The Martian - Isaidub

Out of fear and awe, the crew voted — a small, shaky democratic ritual transmitted to Earth: should they attempt to decode by feeding the phrase back? The vote was unanimous. They would not mute what listened to them. Two nights later, under the frozen light, the probe emitted “Isaidub” in a controlled pattern and recorded what came back. The return signal unfolded like a conversation not with a singular entity but with a system: phase shifts that translated into graphs, graphs that translated into sequences of images. The team called it a lexicon. It was more a map: coordinates and modulatory keys that suggested a network of hollowed caverns stretching for miles, carved by a process that had the patience of glaciers and the intent of craftsmen.