What were you?
When you first start out as a sonar technician and put the hydrophone headphones on, all you hear is a discombobulated world of more than a thousand marine sounds, both artificial and natural. But as you progress through your training, it becomes easy to differentiate between the artificial sounds of a submarine or the natural sounds of marine-life. Soon, you can train your ears to differentiate between individual marine life sounds and artificial sounds. After more than three thousand hours at the sonar station, it was unusual to find anything completely alien to her ears.
She shook her head. Frustrated, she continued to search for the strange sound and the second submarine.
Then she heard the alien sound again.
She smiled.
You’ve come back, have you?
This time she was certain it was artificial.
It was man-made, it must have been. No animal sounds like that. She dithered.
Is it man-made?
Do I interrupt the commander, yet?
She waited. Silent as stone and motionless. She checked the log, four minutes passed, and still, she waited. Nothing. She cursed herself. She tried to breathe silently and strained to listen over the sound of the blood slamming in her eardrums. She slowed her breathing, in a technique she’d picked up in yoga as a means of slowing her heart rate, reducing her blood pressure, and being more in the present.
Then there it was. Unmistakable. Louder this time.
She turned to the tech next to her just as he said it. “Did you get that?”
“What is that?” she asked, excited now.
“I’ve no idea,” he replied. “but we’d better tell the Chief.”
“I’ll start plotting it,” Belinda said, hopeful of an opportunity to prove herself again.
Callaghan squelched the controls on her sonar station to hone in on the heading given by the mysterious sound. The monitor she primarily used was a computer-generated visual representation of the soundtrack on the feed from the sensors. It produced a three-dimensional representation similar to modern radar.
Alternatively, she could switch to an old-fashioned waterfall type screen, which graphed a horizontal measure of bearing, against a vertical increment of frequency. It was this type of device that she had trained on originally, and it was this one she fell back on when exploring the murky depths that the computer algorithms couldn’t diagnose.
The signal she searched was shallow. Very shallow. Which made it harder to detect and distinguish between the other sounds.
To a sonar technician, depth is a friend. The deeper the signal, the less likely it is to be polluted by interference caused by sea life or debris. If you’re lucky, the sound might travel through a deep sound channel — the perfect conditions for sound propagation.
In this case, the sound was in shallow water. Possibly even a hundred feet. The sound image was difficult to make out because the wavelength was being bounced around through the underwater valley through which they were currently traveling.
She let her eyes drift along in time with the leading edge of the waterfall display. She pushed the gain all the way to the maximum. Static and mechanical noise from the ship built a cacophony of baseline noise in her headphones. Winding it back just a touch, she found the noise again — this time with a heading, and with a matching slug shape on the waterfall readout. A rush of adrenaline gushed from her kidneys straight down her spine — shooting into her gut like white-hot fire.
Oh my God! It’s a submarine!
She hit the print detail button and continued scrambling her gear to get a precise reading. As it printed, the Chief Sonar operator reached over and tore off the glossy paper from beside her. With an encouraging pat on the shoulder, he indicated he was taking it to the commander, who was as yet unaware of the situation.
The heading was 225 degrees southwest, at a distance of approximately 7,000 feet. It was coming together for her. She was on this thing.
She took a deep breath to steady herself.
Focus.
Whose is it?
She immediately knew what she was listening to. She set the audio scanner to 60 Hz and listened, waiting. A vessel runs its electronics on alternating current at a set frequency, measured in Hertz. If the electronics on that ship become waterlogged, are improperly mounted against the hull, or damaged they emit the sound of that particular operating current into the ocean.
Ships the world over use a standardized current for their electronics — 50 Hz. There was, however, one nation that used a different current for their entire fleet of submarines run on a 60 Hz system.
The United States.
Belinda’s heart sank. She was looking at a stricken United States submarine. Stranded deep in the ocean and most probably damaged. Her throat tightened, and the moisture evaporated from her mouth. She stared at the worm which was now perfectly focused on her monitor.
Commander Bower stared at the two enlarged images of the Orcasub pilot and copilot. Their faces were distorted by the glass dome, but he hoped someone from one of the digital intelligence teams, back stateside, might be able to improve the image and then identify them.
He put the two images back down next to the navigation table and turned his focus to the downward-facing digital dome.
His eyes swept the surreal environment beneath the Omega Deep, taking in the deep trench, sharp and vertical edges of the sea valley, and finally fixing on the glowing light of the Orcasub. It was moving at a spritely twelve knots — its two occupants, apparently unaware of the massive submarine’s overhead pursuit.
Behind the visual dome, the Omega Deep’s pilot and copilot maintained a course just fifty feet behind and twenty feet above the Orcasub. The water was crystal clear, and the light from the Orcasub was plentiful enough to navigate by.
They followed the Orcasub, matching it as it banked to the right and rose to a hundred and fifty feet in order to enter a smaller tributary valley.
The pilot said, “Requesting approval to follow, sir?”
To the navigation officer, Bower asked, “Does LIDAR mapping confirm there’s enough room to pursue?”
The navigation officer nodded. “The valley is two hundred feet wide and peaks at a depth of fifty feet. If we run out of room, we can ascend and maintain clearance below our keel.”
Bower firmly set his jaw, his brown eyes focused. “All right. Pilot, you have approval to follow them in.” Then, turning to the navigation officer, said, “Mr. Browning, I’m counting on you to ensure we maintain a safe distance from the seascape. The last thing I want to do is explain to Uncle Sam why I just damaged his 30-billion-dollar piece of hardware.”
“Understood, sir.”
The Omega Deep climbed as it trailed the Orcasub into the narrower underwater tributary. The valley’s bottom rose rapidly. While the massive Omega Deep followed, keeping near the top of the valley, the Orcasub trailed along the ancient river.
Unexpectedly, in sudden, rapid ascent, it climbed at a near-vertical angle. Like a modern fighter jet in a balls-out, full effort blast, it powered into what appeared to be an ancient waterfall.
Commander Bower grinned as they pursued the yellow sub from a distance. Whoever was at the controls, piloting the Orcasub, knew what they were doing. Not only did they appear to move without hesitation, but they were also following the line of the ancient tributary just above the seabed. It reminded him of an attack helicopter racing below Viet Cong radar along a valley floor.