The Design and Implementation of a Nanosatellite State-of-Health Monitoring Subsystem

Abstract

This research consists of the design of a low-power, low-cost, nanosatellite computer system solution. The proposed system solution, and design and implementation of a multiple-bus master FPGA and health monitoring space computer subsystem are described.

In the fall of 1998, the US Air Force (USAF) funded Virginia Polytechnic Institute & State University (Virginia Tech), The University of Washington (UW), and Utah State University (USU) with $100,000 each to pursue a formation-flying satellite cluster. The program specified that a cluster of three satellites would maintain radio contact through UHF cross-link communication to report relative positions, obtained through GPS, and coordinate scientific measurement mission activities. This satellite cluster, named Ionospheric Observation Nanosatellite Formation (ION-F) is presently scheduled for launch in June of 2003.

Maintaining some degree of system reliability in the error-prone space environment was desired for this low-cost space program. By utilizing high-reliability components in key system locations, and monitoring less reliable portions of the computer system for faults, an improvement in overall system reliability was achieved. The development of a one-wire health monitoring bus master was performed. A Synchronous Serial Peripheral Interface (SPI) bus master was utilized to extend the communication capabilities of the CPU. In addition, discrete I/O functions and A/D converter interfaces were developed for system health monitoring and the spacecraft Attitude Determination and Control System (ADCS).