Tateo Goka

Development of Multi-Utility Spacecraft Charging Analysis Tool (MUSCAT)

A new numerical software package to analyze spacecraft charging, named ldquomulti-utility spacecraft charging analysis toolrdquo (MUSCAT), has been developed. MUSCAT consists of an integrated graphical user interface tool called ldquoVineyardrdquo and the solver. Vineyard enables satellite engineers to compute spacecraft charging with little knowledge of the numerical calculations. Functions include 3-D satellite modeling, parameter input such as material and orbit environment, data transfer, and visualization of numerical results. Fundamental physical processes of charged-particle-surface interaction are included in the solver. These functions enable MUSCAT to analyze spacecraft charging at geostationary orbit, low Earth orbit, and polar Earth orbit (PEO). The numerical solver code is parallelized for high-speed computation, and the algorithm is optimized to achieve analysis of large-scale PEO satellite in the design phase. Variable time steps are also used to calculate the rapid change of the spacecraft body potential and the gradual change of the differential voltage in a single simulation with a practical number of iterations. In this paper, the functionality, algorithms, and simulation examples of MUSCAT are presented.

Total dose orbital data by dosimeter onboard Tsubasa (MDS-1) satellite

The total dose data from a Tsubasa (MDS-1) satellite, flying in a highly eccentric orbit, is analyzed. The total dose is measured by the small dosimeter using RADFETs. The RADFETs have been calibrated with the Co60 gamma ray source, and 56 devices (denoted DOS-S) were mounted in several experimental modules in the satellite. The total dose data behind certain Aluminum shield domes have been analyzed initially. The total dose change is affected by electron flux in the thin shield. In thicker shield, electron and proton affect the total dose profile.

SEE flight data from Japanese satellites

This paper reviews the SEE (Single Event Effects) which have been observed on Japanese spacecraft in space since 1971, and summarizes the in-orbit SEL (Single Event Latch-up) and SEU (Single Event Upset) data for 10 years from 4 Japanese satellites. The data is separated into solar maximum and solar minimum periods and into Galactic Cosmic Ray (GCR) and South Atlantic Anomaly (SAA) groupings. Heavy ion and proton testing of the same flight parts are reported. Prediction rates using CREME96 codes with heavy ion LET cross sections and 2-parameter fits and CREME96 to proton cross section data are compared with the SEE flight data. We have followed the suggestions of Petersen for a good comparison paper. The extreme value theory is applied for the prediction of the maximum SEE rates from solar flare events and can be used to discriminate the effects of the solar events from a quiescent. Environment, and can also be used to examine outlier data points.

Space radiation environment and its effects on satellites: analysis of the first data from TEDA on board ADEOS-II

The Advanced Earth Observing Satellite II (ADEOS-II) was launched into sun-synchronous, sub-recurrent orbit on December 14, 2002, and its operation terminated unexpectedly on October 24, 2003. While in orbit, the Technical Data Acquisition equipment on board ADEOS-II monitored the space radiation environment and its effects, including total-dose and single-event upset, recording them on 16 M and 64 M-DRAM memories. In this paper, we analyze the first data results from these monitors.

Measurements of Cosmic-Ray Neutron Energy Spectra from Thermal to 15 MeV with Bonner Ball Neutron Detector in Aircraft

Cosmic-ray neutron energy spectra from thermal to 15MeV were measured with a multimoderator spectrometer known as the Bonner Ball Neutron Detector (BBND) at aviation altitude (9–11 km). Four flights were carried out around Nagoya Airport in Japan. The measured data were unfolded using the maximum entropy deconvolution code MAXED, and the derived spectra agreed with the calculated results using the PHITS-based analytical radiation model in the atmosphere (PARMA). The results of the in-flight measurement verified the accuracy of model calculation in regard to the neutrons within a certain energy range.

Compact, lightweight spectrometer for energetic particles

We have developed an energetic particle spectrometer called a standard dose monitor (SDOM) that can discriminate and analyze the energy of electrons, protons, and alphas. SDOMs unique characteristics include a large G-factor, a wide energy range, and the ability to simultaneously identify and analyze the energy of multiple particle types. We plan to use this instrument to update current space radiation environment models.

