By shifting from the conventional frame of thought and utilizing commercial hardware and software elements which are readily accessible and relatively inexpensive, a design can take advantage of the high throughput and capabilities of current technologies. In addition, by allowing the use of commercial technologies in system design, the system designer can incorporate the use of commercial standards, thus providing a system architecture which is scalable, reusable and easily upgradable. The lower cost associated with commercial grade electronics allows migration of a flight design to newer, increasingly capable technologies as they become available. In addition, the lower cost may also permit the construction of several flight testbed systems, allowing development and testing of ideas to occur in parallel. Of course, when using commercial components, potential problems associated with the space flight environment must be overcome [11,12,13].
As with any spacecraft, the hardware must be designed to withstand the harsh conditions associated with launch. This is of particular interest when designing a scalable system using off-the-shelf computer hardware, as most commercial environments are not as physically stressful as a launch vehicle and as a result, the computer boards are not designed with the same stress, vibration, shock, and temperature loads in mind. Special construction techniques should be used during board manufacture to provide the mechanical support necessary to survive the rigorous launch conditions. These techniques should include methods for supporting the board to minimize vibration and flexing, and specifying connector designs which are tolerant of these launch conditions. Maintaining the operating temperature limits of commercial components may place an added burden on the spacecraft thermal subsystem.
Outgassing of the electronics packaging can be a problem when using commercial parts. If outgassing can damage flight system components such as science instrument optics, the use of commercial components may require the use of hermetically sealed enclosures to protect the vulnerable elements.
The radiation environment to which the electronics will be exposed must be analyzed. Certain missions, particularly those of short duration, may experience low total-dose radiation environments which can be easily mitigated by use of shielding. Single event latchups and upsets may be mitigated by utilizing various hardware and software techniques and by incorporating redundant hardware, the added cost of which will in most cases be much less than the cost of radiation hardened circuits. Of course, as in any flight system design, the added weight, volume, and power requirements of the redundant circuitry must be considered.
Some missions may have specific mission requirements which preclude the use of commercial parts. However, the economies of scale provided by the increased numbers of flights enabled by the proposed reusable architecture will provide increased availability of lower cost, high performance space rated electronics suitable for these missions.