David Mozurkewich, Seabrook Engineering, Henrique Schmitt, Naval Research Laboratory, Tom Armstrong, Naval Research Laboratory
Keywords: imaging, interferometry, geosynchronous satellites
Abstract:
Imaging objects in geosynchronous orbit is becoming an increasingly important topic in space situational awareness as evidenced by DARPA recently funding the Galileo program and sponsoring a “deep-space imaging workshop”. Because of the required high-angular-resolution, an interferometer is the instrument of choice; there is, however, little consensus about what that system should look like. The DARPA workshop expanded the discussion to include heterodyne interferometry, telescopes mounted on steerable platforms and many more telescopes. However, it is not obvious how performance of these systems varies as a function of design parameters.
This paper presents quantitative relationships between system parameters and performance. Sensitivity, how faint an object can be imaged, can be improved by increasing the telescope diameters and the quality of the adaptive optics. Increasing the number of telescopes also helps because shorter baselines, which have higher fringe contrast, can be used to phase the array. Once fringes can be measured, the imaging time is determined by how many times the system has to be reconfigured to make observations at all the required spatial frequencies. The relationships presented here have been validated using detailed numerical models. They constrain the parameter space of workable designs and provide a basis for comparing the cost and feasibility of various designs. Low resolution interferometric observations of such satellites is needed in order to further refine the assumptions used in the calculations presented here.
Date of Conference: September 15-18, 2015
Track: Adaptive Optics & Imaging