arXiv subjects

M. Yoshikawa

Publications and source records attributed to M. Yoshikawa.

4 recordsLinked to original sources

arXiv2021

The Scientific Observation Campaign of the Hayabusa-2 Capsule Re-entry

On 5th December 2020 at 17:28 UTC, the Japan Aerospace Exploration Agency's Hayabusa-2 sample return capsule came back to the Earth. It re-entered the atmosphere over South Australia, visible for 53 seconds as a fireball from near the Northern Territory border toward Woomera where it landed in the the Woomera military test range. A scientific observation campaign was planned to observe the optical, seismo-acoustic, radio and high energy particle phenomena associated with the entry of an interplanetary object. A multi-institutional collaboration between Australian and Japanese universities resulted in the deployment of 49 instruments, with a further 13 permanent observation sites. The campaign successfully recorded optical, seismo-acoustic and spectral data for this event which will allow an in depth analysis of the effects produced by interplanetary objects impacting the Earth's atmosphere. This will allow future comparison and insights to be made with natural meteoroid objects.

astro-ph.EP↗

arXiv2021

Hayabusa2 Extended Mission: New Voyage to Rendezvous with a Small Asteroid Rotating with a Short Period

Hayabusa2 is the Japanese Asteroid Return Mission and targeted the carbonaceous asteroid Ryugu, conducted by the Japan Aerospace Exploration Agency (JAXA). The goal of this mission was to conduct proximity operations including remote sensing observations, material sampling, and a Small Carry-On Impact experiment, as well as sample analyses. As of September 2020, the spacecraft is on the way back to Earth with samples from Ryugu with no critical issues after the successful departure in November 2019. Here, we propose an extended mission in which the spacecraft will rendezvous with a small asteroid with ~30 m - ~40 m in diameter that is rotating at a spin period of ~10 min after an additional ~10-year cruise phase. We introduce that two scenarios are suitable for the extended mission. In the first scenario, the spacecraft will perform swing-by maneuvers at Venus once and Earth twice to arrive at asteroid 2001 AV43. In the second scenario, it will perform swing-by maneuvers at Earth twice to reach asteroid 1998 KY26. In both scenarios, the mission will continue until the early 2030s. JAXA recently released the decision that the spacecraft will rendezvous with 1998 KY26. This paper focuses on our scientific assessments of the two scenarios but leaves the decision process to go to 1998 KY26 for future reports. Rendezvous operations will be planned to detail the physical properties and surrounding environments of the target, one of the smallest elements of small planetary bodies. By achieving the planned operations, the mission will provide critical hints on the violent histories of collisions and accumulations of small bodies in the solar system. Furthermore, the established scientific knowledge and techniques will advance key technologies for planetary defense.

astro-ph.IM↗

arXiv2011

Entry Dispersion Analysis for the Hayabusa Spacecraft using Ground Based Optical Observation

Hayabusa asteroid explorer successfully released the sample capsule to Australia on June 13, 2010. Since the Earth reentry phase of sample return was critical, many backup plans for predicting the landing location were prepared. This paper investigates the reentry dispersion using ground based optical observation as a backup observation for radiometric observation. Several scenarios are calculated and compared for the reentry phase of the Hayabusa to evaluate the navigation accuracy of the ground-based observation. The optical observation doesn't require any active reaction from a spacecraft, thus these results show that optical observations could be a steady backup strategy even if a spacecraft had some trouble. We also evaluate the landing dispersion of the Hayabusa only with the optical observation.

physics.data-an↗

arXiv2004

Density fluctuations in the tendem mirror Gamma 10

The tandem mirror GAMMA 10 utilizes an electron cyclotron resonance heating (ECRH) for forming a confinement potential. Density fluctuation is observed using microwaves, such as interferometer, reflectometry and Fraunhofer diffraction (FD) method. An ultrashort-pulse reflectometry has an advantage of detecting fluctuation locally. The wave number can be obtained by the FD method. In the edge plasma region electrostatic probes are used. Fluctuation with coherent mode in several kHz is excited in the hot-ion mode plasma. When the ECRH is applied, electron density in the central cell increases gradually. On the contrary, intensity of the density fluctuation decreases and coherent mode is suppressed. Its frequency also varies with the density increase. In that time, radial potential distribution, i.e., electric field, changes along with the formation of plug potential. From this behaviour it is deduced that the fluctuation deeply relates to the potential formation and improvement of the confinement.

physics.plasm-ph↗