Determining the statistical significance of meteorite–asteroid pairs using geocentric parameters

Context. Orbital similarity between precisely observed meteorite falls and near-Earth asteroids (NEAs) has been presented for decades as evidence that some meteorites are coming directly from these asteroids. However, analysis of the statistical significance of these pairings is mixed. Based on osculating orbital elements, there is no evidence of statistically significant clustering; however, some analyses that account for secular perturbations suggest that streams are present. Aims. We tested the statistical significance of meteorite-dropping fireballs and NEA clustering using the DN similarity function based on four geocentric quantities (U, θ, ϕ, and λ⊙). Methods. We calculated the cumulative similarity found between 46 meteorite falls, 535 potential meteorite-dropping fireballs, and 20 516 NEAs maintained by NEODyS-2, along with 34 836 NEAs maintained by NASA/JPL HORIZONS. Statistical significance was estimated either by (1) using a kernel density estimation-based method to estimate the sporadic background distribution and thus draw random samples or (2) applying a uniform random solar longitude (λ⊙). Each comparison to the synthetic sporadic population was repeated to estimate the 3σ region for which the cumulative similarity distribution is consistent with random association levels. Results. The observed DN cumulative similarity distribution of 46 instrumentally observed meteorite falls, 535 potential meteoritedropping fireballs, and over 30 k NEA radiants (estimated using six different radiant methods) reveals no statistically significant excess of similarity between the populations consistent with streams. Conclusions. Based on nearly 600 fireball observations and geocentric impact parameters, we find there is no statistically significant clustering between meteorite falls and NEAs. If some meteorites arrive in streams, they make up less than ~0.1% of all falls. Recent asteroid or meteoroid physical processes could still explain features found in meteorites, but this activity is not producing distinguishable orbital streams or pairs.