depth, Jeffrey knew, the bilge pumps couldn't possibly keep up with a major leak, and at this depth any leak was major.
'Captain,' Ilse shouted. 'Look at the gravimeter!' Jeffrey saw the image on his screen, the wall of the escarpment. It was shimmering, starting to give way. 'It's an underwater landslide!' Ilse said.
'Helm,' Jeffrey said. 'Ahead flank smartly, full rise on the diveplane functions.' The forward trim amounted to a twenty-five-degree down-bubble.
'Ahead flank smartly, aye,' Meltzer said. 'Full rise on the diveplane functions, aye.' He flicked the engine- order dial with one hand while he pulled back on his control wheel with the other and then turned it, his face grimacing in concentration. 'Maneuvering acknowledges ahead flank smartly.'
The depth gauge showed 15,400 feet. The gravimeter showed a gap in the escarpment, growing into a vicious gouge — it couldn't track the moving boulders, it just showed their effect.
'Sir,' COB said, 'soundings are eighteen thousand feet!'
'Acknowledged,' Jeffrey said. Deep enough to die. 'A seismic sea wave's coming any second from the avalanche!' Ilse yelled.
The depth gauge showed 15,600 feet. The hull groaned again and the ESM room bulkhead started warping against the overhead. Dust from crumpled insulation fell on Ilse and the sonar people.
A terrible roaring shove struck the ship and the inclinometer went to forty-two degrees starboard list. Fifteen thousand eight hundred feet.
'Sounds like we buried them alive,' Van Gelder said, 'before Challenger's torpedo could intercept our unit.' 'Mmph,' ter Horst said. 'I wouldn't entirely count on that. Serves me right for trying to not be too profligate with our weapons expenditure.
Sonar, any contact on the target?'
'Negative, sir,' the sonar chief said. 'Conditions are impossible.'
'Very well,' ter Horst said. 'Number One, detonate the other nuclear torpedo.'
'Detonate the unit from tube two, aye aye,' Van Gelder said. Ter Horst waited till they heard the distant blast, dulled by the intervening escarpment wall. 'Now then,' he said, 'if we can't hear them, they certainly can't hear us. Helm, set maximum revolutions, steer one six zero.'
'Set maximum revolutions, aye aye, sir,' the helmsman said, 'steer one six zero, aye aye…Turbine room answers steam throttles are wide open, sir.'
'We'll head directly to the choke point now,' ter Horst said. 'It should take us three hours. We'll wait for Wilson there, after we string the last of our deployable hydrophone line beyond the bases of the seamounts on both flanks of the hump.'
'Understood,' Van Gelder said.
'Eventually,' ter Horst said, 'if we don't make contact, we'll come back here and use our bottom-penetrating sonar to locate their reactor compartment under all that rock. One way or another the verge of the Prince Edward Fracture will be Challenger's final hunting ground.'
Another atomic detonation went off harshly somewhere past Challenger's starboard quarter. The force of it was amplified and drawn out by the backstop of the escarpment wall, and the gravimeter showed another huge section starting to give way. Above it all Jeffrey heard a snap, and water sprayed into the passageway forward of the ship control station.
'It's just freshwater,' COB said, bypassing the rupture while he tried to do three other things at once. There was computer hardware near that pipe but nothing shorted out.
'It couldn't stand the flexing and the shock,' Jeffrey said. 'Our sea pipes are much stronger but something's gotta give.' The huge main steam condenser cooling loops — vital to the propulsion system's thermodynamic cycle — were made of a different ceramic composite than the hull, designed to withstand intense pressure from within — shear instead of strain — but only up to a point. Challenger's hull openings were her weak spots, like in any submarine.
The gravimeter showed a giant avalanche now, and another seismic sea wave caught the ship.
'Sir,' Meltzer said, 'we're at sixteen thousand feet! I cannot get a positive angle of attack!' More moaning crunching sounded and the deck began to warp.
'Very well, Helm,' Jeffrey said. 'Planing out of the dive just isn't working fast enough. All stop, stop the shaft.'
'All stop, aye!' Meltzer said.
'Maneuvering acknowledges all stop! Stop the shaft, aye! Maneuvering acknowledges stop the shaft!'
'If we need bowplanes,' Jeffrey said, 'we'll move in reverse. The sternplanes will become our bowplanes they're much bigger and they'll have even more bite from the propulsor wash when going backward.'
'Understood,' Meltzer said.
'Back full smartly,' Jeffrey said.
'Back full smartly, aye!…Maneuvering acknowledges back full smartly!'
'Be real careful,' Jeffrey said, 'this evolution makes us very unstable. One more seismic sea wave will be the end of us.'
'Acknowledged!' Meltzer said.
Jeffrey eyed the gravimeter, praying hard against more landslides. 'And try to get us on an even keel before we crash into that cliff.'
1 HOUR LATER
'That's just what I was afraid of, Ilse,' Jeffrey said, looking at the imagery off one of her CD-RW disks, the outflow from a hydrothermal vent she'd once studied in detail. Sessions nodded. 'There'll be massive Doppler distortion along the line of sight, sir, and constant rippling of the acoustic image in the perpendicular plane.' The three of them stared at the picture on Sessions' sonar console.
'Here's a thought,' Ilse said. 'We could do what astronomers do to deal with atmospheric turbulence. Active adaptive optics, except electronically. It's really the same problem.'
'But we need a known bright reference star for that,' Jeffrey said, 'or the equivalent, and this all has to work continuously in real time.'
'That's what I mean,' Ilse said. 'What if we emit an active sonar beam, one that's directionally very tight, at minimum power? Wave it back and forth and grab the micro-echoes off the precipitation particles? That would give a picture of water motion in the megaplume.'
'Sounds great in theory,' Jeffrey said.
'We'd have to work the wide-aperture system as a phased-array antenna,' Sessions said, 'then digest all that raw data and reassemble everything for a sharply focused picture…And that's just to use this telescope thing on one line of bearing.' Sessions turned to Jeffrey. 'I don't know, sir.'
'We'll use finite elements for approximation,' Jeffrey said. 'The processes are chaotic but they're spatially continuous.'
'That's true,' Ilse said. 'The functions would be differentiable, mathematically.'
'We can do a narrowband search to simplify things,' Jeffrey said. 'Even if Voortrekker auto-hovers so their reactor pumps and the rest of the propulsion plant are quiet, they need a bunch of megawatts to run all their computers and their listening gear, and to keep their bow sphere warmed up for active melee ranging once the engagement starts. We'll listen for five-hundred-hertz tonals from their turbogenerators, and fifty-hertz sympathetic line hum. That'll help us filter out irrelevant noise impinging on our hydrophones.'
'I concur,' Sessions said. 'The problem isn't writing the code to do all that, Captain. The systems administrator and his staff have been on it for a while already. They're boilerplating and building from tool kits with the commercial off-the-shelf software we have on board. The problem is running everything fast enough for the lens effect to work.'
'We'll have to make as much space as we can inside our processors,' Jeffrey said, 'dump or switch off everything we don't need on the LAN, other programs, irrelevant data, pieces of the operating system even.'
'Can you do that?' Ilse said.
