Adaptability of a catalog spacecraft bus to diverse science missions

Over the decade, the concept of using "off-the-shelf" spacecraft (SC) buses for space science and earth science missions has become widespread. A "common bus" design approach has used for Geosynchronous (GEO) communications satellites since the early 1970\´s. The success of using common bus designs for the manufacture of GEO communications satellites is due to the commonality of mission requirements and orbit geometry. Science missions, on the other hand, each have unique mission and instrument payload requirements that can vary widely, encompassing orbit geometry, instrument type and configuration, science target, SC attitude, operations concept, and launch scenario. One of the most visible and successful implementations of "off-the-shelf" SC for science applications is the NASA Goddard Space Flight Center (GSFC) Rapid Spacecraft Development Office (RSDO) catalog, first released in 1997. In the current catalog (Rapid II), there are twenty-three different SC bus manufactured by eight aerospace companies. This paper provides a case study describing the adaptation of Spectrum Astro\´s SA-200HP (High Performance) RSDO catalog bus to two very different Low Earth Orbiting (LEO) science missions, Coriolis and Swift, which were both produced via the RSDO. Coriolis is a Department-of-Defense-sponsored sun-synchronous earth observation satellite whose primary instrument, WindSat, is designed to precisely measure the ocean surface wind vector. Swift is a low inclination NASA Medium Explorer (MIDEX) mission to detect and characterize Gamma Ray Bursts (GRBs). The Swift Observatory carries three separate telescopes. In addition to describing how the catalog SC bus was applied to these missions, this paper discusses the unique features and benefits of the catalog bus approach to both the procuring agency and the industry bus provider. Misconceptions associated with the use of the catalog bus approach are also discussed.