Space Interferometry Mission: measuring the Universe

The Space Interferometry Mission (SIM) will be the NASA Origins Program's first space based long baseline interferometric observatory. SIM will use a 10 m Michelson stellar interferometer to provide 4 /spl mu/as precision absolute position measurements of stars down to 20th magnitude over its 5 yr. mission lifetime. SIM will also provide technology demonstrations of synthesis imaging and interferometric nulling. This paper describes the what, why and how of the SIM mission, including an overall mission and system description, science objectives, general description of how SIM makes its measurements, description of the design concepts now under consideration, operations concept, and supporting technology program.