I have recently updated my data base of asteroid rotation rates. The new file includes reliable rotation periods of 688 asteroids. Most of the trends reported earlier remain apparent in the expanded data set. In this paper I concentrate on the rotation statistics of the smallest asteroids, D < 10 km. The main conclusion is that there are no asteroids rotating fast enough that they are in a state of tension, that is, that they would fly apart if they had no tensile strength. In earlier studies, it was not clear whether this is because small asteroids indeed have no tensile strength, or only because such fast rotation is statistically improbable enough that one would not expect to find an end-member of the distribution spinning faster than that limit. A histogram of the spin distribution of the smallest asteroids of the present expanded data set indicates that the distribution at the fast end of rotation frequency is in fact truncated, thus implying that even these small asteroids have no tensile strength, that is, they are not monolithic, and may be "rubble piles."
Lunar and Planetary Science Conference
- Pub Date:
- March 1996