One idea for a Mars habitat is to use a Martian cave or lava tube, and an inflatable air-lock was proposed by Caves of Mars Project for making use of such a structure.[10] The idea of living in lava tubes has been suggest later, noted for its potential to provide increased protection from radiation, temperature fluctuation, Martian sunlight, etc.[11] An advantage of living underground is that it avoids the need to create a radiation shield above ground.[12] Another idea is to use robots to construct the base in advance of human's arrival.[12]