"Mole," he said.

An articulated metal arm unfolded from the nose of the Mole; a camera fixed on him.

"The sky looked a bit more red today."

The transfer of nodules was not slowed but the small lens stayed steady. A red lamp somewhere on the prow of the machine began to pulse. "Please input spectrometer data."

"I don't know what you're talking about," Rees said. "And even if I did, I haven't got a 'spectrometer.' "

"Please quantify input data."

"I still don't understand," Rees said patiently.

For further seconds the machine studied him. "How red is the sky?"

Rees opened his mouth — and hesitated, stuck for words. "I don't know. Red. Darker. Not as dark as blood."

The lens lit up with a scarlet glow. "Please calibrate."

Rees imagined himself to be staring into the sky. "No, not as bright as that."

The glow scaled through a tight spectrum, through crimson to a muddy blood color.

"Back a little," Rees said. "…There. That's it, I think."

The lens darkened. The lamp on the prow, still scarlet, began to glow steady and bright. Rees was reminded of the warning light on the winch equipment and felt his flesh crawl under its blanket of weight. "Mole. What does that light mean?"

"Warning," it said in its flat voice. "Deterioration of environment life-threatening. Access to support equipment recommended."

Rees understood "threatening," but what did the rest of it mean? What support equipment? "Damn you, Mole, what are we supposed to do?"

But the Mole had no reply; patiently it continued to unload its pannier.

Rees watched, thoughts racing. The events of the last few shifts came like pieces of a puzzle to the surface of his mind.