Hirokazu Hoshino

Overview of IKAROS Mission

The Japan Aerospace Exploration Agency (JAXA) makes the world’s first solar power sail demonstration of photon propulsion and thin film solar power generation during its interplanetary cruise by IKAROS (Interplanetary Kite-craft Accelerated by Radiation Of the Sun). It deployed and spans a membrane of 20 m in diameter taking the advantage of the spin centrifugal force. It accelerates and controls the orbit using solar radiation pressure successfully. This is the first actual solar sail flying an interplanetary voyage. This paper presents the summary of development and operation of IKAROS.

The Result of SELENE (KAGUYA) Development and Operation~!2009-06-28~!2009-08-10~!2009-10-01~!

Japan’s first large lunar explorer was launched by the H-IIA rocket on September 14, 2007 and had been in observation operation from December 21, 2007 to June 11, 2009(JST). This explorer named “KAGUYA (SELENE: SELenological and Engineering Explorer)” has been keenly anticipated by many countries as it represents the largest lunar exploration project of the post-Apollo program. The lunar missions that have been conducted so far have gathered a large amount of information on the Moon, but the mystery surrounding its origin and evolution remains unsolved. KAGUYA investigate the entire moon in order to obtain information on its elemental and mineralogical distribution, its geography, its surface and subsurface structure, the remnants of its magnetic field and its gravity field using the scientific observation instruments. The results are expected to lead to a better overall understanding of the Moon’s origin and evolution. Further, the environment around the Moon including plasma, the electromagnetic field and high-energy particles will also be observed. The data obtained in this way is of great scientific value and is also important information in the possibility of utilizing the Moon in the future. This paper describes the highlight of KAGUYA development and operation with some newly developed engineering achievements including a separation mechanism of sub-satellites from main orbiter as well as the latest scientific accomplishment of KAGUYA. Keyword: SELENE, KAGUYA, H-IIA, JAXA, moon, origin and evolution, ground system, GIS, YouTube, WMS, EPO. KAGUYA SATELLITE SYSTEM OVERVIEW KAGUYA consists of a main orbiter at about 100km altitude and two sub-satellites (Relay Satellite named “OKINA” and VRAD Satellite named “OUNA”) in lunar polar orbit. The main orbiter is also called as KAGUYA. The main orbiter weight at the launch is about 2.9 tons and the size of its main body is 2.1m 2.1m 4.8m. This satellite is 3 axis stabilized and the panel (+Z panel) on which mission *Address correspondence to this author at the SELENE Project, Japan Aerospace Exploration Agency, Tsukuba, 305-8505, Japan; E-mail: sobue.shinichi@jaxa.jp instruments heads are installed is pointed to the gravity center of the Moon. About 3.5 kilo watt is the maximum power produced by a solar paddle. The surface of the KAGUYA is covered with the black color conductive MLI (multi-layer thermal insulators) for conductivity requirement of plasma observation instrument (PACE). The on-orbit configuration of the Main Orbiter is shown in Fig. (1) [1-3]. KAGUYA MISSION PROFILE The Lunar transfer orbit which contributes to reduction of mission risk via two phasing loops around the Earth was adopted. KAGUYA was inserted into a polar elliptical orbit at a perilune altitude of 100 km of lunar. The two subThe Result of SELENE (KAGUYA) Development and Operation Recent Patents on Space Technology, 2009, Volume 1 13 satellites (OKINA and OUNA) were separated from the main orbiter at an apolune of 2,400 km and 800 km respectively. Finally the main orbiter reached the circular orbit at about 100 km altitude and the inclination of polar circular orbit is 90 deg. The apolune altitude of OKINA is determined to measure the gravity field anomaly on the far side of the Moon through relaying the Main orbiter s-band signal effectively. The apolune altitude of OUNA is selected for the low order gravity model coefficient measurements using radio sources on the OKINA and OUNA by VLBI method. When OKINA and OUNA separating from the main orbiter, the spin rotation power were added. This subsatellite separation mechanism which gives the rotational and the translational force simultaneously was originally developed for JAXA’s micro-lab satellite. To consider power generation, octagonal prism shape was selected for subsatellites. All faces of satellite are covered with the solar cells, and each sell produces about 70 watt powers. KAGUYA mission profile is shown in Fig. (2). OKINA was impacted to the far side of the Moon on February 11, 2009 and gravity anomaly observation at the far side of the Moon was successful completed. Fig. (1). The on-orbit configuration of the main orbiter. Lift off Separation from H -IIA Rate Dumping Solar Array Paddle Deployment Sun/Star Capture, High Gain Antenna Deployment Altitude Control of Perigee Lunar Elliptical Orbit Insertion Altitude of Perilune about 100 km

Modeling backscatter reflectivity of Ku-band SAR on periodic structures

Recently airborne SAR at very high frequencies, such as X- and Ku-bands, has been widely studied for many applications. In these studies, the backscatter properties at different frequencies have been well discussed. However, these properties of the urban objects and structures have not been sufficiently discussed yet. In this paper, we focus on evaluating the difference of Ku- and X-band SAR intensity of the man-made objects. Multi-frequency simultaneous airborne SAR observation from the same platform under the same condition enables to evaluate subtle difference of backscatter intensity from the periodic structures. This experiment shows that strong backscatter reflectivity of periodic structures is observed under the influence of Bragg scatter. The effect that the periodicity of the surface structures make a difference in multi-frequency SAR reflectance needs to be considered in SAR analysis especially for building structures in urban areas.