小行星433-Eros土壤厚度分布和表面强度估计

Estimation on the regolith thickness distribution and the surface strength of 433-Eros

根据Near探测器飞跃433-Eros小行星时观测得到的重力数据分析,在433-Eros小行星外侧边缘处存在轻微的负布格异常现象(Garmier et al.,2002).本文借鉴Geissler在Ida小行星上的结论,认为该异常是由其表面撞击过程中高速溅射物聚集效应产生的.文中计算表明:在合理范围内调整模型Z参数和强度P参数,Eros上高速溅射物将聚集在其表面边缘外侧,这与Geissler实验结论是一致的.计算结果同时表明433-Eros行星表面的土壤层厚度以及布格异常数值与433-Eros表面物质的强度相关,通过这一相关性,可以约束433-Eros表面的强度参数P及其土壤层分布.取Z模型中Z参数为2.5时,我们估计出Eros表面物质的强度值大约为106Pa,土壤层的堆积情况是全球平均堆积厚度约为30 m,Eros边缘末端处厚度为50 m.

The Bouguer anomalies over the surface of asteroid 433-Eros indicate that there is a slight deficit of mass located at the ends of the asteroid（ Garmier et al.,2002）. We interpret this deficit as an over-accumulation of high-velocity ejecta at these locations,due to the high-velocity ejecta accumulation on the body. We show that no matter how to adjust the parameter P and Z in the reasonable range,the high-velocity ejecta would accumulate at the end of the asteroid which is in accordance with the result of Geissler＇s study on Ida. And we verify that the thickness of the deposits（ and so the Bouguer anomaly） is related to the strength of the bulk material of the asteroid,so we can use this correlation to estimate the strength parameter and regolith thickness distribution on the surface of Eros-433. When we use Z = 2. 5,the results show that the strength of Eros surface is about 106 Pa and the global regolith thickness is about 30 meters while the preferential redepositon on the asteroid ends is about 50 meters.