Recoverability of Known Near-Earth Asteroids

This paper analyzes the current population of known near-Earth asteroids (NEAs) and presents statistics on the recoverability of NEAs with both targeted observation campaigns and all-sky surveys. For an asteroid to be observable at a future apparition, given the right geometry, the plane-of-sky uncertainty must be small enough to be covered by a telescope's field of view and the asteroid must be brighter than the detector's limiting magnitude. Since recoverability is a telescope-dependent property, we select two representative instruments that span a wide range of capability and availability: the 1.0 m I52 telescope of the Catalina Sky Survey and the Hyper Suprime-Cam of the 8.2 m Subaru telescope. Based on this choice, we classify asteroids as recoverable, potentially recoverable, and not recoverable depending on whether they could be detected with an I52-class telescope, only with a Subaru-class telescope, or with neither, respectively. Using these definitions, we find that the majority (90%) of NEAs with H < 22 and most (93%) potentially hazardous asteroids are recoverable or potentially recoverable in the next 50 yr. When considering fainter asteroids down to H <= 28, about two-thirds of the NEA population and half of the low minimum-orbit intersection distance (MOID) asteroids (MOID <= 0.05 au) are either recoverable or potentially recoverable. As of 2019 October 13, the Sentry risk list includes 193 objects with an impact probability greater than 10(-6) that are not recoverable. The fraction of NEAs and low-MOID NEAs that are not recoverable can be reduced by up to 47% and 43%, respectively, when incorporating statistical estimates of serendipitous recoveries by all-sky surveys.