects of thermally induced disturbances. It flew on STS-85 on the Space Shuttle Discover in early August 1997, as a secondary payload on the ASTRO-SPAS free-flying telescope carrier. IPEX consists of a 2.3 m long deployable boom, one end of which is fixed by six struts directly to the structural nodes of ASTRO-SPAS. On-orbit, the truss will undergo microdynamic modal tests. In addition, its accelerometer sensors will "listen" for potential thermal snaps, as the structure flies in and out of Earths shadow. The objectives of the experiment are to assess whether thermal snap will occur for a preloaded jointed structure, and whether such a boom will satisfy the dynamic and thermal stability requirements for precision interferometry. Other main goals of the IPEX project are to validate ground test and modeling techniques. The MIT SSLs work to date on IPEX has focused on predicting the boom response to the disturbance from the Astro-SPAS carriers background noise levels, and to a potential thermal creak disturbance. JPL has a web page with more information about IPEX.