竹内 央

This study investigates the trajectory analysis of small solar sail demonstration spacecraft IKAROS considering the uncertainty of solar radiation pressure. Estimation of solar sail force model in space is the key factor for successful solar sail navigation because the solar sail have large uncertainty due to the flexible membrane. Since the sail wrinkles after the deployment and its surface will suffer from degradation, the solar sail force model is difficult to develop on the ground. In this paper, a practical analysis of estimating the solar sail force model from Doppler and range observable is investigated. This is demonstrated by orbit determination including parameter estimation of solar sail model. Some examples are described to investigate better parameters to estimate the solar sail force model.

Space VLBI (very long baseline interferometry) mission, ASTRO-G, will be launched in 2013 by Japan Aerospace Exploration Agency (JAXA). ASTRO-G is a follow-on mission of HALCA (VSOP) mission in 1990s, which was the world first space VLBI mission. ASTRO-G will consists of a huge synthetic aperture with diameter of 35,000 Km together with radio antennas in the ground. They will achieve the world highest angular resolution imaging by means of 43 GHz observation. This paper describes the advanced key technologies of ASTRO-G such as the 9 m deployable antenna with very accurate surface, the fast rest - to - rest attitude maneuver, and the precision orbit determination above NAVSTAR's orbits. These advance technologies lead ASTRO-G mission to the astronomical observation with the world highest angular resolution.

The solar sailing spacecraft is one of the promising propulsion systems for the future deep space exploration mission. Japan Aerospace Exploration Agency (JAXA) has been studying the spin solar sail spacecraft which has a squared-shape type solar sail. One of the most significant objective to control the satellite orbit of the spacecraft is to estimate the thrust force induced by the photon, namely to establish the acceleration model before the launch. In a view point to use this model in orbit, the calibration of the acceleration model and evaluation of the dynamics on orbit are also important issue. This paper presents the way to construct the acceleration model of the Solar Radiation Pressure (SRP) on ground, and the calibration and evaluation strategy for this model by using the on-orbit data.

深宇宙探査機との通信にはX-bandを用いることが定められている.しかし,帯域は既に混み合っておりX-bandの使用は徐々に困難になりつつある.そのような状況でKa-bandを高速伝送のために使用することは魅力で,今後の深宇宙探査には必須と言われている.宇宙航空研究開発機構の深宇宙局は64mを擁するが,X-bandまでの対応で鏡面精度などKa-bandには使用できない.そこで,より小型のアンテナをアレイ化し64mと等価な機能を持たせ,更にKa-bandへの対応を図る考えが生まれてきた.システムの実現性を検討するにあたり,受信信号の位相差推定の方法が鍵となる.本稿では,これまでに調査・研究してきた深宇宙通信用アレイ地上局のダウンリンク合成の手法について報告する.