The orbit stability and insertion strategy around an small asteroid

Recent small bodies missions have intensively studied the orbit evolution around an irregular shaped bodies such as the comets and the asteroids. One important result obtained indicates the instability occurs when the orbit is direct and the orbital period is identical to that of the body spin period. This trivial instability was well analyzed so far and the criterion evaluating the associated unstable band width in the body spin period domain was developed. However, the numerical experiment results indicate there are still large discrepancies that cannot be accounted by such trivial resonance characteristics. This paper deals with those subjects and attempts to give the new mechanism for them.