Orbit and size distributions for asteroids temporarily captured by the EarthMoon system
Abstract
As a continuation of the work by Granvik et al. (2012), we expand the statistical treatment of Earth's temporarilycaptured natural satellites from temporarilycaptured orbiters (TCOs, i.e., objects which make at least one orbit around the Earth) to the newly redefined subpopulation of temporarilycaptured flybys (TCFs). TCFs are objects that while being gravitationally bound fail to make a complete orbit around the Earth while on a geocentric orbit, but nevertheless approach the Earth within its Hill radius. We follow the trajectories of massless test asteroids through the EarthMoon system and record the orbital characteristics of those that are temporarily captured. We then carry out a steadystate analysis utilizing the novel NEO population model by Granvik et al. (2016). We also investigate how an quadratic distribution at very small values of e_{☉} and i_{☉} affects the predicted population statistics of Earth's temporarilycaptured natural satellites. The steadystate population in both cases (constant and quadratic number distributions inside the e and i bins) is predicted to contain a slightly reduced number of metersized asteroids compared to the values of the previous paper. For the combined TCO/TCF population, we find the largest body constantly present on a geocentric orbit to be on the order of 80 cm in diameter. In the phase space, where the capture is possible, the capture efficiency of TCOs and TCFs is O(10^{6} 10^{4}) . We also find that kilometerscale asteroids are captured once every 10 Myr.
 Publication:

Icarus
 Pub Date:
 March 2017
 DOI:
 10.1016/j.icarus.2016.12.022
 Bibcode:
 2017Icar..285...83F