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Astrophysics Colloquium

Scheduling Optimal Starshade Observations in Exoplanet Imaging Mission Simulations
Presented by Gabriel Soto
Cornell University

Monday, September 21, 2020
Virtual Event starts at 12:00 noon

Abstract
The limited on-board fuel capacity on a starshade and its finite mission lifetime necessitates careful scheduling of observations to maximize the science yield of exoplanet imaging missions under realistic mission constraints. We use EXOSIMS, an open-source exoplanet imaging mission simulator, to create ensembles of end-to-end mission simulations and produce posterior distributions of planet discoveries and the parameters of detected planets for specific mission designs. At each decision step, the simulation scheduler must select the next best star which corresponds to a vast search space of possible starshade slew trajectories. We solve slewing maneuvers as boundary value problems in the circular restricted three body dynamics of the Sun and Earth using two propulsion models: impulsive burns using chemical propulsion and continuous burns using a low-thrust system like solar electric propulsion. Impulsive maneuvers are classified by the amount of Δv required to transfer in and out of station-keeping; continuous maneuvers incorporate the changing starshade fuel mass within the equations of motion. We discuss parameterizations of this slewing fuel cost and heuristics we use within mission simulations. We also present an analytic model for the desired starshade formation flying velocity as a function of the location of the target star in an ecliptic frame, time, and the halo position and velocity. We use this model to simulate impulsive maneuvers during formation flying and present fuel cost as a function of the ecliptic coordinates of the target star and the location of the observatory on a halo orbit. These results are also used as heuristics for optimal target selection.

JPL Contact: Rhonda Morgan


SVCP Astrophysics


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