Assessment of the 5 August 2026 Falcon 9 Upper-Stage Lunar Impact: Energetics, Crater Scaling, and Comparison with LRO Observations

Abstract

The objective of this study was to characterize the human-made object that impacted the Moon on 5 August 2026, to estimate the dimensions of the crater it produced, and to compare the estimates with the crater subsequently measured by the Lunar Reconnaissance Orbiter (LRO). The impactor was the discarded upper stage of a SpaceX Falcon 9 rocket, which struck the surface near Einstein crater at a velocity of 2.43 km/s. The kinetic energy and linear momentum of the impactor were calculated, and the crater diameter was estimated using pi-group scaling relationships and measured rocket-body impacts as empirical analogs. The kinetic energy of the impactor was found to be 1.18 x 10^10 J, equivalent to approximately 2.8 tonnes of TNT. Compact-body pi-group scaling yielded a final rim-to-rim diameter of 46-57 m, and the empirical analogs yielded 26-27 m, leading to a pre-observation preferred estimate of 25 m within a range of 20-30 m. Between 11 and 12 August 2026, LRO imaged a crater approximately 18 m in diameter and less than 3 m deep. The results revealed that the compact-body scaling overpredicted the observed diameter by a factor of 2.6-3.2, whereas the empirical-analog method overpredicted it by 39-50%. When the nearest-mass analog was applied as a single crater rather than as a double crater, the estimated diameter was approximately 18 m, in close agreement with the observation. It was found that the hollow and elongated geometry of the stage, rather than a single equivalent bulk density, is the principal factor governing the crater size. This study provides a direct comparison of impact-scaling methods against a measured artificial lunar crater.