Development of an Advanced Spacecraft Computing Capability, the SC-603e, 15-9093

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Principal Investigators
Michael K. McLelland
Paul H. McGaugh
Benjamin M. Piepgrass

Inclusive Dates: 08/24/98 - 08/24/99

Background - In 1995, SwRI responded to NASA's call for better, faster, cheaper space flight systems with the introduction of the SC-9 family of computers. The SC-9 is based on the VME open architecture and allows spacecraft computers to be configured for specific missions with minimum nonrecurring engineering. This capability greatly reduces technical, schedule, and cost risk by building on flight-proven designs without sacrificing the flexibility to customize the system to a specific mission. Since its introduction in 1995, the SC-9 family has grown to include fifteen off-the-shelf boards with more under development. The SC-9 has been utilized on three missions: Space Station Furnace Facility, Image Spacecraft Control Unit, and Image Central Instrument Data Processor. Boards from the SC-9 family have flown on Deep Space 1 and Seawinds. While SwRI's SC-9 family of I/O and telemetry boards adequately meets client requirements, it has become apparent that for some missions greater processing performance is needed. To meet the need for a high-performance spacecraft computer supported by a wide range of development tools, the SC-603e computer was developed.

Approach - The overall design approach is based on SwRI's extensive design experience with space-qualified VME. The first task was to select a high-performance processor that meets performance requirements and could survive the space harsh environment. With extensive input from SwRI's client base, the Motorola 603e processor chip was selected. The board-level architecture is based on SwRI's highly successful SC-1750 computer, which is still in production for Spectrum Astro Incorporated. This architecture provides the 603e processor chip with 2 megabytes of SRAM, 2 megabytes of EEPROM, and 128 megabytes of DRAM on a single 6U VME board. To complement the memory resources, I/O is also provided that includes one redundant 1553 channel, two RS-422 serial ports, and three timer/interrupt channels. This board is capable of providing 100 million instructions per second of performance, while surviving a radiation environment of 30 kRads total dose with no latch-up.

Accomplishments - The SC-603e has been designed and fabricated and is shown in illustration. The board is currently undergoing functional verification and testing. It will first be delivered to Swales Aerospace for technical evaluation in its C&DH testbed. Swales Aerospace has selected the SC-603e processor for its recently awarded SMEIX light satellite program. Upon completion of testing at Swales, the board will be evaluated at Ball Aerospace for use on several of its on-going missions.



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