instead dubbed “Autonomous Underwater Data Recovery Vehicle.” A state-of-the-art self-propelled sensing unit, Audry contained a side-scan sonar, a magnetometer, and a sub-bottom profiler, all packaged into a torpedo-shaped casing that was simply dropped over the side of the ship. The combined sensors provided the capability to seismically map the seafloor for natural or man-made objects, as well as peer beneath the seabed for buried anomalies. The fish-shaped sensor could skim above the seafloor at a depth of five thousand feet, propelled by a powerful battery pack, which eliminated the need for a lengthy and cumbersome tow cable.
As the Sea Rover approached the search area, Dirk assisted Sum* mer in downloading the search parameters into Audry's navigatiot| computer.
“We'll use the side-scan sonar only so we can run wider search! lanes,” Dirk instructed. “If the I-411 is out there, we ought to be able| to see her sitting up off the bottom.”
“How large a search grid?” Summer asked as she tapped instructions into a laptop computer.
“We have only a rough fix from the Swordfish, so we'll likely have plenty of ground to cover. Let's set the initial search grid at five by five miles.”
“That's still within range of the data relay system. I'll do a quick systems check, then we should be ready to deploy.”
As Audry's software program was reconfigured, the Sea Rover dropped a pair of self-positioning transducers into the water at either end of the search grid. With built-in GPS satellite receivers, the transducers would relay underwater navigational guidance to Audry that would enable the vehicle to run a precise back-and-forth grid pattern several dozen feet above the seafloor. Audry in return would upload packets of data to the transducers at periodic intervals, detailing the sonar's search results.
“Ready with the winch,” a crewman's voice shouted.
Dirk gave the thumbs-up signal, then he and Summer watched as the eight-foot-long, lemon-colored survey vehicle was lifted out of a rack on the rear deck and lowered over the side railing into the water. A white plume of spray from the tail indicated that Audry's small propeller was churning, then the grips from the winch were let go. Lunging like a thoroughbred out of the gates at Santa Anita, the torpedo- shaped vehicle surged down the length of the Sea Rover before submerging under a wave and into the depths.
“Audry has some legs on her,” Dirk noted.
“She's undergone a recent modification and is now capable of running her surveys at a speed of 9 knots.”
“At that pace, she may not give me much time for my favorite part of the search.”
“What's that?” Summer asked, a quizzical look on her face.
“Why, having a beer and a peanut butter sandwich while waiting for the results,” he grinned.
While Audry motored back and forth down neat imaginary lanes a hundred feet above the seafloor, Summer monitored the vehicle's progress on a computer display aboard the Sea Rover. At twenty-minute intervals, a digital data upload was wirelessly transmitted from the transducers to the ship, where further electronic processing converted the binary data bits into a graphical image of the sonar readings. Dirk and Summer took turns scanning through the images of the seabed, searching for linear or angular shapes that might signify a shipwreck.
“Looks like a pepperoni pizza,” Dirk mused as he studied the rock-strewn bottom, seeing odd-shaped boulders that threw off round shadows against the flat backdrop.
“Don't tell me you're hungry again,” Summer replied, shaking her head.
“No, but I bet Audry is. What kind of mileage does she get on a tank of battery acid?”
“The batteries for high-speed operation are only designed to last eight hours. We never run her past seven hours, though, to make sure she has enough juice to propel herself from deep water to the surface. She's been in the water now about six hours,” Summer said, glancing at her watch, “so we'll need to call her back for a battery change within the next hour.”
A pop-up window suddenly appeared on the computer screen, signaling receipt of the latest data upload.
“Only one more file to go till we've covered the first search box,” remarked, standing up from his computer console chair and stretching his arms. “I better identify the boundaries of the next search grid. Can you take a look at the next data feed?”
“Sure, I'll just go ahead and find it for you,” Summer joked as she took his seat and typed a string of commands into the keyboard. A new set of images appeared on the screen, a five-hundred-meter swath of ocean bottom scrolling from top to bottom, which resembled the aerial view of a hard-packed dirt road through the desert. Summer had adjusted the color images in a golden hue so that the occasional rock or mound on the bottom cast a brown-tinted shadow. She studied the monitor closely, watching the same monotonous sea bottom glide by. Suddenly, a dark smudge appeared on the top right side of the screen and grew larger as the readings rolled down. The smudge was a shadow, she quickly realized, created by a long tubular shape that was crisply defined in a dark shade of russet.
“My word, there it is!” she squealed, surprised at her own voice.
A small crowd gathered around Summer as she replayed the image at a slow speed several times. The distinct outline of a submarine was clearly evident, complete with an upright conning tower that cast a long shadow to one side. The image roughened near one end of the vessel, but Summer measured the object at well over three hundred feet.
“Sure looks like a submarine, and a big one,” she said, not sure whether to trust her eyes.
“That's our baby,” Dirk said confidently. “Looks just like the image we scanned of the I-403.”
“Nice work, Summer,” Morgan offered as he approached the commotion.
“Thanks, Captain, but Audry did all the work. We better pull her aboard before she makes her way to China.”
Summer typed in a new handful of commands and a signal was relayed from the transducers to the underwater vehicle. In a matter or seconds, Audry terminated the search pattern and propelled herself upward, where she broke the water's surface a quarter mile away from the Sea Rover. Summer, Dirk, and Morgan watched as a retrieval team in a rubber Zodiac scooted over to the idling yellow sensor and clamped it to the gunwale. The team slowly made their way back alongside the research ship, where Audry was hoisted out of the water and replaced in her cradle on the stern deck.
As the second of the two transducers was hoisted back aboard, Dirk admired a large exploration vessel that was inching past them a mile away, a Japanese flag wafting off its high bow platform.
“Cable-laying ship,” Morgan said, catching Dirk's gaze. “She followed us out of the Inland Sea.”
“She's a beauty. Doesn't appear to be in any hurry,” Dirk said, noting the vessel's slow speed.
“Must be operating under a daily billing rate contract,” Morgan laughed, then turned his attention to ensuring the transducers were securely aboard.
“Maybe,” Dirk replied, smiling, but a vague caution tugged at the recesses of his mind. He shook off the feeling and refocused his thoughts on the task at hand. It was time to take a look. at the I-411 up close and personal.
The crew of the Sea Rover wasted no time in making preparations to investigate the submerged target. Captain Morgan brought the ship around and positioned it directly above the target, using the GPS coordinates identified by Audry. Computerized side thrusters on the research vessel were activated and the Sea Rover was parked in place, constantly self-adjusting its position against the wind and current with the thrusters to remain fixed within a few inches of the designated mark.
On the aft deck, Dirk, Summer, and First Officer Ryan carefully walked through a pre dive checklist for the Starfish. Specifically designed for deep-water scientific exploration, the Starfish was a high-tech submersible capable of operating in depths up to two thousand meters. Resembling a giant translucent ball on a forklift, the Starfish cat-tied two operators in a six-inch-thick reinforced acrylic bubble that offered a panoramic view of the sea. Wedged into a bright orange supporting buttress, the see-through sphere was filled with a myriad of sensors, still and video cameras, and coring devices. Four sets of adjustable thrusters were mounted behind and beneath the bubble, which provided the sub with a high degree of maneuverability. Adding to the functionality were a pair of steel articulating arms mounted on either side of the bubble, which could be used for collecting samples and manipulating the multiple data analysis devices. Since the right mechanical arm was larger in size than the left, the whole submersible took on a crablike appearance when operating on the seafloor.
“I think we're set,” Summer said, eyeing the last item on her clipboard. “You ready to get wet?”
