Nippon Meteor Society

Habikino, Japan

Nippon Meteor Society

Habikino, Japan
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Fujita K.,Japan Aerospace Exploration Agency | Yamamoto M.-Y.,Kochi University of Technology | Abe S.,National Central University | IShihara Y.,Japan National Astronomical Observatory | And 12 more authors.
Publications of the Astronomical Society of Japan | Year: 2011

On 2010 June 13, the HAYABUSA asteroid explorer returned to Earth and underwent a super-orbital atmospheric reentry. In order to recover the sample return capsule and to take ground-based measurements, the Japan Aerospace Exploration Agency organized a ground-observation team and performed optical tracking of the capsule, spectroscopy of the fireball, and measurements of infrasounds and shock waves generated by the fireball. In this article, an overview of the ground-based observation is presented, and an outline of the preliminary results derived from observations is reported. © 2011. Astronomical Society of Japan.


Abe S.,National Central University | Fujita K.,Japan Aerospace Exploration Agency | Kakinami Y.,Hokkaido University | Iiyama O.,Osaka Science Museum | And 5 more authors.
Publications of the Astronomical Society of Japan | Year: 2011

HAYABUSA is the first spacecraft ever to land on and lift off from any celestial body other than the moon. The mission, which returned asteroid samples to the Earth while overcoming various technical hurdles, ended on 2010 June 13, with the planned atmospheric re-entry. In order to safely deliver the sample return capsule, the HAYABUSA spacecraft ended its 7-year journey in a brilliant "artificial fireball" over the Australian desert. Spectroscopic observation was carried out in the near-ultraviolet and visible wavelengths between 3000 A° and 7500 A° at 3-20 A° resolution. Approximately 100 atomic lines such as Fe I, MgI, NaI, Al I, Cr I, MnI, Ni I, Ti I, Li I, ZnI, OI, and NI were identified from the spacecraft. Exotic atoms such as Cu I, MoI, XeI and Hg I were also detected. A strong Li I line (6708 A°) at a height of ̃55 km originated from the onboard Li-Ion batteries. The FeO molecule bands at a height of ̃63 km were probably formed in the wake of the spacecraft. The effective excitation temperature as determined from the atomic lines varied from 4500K to 6000K. The observed number density of Fe I was about 10 times more abundant than MgI after the spacecraft explosion. N+ 2 (1μ) bands from a shock layer and CN violet bands from the sample return capsule's ablating heat shield were dominant molecular bands in the near-ultraviolet region of 3000- 4000 A°.OH(A-X) band was likely to exist around 3092 A°. A strong shock layer from the HAYABUSA spacecraft was rapidly formed at heights between 93 km and 83 km, which was confirmed by detection of N+ 2 (1μ) bands with a vibration temperature of ̃13000K. Gray-body temperature of the capsule at a height of ̃42 km was estimated to be ̃2437K which is matched to a theoretical prediction. The final message of the HAYABUSA spacecraft and its sample return capsule are discussed through our spectroscopy. © 2011. Astronomical Society of Japan.


Ueda M.,Nippon Meteor Society | Shiba Y.,Nippon Meteor Society | Yamamoto M.-Y.,Kochi University of Technology | Fujita K.,Japan Aerospace Exploration Agency | And 8 more authors.
Publications of the Astronomical Society of Japan | Year: 2011

The asteroid explorer HAYABUSA reentered into the Earth's atmosphere on 2010 June 13. We made simultaneous TV (television) observations at seven ground sites in order to calculate the trajectories of HAYABUSA and its sample return capsule (SRC), which both reentered into the atmosphere. Our TV observations showed that, after HAYABUSA reentered the atmosphere, the beginning time of its light emission on video was 13:51:57.4 UT at a height of 101.0±0.2 km. The end time was 13:52:42.0 UT at a height of 38.6±0.2 km. The initial velocity at the beginning was 12.1±0.3 kms1, and the entry angle was 9°. After identifying SRC as separated light emission independent of the mother spacecraft, we analyzed the trajectory of SRC from a height of 52.9 km to 35.7 km based on video images. The actual trajectory of the capsule, determined from the TV observations, was almost the same as the predicted trajectory in terms of the position, velocity, and time. We then calculated the fall spots of the SRC heat shields from the multisite TV observations. © 2011. Astronomical Society of Japan.


Suzuki H.,Rikkyo University | Nakamura T.,Japan National Institute of Polar Research | Vadas S.L.,NorthWest Research Associates, Inc. | Tsutsumi M.,Japan National Institute of Polar Research | And 2 more authors.
Journal of Geophysical Research: Atmospheres | Year: 2013

A fireball meteor with a visual magnitude over -6 followed by a persistent train was observed by two all-sky cameras for detecting the aurora and sodium airglow at Syowa Station (69.0°S, 39.5°E), Antarctica, on 7 June 2008. The orbit and other parameters of the fireball were estimated with an all-sky television camera for detecting the aurora. After the passage of this fireball, a circular train in the Na airglow was observed. This train expanded to a diameter of about 50 km in 9 min. Assuming that the fireball contained and emitted Na, we found this ring to span the altitudes of z = 76 to 87 km. The ring's mean motion was most likely caused by a large-scale, inertia-gravity wave with a vertical wavelength of ~16 km and an amplitude of ~30 m/s in the mesopause region. ©2013. American Geophysical Union. All Rights Reserved.


