Engineering topics

Farinella, P.

Publications and source records attributed to Farinella, P..

4 records

NASA NTRS1993

Deviations from the straight line: Bumps (and grinds) in the collisionally evolved size distribution of asteroids

Dohnanyi established that the size distribution of a collisionally relaxed population is a power-law with a -3.5 slope (incremental diameter), provided that: (1) collisional parameters are independent of size and (2) there is no lower limit on the population size for shattering impacts. In the course of studying collisional effects over a wide range of asteroid sizes (cm up to hundreds of km range), we have investigated the consequences of relaxing the second condition, while maintaining the first one.

Davis, D. R.↗

NASA NTRS1992

The collisional lifetime of asteroid 951 Gaspra

We estimate the collisional lifetime of asteroid 951 Gaspra, the first target of an asteroid encounter by an interplanetary space probe. Plausible values range between 10 exp 8 and a few times 10 exp 9 yr, mainly depending on the impact strength of the body and the existing population of sub-km sized projectiles - both quantities for which only indirect observational evidence is currently available. Thus, Gaspra is most likely to be a fragment from a larger asteroid that was shattered in the past. Moreover, unless its material is very resistant to impact break-up (such as iron), Gaspra's surface is among the youngest extraterrestrial surfaces seen in the solar system (apart from active comet nuclei). However, better data on the abundance of very small asteroids are needed to determine its age in a more reliable way.

Farinella, P.↗

NASA NTRS1992

Asteroid collisional evolution - An integrated model for the evolution of asteroid rotation rates

A comprehensive model for the changes in asteroid spin rates due to large collisions was developed by combining the theoretical results of Cellino et al. (1990) with previously published work on spin rate changes for cratering impacts (Harris, 1979; Dobrovolskis and Burns, 1984). The spin change algorithm, when incorporated into an existing simulation of collisional effects on asteroid sizes, produced an integrated model for studying the simultaneous evolution of asteroid sizes and spin rates over the solar system history. As a result of an analysis of 32 collisional scenarios with regard to the change in the spin rate as a function of asteroid size, it is concluded that the spin rates of all asteroids, except possibly the largest ones, have been significantly altered by collisions over the solar system history and that, in general, shattering impacts are much more important than cratering events in changing the spin of asteroids.

Farinella, P.↗

NASA NTRS1986

Catastrophic disruption of asteriods and satellites; Proceedings of the International Workshop, Pisa, Italy, July 30-August 2, 1985

Theoretical, numerical, and experimental investigations of the violent disruption of asteroids or planetary satellites are discussed in reviews and reports. Topics examined include acceleration techniques and results of experiments simulating catastrophic fragmentation events; laboratory simulations of catastrophic impact; scaling laws for the catastrophic collisions of asteroids; asteroid collisional history, the origin of the Hirayama families, and disruption of small satellites; and the implications of the inferred compositions of a steroids for their collisional evolution. Diagrams, graphs, tables, and a summary of the discussion at the workshop are provided.

Davis, D. R.↗