Yokohama National University Faculty of Environment Information Sciences
Yokohama National University Graduate School of Environment and Information Sciences
Yokohama National University Graduate School of Environment and Information Sciences
出版者
宇宙航空研究開発機構宇宙科学研究本部
出版者（英）
Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA/ISAS)
雑誌名
第15回アストロダイナミクスシンポジウム講演後刷り集 2005
雑誌名(英)
Proceedings of 15th Workshop on JAXA Astrodynamics and Flight Mechanics
Exploration to asteroid in the solar system has been focused by space scientists because asteroids have different features from large planets. The target asteroid is usually not specified. Calculation of trajectory to an asteroid is also interest problem for space engineers because it is necessary to select a target asteroid and to design trajectory simultaneously. The purpose of this paper is to provide the technical information for the selection of a target from many asteroids. To simplify the problem, the following assumptions are used in this paper. The target asteroid's orbit is elliptic in the earth's orbital plane. The explorer is under influence of only the gravitational acceleration of the sun. Impulse approximation adopts the calculation in this paper. The minimum fuel trajectories are selected to minimize the summation of Delta Vs at the departure from the earth and at the arrival to the asteroid. Orbital energy is given as a function of semi-major axis, thus the relation between eccentricity and Delta V are shown numerically. The results show that 'critical eccentricity' is a significant parameter. Critical eccentricity, e(sub CR), is defined as an eccentricity when the elliptic orbit tangents the circular orbit. When the eccentricity is less than the critical eccentricity, two orbits do not across each other. The total Delta V also depends on the relative position of the earth and the target asteroid at the departure time of explorer. The minimum Delta V at the best departure time can be calculated for given eccentricity. While the eccentricity is less than e(sub CR), the value of minimum Delta V does not depend on eccentricity largely. The other hand, in the region of eccentricity is larger than e(sub CR), the value of minimum Delta V is increasing as the eccentricity is increasing. Thus it can be said that the better candidates for searching are asteroids whose eccentricities are less than e(sub CR). However, the value of minimum Delta V changes depending on the departure time in the case of small eccentricity. It means that large additional Delta V is necessary when the departure time is delayed by some reason. Finally, it is concluded that the best candidate is an asteroid whose eccentricity is e(sub CR).
Eccentricity of an asteroid's orbit for the minimum fuel exploration
