Seismic Recovery of Acoustic Source Height During the OSIRIS-REx Sample Return Capsule Re-Entry

Abstract

Controlled hypersonic reentries with well-constrained trajectories are exceedingly rare, yet they provide valuable reference cases for validating geophysical source characterization methods applicable to bolides and space debris. The 24 September 2023 re-entry of the OSIRIS-REx Sample Return Capsule, the first interplanetary capsule to return over the contiguous United States in nearly two decades, presented such an opportunity. Here, we present seismic observations of this event recorded at 16 stations across three sites at ground distances of 7–20 km from the trajectory. Using eigenray tracing through ground-to-space atmospheric specifications, we invert picked acoustic-to-seismic travel times for effective shock-generated acoustic source altitudes along the known trajectory. The method recovers source heights of 57.9–59.5 km with travel-time residuals <1 s across all stations. The seismic-derived source heights, when compared at their along-track positions, fall within the range of previously published infrasound-derived heights for the corresponding trajectory segment, with intermethod differences comparable with the timing-based uncertainty. These results suggest that air-to-ground coupling does not introduce a resolvable systematic timing bias in the picked near-field seismic arrivals, supporting seismic observations as a complementary tool for altitude estimation of bolides, re-entry vehicles, and other hypersonic atmospheric sources.