NPOESS conical microwave imager sounder: RFI issues and progress

The Integrated Program Office (IPO) of the National Polar-orbiting Operational Environmental Satellite System (NPOESS) is currently engaged in developing the next-generation microwave radiometer known as Conical Microwave Imager/Sounder (CMIS). CMIS will replace the current Special Sensor Microwave/Imager (SSM/I) and its follow-on, the Special Sensor Microwave Imager Sounder (SSMIS). The first CMIS launch is currently scheduled for 2010 and is responsible to produce 22 Environmental Data Products (EDRs). The major design features of CMIS payload have been finalized. The baseline CMIS design has ´window´ channels at 6, 10, 18, 37, 89 and 166 GHz and ´sounding´ channels at 50-60, 23 and 183 GHz. It employs a dual-reflector system utilizing a 2.2 m offset parabolic reflector for 6.6 to 89 GHz and a similar ∼0.7 × 0.5m reflector for channels at 166 and 183 GHz. The two reflectors are oriented at positions 180 degrees about the sensor spin axis. In addition, CMIS will have polarimetric capability at 10, 18 and 37 GHz, and employ a suite of 40 Fast Fourier Transform (FFT) channels centered at 60.4347 GHz. CMIS will have a data rate of ∼500 kb/s, mass of ∼379kg and will require ∼350W of power. This paper will discuss the status of the CMIS design and specifically address several options that were considered for mitigation of RF Interference (RFI) at 6 and 10 GHz. Detailed trade analyses were performed to improve the likelihood that CMIS will be able to operate effectively in the C-band region. An end-to-end analysis of the impacts of these CMIS design options on Soil Moisture, Sea Surface Temperature, and other environmental data products was performed. Status of the overall CMIS development will also be provided.