Keith almost certainly had not been able to move his ship. Without propeller or emergency propulsion, she must be immobile under the ice, probably resting with the top of her sail against the underside. If she was not in the position reported by Keith, it must be because of drift due to currents and ice movement. She could not be far away. A few miles at most.
Manta began circling the datum, plotted at Cushing’s position as last reported, at slow speed, listening intently at the designated times for evidence of her presence. She made two complete circles two miles in diameter, then slowly changed the circle into an ever enlarging spiral, at maximum submergence depth.
Richardson was beginning to curse himself for not having selected a signal frequency at least twice as rapid when, at long last, the first faint beeps on the active echo-ranging sonar were heard. “He wasn’t on for long, only about three pings,” Jeff Norton reported, breathlessly. “I was right there in the sonar shack. It was right on time, but we didn’t get a good bearing because he quit too soon.”
“What’s the approximate direction?” Buck asked the question quietly, well aware that the primary requirement he had laid on his sonar crew had been to obtain the bearing of anything they heard. He had not directed Jeff to be in the sonar cubicle, but was not surprised that Manta’s communications officer, also sonar officer, had taken it on himself to be present at that critical instant. Buck’s astonishment was over the fact that an accurate true bearing had not been obtained.
“Southwest. But the three beeps came in so fast and were so faint that we hardly heard them. We could barely make them out on our scope. I’m awfully sorry, Captain. They definitely were from the southwest quadrant, but that’s all I’m really sure of.” Norton was clearly abashed by his failure, and by his skipper’s disapproval.
“Maybe he’s a lot farther away than we thought,” Rich muttered. “That would account for their faintness and missing a couple of pings.”
“Make your course southwest by grid,” Buck said to the OOD. “Increase speed to ten knots. In half an hour we’ll be five miles closer to him.” He consulted his watch. “The next signal is air blowing. It’s due in thirty-two minutes and will last ten seconds.”
Nothing was heard at the appointed time, nor at the next, twenty-seven minutes later, when the police whistle was scheduled. “We’ll continue as we are for the next period,” Buck said. “That will be another fifteen minutes, and we’ll be twelve miles nearer to him, if that was Keith we heard. Then we’ll circle again, if we don’t pick up anything.” Rich was nodding his approval. The next signal scheduled was the whistle again, but the one following that, in forty-three minutes, was to be echo-ranging at long scale, five pings at maximum gain.
It had been assumed that the pings of the active echo-ranging sonar would most likely have the greatest range, be heard from the greatest distance. On hearing them, Manta would send her own ping simultaneously with the termination of Cushing’s fifth, beamed in the direction from which that signal had been received, and start a stopwatch the instant the transmission was cut off. Cushing would have started a stopwatch with the cutoff of her own fifth ping, would stop it with receipt of Manta’s, and transmit a single short sixth ping to stop the Manta’s watch. Sound travels 1,600 yards per second in water. Since a round trip by sound was involved, the time in seconds on their stopwatches, multiplied by 800 yards, would give each submarine the approximate distance to the other. Once bearing and distance had been determined, closer approach would be facilitated by air blowing or the whistle, until finally the Cushing would “talk” the Manta into close proximity.
With forty-three minutes to wait, again Richardson’s impatience caused him to curse the long time delays he had built into the system, forgetting the purpose: to make their function less obvious to a chance listener. At minimum speed, Manta slowly described several complete circles in the water. She was as though suspended in space. Above, below, in all directions, nothing but water. Hundreds of feet above, a solid, impervious sheet of ice, twenty feet thick or more, but irregular, some places thinner than others. Below, thousands of feet below, the floor of the Arctic Ocean, slimy with the primordial ooze of aeons, split into two deep basins by the Lomonosov Ridge. North, east, south or west, whether on polar grid chart or any other, an area the size of Australia, or the United States. Manta: a tiny blob of life, of protoplasm, the size of a particle of dust, or sand, launched into an olympic-sized swimming pool in search of another dust-sized particle of life.
When there were only five minutes left to wait, Buck, Rich and Jeff Norton all crowded into Manta’s cramped sonar room, leaning over the operator’s shoulder, trying not to press into his needed working space. Norton held a stopwatch in his hand; the sonarman, Rich noted, held another. Rich and Buck stared at their wristwatches. “Half a minute,” said Buck. There was a twenty-four-hour clock attached to the sonar room bulkhead. It had been synchronized with the ship’s chronometers, as had the watches worn by Rich, Buck and Jeff Norton, and carefully reset to Greenwich Mean Time. It had been necessary to hold the clock mechanism so that the second hand would also be on GMT, and now the benefit was apparent. Keith would also have done this, would probably start his pings on the second.
Norton made a snapping motion with his forearm precisely as the twenty-four-hour clock reached sixteen hours, twenty-eight minutes and zero seconds, started his stopwatch. The second hand crawled slowly around its dial. Rich had stopped breathing. So had everyone else in the tiny compartment. The second hand was at seventeen when a spoke of light appeared on the dial of the sonar receiver. Norton stopped his watch, and simultaneously a faint but clearly recognizable ping filled the compartment.
“Seventeen seconds and a fraction,” said Norton. “Make it seventeen and a half.”
“Sh-h-h-h; don’t talk!” whispered Buck.
The spoke had vanished, leaving a decaying fluorescence where it had been on the tube. Then it reappeared, along with the amplified but still faint ping, reinforcing and brightening the same spoke, went out again, came on again. Rich could see the sonarman orienting his transmitter, softly fingering his hand keying button with his right hand, holding the stopwatch in his left. Simultaneously with the cessation of the fifth ping, and its light-spoke, he punched his hand key and started his stopwatch. A brilliant white spoke in the dark red sonar scope dial overlaid and dwarfed the dimmer one from the distant station. The receiver had been automatically blanked while the signal was being sent, but its reverberations filled the room the moment the key was lifted. One could hear the sound signal beaming out, traveling 1,600 yards per second toward the source of the five sequential incoming pings.
Jeff Norton had reset his watch, started it again at the same time as his sonarman, was figuring on a scrap of paper. “If Captain Leone had his watches zeroed on GMT the way we did,” he said, “and if he sent his first ping out exactly on the dot, he’s twenty-eight thousand yards away; fourteen miles.”