Satellite Systems Software Col. John Keesee MIT Dept. of Aero/Astro 19 October 2003 Outline • Definitions • Software design process • Design rules • Software costing Space System Software puter systems and their software provide unprecedented capability on orbit, but drive system cost and complexity Computer System Definitions • Embedded System – Built-in processor providing real time control • Real-Time processing – Handling or processing data at the time events occur • Hard Real-Time – Precise timing required to avoid severe consequences Computer System Definitions • Soft Real-Time – Tasks must pleted in a timely manner, but missing a time boundary has minor consequences • Operating System Software – Manages puter’s resources (. I/O, memory) • Application Software – Mission-specific software related to the user instead of the support of puter Types Of Software Application Software: Operating System Software: • Higher level functions that are •Low level functions that provided to meet mission bridge application software requirements. to processing hardware. – Communications - Executive or run-time control – Attitude and Orbit - Kernel functions Determination and Control - Input/Output (I/O) device handlers – Navigation - Built in Test (BIT) – Autonomy - Math Utilities – Fault Detection – Mission Management – Payload Management • Continues to increase as •Usually will not increase requirements “creep” and after CDR. problems are encountered. Computer Resource Estimation • Define processing tasks – Application software PDR - Operating system functions • Estimate software size and throughput • Establish a cost for spacecraft software • Evaluate development and test requirements • Create funding profile for development and puters and equipment. • Identify life-cycle support costs – On-orbit operations and support CDR - Upgrades, enhancements, modificatio
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