 A-block, the southern module, contains the radio room and communications hub, medical facility, darkroom, various research project offices, leader's office, two physics labs, wet lab, store-rooms, another laundry, and accommodation units.The modules are linked by single-story connections that also serve as entrances with stairways down to the surface 4m below the base.Each link contains an entrance hall with two sets of doors (creating a rudimentary 'air-lock' to prevent excessive cooling when entering and exiting the base) as well as a change-room, ablution facility and electronic distribution boards.