A Novel Approach to Asteroid Impact Monitoring

Abstract Orbit-determination programs find the orbit solution that best fits a set of observations by minimizing root mean square residuals fit. For near-Earth asteroids, uncertainty may be compatible with trajectories impact Earth. This paper shows how incorporating condition as an observation in orbit-determination process results robust technique for finding so-called virtual impactors, i.e., regions parameter space leading to impacts. The pseudo-observation are b -plane coordinates at time close approach and is fraction Earth radius. extended filter converges naturally impacting if allowed observations. resulting provides excellent geometric representation impactor. As result, probability can efficiently estimated exploring this region using importance sampling. proposed systematically handle large number parameters, account nongravitational forces, deal nonlinearities, correct non-Gaussian initial distributions. algorithm has been implemented into new impact-monitoring system JPL called Sentry-II, after undergoing extensive testing. main advantages Sentry-II over previous Sentry orbits perturbed forces it generally more when dealing pathological cases. run times completeness both systems comparable, 99% being 3 × 10 ?7 .