The roof was clear. Rico rose and jogged over to the building's southern face. Shank followed. They pulled black climbing ropes from their harnesses and thrust K-2 autopitons against the low ferrocrete wall rising like a rim from around the edge of the roof. The cryomag tips of the K-2s burned holes straight into the crete. Secondary probes then extended outward from the pitons' main shaft, embedding the devices in the crete.