It was not a large enough deviation to affect the integrity of the search, but a small one that could be easily compensated for if the signals did not turn out to be the target of interest.
The robot turned seven more degrees to starboard, and was almost instantly rewarded with a third acoustic signal. Another search of the mission library revealed that this new frequency, Investigatory Signal #3, was also one of the tonals that the target was known to generate.
More significantly, this third tonal was one of the designated
In the world of passive sonar, a class identifier is the acoustic equivalent of DNA evidence. It’s as close to positive identification as the physical limitations of the audio spectrum will permit.
The robot’s mission library included the acoustic class identifiers for the target Mouse had been programmed to find. Based on the newly-detected frequency, the computer elevated its confidence factor to 98.2 %. Mouse was now 98.2 % certain that it had located the assigned target.
This new confidence level was more than high enough to justify abandoning the search plan to pursue the source of the frequencies. Mouse shifted from
The mode shift triggered a bug in Mouse’s core operating program. If the code had functioned as its programmers intended, a subroutine would have recorded the nature of the mistake for future correction, and then bypassed the error to allow the robot to continue functioning. But the software glitch got in the way.
Instead of bypassing the error, the faulty program activated Mouse’s emergency maintenance routine, falsely informing the robot that it had suffered crippling damage, and ordering it to return to its point of launch to surface for repairs.
The robot noted the damage alert immediately, and prepared to terminate the mission and head for the launch and recovery coordinates.
But Ann Roark’s software patch was installed and at work. As with the rescue of the
(1) <<<< IF [emergency_maintenance_routine = active]
(2) CANCEL [emergency_maintenance_routine]
(3) RESUME [normal_operation]
(4) INVERT [last_logical_conflict] >>>>
The first line of code triggered the workaround the instant that Mouse’s computer kicked into emergency maintenance mode. The second line canceled the order for emergency maintenance mode. The third line ordered the robot to ignore the error and continue operating as if no fault had been reported. The last line of the workaround inverted the logical conflict that had triggered the original error.
The Mouse unit had responded to a false report that it had sustained critical damage. Ann’s code patch inverted the logical state of the erroneous report, switching “CRITICAL DAMAGE = YES” to “CRITICAL DAMAGE = NO” in the robot’s memory.
The conflict was eliminated. The computer determined that all conditions had been met for the autonomous phase of the mission to commence. The robot made a five degree starboard turn to improve its angle of approach, and began moving toward the target.
Mouse had no idea of the nature of its quarry, or the ultimate purpose of its mission. It thought only in terms of waypoints, frequencies, obstacles, and manipulator functions.
Two hundred feet beneath the ice pack, in a body of water that most people couldn’t find on a map, a small unarmed robot glided through the darkness toward a 13,000-ton nuclear missile submarine.
CHAPTER 55
Ann Roark was looking the other way when the icon popped up on the display of her laptop. When she looked up, the computer showed only the ship’s position indicator and a silhouette map of the Sea of Okhotsk. She glanced back down, perhaps a second later, and the triangular green symbol was burning bright on the screen.
Ann had the laptop speakers muted, so the arrival of the icon came without sound or commotion, but it startled her just the same. Something heavy clunked inside of her, as she realized that the next scene of this crazy little drama was about to play itself out.
She thumbed the trackball, scrolling the computer’s cursor over the green triangle. A small block of alphanumerical data appeared to the left of the icon. Ann read the little status report twice, to be certain that she was interpreting the situation correctly.
Then she leaned back in her seat and glanced around. None of the Navy people happened to be standing nearby at the moment, so she stood up, stretched, and walked briskly over to the Tactical Action Officer’s station.
She didn’t know the man in the TAO chair, but she recognized from the silver bars on his collar that he was a lieutenant. The Navy guys called those bars
She tapped the TAO on the shoulder. The man recoiled at her touch, and Ann felt a tiny hint of satisfaction at having startled one of the warrior types. Obviously, she wasn’t the only person feeling the pressure.
When the man looked up, Ann pretended she hadn’t noticed his flinch. “I don’t have a headset, so I couldn’t call you on the net,” she said. “My robot has found your submarine.”
The man sat up straighter. “What? Are you sure?”
Ann looked back toward her laptop. “Yeah. That’s what Mouse is telling me, anyway.”
The man keyed his microphone, and spoke into his headset. “USWE — TAO. Can you step over to my station, Chief? I need to talk to you.”
The redheaded Sonar Technician, Chief McPherson, appeared at the TAO’s chair a few seconds later. The cord of a disconnected headset was draped around her neck. “What’s up, sir?”
The TAO inclined his head in Ann’s direction. “Ms. Roark’s robot has detected the target.”
Chief McPherson raised her eyebrows. “You’ve got high-confidence classification on the contact?”
“Yeah,” Ann said. “Mouse detected three frequencies consistent with a Delta III submarine. One of them is flagged as a class identifier.”
The chief gave a thumbs-up gesture. “Excellent! We need to get a tactical feed to Fire Control immediately.”
Her face took on a thoughtful expression. “We can’t hook your laptop into CDRT or Fire Control, so we’ll have to do this old school. I’ll station a phone talker over your shoulder. He’ll relay the data to us, and we’ll punch it into the system manually.”
Ann held up a hand. “Whoa there, cowboy. I can get you a recent position for the sub, but I can’t give you real-time information.”
Chief McPherson’s eyebrows narrowed. “Why not?”
Ann struggled to keep the frustration out of her voice. “Because your captain told me to lock out the acoustic modems,” she said. “Remember that strategy meeting in the wardroom? You guys decided to restrict Mouse’s communications to low-power UHF, so the submarine can’t detect him. He can’t transmit or receive UHF when he’s