Kero J.,Japan National Institute of Polar Research | Kero J.,Umeå University | Szasz C.,Japan National Institute of Polar Research | Nakamura T.,Japan National Institute of Polar Research | And 6 more authors.
Monthly Notices of the Royal Astronomical Society | Year: 2012

The aim of this paper is to give an overview of the monthly meteor head echo observations (528.8h) conducted between 2009 June and 2010 December using the Shigaraki Middle and Upper atmosphere radar in Japan (34°.85 N, 136°.10 E). We present diurnal detection rates and radiant density plots from 18 separate observational campaigns, each lasting for at least one diurnal cycle. Our data comprise more than 106000 meteors. All six recognized apparent sporadic meteor sources are discernable and their average orbital distributions are presented in terms of geocentric velocity, semimajor axis, inclination and eccentricity. The north and south apex have radiant densities an order of magnitude higher than other apparent source regions. The diurnal detection rates show clear seasonal dependence. The main cause of the seasonal variation is the tilt of the Earth's axis, causing the elevation of the Earth's apex above the local horizon to change as the Earth revolves around the Sun. Yet, the meteor rate variation is not symmetric with respect to the equinoxes. When comparing the radiant density at different times of the year, and thus at different solar longitudes along the Earth's orbit, we have found that the north and south apex source regions fluctuate in strength. © 2012 The Authors Monthly Notices of the Royal Astronomical Society © 2012 RAS.


Yamamoto M.-Y.,Kochi University of Technology | Ishihara Y.,Japan National Astronomical Observatory | Hiramatsu Y.,Kanazawa University | Kitamura K.,Kochi University of Technology | And 4 more authors.
Publications of the Astronomical Society of Japan | Year: 2011

Acoustic/infrasonic/seismic waves were observed during the re-entry of the Japanese asteroid explorer "HAYABUSA" at 6 ground sites in Woomera, Australia, on 2010 June 13. Overpressure values of infrasound waves were detected at 3 ground sites in a range from 1.3 Pa, 1.0 Pa, and 0.7 Pa with each distance of 36.9 km, 54.9 km, and 67.8 km, respectively, apart from the SRC trajectory. Seismic waveforms through air-to-ground coupling processes were also detected at 6 sites, showing a one-to-one correspondence to infrasound waves at all simultaneous observation sites. Audible sound up to 1 kHz was recorded at one site with a distance of 67.8 km. The mother spacecraft was fragmented from 75 km down to 38 km with a few explosive enhancements of emissions. A persistent train of HAYABUSA re-entry was confirmed at an altitude range of between 92 km down to 82 km for about 3minutes. Light curves of 136 fragmented parts of the spacecraft were analyzed in detail based on video observations taken at multiple ground sites, being classified into three types of fragmentations, i.e., melting, explosive, and re-fragmented types. In a comparison between infrasonic waves and video-image analyses, regarding the generation of sonicboom type shock waves by hypersonically moving artificial meteors, both the sample return capsule and fragmented parts of the mother spacecraft, at an altitude of 40±1 km were confirmed with a one-to-one correspondence with each other. © 2011. Astronomical Society of Japan.


Kero J.,Umeå University | Fujiwara Y.,Nippon Meteor Society | Abo M.,Tokyo Metroplitan University | Szasz C.,Swedish Institute of Space Physics | Nakamura T.,Japan National Institute of Polar Research
Monthly Notices of the Royal Astronomical Society | Year: 2012

On 2011 October 8, the Earth passed through a stream of dust ejected by the comet 21P/Giacobini-Zinner during its perihelion passage of the year 1900, causing an outburst of October Draconid meteors. 13 Draconids were observed among ~6300 meteor head echoes with precisely determined orbits during an observational campaign ranging from October 8 05:00 ut to October 9 13:00 ut with the Shigaraki middle and upper atmosphere (MU) radar in Japan (34°85N and 136°10E). The meteor outburst occurred while the Draconid radiant was descending below and 2h later rising up above the horizon. Therefore, 11 of the detections were from very low (<15°) elevation. The detection altitudes of the Draconids were high compared to sporadic meteors of the same velocity and radiant elevation. The weighted mean geocentric velocity of the 13 Draconids was 20.6 ± 0.4kms -1, and the weighted mean radiant located at right ascension α = 263°3 ± 0°6 and declination δ = 55°8 ± 0°2. © 2012 The Authors. Monthly Notices of the Royal Astronomical Society © 2012 RAS.


Kero J.,Japan National Institute of Polar Research | Szasz C.,Japan National Institute of Polar Research | Nakamura T.,Japan National Institute of Polar Research | Meisel D.D.,SUNY Geneseo | And 5 more authors.
Monthly Notices of the Royal Astronomical Society | Year: 2011

The aim of this paper is to demonstrate the capabilities of a new automated analysis scheme developed for meteor head echo observations by the Shigaraki middle and upper atmosphere (MU) radar in Japan (N, E). Our analysis procedure computes meteoroid range, velocity and deceleration as functions of time with unprecedented accuracy and precision. This is crucial for estimations of meteoroid mass and orbital parameters, as well as investigations into meteoroid-atmosphere interaction processes. We collected an extensive set of data (>500h) between 2009 June and 2010 December. Here, we present initial results from data taken in 2009 October 19-21. More than 600 of about 10000 head echoes recorded during 33h were associated with the 1P/Halley dust of the Orionid meteor shower. These meteors constitute a very clear enhancement of meteor radiants centred around right ascension α= and declination δ= Their estimated atmospheric entry velocity of 66.9kms-1 is in good agreement with 1P/Halley dust ejected in the year 1266 bc, which, according to simulations, crossed Earth's orbit at the time of our observation. The Orionid activity within the MU radar beam reached about 50h-1 during radiant culmination. The flux of sporadic meteors in the MU radar data, coming primarily from the direction of the Earth's apex, peaked at about 700h-1 during the same observations. © 2011 The Authors Monthly Notices of the Royal Astronomical Society © 2011 RAS.

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