A Low Power Command and Control Module for Small Satellites

Utah State University/Space Dynamics Laboratory has developed a low power computer system for command and control, attitude determination, and telemetry for small spacecraft. The system has been developed for the 15-kilogram class Ionospheric Observation Nanosatellite Formation (ION-F) satellites. This constellation of three satellites is being built by Utah State University (USUSat), University of Washington/Cornell University (DawgStar), and Virginia Polytechnic Institute (HokieSat) and is part of the AFSOR/DARPA University Nanosatellite program with additional support from industry, NASA, the Air Force Research Labs, and the Air Force Space Test Program. The command and data handling (C&DH) system is based upon industrial-grade components, including a third generation Hitachi SuperH RISC processor and radiation tolerant ACTEL FPGAs. The memory subsystem is comprised of 256 Kbytes of EEPROM, 8 Mbytes of redundant flash memory, and 5 Mbytes of SRAM. The C&DH system also contains a 16 Mbyte telemetry buffer, digital and analog I/O interfaces, and a DMA-oriented CMOS camera system. The C&DH is radiation tolerant to approximately 5k Rad total dose. Single event upsets are dealt with at the hardware level by over current monitoring circuitry, redundant voting memory configurations, and multiple software watchdog timers. The entire computer system consumes less than 1.75 Watts peak, with an average of 1 Watt, and provides an 80-MIPS, 32-bit computation platform for a small spacecraft. An initial prototype satellite has successfully passed extensive environmental testing and demonstrated the advanced capabilities of the ION-F C&DH system