Evacuation method and outgassing rate of a lunar regolith simulant for deep drilling tests

A novel method to evacuate large bins of lunar regolith simulant for deep drilling tests was proposed in the current work. This method can be used to simulate a vacuous lunar regolith environment to a maximum penetration depth of 2 m. An experimental apparatus was built and is composed of a vacuum chamber, a specially designed regolith container and a vacuum pumping system. A pressure on the order of 10 Pa could be reached with the 4.3 m ³ vacuum chamber when compacted lunar regolith simulant with a volume of 0.4 m ³ was loaded. A theoretical model to predict vacuum degree was proposed basing on the viscous flow theory. Evacuation experiments with or without lunar regolith simulant inside the chamber were performed and the outgassing properties of lunar regolith simulant was experimentally studied. The results show that the outgassing rate of the lunar regolith simulant was about 10 ⁷ times to that of the electro-polished stainless-steel.