The HESP/R satellite project

The aim of the HESP/R (High Energy Solar Physics/Radiation) satellite project is to obtain data of γ-ray, hard X-ray soft X-ray, EUV, and visible radiation of solar flares at the next solar maximum in order to study physics of flares. The HESP/R will be a spinning satellite of 4–5 rotations per min., and the spin axis is off-set by a small angle (0.5°–1.0°) from the Sun. Total weight will be 400 kg and launched in 1991 with M-3S-II rocket by ISAS.     

A simulation study for anticipated accuracy of lunar gravity field model by SELENE tracking data

Results of numerical simulations are presented to examine the global gravity field recovery capability of the Japanese lunar exploration project SELENE (SELenological and ENgineering Explorer) which will be launched in 2007. New characteristics of the SELENE lunar gravimetry include 4-way satellite-to-satellite Doppler tracking of main orbiter and differential VLBI tracking of two small free-flier satellites. It is shown that the proposed satellite constellation will provide the first truly global satellite tracking data coverage. The expected results from these data are; (1) drastic reduction in far-side gravity error, (2) estimation of many gravity coefficients by the observation, not by a priori information, and (3) one order of magnitude improvement over existing gravity models for low-degree field.     

Japanese moon lander SELENE-2—Present status in 2009

JAXA is planning exploration missions to the moon, following upon the Kaguya (SELENE) mission., These missions aim to demonstrate some new technologies, observe the moon scientifically, investigate technical, social and political feasibility of utilizing the moon. For the first step of the missions, the phase A study of SELENE-2 has started from the summer of 2007. This mission will demonstrate the effectiveness of several technologies including precision landing, hazard avoidance, surface mobility, and night survival technologies. In situ geological and geophysical observations will be conducted to improve our knowledge on the origin and the evolution of the moon. Investigating the lunar surface conditions and its potential for in situ resource utilization will provide key information for future human exploration missions. This paper presents the current status of the SELENE-2 mission, its objectives, its design, and other important aspects of its development such as international cooperation.     

Digital beam forming (DBF) antenna system for mobile communications

We demonstrate the feasibility of a digital beam forming (DBF) and beam space CMA (Constant Modulus Algorithm) adaptive array antenna by implementing a digital signal processor (DSP) in ASICs using field programmable gate arrays (FPGA), this DBF can synthesize 16 multi-beams and eliminate interference signals by CMA adaptive processing. The whole function was implemented in 10 DSPs about 127,000 equivalent gates. Simple experimental results have confirmed the basic function of the DBF and BSCMA adaptive array antenna     

Studying the Lunar Ionosphere with SELENE Radio Science Experiment

Radio occultation observations of the electron density near the lunar surface were conducted during the SELENE (Kaguya) mission using the Vstar and Rstar sub-satellites. Previous radio occultation measurements conducted in the Soviet lunar missions have indicated the existence of an ionosphere with peak densities of several hundreds of electrons per cubic centimeters above the dayside lunar surface. These densities are difficult to explain theoretically when the removal of plasma by the solar wind is considered, and thus the generation mechanism of the lunar ionosphere is a major issue, with even the validity of previous observations still under debate. The most serious error source in the measurement is the fluctuation of the terrestrial ionosphere which also exists along the ray path. To cope with this difficulty, about 400 observations were conducted using Vstar to enable statistical analysis of the weak signal of the lunar ionosphere. Another method is to utilize Vstar and Rstar with the second one being used to measure the terrestrial ionosphere contribution. The observations will establish the morphology of the lunar ionosphere and will reveal its relationship with various conditions to provide possible clues to the mechanism.     

Fundamental studies concerning planetary quarantine in space.

If there is a possibility that the organisms carried from Earth to space can live for a significant period on planets, the contamination of planets should be prevented for the purpose of future life-detection experiments. In connection with quarantine for interplanetary missions, we have examined the survivabilities of terrestrial microorganisms under simulated space conditions. In this study, examined the survivabilities of terrestrial organisms under simulated Mars conditions. The Mars conditions were simulated by ultraviolet (UV) and proton irradiation under low temperature, high vacuum, and simulated gaseous conditions. After exposure to the simulated Mars condition, the survivabilities of the organisms were examined. The spores of Bacillus subtilis and Aspergillus niger, some anaerobic bacterias and algaes, showed considerably high survivabilities even after UV and proton irradiation corresponding to 200 years on Mars. This subject is not restricted to academic curiosity but concerns problems involving the contamination of Mars with terrestrial organisms carried by space-probes.     

3-D magnetic field and current system in the heliosphere

In this paper a global system of the magnetic field and current from the interaction of the solar wind plasma and the interstellar medium is modeled using a 3-D MHD simulation. The terminal shock, the heliopause and the outer shock are clearly determined in our simulation. In the heliosheath the toroidal magnetic field is found to increase with the distance from the sun. The magnetic field increases rapidly in the upstream region of the heliosheath and becomes maximum between the terminal shock and the heliopause. Hence a shell-type magnetic wall is found to be formed in the heliosheath. Because of this magnetic wall the radially expanding solar wind plasma changes its direction tailward in all latitudes except the equatorial region. Only the equatorial disk-like plasma flow is found to extend to the heliopause through the weak magnetic-field region around the equator. Two kinds of global current loops which sustain the toroidal magnetic field in the heliosphere are found in our simulation.The influence of the 11-year solar cycle variation of the magnetic polarity is also examined. It is found that the polarity of the toroidal magnetic field in the heliosheath switches at every solar cycle change. Hence the heliosheath is found to consist of such magnetized plasma bubbles. The neutral sheets are found to extend between such magnetized plasma bubbles in the 3-D heliosheath in a complicated form. The magnetic-pressure effect on the heliosheath plasma structure is also examined.     

The diffuse soft X-ray sky

The current status of the investigation of the soft X-ray diffuse background in the energy range 0.1–2.0 keV is reviewed. A consistent model, based on the soft X-ray brightness distribution and the energy spectrum over the sky, is derived. The observed diffuse background is predominantly of galactic origin and considered as thermal emission for the most part from a local hot region of temperature ≈10⁶ K which includes the solar system. Several pronounced features of enhanced emission are interpreted in terms of hot regions with temperatures up to 3×10⁶K, some of which are probably old supernova remnants. The properties of the soft X-ray emitting regions are discussed in relation to the observational results on O vi absorption.     

An observation of snow melting process from remotely sensed data

Observations of satellite images have shown that the snow melting in mountainous area proceeds more repidly in the east-facing slope of the valley than in the west-facing one. The energy for melting snow consists of the total from the atmosphere and from the solar rays. The diurnal variation of the solar energy into the snow in the east-facing slope differs from that in the west-facing slope. This causes the heighest value of the instantaneous energy for melting snow to occur in the west-facing surface. As one of the reasons for the above tendency, the difference of the heighest value to melt snow may be taken into account.