Instrument Ground Support Equipment (IGSE) software reuse from one mission to the next is a practical necessity in the aerospace industry. Schedule and budget constraints often dictate significant reuse of heritage designs when proposing, designing and implementing IGSE for new missions. This practice often results in a fight coupling between the IGSE designs of successive missions. In situations such as this, a forward-looking software reuse strategy can be very effective in reducing the cost of future IGSE designs, and improving the software quality of the IGSE for both current and future missions. A forward-looking software reuse strategy is one that anticipates the future direction of IGSE design/architecture and factors that anticipated/planned direction into the architecture of the current design. This typically takes the form of reusable interfaces that partition the problem space into encapsulated pieces that can be easily replaced or refactored in future designs. Rather than attempting to describe the technique in abstract terms (which can become rather nebulous), we'll illustrate the point using a specific example of how this technique was applied to the design of the command-generating portion of the MErcury Surface, Space ENvironemnt, GEochemistry, and Ranging (MESSENGER) mission IGSE software. We'll show that a forward-looking software reuse strategy resulted in higher quality IGSE software for the MESSENGER mission, and also higher quality and less costly IGSE software for subsequent missions that reused this software. (1 2).
