Hajime Yano

Microparticle Acceleration by a Van de Graaff Accelerator and Application to Space and Material Sciences

Abstract A microparticle (dust) ion source has been installed in the 3.75xa0MV Van de Graaff electrostatic accelerator and a new beam line for microparticle experiments has been built at the HIT facility of Research Center for Nuclear Science and Technology, the University of Tokyo. Microparticle acceleration has been successful in obtaining expected velocities of 1–20xa0km/s or more for micron- or submicron-sized particles. Development of in situ dust detectors on board satellites and spacecraft in the expected mass and velocity range of micrometeoroids and investigation of hypervelocity impact phenomena by using time-of-flight mass spectrometry, impact flash measurement and scanning electron microscope observation for metals, polymers and semiconductors bombarded by micron-sized particles have been started.

Response of Piezoelectric Lead–Zirconate–Titanate to Hypervelocity Silver Particles

A lead–zirconate–titanate (PZT) element was studied by bombarding silver particles in the mass range from 1 to 100 pg, and the velocity from 2 to 6 km/s. Output signals were uniquely identified on impact and characterized by Fourier analysis. It was found that incident energies above 100 nJ were uniquely determined by a single PZT element. We discussed its potential as a real-time detector for space dust and debris.

The first results of meteoroid and debris impact analyses on Space Flyer Unit

Abstract The Space Flyer Unit (SFU) was retrieved from space after its 10-month mission in January 1996. Here we report the first findings from the post flight analysis of its Kapton MLI and Teflon radiators in terms of impact flux, crater morphology and implications of impactors origins. The impact flux on the Sun face is also compared with the LDEF, EuReCa and HST data. On the Kapton MLI, some directional information can be deduced and its capture cell structure promises a high survivability of residues for chemical analysis. The peripheral flux variation is not inconsistent with the EuReCa data favouring for the Earths apex. The anti-Sun face flux exceeded the Sun face by a factor of 1.7. The size distribution index of the impact features on the Sun face Teflon agreed with the certain size ranges of the previous spacecraft. Plans of forthcoming studies such as detailed CCD/laser scanning, calibration impact experiments and chemical analysis are also addressed.

Microparticle acceleration for hypervelocity experiments by A 3.75MV van de Graaff accelerator and a 100KV electrostatic accelerator in Japan

Abstract In-situ dust detectors have been calibrated by dust electrostatic accelerators that can accelerate projectiles to expected mass and velocity ranges of space debris and micrometeoroids. Unfortunately, In Japan, there was no such a facility dedicated to space science research until our research group was established a few years ago. Therefore, we have developed two high voltage accelerators. One is a modified 3.75MV Van de Graaff accelerator operated by High Fluence Irradiation Facility, Research Center for Nuclear Science and Technology, the University of Tokyo (HIT), and the other is a 100kV accelerator dedicated to dust experiment at the Institute of Space and Astronautical Science (ISAS). The particle velocity using the HIT Van de Graaff accelerator is higher than those reported in other accelerator facilities under the same particle mass conditions and encompasses the desired velocity range of micro-meteoroid. Time-Of-Flight dust mass spectrometer and Hybrid dust detector which are under development in Japan have been investigated using HIT dust accelerators. We have also constructed a 100kV electrostatic accelerator designed for easier handling and lower cost operation which is dedicated to dust acceleration, because the HIT Van de Graaff accelerator is being used for ion beam experiments mainly.

Antarctic micrometeorites collected by the Japanese antarctic research expedition teams during 1996–1999

The Japanese Antarctic Research Expedition (JARE) teams have started collection of unmelted and melted micrometeorites (MMs) in Antarctica since 1996. Some results of the consortium studies are: (1) relatively common occurrence of magnesiowustite (MW) in unmelted MMs, (2) coexistence of MW with low-Ca pyroxene in moderately heated MMs, and (3) evidence that MMs were formed as small particles, rather than fragments of larger bodies, with

DIVISION III: COMMISSION 15: PHYSICAL STUDIES OF COMETS AND MINOR PLANETS

The report of Commission 15 was prepared primarily by the chairpersons of its two working groups: the Minor Planet Working Group and the Comet Working Group. In particular, the Minor Planet section was created by A. Cellino with a little help from E. Tedesco and the Comet section by T. Yamamoto with the assistance of D. BockeleeMorvan, W. Huebner, A. Bhardwaj, D. Biesecker, L. Jorda, H. Kawakita, H. U. Keller, H. Kimura, A. Kouchi, and D. Prialnik. E. Tedesco was responsible for the Introduction, final editing, and merging of the two reports. Scientific activity in the field has continued to grow in the past three years, as evidenced by publication of 700 papers in the refereed literature, compared with about 400 during the previous triennium. A comprehensive overview of so large a publication list cannot be accomplished in the space at our disposal. We have therefore chosen to highlight a representative subset of these publications to provide a snapshot of the current state of the field, and, as in the last several reports, without including a comprehensive bibliography. Instead, a complete list of the references used in creating this report, assembled by searching the ADS abstract service (http://adsabs.harvard.edu/abstract−service.html) to generate a list of refereed papers published between July 2002 and June 2005, inclusive, is available in the Archive section of the Division III Physical Studies of Comets and Minor Planets web site. This site can be reached (since it does not have a permanent home) via a link from the IAU home page.