Keep Investigating

When they lay down in their tent that night, the wind outside was quieter than it had been over the past few days.

Harry listened to the faint sounds coming from the distant ice sheet. Beneath him, the low-frequency vibration in the ground continued through the night, pulsing every dozen seconds or so like a vast, slow heart beating deep below.

The next morning, when he stepped out of the tent, the sky was clearer than the day before.

Most of the clouds had parted. Anaka had already heated a kettle of water outside the tent, and they ate a simple breakfast of compressed biscuits and hot tea.

After breakfast, they did not hurry to leave the plateau. Instead, they surveyed the surrounding area more thoroughly.

Harry traced the passage between the central and eastern nodes with his senses. It connected two cavities, with energy flowing slowly back and forth between them. The frequency was very low and the amplitude small, but the direction of the flow was clear.

It gathered from the eastern auxiliary node toward the central main node, then spread south and southeast from the main node before joining the signal path to Cape Relay Point.

"The eastern auxiliary node is feeding energy to the main node," Harry told Isabelle as he stood. "The main node mixes that energy with its own signal, then transmits it south. The chain as a whole runs one way: from the auxiliary node to the main node, then to the relay point."

"If the auxiliary node stopped feeding it energy, would the main node's signal weaken?" Isabelle asked.

"Possibly. But the auxiliary node's signal is still going strong. There's no sign of it weakening." Harry brushed the dirt from his hands. "Both nodes are running. The chain is intact."

At the