A Distributed Computing Architecture for Small Satellite and Multi-Spacecraft Missions

Distributed computing architectures offer numerous advantages in the development of complex devices and systems. This paper describes the design, implementation and testing of a distributed computing architecture for low-cost small satellite and multi-spacecraft missions. This system is composed of a network of PICmicro® microcontrollers linked together by an I2C serial data communication bus. The system also supports sensor and component integration via Dallas 1-wire and RS232 standards. A configuration control processor serves as the external gateway for communication to the ground and other satellites in the network; this processor runs a multitasking real-time operating system and an advanced production rule system for on-board autonomy. The data handling system allows for direct command and data routing between distinct hardware components and software tasks. This capability naturally extends to distributed control between spacecraft subsystems, between constellation satellites, and between the space and ground segments. This paper describes the technical design of the aforementioned features. It also reviews the use of this system as part of the two-satellite Emerald and QUEST university small satellite missions

Smaller than Small, Faster than Fast, Cheaper than Cheap: The BARNACLE Satellite Project

The BARNACLE micro-satellite is an extremely simple low-cost space vehicle for the characterization of electronic instruments in space. The satellite was developed in less than one year by a group of seven undergraduate engineering students with no previous spacecraft design experience. The satellite was built for under $2,000 of the students own money with most of the hardware donated by industry and university sponsors. The craft includes a Motorola 68HC11 microprocessor-based subsystem for system control, with a logic system to back up the processor in the case of failure. Power is regulated by high-efficiency switching mode regulators in the power subsystem. Communications between the craft and ground stations is handled by the communications subsystems providing full-duplex AFSK communications at 1200 baud. The instruments are interfaced to the control core logic and microprocessor through the sensor interface subsystem. After testing, the satellite will be launched in a tube configuration aboard a non-orbital sounding rocket in August 1998. A cube configuration of the same satellite is being considered for an orbital launch in 1999

A Standardized, Distributed Computing Architecture: Results from Three Universities

At the 16th AIAA/USU Conference on Small Satellites, researchers at Santa Clara University (SCU) proposed a distributed computing architecture for small or multi-spacecraft missions. This architecture extended existing I2C, Dallas 1-wire and RS232 data protocols and was adaptable to a number of microcontrollers. Since then, that architecture has been implemented on six university-class space missions at three different universities. As “early adopters”, these universities had the typical challenges of working with a new, evolving standard and adapting the standard to their hardware and mission needs. Each faced additional, program-specific challenges related to project size, scope and infrastructure as well as the student background/training. Still, because of this architecture, every school saw three improvements: accelerated integration and training of new students; rapid modifications of existing systems; and school-wide collaboration among robotics projects. This paper reviews SCU’s distributed computing architecture, discusses the details of its implementation at all three universities, and provides lessons learned/lessons applied to six spacecraft programs: Akoya-A/Bandit-A & Akoya- B/Bandit-C at Washington University in St. Louis, EMERALD & ONYX at SCU, and FASTRAC and ARTEMIS at the University of Texas-Austin. The merits of adopting this architecture as a standard for university-class spacecraft are also reviewed