[M-TT43] Brand-new scope of coupling geophysics being established by infrasound and associated waves

[MTT43-P04] Infrasound and seismic multiple-site observation of shock waves induced by hypersonic reentry of HAYABUSA-2 sample return capsule on Dec. 6, 2020

*Masa-yuki Yamamoto¹, Yoshihiro Hiramatsu², Shinsuke Abe³, Yoshihiro Kakinami⁴, Norihisa Segawa⁵, Hiroshi Katao⁶, Yoshiaki Ishihara⁷, Taichi Kawamura⁸, Satoshi Nozawa⁹, Muneyoshi Furumoto¹⁰, Phil Bland¹¹, Eleanor Sansom¹¹, Hadrien Devillepoix¹¹, Martin Towner¹¹, Yuichiro Inoue¹, Islam H. Hamama¹, Masato Yazawa¹², Kazuhisa Fujita⁷, Makoto Yoshikawa⁷ (1.Kochi University of Technology, 2.kanazawa University, 3.Nihon University, 4.Hokkaido Information University, 5.Kyoto Sangyo University, 6.Kyoto University, 7.JAXA, 8.Institut de Physique du Globe de Paris, 9.Ibaraki University, 10.Tono Research Institute of Earthquake Science, 11.Curtin University, 12.Mathematical Assist Design Laboratory)

Keywords:Infrasound, Shock wave, Multiple-site array observation, Reentry, HAYABUSA2

On Dec. 6, 2020, the JAXA HAYABUSA2 spacecraft returned to the Earth and its sample return capsule (SRC) was successfully landed on the desert area of Woomera, South Australia. At the time of hypersonic reentry of SRC in the upper and middle atmosphere, shock waves can be generated from the Mach cone along the shallow angle trajectory of SRC directly injected from the outer space. In 2010, the HAYABUSA SRC also successfully landed on the ground in the same desert area. At that time, we tried to detect the shock waves coming from the Mach cone of SRC, but little bit different condition that the mother spacecraft also reentered because of the lack of its capability to escape from the Earth's gravity due to the partial malfunction, therefore, multiple shock waves were observed at 5 sensors at that time. Over 20 seismometers simultaneously detected N-type signals with an air-to-ground coupling process at that time, as well (e.g. Yamamoto et al., 2011). After the event, we have been developed new infrasound sensors of INF01 and INF04 with data loggers by ourselves collaborating with some manufacturing companies, thus this time, we can deploy 30 sensors in a 100 km scale target area. Besides, 6 low-cost seismometers were also deployed at 4 sites.

For detecting precise trajectory and yield energy from the dataset of over-pressure amplitude at each site, we deployed 30 sensors on ground in the Woomera Prohibited Area (WPA). As for the INF04 sensors, we used 7 sites using 4 sensors per each, getting N-type waveform at every 27 sensors, except for 1 possible malfunctioned sensor. The waveform was almost the same as the HAYABUSA SRC reentry but without any complex features of the followed period just after the N type signal. The air-to-ground coupling process is also roughly investigated in comparison with previous result in 2010. By using these datasets, we will show the prompt report of the whole of the observation about the infrasound and seismic observation for HAYABUSA2 reentry. The possibility of the yield energy estimation and precise trajectory determination will be discussed in this talk.

Reference:
Yamamoto, M.-Y., Ishihara, Y., Hiramatsu, Y., Kitamura, K., Ueda, M., Shiba, Y., Furumoto, M., Fujita, K., Detection of Acoustic/Infrasonic/Seismic Waves Generated by Hypersonic Re-Entry of the HAYABUSA Capsule and Fragmented Parts of the Spacecraft, Publ. Astron. Soc. Japan, 63, 971-978, 2011.