Spacecraft Computer Systems Colonel john e Keesee
Spacecraft Computer Systems Colonel John E. Keesee
Overview Spacecraft data processing requires microcomputers and interfaces that are functionally similar to desktop systems However, space systems require Low power. volume. and mass High reliability and fault tolerance
Overview • Spacecraft data processing requires microcomputers and interfaces that are functionally similar to desktop systems • However, space systems require: – Low power, volume, and mass – High reliability and fault tolerance
Outline · Definitions Computer system specification Estimating throughput and processor speed requirements Computer selection · Memory · Mass storage Input/Output · Radiation hardness Fault tolerance Error detection and correction Integration and test
Outline • Definitions • Computer system specification • Estimating throughput and processor speed requirements • Computer selection • Memory • Mass storage • Input/Output • Radiation hardness • Fault tolerance • Error detection and correction • Integration and test
Definitions Embedded system -a built-in processor providing real-time control as a component of a larger system often with no direct user interface Real-time processing- Handling or processing information at the time events occur or when the nformation is first created
Definitions • Embedded system – A built-in processor, providing real-time control as a component of a larger system, often with no direct user interface • Real-time processing – Handling or processing information at the time events occur or when the information is first created
Definitions(continued) Hard real-time- Requires precise timing to achieve correct results where missing at time boundary has severe consequences Soft real-time- Requires that the tasks be performed in a timely manner, where missing a time boundary results in degraded but continuous performance
Definitions (continued) • Hard real-time – Requires precise timing to achieve correct results, where missing at time boundary has severe consequences • Soft real-time – Requires that the tasks be performed in a timely manner, where missing a time boundary results in degraded but continuous performance
Definitions(continued) Operating system software-Manages the computers resources such as input/output devices, memory, and scheduling of application software Application software- Mission-specific software which does work required by the user or the mission rather than in support of the computer
Definitions (continued) • Operating system software – Manages the computer’s resources, such as input/output devices, memory, and scheduling of application software • Application software – Mission-specific software which does work required by the user or the mission rather than in support of the computer
Computer System Specification 1. Allocate mission and system requirements to computer systems 2. Define the computer system's operational modes and states 3. Functionally partition and allocate the computational requirements to space or ground, payload or spacecraft, individual systems, and to hardware or software
Computer System Specification 1. Allocate mission and system requirements to computer systems 2. Define the computer system’s operational modes and states 3. Functionally partition and allocate the computational requirements to space or ground, payload or spacecraft, individual systems, and to hardware or software
Computer System Specification 4. Evaluate internal and external interfaces 5. Select the baseline architecture 6. Form the baseline system specification
Computer System Specification 4. Evaluate internal and external interfaces 5. Select the baseline architecture 6. Form the baseline system specification
State Transition diagram ibit Prelaunch Standby Intelize or Trevel Fallure Resolve Checkout OK OK Failure On-station Self Teet Hard Eor Fallure Contingent Checkout Resolved
State Transition Diagram
Functional Partitioning Perform processing Perform processing In space d on ground Perform processing Perform processing In hardware In sottware Allocate processing do not allocate between spacecraft processing between bus and payloads spacecraft bus and ds payloads Allocate processing Do not allocate along processing along organizational lines organizational lines
Functional Partitioning P e r fo r m p r o c e s s i n g i n s p a c e P e r fo r m p r o c e s s i n g o n g r o u n d P e r fo r m p r o c e s s i n g i n h a r d w a r e P e r fo r m p r o c e s s i n g i n s o ft w a r e A l l o c a t e p r o c e s s i n g b e t w e e n s p a c e c r a ft b u s a n d p a y l o a d s D o n o t a l l o c a t e p r o c e s s i n g b e t w e e n s p a c e c r a ft b u s a n d p a y l o a d s A l l o c a t e p r o c e s s i n g a l o n g o r g a n i z a t i o n a l l i n e s D o n o t a l l o c a t e p r o c e s s i n g a l o n g o r g a n i z a t i o n a l l i n e s
