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This paper presents the proto-flight model results of X band synthetic aperture radar for small satellites including the RF power amplifier, high speed data storage/transmission system, and the ground SAR response test results. The specifications of SAR performance are single polarization SAR with 3m ground resolution for strip map mode. 1 m ground resolution can be achieved with sliding spot light mode under condition of limited value of NESZ at 600km altitude orbit. The data down link is high speed X band down link with 2-3 Gbps. In May, 2019, 2.5Gbps down link with 64APSK modulation in dual polarization channels was demonstrated by RAPIS-1 Satellite. We will launch the first demonstration SAR satellite in 2020 as collaboration with a private company.

We are developing 2.8Gbps down link in X band (8025-8350MHz) from small SAR observation satellites. The modulation is 64APSK of DVB-S2X with symbol rate of 300Msps. Dual polarization channels are applied to the system. We have tested an engineering model of the transmitter, and the on-board antenna with high cross-polarization discrimination (XPD). The ground antenna with high XPD is also developed. This down link system will be demonstrated in 2019 by JAXA advanced small satellite.

This paper presents the engineering model results of this X band synthetic aperture radar for small satellites and its application to constellation missions.The specifications of SAR performance are single polarization SAR with 1m ground resolution at 350 km altitude and with 3m ground resolution at 600km altitude orbit. A satellite is supposed to be 130kg in mass and the size is 0.7m x 0.8m x 0.9m on a rocket. A size of the deployed antenna is 4.9m x 0.7m. A chirped transmitting signal is amplified in a six GaN HEMT 200W amplifier modules to be combined in a waveguide resonator. The type of antenna system is deployable plane antenna due to its compact stow volume. Novel parallel plate slotted array antennas have been developed. We have performed compact range test, near-field measurement of an antenna wing with 2.8m x 0.7m size. The peak aperture efficiency is measured to be higher than 50%. We will launch the first demonstration satellite in late 2019. We finally will build a constellation of several tens SAR satellites with 1-3m resolution to realize from every day to every few hours revisit.

University of Tokyo and Japan Aerospace Exploration Agency (JAXA) are developing a 50kg-class microspacecraft named “PROCYON” for deep space exploration. PROCYON will conduct two missions: 1) demonstration of micro-spacecraft bus system for deep space exploration, and 2) demonstration of asteroid close flyby observation. In order to develop the spacecraft with very low cost (less than a few million dollars), most of the bus system is based on that of Earth-orbiting micro satellite, excluding the communication system and propulsion system which are newly developed for the deep space mission. PROCYON is scheduled to be launched at the end of 2014 together with Japanese second asteroid sample return spacecraft Hayabusa-2. The success of PROCYON will demonstrate that a small-scale spacecraft for deep space exploration can be built with very low cost, which will enable more frequent and challenging deep space exploration.

A new type of Micro Sun Sensor (MSS) was started development for use on JAXA’s small satellites and space exploring spacecraft as attitude sensor. In recent years, small satellites are used for various missions, such as the Earth observation and science observation, and high functional attitude control system for small satellite is also required. Therefore, the sun sensor for small satellite is required to be good balance of its dimension, mass, power consumption and performance. The detector of the MSS is a CMOS Active Pixel Sensor (APS). The adoption of the CMOS APS contributes to simplicity and compactness on the MSS. The MSS is equipped with a commercial-grade CMOS APS. The state-of-the-art commercial APS is low cost and high performance. For radiation effect investigation, the tolerance for gamma rays and proton irradiation were tested. The Ground Test Model (GTM) of the MSS was fabricated and also has been tested. This paper reports the description of the MSS, the result of the radiation test for commercial APS and ground optical performance test of the MSS GTM.

著者人数: 12名, 資料番号: SA1003124000