Burrowing through anything other than loosely packed soil by necessity creates a larger volume of tailings than the original rock which has to be constantly cle

Burrowing through anything other than loosely packed soil by necessity creates a larger volume of tailings than the original rock which has to be constantly cleared to the surface. Packing a useful science lab into a robot small enough to burrow through loose top soil on Venus (which may or may not be very deep or even really exist since we know very little about the surface of Venus) would be difficult to impossible. Second in the case of going through hard rock via drilling, the drill teeth have a limited life span and would be extremely difficult to replace in an automated way.