E10.2 Introducing the MOUC score: a quantitative metric to systematically characterize under-detected NEA populations

Tracking Near-Earth Asteroids (NEAs) is crucial for assessing potential Earth impact risks to inform and design effective mitigation strategies. Current surveys achieve an estimated detection completeness of approximately 88This paper investigates families of potentially undiscovered NEAs by comparing the observed NEA population with current asteroids population models. The objective is to identify natural and artificial factors contributing to gaps in NEA discovery and follow-up, including intrinsic dynamical effects or observational limitations. Our approach evaluates discrepancies between observed and predicted orbital densities by means of geodesic distances in the orbital-element space, where magnitude filters have been applied. We introduce a quantitative metric to systematically characterize under-detected NEA populations. Applying this metric reveals two prominent groups of likely uncatalogued objects: (i) NEAs with eccentricities between 0.4 and 0.6, inclinations below 20, and perihelion distances between 1.1 au and 1.3 au; and (ii) NEAs with low perihelion distances and high inclinations. We find that survey-selection effects and limited Southern Hemisphere coverage are the primary drivers of the missing discoveries in these regions. For the high-inclination, low-perihelion family, we further identify a marked sky-plane clustering along a tilted axis, concentrated within one half of the sky. This pattern has direct implications for future observational strategies and motivates targeted planning to close current detection gaps in planetary defence monitoring.