We propose to design and implement an Observation System Simulation Experiment (OSSE) testbed for obtaining space-borne high resolution soil moisture data in support of the NRC?s 2007 Decadal Survey Missions. The OSSE testbed focuses on land surface studies which are related to 8 of the 15 Decadal Survey suggested missions. The soil moisture OSSE testbed will be built upon the NASA supported ESMF infrastructure. This project will develop a generic OSSE testbed framework for Earth science application products and will determine their potential value and readiness for decision support needs. An innovative multiscale data assimilation technique will be developed and incorporated into the OSSE framework to enable near-real-time processing of satellite observed soil moisture data. This technique is expected to improve the quality of spaceborne soil moisture products by increasing both the accuracy and resolution. The idea is to take advantage of high r esolution precipitation products, topographic information and land surface models simultaneously and downscale the remotely observed soil moisture data from the existing footprint scale to a much high resolution scale to fulfill various Earth Science application needs. To demonstrate the OSSE framework, a mission specific case will be developed and targeted on the SMAP mission. SMAP retrieval algorithms which are implemented as an ESMF compatible plug-in module can generate the virtual observations by sampling the ?virtual land surface truth?. We will obtain soil-moisture signatures from GPM data and derived topographic properties using SRTM data. The virtual observations and soil-moisture signatures are then assimilated into the Land Information System to obtain high resolution soil moisture maps. The OSSE testbed will also provide the capability of studying the scaling behavior of soil moisture when forced by the input data (synthetic or in situ) across scales. The outcome of this study will be to provide crucial decision support to end users.