The study of a super low altitude satellite

Abstract

This paper reports a study of a super low altitude satellite. The altitude of this satellite's orbit is lower than ever before. The altitude of a conventional earth observing satellite is generally around from 600km to 900km. The lowest altitude of earth observing satellites launched from Japan was 350km of the Tropical Rainfall Measuring Mission (TRMM). In contract, the satellite in this paper is planned to orbit at the altitude below 200km. Furthermore, the duration of the flight is more than two years. Any satellite in the world has not flied such a low altitude. The satellite in such a low orbit drops in a short period. Our satellite will cancel the air drag by a thrust of an ion engine. For that purpose, usually, a drag-free system will be applied. That causes a complicated and expensive satellite system. On the other hand, we succeeded in finding a robust control law in a simple system even for the unpredictable change of the air drag. If the altitude is low, the spatial resolution of an optical sensor improves. If a SAR is equipped on the satellite, the consumed electric power of the SAR is extremely reduced as well as the spatial resolution improves.