Presentation #115.04 in the session Modeling Physical Properties of NEOs.
An asteroid’s interior influences the response of its surface and shape to external forces, including meteoroid impacts, tidal effects, and solar radiation. However, asteroid interiors remain poorly understood. (433) Eros is a 20-km diameter near-Earth asteroid (NEA) with surface expressions that suggest a heavily fractured yet coherent interior, evidenced by craters formed with structural control and surface lineaments, which are a universal feature on asteroids of this size class. Furthermore, statistical models of the depletion of small craters with diameters D < 100 m suggests that impact-induced seismicity has refreshed the surface. However, it is unclear whether seismic shaking on fractured asteroids leads to global or regional resurfacing. Here we report on measurements of the degradation of the D > 200 m crater population in the vicinity of the 7.5 km-diameter Shoemaker crater. We find that craters with D > 500 m have depth-to-diameter ratios increasing with surface distance from the crater center, while craters with D < 500 m exhibit no such trend. We determine from these observations that a surface seismic wave produced by the Shoemaker-crater impact erased craters with D < 500 m up to 10 km away from the crater center, resurfacing ~20% of Eros’ surface. We will discuss the implications of our results for Eros’ seismic properties and interior, the age of the Shoemaker-crater forming event, and the delivery of small (< 1 km) S-type asteroids to near-Earth space.