Preparation for curation of Hayabusa2-returned samples in JAXA

The Tenth Symposium on Polar Science/Special session: [OA] Antarctic meteorites, Thur. 5 Dec. / 3F Multipurpose conference room, National Institute of Polar Researc

The collection of micrometeorites in the Yamato Meteorite Ice Field of Antarctica in 1998

In austral summer season of 1998,we collected micrometeorites at the Meteorite Ice Field around the Yamato Mountains, Antarctica. It was the first attempt to collect micrometeorites at inland bare ice in Antarctica and to use a filter with 10μm openings; it can capture particles that overlap in size with interplanetary dust particles collected in stratosphere. At the inland bare ice of the Antarctic Continent, an ancient flux of extraterrestrial dust is thought to be preserved in contrast with bare ice along the shore of the continent. For collecting micrometeorites from the bare ice, we used a tented sledge equipped with appliances for melting ice and filtering the melted water. We melted ∿ 36 tons of ice and obtained particles containing micrometeorites at 24 points in three areas of the Meteorite Ice Field

Meteorite search by JARE-39 in 1998-99 season

A meteorite search party composed of eight men of the 39th Japanese Antarctic Research Expedition (JARE) collected 4136 meteorites on bare ice areas around the Yamato Mountains and the Belgica Mountains in 1998-99 field season. Approximately 4100 meteorites have been collected around the Yamato Mountains. They include many kinds of rare meteorites. By classification in the field, 2 lunar meteorites, 3 irons, 4 stony irons, 15 ureilites, 37 diogenites, 63 eucrites, 29 unclassified achondrites and 160 carbonaceous chondrites are distinguished. The number of irons is very small for such a great number of the meteorites. We also searched for meteorites around the Belgica Mountains. Twenty-one meteorites have been collected. All of them are ordinary chondrites

Formation processes of magnetic spherules collected from deep-sea sediments -Observations and numerical simulations of the orbital evolution-

Spherules collected from deep-sea sediments were analyzed for major chemical compositions and examined for textural relationships. Two main types of internal texture are observed in Ni-bearing I-type spherules : spherules with Ni-free Fe-oxide mantle and Fe-Ni metallic cores and Fe-Ni oxide spherules without metallic cores. Cores are often observed off-centered. S-type spherules show porphyritic, barred, and fine-grained types of texture. Relict olivine grains are found in some porphyritic S-type spherules. A cooling rate of 55℃/s was calculated for one of these grains based on chemical zonal patterns. For I-type spherules, numerical simulations were performed to constrain the relationship between temperatures, radii of spherules, and the apparent gravitational acceleration with the spherule as a stationary frame of reference. Results indicate that a) spherules lose most of their original mass by evaporation over 1900℃, and, b) the apparent gravitational acceleration is at a maximum during the last stage of evaporation. Based on the observations and numerical simulations of I-type spherules, we propose the following model for their formation : during ablation, the metallic core is off-centered, a surface of the core is then exposed to the air due to the strong apparent gravitational acceleration and, finally, oxidation reactions can proceed on the exposed core surface

Medical Curriculum to Motivate Students

Despite advancements in the pedagogy of medical education in various fields, Japan has no standardized medical English education. The U.S. Medical Licensing Examination (USMLE) Study Group of Tokushima is an extracurricular activity in which medical students and recent graduates meet every 1–2 months. The aim is to stimulate students’ curiosity ; cultivate their initiative, self-efficacy, and English learning goals ; and motivate them to be self-regulated learners. Accordingly, we conducted near-peer teaching style lectures that focused on sharing medical English-related experiences, so students could have regular opportunities to visualize the benefits of learning medical English. Following the activities, we observed increased motivation and self-study among students, resulting in a high USMLE passing rate. Furthermore, five members started their training at American hospitals and pursued careers in English-speaking environments. Thus, near-peer teaching style leads to shared medical English-related experiences that help students to visualize English-related opportunities. This education style taught by similar generations aids in setting a specific goal by providing access to role models, cultivating their initiative and self-efficacy, motivating them to learn English, and producing positive outcomes. Modifying the curriculum to actively create opportunities for students to visualize themselves in an international environment can motivate them to continue learning English

