SMAP Observatory configuration, from concept to preliminary design

SMAP (Soil Moisture Active and Passive) is a scientific mission to provide global mapping of Earth soil moisture and freeze/thaw state. In order to accomplish this mission the Observatory accommodates two primary Instruments L-band (1.26 GHz) Radar and L-band (1.4 GHz) Radiometer. Both Instruments use a shared 14.6 RPM spinning Antenna System with 6 m diameter deployable Reflector. The key challenges for the Observatory configuration are accommodation of the primary Instruments (Radar and Radiometer), and the supporting subsystems, all the while meeting all operations, pointing, environment requirements, and launch vehicle accommodation. This paper will describe the evolution of the SMAP Observatory configuration and major trade-offs from conceptual to preliminary design.