NEOPROP2 – Enhanced Orbit Propagator
In 2012 for the Space Situation Awareness program, Astos Solutions developed a new orbital propagator algorithm in order to assess the potential risk of impact of a NEO. It computes orbital properties, MOID, and close approaches of asteroids at Earth based on observation data provided by observatories and radar stations across the globe. The NEOPROP software has two separate modules: 1. The Analytical Module makes use of analytical algorithms in order to rapidly assess the impact risk of a NEO. It is responsible for the preliminary analysis. An Orbit Determination algorithm determines the initial state, along with its uncertainty, and the MOID of the NEO. 2. The Numerical Module makes use of numerical algorithms in order to refine and to better assess the impact probabilities of a NEO. The initial state provided by the Analytical Model is used to numerically propagate the trajectory. Along with the numerical propagation of the nominal state, several virtual asteroids can be created and numerically propagated in order to determine the MOID. This MOID computation differs from the analytical one since it takes into consideration the full dynamics of the problem (all the relevant perturbations).
During this project the tool will be extended to consider not only NEOs but all solar systems object and to compute impact probabilities as Torino scale and Palermo scale values. Moreover, currently the least square technique used to determine orbital properties does not always converge in case when there are many observations, discontinuities or close approaches within the observation set. The set of observations is manually split into intervals, whereas first the orbit determination is performed just with the oldest interval and then intervals are gradually added, always using the results of the previous run as initial guess. The effect of different automatic splitting techniques on the convergence will be analyzed and eventually implemented. At the end of the project, the updated NEOPROP software will be integrated into the ESA NEO Coordination Centre located in Frascati (Italy).