EXOSIMS generates and analyzes end-to-end simulations of space-based exoplanet imaging missions. The software is built up of interconnecting modules describing different aspects of the mission, including the observatory, optical system, and scheduler (encoding mission rules) as well as the physical universe, including the assumed distribution of exoplanets and their physical and orbital properties. Each module has a prototype implementation that is inherited by specific implementations for different missions concepts, allowing for the simulation of widely variable missions.

NEXO (Nonsingular Estimator for EXoplanet Orbits) fits exoplanet orbits to direct astrometric measurements using nonlinear batch estimation and nonsingular orbital elements. The estimation technique is based on the unscented transform, which approximates probability distributions using finite, deterministic sets of weighted sample points. Furthermore, NEXO uses Gaussian mixtures to account for the strong nonlinearities in the measurement model. As a fitting basis, it uses a set of orbital elements developed specifically for directly observed exoplanets, combining features of the Thiele–Innes constants and the Cohen–Hubbard nonsingular elements.