For a planetary surface exploration, grinding and drilling equipment is one of the mo st important devices in geological observation of sampled rocks. However, the equipment can't be directly applied for works in the space. More spe cifically, the weight of drilling and grinding mac nines generally used on the Earth is so heavy, an d they need lubricant. Therefore it is difficult to use them in the space. In this paper, we analyze t ransient process of destroyed surface of rocks. Especially, we focus on contact points between sampled rocks and the top of a horn. Through the analysis, we can suggest that a ultra sonic based device is effective to implement drilling and grinding of rocks in the space. The analysis suggests that a ultra sonic based device is effective to realize drilling and grinding of rocks in the space.