Verification of Multi-Utility Spacecraft Charging Analysis Tool (MUSCAT) via laboratory test

Multi-utility Spacecraft Charging Analysis Tool (MUSCAT), a spacecraft charging analysis software, has been developed as a joint work of JAXA and KIT. Experiments for the fundamental code validation were carried out at the plasma chamber of LaSEINE in KIT to show accuracy of the solver. We evaluated that the test section in the chamber with respect to the plasma environment by measuring two-dimensional plasma distribution and plasma drift velocity. A cube area of 400mm on a side whose center located at the 550mm downstream from plasma source can be considered as the test section with no plasma flow. The averaged plasma density, temperature and plasma potential within this test section were 3±2x10 12 m -3 , 2±1eV and 10±5V, respectively. The length of test section 400mm corresponds to about 67λ D . Spatial distribution of electric potential and IV characteristic curve were measured with an emissive probe and the Langmuir probe whose electrode were cubic in shape to adjust the rectangular numerical domain of MUSCAT. Comparing those experimental results with the numerical ones, both had good agreements. These results show that the physical functions of MUSCAT simulate charging processes quite well. Also, numerical model of the cell-side of solar array paddle was obtained. Conductor patches whose size is the quarter of total amount of the interconnector exposed area put on the coverglass can simulate the cell-side of a real solar array with respect to current collection.

Recent Progress of Development of Multi -Utility Spacecraft Charging Analysis Tool (MUSCAT)

A new numerical software package to analyze spacecraft charging, named ldquomulti-utility spacecraft charging analysis toolrdquo (MUSCAT), has been developed. MUSCAT consists of an integrated graphical user interface tool called ldquoVineyardrdquo and the solver. Vineyard enables satellite engineers to compute spacecraft charging with little knowledge of the numerical calculations. Functions include 3-D satellite modeling, parameter input such as material and orbit environment, data transfer, and visualization of numerical results. Fundamental physical processes of charged-particle-surface interaction are included in the solver. These functions enable MUSCAT to analyze spacecraft charging at geostationary orbit, low Earth orbit, and polar Earth orbit (PEO). The numerical solver code is parallelized for high-speed computation, and the algorithm is optimized to achieve analysis of large-scale PEO satellite in the design phase. Variable time steps are also used to calculate the rapid change of the spacecraft body potential and the gradual change of the differential voltage in a single simulation with a practical number of iterations. In this paper, the functionality, algorithms, and simulation examples of MUSCAT are presented.

Compact Energetic Light Particle Detector and Spectrometer

We have developed a megaelectron-volt class energetic charged-particle spectrometer based on a novel configuration and processing algorithm. The National Space Development Agency of Japan has undertaken a program to develop a particle monitor capable of discriminating and measuring protons in the range from 0.9 to 150 MeV, electrons in the range from 0.5 to >10 MeV and alpha particles >8 MeV, all within a single sensor called the standard dose monitor. The goal is to utilize sensors with nearly identical design and performance on several simultaneous missions to develop a clearer understanding of particle energies and their variability as a function of solar activity, latitude, and altitude. To date, four flight model sensors have been delivered. The sensors are designed to detect accurately the higher-energy particles and high count rates present during active solar periods. In addition, this sensor exhibits extremely efficient discrimination between low-energy electrons and protons. The sensors have been calibrated over nearly their entire particle-energy range. The design is described and calibration data are compared with the results of a Monte Carlo sensor performance model.

HELIUM ISOTOPES IN THE RADIATION BELTS OBTAINED BY HIT ONBOARD TSUBASA

The helium isotopes were observed by Heavy Ion Telescope (HIT) onboard the TSUBASA satellite from March, 2002 to September, 2003 in the geostationary transfer orbit. The mass resolution of the HIT instrument is ~ 0.25 amu in energy range 20÷43 MeV/nucleon for helium isotopes. Helium data in the quiet periods were analyzed to obtain the spatial and temporal variation of fluxes of helium isotopes, 3He and 4He. From this analysis, the enhancement of 3He flux as compared with 4He one in low L-value was found. Both of the helium fluxes strongly fluctuated in their L-distributions in each period.