Speakers
Description
Only a handful of proxy strength measures are available for decameter and smaller NEAs. One data source which can address the question of meter-sized NEO structural strength is the recent release of over 800 light curves for bolides detected by US Government sensors since 1988. A subset of these events (about 270) also have trajectory, speed and height at peak brightness information. These data, together with the recently available lightcurves, afford the possibility of applying ablation modelling to infer strength based on fragmentation heights. Among these 270 bolides with photometric and metric information, we found a dozen events which stood out from the rest of the population in that they reached peak brightness at very high altitudes (>50 km) and had very low entry speeds. Among these dozen, two were clearly on cometary-type orbits, while the remainder were on asteroidal orbits. Of the asteroidal bodies, all showed global strengths of order ~100 kPa or lower. Here we report on ablation modelling to assess the potential structural makeup of these bodies together with their potential escape regions from the main belt based on current orbits. Our modelling suggests these meteoroids are very weak and potentially rubble pile structures. They comprise ~5% of all meter-sized Earth impactors detected by the USG sensors.
