He sank into the contour couch, fired his roll jets, went into a turn.

The little disk hesitated, then began gliding toward the edge of the screen; but instead of disappearing, it bounced back out into the middle, like a tennis ball. For crying out loud!

“You bastard!” His voice was full of vile loathing.

Thanks to this latest gambit, he had almost gone into stationary orbit! Yet the fact remained: the light had not left the screen when he turned. That could mean only one thing: the light was artificial, generated by the screen itself. A screen, after all, is not a window. A manned spacecraft is equipped not with windows but with video scanners, with cameras mounted externally on the ship’s armored hull, together with a transformer for converting the electrical impulses into images on a cathode-ray tube. Was this just some screwy malfunction in the scanner? Had the same thing happened to Thomas’s and Wilmer’s? And what became of them, anyway?

No time to think about such things now. Better to flip on the emergency transmitter.

“Patrolship AMU-111 to Base,” he said. “AMU-111 to Base. Present reading: sector boundary one-zero-zero-nine-dash-one-zero-one-zero, equatorial zone. Have located trouble, am coming home…”

Pirx landed some six hours later, at which time a full-scale inquiry was launched, the investigation lasting an entire month. The first thing to be overhauled was the scanner. It was a new, improved model, installed on all the AMU ships the year before and until now having a perfect performance record. Not a single malfunction had been reported.

After laborious testing, the electronics engineers finally discovered the cause of the light. After several thousand hours of testing, the vacuum in the cathode-ray tube developed a leak, causing a loose charge to appear on the screen’s inner surface, observable on the outer screen as a milky-white spot.