Detection of Soluble Organic Matter in Antarctic Micrometeorites

The Tenth Symposium on Polar Science/Poster presentations: [OA] Antarctic meteorites, Wed. 4 Dec. / Entrance Hall (1st floor), National Institute of Polar Researc

Special issue “Science of solar system materials examined from Hayabusa and future missions (II)”

Six years have passed since the first asteroid sample was returned from the S-type near-Earth asteroid 25143 Itokawa by the JAXA’s Hayabusa mission in 2010 (Yada et al. 2014). Considerable progress has been made in the study of surface regolith materials and the understanding of planetary surface processes such as space weathering (Noguchi et al. 2011), the chronology of Itokawa and its dynamic evolution processes (Nagao et al. 2011; Park et al. 2015), and the thermal alteration undergone in parent bodies (Nakamura T et al. 2011). Discussions of new findings from the Hayabusa-returned samples and from a large collection of meteorites, micrometeorites, and interplanetary dust particles have continued, especially at the annual international Hayabusa symposia of solar system materials (Okada et al. 2015). Progress in sample return science has driven the next stage of exploration. Now, two new sample return missions to primitive, volatile-rich asteroids, JAXA’s Hayabusa2 (Tsuda et al. 2013) and NASA’s OSIRIS-REx (Lauretta et al. 2012), are en route to their target bodies, C-type 162173 Ryugu and B-type 101955 Bennu, respectively. It is our great pleasure to present our second special issue of the journal Earth, Planets and Space, “Science of solar system materials examined from Hayabusa and future missions (II).” This special issue is based on discussions during the Hayabusa 2014 symposium, which featured new results from Hayabusa-returned samples and related studies, but was also open to any scientific results regarding primitive bodies and the early solar system, the results of laboratory experiments and ground-based observations, and reports of new instruments and methods. We will begin with a brief introduction to the missions of the Hayabusa and its successor Hayabusa2. In addition, all six manuscripts published in this special issue are reviewed below

Erratum to: Special issue “Science of solar system materials examined from Hayabusa and future missions (II)”

In the version of this article that was originally published (Okada et al. 2017), there was an error in the title. The phrase “Preface: The Earth, Planets and Space” has been removed from the beginning of the title and the original article has been updated. The publisher apologises for these errors

H, C, and N isotopic compositions of Hayabusa category 3 organic samples

Since isotopic ratios of H, C, and N are sensitive indicators for determining extraterrestrial organics, we have measured these isotopes of Hayabusa category 3 organic samples of RB-QD04-0047-02, RA-QD02-0120, and RB-QD04-0001 with ion imaging using a NanoSIMS ion microprobe. All samples have H, C, and N isotopic compositions that are terrestrial within errors (approximately ±50‰ for H, approximately ±9‰ for C, and approximately ±2‰ for N). None of these samples contain micrometer-sized hot spots with anomalous H, C, and N isotopic compositions, unlike previous isotope data for extraterrestrial organic materials, i.e., insoluble organic matters (IOMs) and nano-globules in chondrites, interplanetary dust particles (IDPs), and cometary dust particles. We, therefore, cannot conclude whether these Hayabusa category 3 samples are terrestrial contaminants or extraterrestrial materials because of the H, C, and N isotopic data. A coordinated study using microanalysis techniques including Fourier transform infrared spectrometry (FT-IR), time-of-flight secondary ion mass spectrometry (ToF-SIMS), NanoSIMS ion microprobe, Raman spectroscopy, X-ray absorption near edge spectroscopy (XANES), and transmission electron microscopy/scanning transmission electron microscopy (TEM/STEM) is required to characterize Hayabusa category 3 samples in more detail for exploring their origin and nature.This research was supported by the JSPS Strategic Fund for Strengthening Leading-edge Research and Development to the JAMSTEC