Development of subsurface radar system onboard scientific satellites

2000 Fiscal Year Final Research Report Summary

• Project/Area Number: 11554018
• Research Category: Grant-in-Aid for Scientific Research (B).
• Allocation Type: Single-year Grants
• Section: 展開研究
• Research Field: Space and upper atmospheric physics
• Research Institution: KYOTO UNIVERSITY
• Principal Investigator: HIROTSUGU Kojima Kyoto University, Radio Science Center for Space and Atmosphere, Associate Professor, 宙空電波科学研究センター, 助教授 (10215254)
• Co-Investigator(Kenkyū-buntansha): KASAHARA Yoshiya Kyoto University, Graduate school of Infomatics, Research Associate, 大学院・情報学研究科, 助手 (50243051) ; OKADA Masaki National institute of polar research, Research associate, 助手 (40270425) ; YAGINTAI Satoshi Kanazawa University, Dept. Of Engineering, Associate Professor, 工学部, 助教授 (30251937) ; KASABA Yasumasa Institute of Space and Astronautical Science, Research Associate, 助手 (10295529) ; SHINOHARA Naoki Kyoto University, Radio Science Center for Space and Atmosphere, Research Associate, 宙空電波科学研究センター, 助手 (10283657)
• Project Period (FY): 1999 – 2000
• Keywords: Survey of subsurface / Radar / Mission to planets / Pulse radar / Echo / Layer / Pulse compression / FDTD

Research Abstract

The subsurface radar system onboard scientific satellites is very important technology for the future space mission in order to investigate materials and structures under the surface. We studied the subsurface radar system onboard subsurface radar system onboard satellites using the computer simulations. There exist many limitations of the subsurface radar system onboard satellites such as the weight budget, and power budget. Therefore, it is very important to survey the capability of the radar system based on the minimum specifications. Further, in order to survey the subsurface, we need the long wavelength radio waves, which mean that it needs the antenna with the long elements. Since we cannot expect the intense backscatter echoes from the subsurface, we cannot make use of the side-looking type radar. In order to overcome these limitations and propose the best solution of the subsurface radar system, we need to perform computer simulations based on the various simulation models. First, we developed the computer simulation program based on the FDTD method, which is mainly customized for the use of the subsurface radar development. Secondly, we performed the simple computer simulations based on the uniform subsurface layers and found that the multiple reflection effects between each layer can be the source of the noise in this radar system. As the next step, we adopted the mountain or other irregularities of the surface and performed computer simulations. These computer simulations show that the observed echoes are very noisy under the mixtures of echoes from the surface of the ground, and from the surface irregularities in addition to the effects of multiple reflections. Further, we performed many computer simulations including the motion of the spacecraft, and found that most of noises can be removed due to the time variation of echoes according to the spacecraft motion.