Preliminary stray light analysis for the StarLight Mission

StarLight (formerly ST3) is a separated spacecraft interferometer mission scheduled for launch in late 2005. StarLight will be the first space mission ever to perform astronomical observations on one spacecraft while a large object (a second spacecraft, in full sun), is intentionally placed in the instrument field of view. Though sunshades keep the second "collector" spacecraft in nearly total darkness, it can nevertheless deliver stray sunlight into the StarLight optical system on the "combiner" spacecraft by at least two routes, potentially obscuring the star or causing signal variations which corrupt the interferometer data. StarLight is intended to serve as a technology pathfinder for future formation-flying astronomical missions, and therefore should address stray light problems as thoroughly as possible within the budget and schedule. This paper presents recent preliminary analysis of glint and stray light concerns for StarLight, to help us prioritize our activities.