Thermal, structural, and optical analysis of balloon-borne coronagraphic imaging system

We present a thermal, structural and optical performance analysis for the Planetary Imaging Coronagraph Testbed Using a Recoverable Experiment for Debris Disks (PICTURE-D), a NASA balloon-borne observatory designed to image dust and debris disks around nearby stars in reflected visible light. Key components of PICTURE-D include a 60 cm off-axis telescope, a vector vortex coronagraph to suppress stellar light, and two MEMS based deformable mirrors for wavefront sensing and control. The balloon flight environment presents key challenges to the stability of the wavefront required for imaging. Low ambient temperature and pressure induce thermo-mechanical deformation of the observatory and limit the performance of the coronagraph. Using an integrated finite element model of observatory plus the coronagraph, we model the thermo-structural evolution of the observatory and assess the coronagraphic performance of the instrument.