An infrasound source analysis of the OSIRIS-REx sample return capsule hypersonic re-entry

📝 Abstract

The OSIRIS-REx sample return capsule hypersonic re-entry into the atmosphere is a rare opportunity to test a variety of sonic boom source models since the projectile dimensions are well characterized. While the as-flown flight path is unknown, the predicted flight path enables a rough approximation of the source Mach number and location. Six infrasound microphones deployed in the boom carpet along the predicted flight path recorded impulsive signals from the OSIRIS-REx re-entry. Using a suite of atmosphere profiles and the geometric acoustics approximation, we estimate locations with uncertainty estimates along the flight path from which the signals were emitted. Acoustic overpressure and signal duration predictions from Whitham’s far field theory, Carlson’s simplified sonic boom prediction method, and a drag-dominated hypersonic model are analyzed with uncertainty estimates from the location estimate. While the Carlson simplified sonic boom prediction method could be accurate, our preference is for the drag-dominated source model. Using this source model with an inviscid Burgers’ equation solver for propagation, we obtained an excellent match to the recorded data. These results will help better inform future sample return capsule re-entry observation campaigns as well as contribute to a better understanding of high altitude infrasonic sources.

💡 Analysis

The OSIRIS-REx sample return capsule hypersonic re-entry into the atmosphere is a rare opportunity to test a variety of sonic boom source models since the projectile dimensions are well characterized. While the as-flown flight path is unknown, the predicted flight path enables a rough approximation of the source Mach number and location. Six infrasound microphones deployed in the boom carpet along the predicted flight path recorded impulsive signals from the OSIRIS-REx re-entry. Using a suite of atmosphere profiles and the geometric acoustics approximation, we estimate locations with uncertainty estimates along the flight path from which the signals were emitted. Acoustic overpressure and signal duration predictions from Whitham’s far field theory, Carlson’s simplified sonic boom prediction method, and a drag-dominated hypersonic model are analyzed with uncertainty estimates from the location estimate. While the Carlson simplified sonic boom prediction method could be accurate, our preference is for the drag-dominated source model. Using this source model with an inviscid Burgers’ equation solver for propagation, we obtained an excellent match to the recorded data. These results will help better inform future sample return capsule re-entry observation campaigns as well as contribute to a better understanding of high altitude infrasonic sources.

📄 Content

In Press at the Journal of the Acoustical Society of America An infrasound source analysis of the OSIRIS-REx sample return capsule hypersonic re-entry Jordan W. Bishop,a Philip Blom, Chris Carr, and Jeremy Webster Los Alamos National Laboratory, Los Alamos, NM 87545, USA 1 arXiv:2512.03119v1 [physics.ao-ph] 2 Dec 2025 The OSIRIS-REx sample return capsule hypersonic re-entry into the atmosphere is a rare opportunity to test a variety of sonic boom source models since the projec- tile dimensions are well characterized. While the as-flown flight path is unknown, the predicted flight path enables a rough approximation of the source Mach num- ber and location. Six infrasound microphones deployed in the boom carpet along the predicted flight path recorded impulsive signals from the OSIRIS-REx re-entry. Using a suite of atmosphere profiles and the geometric acoustics approximation, we estimate locations with uncertainty estimates along the flight path from which the signals were emitted. Acoustic overpressure and signal duration predictions from Whitham’s far field theory, Carlson’s simplified sonic boom prediction method, and a drag-dominated hypersonic model are analyzed with uncertainty estimates from the location estimate. While the Carlson simplified sonic boom prediction method could be accurate, our preference is for the drag-dominated source model. Using this source model with an inviscid Burgers’ equation solver for propagation, we obtained an excellent match to the recorded data. These results will help better inform fu- ture sample return capsule re-entry observation campaigns as well as contribute to a better understanding of high altitude infrasonic sources. ajwbishop@lanl.gov 2 LA-UR-25-24888 I. INTRODUCTION Infrasonic waves are low-frequency acoustic waves (≤20 Hz) that can propagate long distances through the windy, attenuating atmosphere. Infrasound is emitted from many natural sources, such as bolides and lightning, as well as anthropogenic sources such as ex- plosions, industrial activity, and flight vehicles (e.g., Balachandran et al., 1971). Objects moving through the atmosphere faster than the local sound speed generate a conical shock wave called a sonic boom. The ratio of the object’s speed v to the local adiabatic sound speed c0 is termed the Mach number M, which is used to characterize different fluid flow regimes around the object (Anderson, 1984). The supersonic flow regime occurs when the fluid flow has a Mach number greater than one in the entire region of interest and is char- acterized by discontinuities in the stream lines of the flow. A fundamental aspect of this regime is that perturbations to the flow can only propagate downstream. At Mach numbers above approximately five, the flow enters the hypersonic regime, where high temperatures and interactions between the shock wave and the viscous boundary layer on the object, among other physical effects, become increasingly important flow phenomena (Anderson, 1984; Anderson, 2006). Sonic booms from supersonic or hypersonic motion can travel large distances (100s to over 1000 kilometers) at infrasonic frequencies through the atmosphere (e.g., Donn et al., 1968; Liszka, 1978; Rogers and Gardner, 1980), where they eventually pass from the weak-shock into the linear acoustics regime. 3 Carrying samples from the near-Earth asteroid 101955 Bennu, the NASA (National Aeronautics and Space Administration) OSIRIS-REx (Origins, Spectral, Interpretation, Resource Identification, and Security-Regolith Explorer) SRC (sample return capsule) re- entered Earth’s atmosphere on September 24th, 2023 (Lauretta et al., 2017). The SRC obtained hypersonic speeds during its trajectory, which entered Earth’s atmosphere over California before touching down at the Utah Test and Training Range in Dougway, Utah (Ajluni et al., 2015; Francis et al., 2024; Lauretta et al., 2017). The resulting geophysical signals (acoustic, seismic, and electromagnetic) were recorded by a collaborative, multi- institution effort (Silber et al., 2024). Joining Genesis (2004), Stardust (2006), Hayabusa 1 (2010), and Hayabusa 2 (2020), the OSIRIS-REx SRC was just the fifth SRC to be recorded acoustically as it returned to Earth since the end of the Apollo missions in the 1970s (Silber et al., 2023). Given the well-known SRC dimensions, the predicted atmospheric re-entry speed of 12 km/s (Lauretta et al., 2017), and the relatively well-characterized trajectory, this re-entry allows a rare test of acoustic source and propagation models for a hypersonic “artificial meteor” (Ceplecha et al., 1998; Silber et al., 2023). The physics of sonic boom generation and propagation from supersonic aircraft is well known, with many studies examining the effects of sonic booms on structures as well as human annoyance towards civilian supersonic transport (e.g., Carlson and Maglieri, 1972; Maglieri et al., 2014; Plotkin, 2002). Sonic booms from supersonic aircraft, such as the Concorde, have also been

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