Orbit Analysis of HAYABUSA around Asteroid ITOKAWA
- Paper number
IAC-06-C1.5.09
- Author
Mr. Hitoshi Ikeda, Kyushu University, Japan
- Coauthor
Mr. Takashi Kominato, Japan
- Coauthor
Mr. Masatoshi Matsuoka, Japan
- Coauthor
Dr. Makoto Yoshikawa, Japan Aerospace Exploration Agency (JAXA), Japan
- Year
2006
- Abstract
On 12 September 2005, HAYABUSA (MUSES-C) spacecraft, which was launched by M-V rocket on 9 May 2003, arrived at near-Earth asteroid (25143) Itokawa, and made various kinds of observations while hovering around the asteroid. In this paper we mention about the motion of HAYABUSA around Itokawa, especially from the point of solar radiation pressure and gravity of Itokawa. There are 4 major tasks of space engineering in this mission: electric propulsion, autonomous navigation, sample collection from the asteroid’s surface, and reentry into the Earth’s atmosphere from interplanetary orbit. At first HAYABUSA hovered around “Gate position” at an altitude of about 20 km from the Itokawa’s surface. After observing the asteroid for a while, HAYABUSA descended from Gate position to “Home Position” at an altitude of about 7 km from the itokawa’s surface. Since then HAYABUSA made detailed observations of Itokawa and tried to touch down on its surface. On 3 October 2005, one of the reaction wheels had a trouble, and the attitude control was done by the chemical thrusters from then on. Unfortunately the chemical thrusters generated unintended minute orbital acceleration, so it became difficult to estimate the precise solar radiation pressure and the gravitational acceleration by Itokawa. For such reasons, we estimated the solar radiation pressure and the gravitational acceleration by Itokawa by using the range and Doppler data from 12 September to 2 October 2005 (reaction wheels were well-behaved in this term). We assume a simple physical model that HAYABUSA is affected by only solar radiation pressure and gravity of Itokawa (point mass model), and then fit the Doppler data directly by using least-square method. When spacecraft is located at Gate position, the magnitude of gravitational acceleration by Itokawa is only a few percent of the magnitude of the acceleration by the solar radiation pressure. Therefore, we estimated the solar radiation pressure from the Doppler data obtained at Gate position, and Itokawa’s mass from the Doppler data obtained at Home position. As the results of analysis, we estimated solar radiation pressure with an uncertainly of 2%, and gravity of Itokawa with an uncertainly of 15%.
- Abstract document
- Manuscript document
IAC-06-C1.5.09.pdf (🔒 authorized access only).
To get the manuscript, please contact IAF Secretariat.