On multidisciplinary modeling of the Space Interferometry Mission

By measuring the positions and motions of stars very precisely, the Space Interferometry Mission (SIM) will produce a wealth of new astronomical data and serve as a technology pathfinder for future astrophysics missions providing a leap forward in space based astronomy beyond the Hubble Space Telescope. SIM will present unprecedented challenges in the measurement and control of distributed optical surfaces mounted on precision space structures, hence driving the technological state-of-the-art in the areas of alignment and stabilization of optical-mechanical systems, deployable structures, vibration isolation and suppression, laser metrology, and the integration and autonomous operation of complex systems. The precise tolerance required by the SIM instrument facilitates the investigation of many design options, trades, and methods for minimizing interaction between the actively controlled optics and the structure. The paper provides an overview of the multidisciplinary integrated modeling methodology for SIM that encompasses the optics, structures, dynamics, and control disciplines within a common software environment. The modeling methodology is rooted in a closely tied validation program which is necessary to alleviate the paradox of modeling a spacecraft that does not yet exist. The highest fidelity integrated SIM model to date, examples of utility, and incorporation into the overall instrument design are highlighted.