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.'
'How much fallout is there with a nuclear torpedo or, or a depth charge?'
'Nothing like an H-bomb used on land.'
'But how bad is it?'
'Not counting any from the ships they hit?' Sessions said. 'There're the weapon parts, of course, vaporized. Fish and plankton, what's left of 'em. And loads of radioactive steam, from carbon, sodium, trace metals in the seawater, by neutron activation.'
'Tidal waves?'
'At least two surges,' Sessions said, still watching his displays. 'They subside eventually with the kind of warhead yield we're using.'
'So they aren't like the big ones from an earthquake?' Ilse said. 'Like that one in the Caribbean that wrecked your cruiser Memphis years ago?'
Sessions shook his head. 'Then the thing's a meter high way out at sea, but moving literally fast as a jumbo jet, piling up murderously onshore. Nuclear tsunamis act more like ripples in a pond, except they're fifty, sixty feet from crest to trough. They die off, mostly, in a matter of miles.'
'Can't big surface ships just ride that out in open water? I got caught on the edge of a typhoon once, on a research trip.'
'Yeah,' Sessions said, 'assuming the enemy doesn't ripple fire or hit from several bearings at once. A ship's hydrophones will give some warning, if you don't receive it on the data links or see the fireball glow, and you can turn bows-on. Still one hell of a ride.'
'I can imagine.'
Sessions turned to face Ilse. 'The worst is if you're close, caught by the blast itself, or lose propulsion from the shock and take a wave from off the beam that's any higher than you're wide. Busted open, capsized, either way you've had it.'
'Warhead locks are bypassed,' Jeffrey said. 'Special weapon loaded in tube seven.'
'Very well, Fire Control,' Wilson said. 'I am relaying the permissive action link code.'
'Green light in the torpedo room,' Jeffrey said. 'PAL code is accepted. Weapon is enabled, armed guard has withdrawn.'
'Very well, Fire Control,' Wilson said.
From here Jeffrey knew the procedures were the same as were used with a conventional fish. To be fully armed, the warhead had to first be surrounded by seawater, then get an electronic signal, then feel the g-force of launch, then run out for a preset safety distance.
'Make tube seven ready in all respects,' Wilson said. 'Tube seven, firing point procedures, area burst on Master 1 and Master 2.'
'Solution ready,' Jeffrey said. 'Ship ready…Weapon ready.'
'Match generated bearings,' Wilson said, 'and shoot.'
'Unit from tube seven fired electrically,' Jeffrey said. 'Unit is swimming out.'
'Unit is running normally,' Sessions said.
'Time to target?' Wilson said.
'Current range is fifteen thousand yards, sir,' Jeffrey said. 'We should detonate in ten minutes.'
'Very well,' Wilson said. 'I intend to put some distance between us and our unit's track, but we'll do it stealthily and keep the layer between us and our quarry. Helm, make your course two six five, make your depth one eight zero feet.'
'Aye, sir,' Meltzer said.
'Captain,' Jeffrey said, 'since we're about to make one hell of a datum anyway, recommend we increase speed slightly to gain more track separation.'
'Concur, Fire Control,' Wilson said. 'Helm, ahead one third, make turns for eight knots.
' Meltzer acknowledged.
'I intend to leave our towed array deployed,' Wilson said.
'I concur, sir,' Jeffrey said. 'Sonar, there could be more enemy boats out there.'
'Understood, Commander,' Sessions said.
'Hull popping sounds on the towed array,' Sessions said, 'bearing three five five true!
Assess the transient as coming from Master 1.'
'Interpretation?' Jeffrey said.
'More hull popping sounds on bearing zero zero five! Assess both targets are rising!'
