Tatsuaki Okada

47th ISAS Lunar and Planetary Symposium (August 4-6, 2014. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA)(ISAS)), Sagamihara, Kanagawa Japan

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.

The performance of wire-sawing in vacuum has been investigated for future lunar and planetary explorations. Nickel fixing abrasives adhered on a rock specimen in vacuum and the rock was hardly cut. In this report, the causes of the adhesion were estimated by friction tests. The nickel surface became oxide in air and more brittle than pure nickel. Consequently, nickel was removed in air. On the other hand, nickel was not oxidized in vacuum and was still tough and soft after rubbing. In addition, debris adhered on the machined area by electrostatics. Consequently, the abrasives slipped on the nickel and machining did not progress.

The Memorandum of Understanding signed between the Japanese Aerospace Exploration Agency (JAXA) and the German Aerospace Centre (DLR) during the 63rd International Astronautical Congress (IAC) in Naples, paves the way for the Mobile Asteroid Surface Scout (MASCOT) participation in JAXAs Hayabusa-II mission. Like its famous predecessor, Hayabusa-II is foreseen to study and return samples from a Near-Earth Asteroid. In contrast to the previous mission, Hayabusa-II will also include a small lander package being developed by DLR and the Centre National d'Etudes Spatiales (CNES): the aforementioned MASCOT. Scheduled for a launch in 2014, Hayabusas-II journey will take 4 years until it will arrive at 1999JU3, a C-type asteroid. Following the initial remote sensing operations, MASCOT will be released to the surface and perform its science operations at its first location. Once this is complete, MASCOT will be able to 'hop' from one measurement site to the next. The payload suite will comprise a near-infrared microscope (MicrOmega, IAS Paris), a camera (CAM, DLR Berlin), a radiometer (MARA, DLR Berlin) and a magnetometer (MAG, TU Braunschweig). Realizing MASCOTs mission is difficult due to the strict mission requirements, the harsh landing environment and a short development time for a piggyback deep space mission. Aiming for high performance and reliability requires creative design solutions and novel developments in order to meet all challenges and to stay inside the mass limit of 11 kg. The status of MASCOT up to end of Phase B was presented at the 63rd IAC. With a flight model delivery scheduled for March 2014, the mission is now in the final stage of development and testing. The results of these tests have shown the strict limits of the structure and thermal design, and highlighted the risk in such a short project development. Lessons have also been learned regarding margin policy for such small spacecraft. Despite these challenges, the project is on-track, with all delivery milestones expected to be met. These last few months will serve to verify all of the design assumptions, before the launch in late 2014.

Thermal infrared imager system is developed for HAYABUSA2, which is planned to be launched in 2014 and aims at sample-return from a C class near-Earth asteroid 1999JU3 considered to contain organic or hydrated materials. The system consists of a thermal-infrared imager (TIR) and a digital electronics, which is used not only for the scientific investigation of physical properties of the asteroid surface, but also for the assessment of landing site selection and safe descent operation onto the asteroid surface with in situ measurement.Since round trip communication time between the asteroid and the Earth is more than thirty minutes, onboard automatic data processing function and high speed data recording capability are provided to exploit the limited downlink capacity which is up to 32kbps.TIR adopts an uncooled bolometer with 320 x 240 effective pixels. Image operations as multiple images summation, dark image subtraction, and the compensation of dead pixels are processed onboard. A processing module is connected to sensor interfaces through SpaceWire in order to provide deterministic processing time. Data compression is also provided to reduce restriction on storage capacity and operation time, which provides the equivalent compression ratio as JPEG2000 in 1/30 processing time in average. A high speed data recorder is also connected through SpaceWire in 50Mbps in order to record TIR data in parallel with other sensor data.The modularity of SpaceWire enables to use as built devices for TIR and inherits the same design as the long-wavelength infrared imager developed for the Venus climate orbiter Akatsuki.

We identified minerals on the surface of polished surfaces of Itokawa dust particles by micro-Raman spectroscopy. Their sizes ranged from 30 to 150 μm across. Olivine, pyroxenes, plagioclase and chromite were identified, which correspond to SEM/EDX observations and analyses of these samples. Although Raman spectroscopy is suitable for the identification of maskelynite (diaplectic glass transformed from plagioclase), we could not find maskelynite in all of the samples investigated. This fact suggests that the shock stage of the samples did not reach S4, which is consistent with the other results of the Hayabusa initial analyses.