Effects of Earth encounters on the physical properties of near-earth objects

Abstract

The effects of Earth encounters on the physical properties of near-Earth objects (NEOs) have been shown to be significant factors in their evolution. Previous studies have examined the effects of these encounters on reflectance spectra based on observational measurements, and effects such as spin state and shape changes have been studied for specific asteroids and through simulation. In this project, an automated light-curve fitting routine was developed to support data reduction in an ongoing NEO survey. Additionally, data from previous NEO surveys were used to support simulation results by showing differences between encounter and non-encounter populations' rotational frequency distributions. These results demonstrate that Earth encounters have an effect on asteroid rotation by increasing the overall frequency as well as causing a wider distribution of frequencies when compared to non-encounter populations of NEOs. These data were, however, unable to show any effect on asteroid shape brought on by planetary encounters. A frequency comparison between NEOs that likely had Earth encounters to main-belt-equivalent asteroids did not show the same encounter effect, though the 'equivalent' asteroid populations were likely affected by a size/spin-rate bias.