Trajectories and attitudes of an asteroid sample return spacecraft "Hayabusa" during touchdowns on Itokawa

Paper number

IAC-06-E2.2.04

Author

Ms. Saika Aida, University of Tokyo, Japan

Coauthor

Dr. Junichiro Kawaguchi, Japan Aerospace Exploration Agency (JAXA)/ISAS, Japan

Year

2006

Abstract

On May 9th of 2003, the Institute of Space and Astronautical Science (ISAS) launched an asteroid sample return spacecraft called “HAYABUSA” (named after falcon). HAYABUSA aims for the world’s first sample return from an asteroid along with demonstrations of several space engineering technologies for sample-return. Samples from an asteroid provide us clues as to origins of planets and asteroids. After more than two years’ cruising phase by its ion engines, it arrived at ITOKAWA (Asteroid 25143) on September 12th of 2005. In the vicinity of the asteroid, HAYABUSA succeeded in detail asteroid observations and carried out five times’ descent operations including twice landing operation on ITOKAWA to obtain asteroid samples. Its earth return is expected around 2010. 

In this research, HAYABUSA’s trajectories and attitudes during its touchdowns are analyzed. Its motion on ITOKAWA has already been estimated from some sensor data for some extent. However, such estimates are based on limited sensor data among lots of those available. In addition, disturbances due to asteroid’s gravity, solar pressure and attitude fluctuations are not included. For some reasons, it is difficult to determine the spacecraft’s accurate status during its descents toward ITOKAWA: uncertainty of the asteroid’s mass and position, HAYABUSA’s unstable attitudes due to its reaction wheels’ troubles, and fragmentary data from navigation sensors. Therefore, the precise analysis of HAYABUSA’s touchdown behaviors is meaningful to utilize obtained data to evaluate touchdowns operation and investigate the asteroid deeply. Also, two bounds during the first touchdown are worth further analysis. From some sensor data, HAYABUSA was found to have bounded twice on ITOKAWA and stayed there for about thirty minutes. If trajectory and attitudes during bounds are revealed, detail investigations of asteroid’s surface and collision influence on the spacecraft become possible.

Here, most of available navigation sensor data are used to analyze HAYABUSA’s motion, such as range rate, distance data from LIDAR (Light Detection and Ranging), distance and attitude data from LRF (Laser Range Finder), and asteroid images from ONC (Optical Navigation Camera). Actually, they are not continuous because of spacecrafts’ position and telemetry condition. So the analysis was made by combining several kinds of this fragmentary sensor information. Furthermore, influence from asteroid’s gravity, solar pressure and attitude fluctuations are also considered to analyze HAYABUSA’s behaviors on ITOKAWA precisely.

Abstract document

IAC-06-E2.2.04.pdf

Manuscript document

IAC-06-E2.2.04.pdf (🔒 authorized access only).

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