System engineering for spaceborne optical interferometers

Spaceborne optical interferometry truly represents uncharted territory - one in which the community developing such missions is still "learning the ropes". This paper is based on a collection of lessons-learned based on related missions including StarLight, a formation-flying stellar interferometry mission that merged with the Terrestrial Planet Finder technology development program just prior to entering phase C/D, the Space Interferometry Mission (currently in phase B), and the Shuttle Radar Topography Mission (a radar interferometer which flew in 2000). In first order, optical interferometry missions differ from classical deep-space science missions in several key respects: they are highly distributed systems, they are sensitive to small, cross-coupling error sources, and their operation is very complex. This leads to three unique system engineering challenges associated with implementing such missions: error handling and performance modeling, validation and verification (V&V), and system robustness. With an upcoming suite of interferometry missions approaching the transition from technology-development mode to flight project implementation mode the time is ripe for a discussion of these challenges and proposed solutions.