Unfortunately, this had to be a visual search. The drawing-board boys had designed the picket buoys so they would not be detected, and thoughtfully made them self-destroying in case they were. If anywhere near, a submarine would be recorded, and the under-ice warning system had actually worked against their own submarines. But the picket buoys in this sector, one by one, had died without a warning sound except, as scuttlebutt would have it, a toothy crunch.
"This pack ice has changed," Barney's voice muttered.
Barney and the Murderer had been one of the diving teams out there when a submarine ejected the buoys beneath the polar ice. A buoy would squirt from a torpedo tube. When the non-magnetic float struck the underside of the ice, metal rods clutched upward like the legs of a spider clinging to the ice. A thread-like cable lowered the tiny instrument capsule into the depths. The capsule's small size was intended to foil typical mine detection sonar, while the float was supposed to merge with irregularities of sonic reflection on the underside of the ice. Some admiral had even ordered the floats painted white, but they still cut off light and appeared dark from beneath the ice.
After the divers had melted a quick hole through two or three feet of pack ice and extended the whip-like aerial into the polar air, headquarters could keep track of the drifting buoy's location. Intermittently, for the classified number of years the batteries were supposed to last, each buoy would broadcast its own identification code, only coming through with a high wattage warning when its instrument capsule in the depths of the Arctic Ocean was awakened. The joker here, the Murderer thought, was that the aerials might be hard to see, but any simple fool could make himself a radio location finder. Live buoys could be hunted from the surface ice.
"How dry I am," Barney's voice croaked unmusically, "how dry I be, nobody knows—nobody cares—"
Now the white underside of the ice drooped in downward bulges, indicating thicker masses of old ice that had been frozen into the pack. The Murderer saw the gray outline of driftwood entombed in this old ice.
"Drift ice from the Siberian rivers," Barney croaked. "When we planted the picket buoys, our sector didn't have any of this."
The Murderer looked down at his instruments, preparing to change course.
"My God, look!" Barney's voice croaked, and his black rubber arm pointed upward.