Accumulation of soil: After the arm has been lowered, the rover pushes the inlet through the
soil at a shallow angle (here 15 degree), as shallow angles have been proven to
result in low excavation forces. Both outlet ports are blocked by the spring-loaded gates and the
vibration motor is operating. After a sufficient time, indicated by the front
area of the inlet being filled with regolith or an increasing surcharge mass, the
vibration motor stops, and the mechanism
moves into position 2 - the pre-separation phase.