Extending the product family approach to support safe reuse

Upcoming spacecraft will reuse software components to the extent that some systems will form product families of similar or identical units e g a eet of spaceborne telescopes Missions such as these must be demonstrably safe but the consequences of broad reuse are hard to evaluate from a software safety perspective This paper reports experience specifying an interferometer telescope subsystem as a product family and supplementing the speci cation with results from a failure analysis Extensions to the product family approach with lessons learned are discussed in three areas integration of safety analysis with the product family approach modeling decisions that have safety implications e g how to handle near commonalities establishing a hierarchy of variabilities and specifying dependencies among options and use of the product family requirements for design evaluation of reusable components as well as a speci c product