A drilling tactic to tackle indeterminable environment in lunar regolith sampling

Drilling and coring, as a main sampling method to acquire subsurface media, has been generally utilized in the extraterrestrial explorations. Due to the indeterminacy of the media beneath the planetary surface which is mainly caused by the various formation processes of planet, there will be great discrepancies of the drilling load between the different locations on the planet. Thus, how to identify the medium at the present drilling position and then regulate drilling strategy to guarantee the load in an acceptable region are critical to ensure the drilling reliability. In order to handle the indeterminable environment in planetary sampling, this paper presents a drilling tactic by way of recognizing the media drillability and controlling the penetrations per revolution (PPR) during drilling process. Theoretical and experimental research on interaction between drill and media during PPR controlled drilling is utilized to solve the relation between the PPR and drilling load. Finally, a drilling test of stratified media based on on-line recognition is carried out to verify the feasibility of the drilling tactic.