Deriving Telescope Wavefront Error (Wfe) Stability Error Budget From Coronagraph Performance

Missions to directly detect exoplanets with a coronagraph, such as the potential Habitable Exoplanet (HabEx) mission, require an optical telescope with extreme wavefront stability. The key systems engineering question is: 'How stable?' The poetic answer is 10 picometers per 10 minutes. But, what is the actual spatial distribution of this error allocation? This paper defines a science-driven systems-engineering process to derive the telescope's wavefront stability error budget specification from the coronagraph's performance; reviews previous studies into coronagraph sensitivity to wavefront error instability; and demonstrates the method by comparing the performance of coronagraph telescope combinations.