Ishihara, Yoshiaki; Hiramatsu, Yoshihiro; Yamamoto, Masa-yuki; Furumoto, Muneyoshi; Fujita, Kazuhisa, E-mail: ishihara.yoshiaki@nies.go.jp2012
AbstractAbstract
[en] The Hayabusa, the world’s first sample-return minor body explorer, returned to the Earth, and reentered the Earth’s atmosphere on June 13, 2010. Multi-site ground observations of the Hayabusa reentry were carried out in the Woomera Prohibited Area (WPA), Australia. The ground observations were configured with optical imaging with still and video recordings, spectroscopies, and shockwave detection with infrasound and seismic sensors. At three main stations, we installed small aperture infrasound/seismic arrays, as well as three single component seismic sub stations. The infrasound and seismic sensors clearly recorded sonic-boom-type shockwaves from the Hayabusa Sample Return Capsule (H-SRC) and the disrupted fragments of the Hayabusa Spacecraft (H-S/C) itself. Positive overpressure values of shockwaves (corresponding to the H-SRC) recorded at the three main stations were 1.3 Pa, 1.0 Pa, and 0.7 Pa with slant distances of 36.9 km, 54.9 km, and 67.8 km, respectively. Incident vectors of the shockwave from the H-SRC at all three arrays are estimated by an F-K spectrum and agree well with those predicted. Particle motions of ground motions excited by the shockwave show characteristics of a typical Rayleigh wave.
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Copyright (c) 2012 The Society of Geomagnetism and Earth, Planetary and Space Sciences, The Seismological Society of Japan; Country of input: International Atomic Energy Agency (IAEA)
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Journal Article
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Earth, Planets and Space (Online); ISSN 1880-5981; ; v. 64(7); p. 655-660
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Yamamoto, Keiko; Otsubo, Toshimichi; Matsumoto, Koji; Noda, Hirotomo; Namiki, Noriyuki; Takeuchi, Hiroshi; Ikeda, Hitoshi; Yoshikawa, Makoto; Yamamoto, Yukio; Senshu, Hiroki; Mizuno, Takahide; Hirata, Naru; Yamada, Ryuhei; Ishihara, Yoshiaki; Araki, Hiroshi; Abe, Shinsuke; Yoshida, Fumi; Higuchi, Arika; Sasaki, Sho; Oshigami, Shoko2020
AbstractAbstract
[en] The precise orbit of the Hayabusa2 spacecraft with respect to asteroid Ryugu is dynamically determined using the data sets collected by the spacecraft’s onboard laser altimeter (LIght Detection And Ranging, LIDAR) and automated image tracking (AIT). The LIDAR range data and the AIT angular data play complementary roles because LIDAR is sensitive to the line-of-sight direction from Hayabusa2 to Ryugu, while the AIT is sensitive to the directions perpendicular to it. Using LIDAR and AIT, all six components of the initial state vector can be derived stably, which is difficult to achieve using only LIDAR or AIT. The coefficient of solar radiation pressure (SRP) of the Hayabusa2 spacecraft and standard gravitational parameter (GM) of Ryugu can also be estimated in the orbit determination process, by combining multiple orbit arcs at various altitudes. In the process of orbit determination, the Ryugu-fixed coordinate of the center of the LIDAR spot is determined by fitting the range data geometrically to the topography of Ryugu using the Markov Chain Monte Carlo method. Such an approach is effective for realizing the rapid convergence of the solution. The root mean squares of the residuals of the observed minus computed values of the range and brightness-centroid direction of the image are 1.36 m and 0.0270°, respectively. The estimated values of the GM of Ryugu and a correction factor to our initial SRP model are 29.8 ± 0.3 m3/s2 and 1.13 ± 0.16, respectively.
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Copyright (c) 2020 © The Author(s) 2020; Indexer: nadia, v0.3.6; Country of input: International Atomic Energy Agency (IAEA)
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Earth, Planets and Space (Online); ISSN 1880-5981; ; v. 72(1); vp
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