Japan Aerospace Exploration Agency

About: Japan Aerospace Exploration Agency is a facility organization based out in Tokyo, Japan. It is known for research contribution in the topics: Galaxy & Telescope. The organization has 4327 authors who have published 12054 publications receiving 208330 citations.

New Constraint-Handling Method for Multi-Objective and Multi-Constraint Evolutionary Optimization

Abstract: A new constraint-handling method based on Pareto-optimality and niching concepts for multi-objective multi-constraint evolutionary optimization is proposed. The proposed method does not require any constants to be tuned for constraint-handling. In addition, the present method does not use the weighted-sum of constraints and thus does not require tuning of weight coefficients and is efficient even when all individuals in the initial population are infeasible or the amount of violation of each constraint is significantly different. The proposed approach is demonstrated to be remarkably more robust than the dynamic penalty approach and other dominance-based approaches through the optimal design of a welded beam and conceptual design optimization of a two-stage-to-orbit spaceplane.

Hayabusa‐returned sample curation in the Planetary Material Sample Curation Facility of JAXA

Abstract: – The Planetary Material Sample Curation Facility of JAXA (PMSCF/JAXA) was established in Sagamihara, Kanagawa, Japan, to curate planetary material samples returned from space in conditions of minimum terrestrial contaminants. The performances for the curation of Hayabusa-returned samples had been checked with a series of comprehensive tests and rehearsals. After the Hayabusa spacecraft had accomplished a round-trip flight to asteroid 25143 Itokawa and returned its reentry capsule to the Earth in June 2010, the reentry capsule was brought back to the PMSCF/JAXA and was put to a series of processes to extract recovered samples from Itokawa. The particles recovered from the sample catcher were analyzed by electron microscope, given their ID, grouped into four categories, and preserved in dimples on quartz slide glasses. Some fraction of them has been distributed for initial analyses at NASA, and will be distributed for international announcement of opportunity (AO), but a certain fraction of them will be preserved in vacuum for future analyses.

Variation of inner radius of dust torus in ngc4151

Abstract: Long-term optical and near-infrared monitoring observations for a type 1 active galactic nucleus (AGN) NGC 4151 were carried out for six years from 2001 to 2006 by using the MAGNUM telescope, and delayed response of flux variations in the K(2.2 μm) band to those in the V(0.55 μm) band was clearly detected. Based on cross-correlation analysis, we precisely measured a lag time Δt for eight separate periods and we found that Δt is not constant, changing between 30 and 70 d during the monitoring period. Since Δt is the light travel time from the central energy source out to the surrounding dust torus, this is the first convincing evidence that the inner radius of the dust torus did change in an individual AGN. In order to relate such a change of Δt with a change of AGN luminosity L, we present a method of taking an average of the observed V-band fluxes that corresponds to the measured value of Δt, and we find that the time-changing track of NGC 4151 in the Δt versus L diagram during the monitoring period deviates from the relation Δt ∝ L 0.5 expected from dust reverberation. This result, combined with the elapsed time from period to period for which Δt was measured, indicates that the timescale of dust formation is about one year, which should be taken into account as a new constraint in future studies of dust evolution in AGNs.

Ground calibration of the high-sensitivity SELENE lunar magnetometer LMAG

Abstract: Ground calibration experiments of the SELENE high sensitivity fluxgate Lunar Magnetometer (LMAG) have been performed in order to determine the alignment, sensitivity, and offset of the sensors (MGF-S). It is checked out that the sensors are orthogonal to each other within 0.4 degrees, and the linearity of the ambient magnetic field and the output from the sensors are confirmed. Also, the temperature dependences of the offset and sensitivity are examined but no clear signatures of temperature dependencies can be seen. SELENE has an in-flight calibration system in order to determine the direction of the magnetometer routinely. The magnetic fields generated by the sensor alignment monitor coil (SAM-C) system are used for the in-flight calibration. The magnetic field distributions generated by SAM-C are determined and the accuracy of determination of the magnetometer position and direction is estimated. Multiple measurements will allow us to determine the direction of MGF-S with about 0.1-degree accuracy. Appropriate corrections from the results of the ground and in-flight calibrations will allow us to recover the magnetic field near the moon with accuracy about 0.1 nT.

Gauge adjusted global satellite mapping of precipitation (GSMaP_Gauge)

Abstract: Precipitation is one of the most important resources for human activity, and global distribution of precipitation amount and its change are essential data for modeling the water cycle and global energy cycle. Space-borne Passive Microwave Radiometers (PMRs) are working on many satellites. PMR observes emission and scattering from precipitation and provide uniform global data. The Global Satellite Mapping of Precipitation Moving Vector with Kalman-filter (GSMaP_MVK) estimates hourly and 0.1 degree gridded precipitation map from PMRs. Because land is radiometrically warm region, estimation of precipitation over land is difficult. Global precipitation over land, however, is most important for human activity, such as management of water and flood warning. We are developing a gauge adjusted algorithm for GSMaP (GSMaP_Gauge). In this paper, we show performance of the algorithm and some initial evaluation tests. We introduce the GSMaP_Gauge algorithm and show the validation of the algorithm.