By the end of the day Hunt's mind was in a whirl. New information was coming in faster than he could digest it. The questions in his head were multiplying at a rate a thousand times faster than they could ever be answered. The riddle of the Ganymean spaceship grew more intriguing with every new revelation, but at the back of it there was still the Lunarian problem unresolved. He needed time to stand back and think, to put his mental house in order and sort the jumble into related thoughts that would slot into labeled boxes in his mind. Then he would be able to see better which question depended on what, and which needed to be tackled first. But the jumble was piling up faster than he could pick up the pieces.

The banter and laughter in the mess after the evening meal soon became intolerable. Alone in his room, he found the walls claustrophobic. For a while he walked the deserted corridors between the domes and buildings. They were oppressive; he had lived in metal cans for too long. Eventually he found himself in the control tower dome, staring out into the incandescent gray wall that was produced by the floodlights around the base soaking through the methane-ammonia fog of the Ganymedean night. After a while even the presence of the duty controller, his face etched out against the darkness by the glow from his console, became an intrusion. Hunt stopped by the console on his way to the stairwell.

"Check me out for surface access."

The duty controller looked across at him. "You're going outside?"

"I need some air."

The controller brought one of his screens to life. "You are who, please?"

"Hunt. Dr. V. Hunt."

"ID?"

"730289 C/EX4."

The controller logged the details, then checked the time and keyed it in.

"Report in by radio in one hour's time if you're not back. Keep a receiver channel open permanently on 24.328 megahertz."

"Will do," Hunt acknowledged. "Good night."

"Night."

The controller watched Hunt disappear toward the floor below, shrugged to himself, and automatically scanned the displays in front of him. It was going to be a quiet night.

In the surface access anteroom on the ground level, Hunt selected a suit from the row of lockers along the right-hand wall. A few minutes later, suited up and with his helmet secured, he walked to the airlock, keyed his name and ID code into the terminal by the gate, and waited a couple of seconds for the inner door to slide open.