Rut if we go in faster, they could hear us, and Captain Wilson said to go in fast. I don't want to die, Ilse told herself, not like this so soon. I have something to do first, dammit.
"'Time's running out, Mr. Fuller," Wilson said. "What do you think?"
"It would be ideal, sir," Jeffrey said, "if we could time our shots to hit them just as they come up through the layer to launch their missiles."
"Devoutly to be wished," Wilson said, "but unrealistic. By the time we got in close enough for a good attack, they'd almost surely make a counterdetection and gel off a snap shot at us with a nuclear torpedo. So how could we tell they're going for the surface, assuming that's their plan, if we can't even hear them?"
"We couldn't, sir," Jeffrey said. "But if they rise above the layer prematurely, they'll hear our own fish coming in plenty of time to evade and counterfire."
"At close enough range they might even hear the ADCAPs through the layer," Wilson said. "You know acoustic shadow masking's always an iffy thing."
"I'm starting to change my mind on something, sir," Jeffrey said.
"Oh?" Wilson said.
"I think maybe we should use a single weapon, a fission warhead. Set for highest yield, one-tenth KT. It's got a lethal radius big enough to catch them both, even if they run, even with some error in the firing solution." Relying on just two stale data points was not recommended practice, Jeffrey knew.
"Concerned that we're outnumbered?" Wilson said.
"Respectfully, sir, yes. The fuel-cell Klasse 212s are vulnerable with all that liquid hydrogen on board, but they have twelve torpedo tubes between them, to our eight."
"And taking potshots with our ADCAPs would just tip them off?"
"Affirmative, sir."
"Then what about going active, disguise our ping as biologic?"
"You know how I feel about that, Captain. Once we start, we'd have to keep it up. Shrimp don't click real loud just once. Whale songs go on for minutes, even hours, so they can stay in touch moving in and out of each other's convergence zones. The enemy boats would track the source, watch our maneuvers. The water here's too quiet."
"I concur, sir," Sessions said. "The range is a bit extreme for that tactic in any case."
Wilson gave Jeffrey a hard look. "Still don't want to call for help?"
"Sir," Jeffrey said, "our aircraft are heavily committed all along the front. If we suddenly vector in more stuff, including those two ASW helos we were working with, the 212s will know for sure we know they're here. We'll lose the element of surprise, and they'll fire off their missiles. The whole point of Challenger is we're invisible till we strike."
"What's range and bearing to the helos?" Wilson said. "Twenty miles now, sir," Jeffrey said. "Bearing one seven five, crosswind from us."
"All right, then," Wilson said. "Debate's over. Assistant Navigator, let the rough log show that at … zero five two three Zulu this day, CinCPAC Theater Nuclear Forces rules of engagement were satisfied for a tactical nuclear launch against submerged enemy contacts."
"Assistant Navigator," Jeffrey said, "I concur." Jeffrey breathed a sigh of relief. Compared to this, Prospective Commanding Officers School would be a cinch.
"Sonar," Wilson said, "where's the layer?"
"One nine zero feet, sir," Sessions said.
"Helm," Wilson said, "ahead one third, make turns for four knots."
"Ahead one third," Meltzer said, "make turns for four knots, aye … Maneuvering acknowledges turns for four knots, sir."
"Make your depth one five zero feet."
"Make my depth one five zero feet, aye," Meltzer said.
"Fire Control," Wilson said, "have Combat Systems warm up a nuclear Mark 88 torpedo. Same presets you put in the ADCAPs, to run above the layer. Load it in tube seven."
"Aye aye, sir," Jeffrey said.
"That way we'll slap them down real good if they stay deep," Wilson said, "and blow them to kingdom come if they've gone shallow."
Jeffrey relayed the commands and took the electronic acknowledgments. He eyed his weapons status screen as tube seven's outer door rotated closed, sea pressure was relieved, the water drained, and the inner door swung open. The weapons autoloader shuffled the units around on the racks, then presented a wide-bodied Mark 88 at tube seven's breach. Lights in the CACC started flashing.
"General security alarm," Jeffrey said. "A special weapon has been shifted."
"Special weapon handling is authorized," Wilson said.
"Very well," Jeffrey said. "Disregard the alarm." The lights stopped blinking. Next Jeffrey watched as the fire control technicians on the CACC starboard side worked their consoles, establishing the weapon presets — under current nuclear war-fighting protocols the combat systems officer himself, called "Weps" for short, manned a retrofitted station on a lower deck, for two-man positive control.
Jeffrey knew that overall authorization for tactical nuclear weapons had been handed down by the President after the war broke out. Final decisions were made on the spot by Challenger's senior officers.
"XO," Wilson said, "take the conn. Messenger of the Watch, have Weps meet me in my state-room. Assistant Navigator, accompany me with the electronic logbook. I'm going for the special weapons enabler tool."
Ilse and Sessions spoke in undertones, their voices blending with the constant murmuring of CACC technicians.
"Ever seen a nuclear torpedo detonate?" Sessions said. He kept his eyes glued to his sonar screens. Ilse shivered. "No. Have you?"
"Just on film. It's awesome. Surface units caught some footage when things first got hot in the Atlantic."
"What's it like?" Ilse said.
"Depends on warhead yield and depth when it goes off."
"How big do they get?"
"U-235, using just one critical mass, you can go up to maybe twenty kilotons."
"In this war that's pretty much a strategic weapon," Ilse said.
"Yup," Sessions said. "For comparison Hiroshima was roughly twelve. Nagasaki, they used a plutonium bomb, maybe twenty-two KT. Warsaw, when this war broke out, they think was ten."
"So what happens when one goes off underwater?"
"There's two things — really just like a regular depth charge, only bigger. Step one, warhead blows. That immediately lifts the surface of the sea, 'cause water's incompressible, and sends a suction wave back down."
"You get a big white fountain?"
"With a dot one KT explosion, could be a hundred yards across. Step two, blast of dirty water hits the surface from below, bigger than the first spout. That's the warhead burst itself. It pulsates as it rises."
"The bubble energy fights back and forth with the water pressure?" Ilse realized now that everyone said "dot" instead of "point" for decimals — less ambiguous?
"In this case that's the fireball," Sessions said. "It's buoyant, hot as hell, so it comes up really fast. There's a nasty airborne shock wave when it breaks the surface."
"How hot is it?"
"Try ten million centigrade."
"Ouch."
"It dissipates, cooling on the way, but being underwater doesn't help."
"How come?"
"Compared to air, the hydrostatic pressure confines the blast, concentrates the fireball. The water boils, of course, but that won't carry off much heat. Seawater's got poor transparency too, from all the stuff that's floating in it—"
"Suspended particulates, organic matter. "
"Yeah, Ilse, you would know. The whole photon flash on detonation, the gamma rays and X rays, ultraviolet, visible and infrared, not to mention all the neutrons, they get held in close, strengthening the fireball. On the other hand, seawater does suppress the EMP, the electromagnetic pulse that fries unshielded circuits … Anyway, first you have this giant burst of water, then you get the fireball. Timing between the two depends how deep the thing went off. There'll also be what's called the base surge, a kind of ground fog that spreads out like a fluid and evaporates, ocean surface atomized by the vicious shock wave through the water. You know an underwater blast's much more destructive to naval vessels than an airburst at a given distance. Water's much more dense and rigid, and sound travels five times as fast."