Modeling of 3D trajectory of Hayabusa2 re-entry based on acoustic observations

Abstract

On 2020 December 5 at 17:28 UTC, Japan Aerospace Exploration Agency’s Hayabusa2 sample return capsule (SRC) re-entered Earth’s atmosphere. The capsule passed through the atmosphere at supersonic speeds, emitting sound and light. The inaudible sound was recorded by infrasound sensors installed by Kochi University of Technology and Curtin University. Based on analysis of the recorded infrasound, the trajectory of the SRC in two cases, one with constant-velocity linear motion and the other with silent flight, could be estimated with an accuracy of ${0{_{.}^{\circ}}5}$ in elevation and 1° in direction. A comparison with optical observations suggests a state of flight in which no light is emitted but sound is emitted. In this paper, we describe the method and results of the trajectory estimation.

A Review of Infrasound and Seismic Observations of Sample Return Capsules since the End of the Apollo Era in Anticipation of the OSIRIS-REx Arrival

“…The N-wave recorded by 27 out of 28 infrasound sensors resembled that of Hayabusa 1. The seismic signatures were captured as well [9,106]. The Hayabusa 2 SRC hypersonic re-entry also generated audible sounds at 18:32:15 UTC that were reminiscent of a mine blast as per observer reports on site as well as casual witnesses in the Coober Pedy township.…”

“…Launched at 04:22:04 UTC on 3 December 2014, the Hayabusa 2 mission aimed to study the near-Earth asteroid 162173 Ryugu, retrieve samples from its surface, and bring those samples to Earth for further analysis. Like its predecessor Hayabusa 1, the Hayabusa 2 SRC was scheduled to land at the Woomera Prohibited Area, South Australia [9,105,106]. The spacecraft released the SRC on 5 December 2020, and with the remaining xenon propellant continued on an extended mission to explore other targets of interest [107].…”

“…The arrival of the Hayabusa 2 SRC was recorded by a large complement of instruments (Table 1) with the goal of capturing all aspects of the re-entry [9,106]. Its luminous path lasted 53 s, starting at an altitude of 103 km (17:28:38 UTC), and ending at 39 km (17:29:31 UTC).…”

“…This region was almost directly underneath the flight path of the SRC [9]. The amount of data collected allowed for a comprehensive analysis, including a 3D trajectory reconstruction based on infrasound detections [106]. The first signal was detected at 17:31 UTC, with airwaves sweeping the arrays from the southernmost to northernmost one, indicative of shockwave propagation from the trajectory.…”

Infrasound Monitoring for Disaster Prevention from Geophysical Perspectives.

“…Notably, we conducted a calibration experiment measuring shock wave energy using re-entries of arti cial bodies from the HAYABUSA capsule/spacecraft (Yamamoto et al, 2011). Additionally, recent observations of infrasound from the sample return capsule of HAYABUSA2 (Sansom et al, 2022) were instrumental in detecting its re-entry trajectory solely through acoustic observation . Note that the upper frequency limit of absolute-type sensors can be adjusted via a resolution parameter, albeit as a trade-off.…”