CYGNSS command and data subsystem and electrical power subsystem phase A and B developments

The Cyclone Global Navigation Satellite System (CYGNSS), which was selected as the Earth Venture-2 investigation by NASA´s Earth Science System Pathfinder (ESSP) Program, measures the ocean surface wind field with unprecedented temporal resolution and spatial coverage, under all precipitating conditions, and over the full dynamic range of wind speeds experienced in a tropical cyclone (TC). The CYGNSS flight segment consists of 8 microsatellite-class observatories, which represent SwRI´s first spacecraft bus design, installed on a Deployment Module for launch. The microsatellites (microsats) are identical in design but provide their own individual contribution to the CYGNSS science data set. Within the first year of the CYGNSS program (Phase A and B), the design has been analyzed, vetted, and reviewed which culminated in a succession of updates and design improvements. This paper will discuss relevant updates to the electrical systems of the microsat, specifically the command and data subsystem (CDS) and the electrical power subsystem (EPS). For the CDS, more detailed analysis of the communication link and maturation of the transceiver module design are presented. The link budget was reviewed by the team and verified via simulation. The transceiver module has moved to a dedicated box consisting of a radio frequency (RF) board and a digital signal processing (DSP) board. For the EPS, a detailed power analysis of the mission has led to an update in the solar array configuration. The details of the power analysis, which is performed in STK and Matlab, are presented.