Description of Driving Event:
Outmoded Design of Space Shuttle General Purpose Computer (GPC) Limit Software and Hardware Upgrades
Lesson(s) Learned:
Outmoded Design of Space Shuttle General Purpose Computer (GPC) Limit Software and Hardware Upgrades
Recommendation(s):
Outmoded Design of Space Shuttle General Purpose Computer (GPC) Limit Software and Hardware Upgrades
Evidence of Recurrence Control Effectiveness:
The Space Shuttle Program is addressing the finding and recommendation identified by the ASAP.A review of the GPC and its flight software was performed in April 1998. Based on current estimates on GPC mean time between failures, the flight hardware and spares are expected to be available through at least 2016 (and likely significantly later). The flight software estimate on memory availability and usage has projected that memory capacity would be expected to reach its limit in the 2005-2006 time-frame. A software architecture strategy as part of the overall SSP avionics upgrade effort is being developed which will mitigate the memory capacity concern. This strategy will partition the critical software such as flight control and guidance from software that requires periodic change. The result of this partition would allow those stable software functions like flight control to remain within the current GPC's while allowing those functions that frequently change to be migrated to a newer computer technology. The offloading of the software functions such as display processing and systems management from the current GPC's should permit current GPC memory capacity to remain acceptable through at least 2020. Additionally the software subject to frequent change would be located within a system, which will be designed to be more easily reconfigurable than the existing system. In summary, a supportability concern does not exist for the current GPC's. Continued use of the existing GPC's and their established processes will maintain high levels of safety. Software partitioning involving the offloading of software functions to a more flexible system will provide sufficient memory availability for future GPC software changes. This approach will provide an evolutionary and a migration path to full GPC upgrade if it is later required.
Documents Related to Lesson:
N/A
Mission Directorate(s):
- Exploration Systems
- Aeronautics Research
Additional Key Phrase(s):
- Aerospace Safety Advisory Panel
- Computers
- Policy & Planning
- Software
- Spacecraft
Additional Info:
|
