Performing simultaneous high-contrast imaging and astrometry observations of a star, increases the detection efficiency, and characterization accuracy of single- and multiple- planetary systems around nearby stars. Combining the data generated with both techniques allows solving the Semi-Major Axis, period, and planetary mass in the system faster and more precisely than using imaging or astrometry data separately. I addition, it allows measuring the planetary mass independently from its brightness resolving the mass/albedo degeneracy when only direct imaging observations are available. Independent albedo determination allows obtaining calibrated planet photometry enabling better atmosphere characterization.
To perform direct imaging and astrometry observations the telescope requires two instruments: a high-performance coronagraph to perform direct imaging, and a wide field camera astrometric accuracy able to deliver sub-micro arc second astrometry accuracy if earth-like planetary science is pursued. Such accuracy is only possible after calibrating relative distortions between astrometric observations, which at the sub-micro arc second regime dominates the error budget. We propose to utilize a diffractive pupil, in which an array of dots on the primary mirror generates polychromatic diffraction spikes in the focal plane, to calibrate the dynamic distortions of the optical system. In this talk, we present the results of the NASA TDEM effort to demonstrate the diffractive pupil concept on wide-field images while simultaneously performing high-contrast imaging. We also discuss the opportunity that this mission architecture could offer to future probe missions and flagships such as HabEX and LUVOIR
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