Sword of Shiva - Страница 45


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Even the moonlight had been taken into account. According to the nautical almanacs, official moonset was still five minutes away, but the lower half of the silvery orb was already disappearing below the western horizon. By one minute after midnight, the last of the moon would be hidden behind the curve of the earth. Under simple starlight, the reactive camouflage that coated both ships would make them difficult to detect visually — either by human eye, or by optical sensors.

An adaptive infrared suppression system kept each ship’s thermal footprint within half a degree of the ambient air temperature, and the ships’ acoustic signatures had been minimized by seventh-generation silencing, active noise-control modules, and acoustically-isolated engineering plants.

Despite the rumors that floated around the internet, this cunning array of technologies did not render the American warships invisible. If there was a way to make 9,800 tons of steel vanish entirely, the engineers of the U.S. defense industry had not yet stumbled across the secret. Even in full stealth mode, USS Towers and USS Donald Gerrard were not undetectable. They were simply less detectable.

* * *

The distinction between those two states — undetectable, and less detectable — was very much on the mind of Commander Katherine Silva as she stood next to Captain Bowie in CIC and watched the Aegis tactical display. Under other conditions, the theoretical gap between a low detection threshold and a zero detection threshold might have been the subject of a stimulating technical debate. But under the current circumstances, that narrow theoretical gap could easily mean the difference between life and death.

On the screen, the blue symbols representing the Towers and the Gerrard were sliding into the red colored areas which depicted the radar coverage zones of the nearest Chinese warships. The zones were color-coded by estimated probability of detection: lighter shades of red for low probability, darker shades for high probability. Out at the fringes of the enemy’s radar coverage, the color was a red so light that it verged on pink. Closer to the Chinese aircraft carrier, the reds deepened to the shade of blood.

The American ships were on nearly reciprocal courses, the Towers moving west and the Gerrard moving east, both converging slowly on the formation of Chinese warships that lay between them. At some point, the two U.S. Navy destroyers would pass some indefinable boundary, where microwave-deflecting hull geometries and radar-absorbent tiles could no longer hide them from the sensors of their enemies. The goal was to begin the attack before crossing that invisible threshold.

If all went according to plan, the Chinese wouldn’t suspect the presence of the American ships until they detected incoming missiles. And then it would be too late.

Silva’s eyes stayed locked on the display screen. Adjacent to the symbol for the Towerswas a highlighted data-field containing the current calculated probability of detection, expressed as two sets of numerals separated by a slash: 62.0 / 7.8. The first set of digits — provided for purposes of comparison — was calibrated to the radar cross-section of a standard Arliegh Burke class destroyer. The second set of digits was adjusted for the minimized radar signature of a modified Flight III Arliegh Burke class ship.

Based on received signal strength at the ship’s current position, the Aegis command and decision computer predicted a 62 % chance that an unmodified Arliegh Burke destroyer would be detected by the Chinese radar, and a 7.8 % chance that the same Chinese radar sensors would detect the Towers.

While Silva watched, the readout changed to 68.2 / 9.1, as USS Towers edged closer to the defensive screen of the Chinese aircraft carrier.

From an intellectual perspective, Silva acknowledged that nine percent didn’t seem like bad odds, especially compared to the nearly seventy percent that a less stealthy ship would be facing right now. But for all the cutting-edge technology, there was nearly a one-in-ten chance that a Chinese radar operator would peer into the clutter of random sea returns on his scope, and spot a tiny smudge of pixels that represented USS Towers.

Silva tore her gaze away from the probability of detection readout, and took in the overall tactical situation. The enemy aircraft carrier was screened by four surface combatants: a pair of Type 054A (Jiangkai II class) multi-role frigates to the northwest and southwest, and a pair of Type 51C (Luzhou class) air-defense destroyers to the northeast and southeast. This put both of the Chinese destroyers on the eastern side of the formation — closest to the Towers—presumably to provide air coverage against the retreating Midway strike group.

The symbols for the Chinese ships were enclosed by ellipsoids of dotted lines, representing calculated areas of uncertainty. The enemy ships were estimated to be somewhere within those areas of uncertainty, but their exact positions were unknown.

With their own radar transmitters shut down, Towers and Gerrard were relying on tracking information from their AN/SLQ-32(V)3 electronic warfare systems. The SLQ-32 (or Slick-32, as the system’s operators preferred to call it) was capable of detecting, identifying, and tracking virtually every search, targeting, or navigation radar devised by man. But for all its adaptability and processing power, the Slick-32 was a passive sensor. It could determine the direction of an enemy radar source; but it had no ability to measure how far away the hostile emitter might be. This bearing-only data was sufficient for targeting Harpoon missiles, but lacked the range information critical to most other weapon systems.

If the Towers and Gerrard had not been operating under strict emission control, they could have exchanged lines-of-bearing through the tactical net, establishing and maintaining cross-fixes for the enemy radars, neatly pinpointing each of the Chinese warships on a continual basis. Instead, they were making due with periodic data feeds from a NightEagle III unmanned aerial vehicle flying slow surveillance passes over the enemy formation at 20,000 feet.

Constructed from radar-transparent composites, the UAV was small, lightweight, and relatively stealthy. Every fifteen minutes or so, it pointed an ultraviolet diode laser to the heavens, and squirted a packet of digital information toward one of eleven Fleet SATCOM communications satellites in orbit. The satellite promptly encoded the UAV’s targeting data, and transmitted it back toward the earth as an encrypted UHF radio signal, where it was received and decrypted by the two American destroyers.

During these periodic updates, the area of uncertainty for each Chinese ship shrank to a discrete point, and the Towers and Gerrard knew the exact position of every enemy vessel. But as the minutes ticked away and the Chinese ships maneuvered within their formation, the American Slick-32 systems could only track bearings. The estimations of target range became progressively less reliable, and the ellipsoid areas of uncertainty began to grow again.

The NightEagle III was capable of maintaining continuous uplink with the satellites, providing constant position updates for the enemy warships, but the UAV had been programmed to avoid detection. There were at least three flights of J-15 fighter jets circling over the area, providing air cover for the Chinese carrier. The UAV’s laser communication link was covert, but it was not completely invisible.

Again, it came down to the difference between undetectable, and less detectable. The success or failure of this mission — life or death — depended on keeping the UAV and both American warships below the threshold of detection.

Any one of those Chinese planes might bounce a lucky radar echo off the Towers or the Gerrard at any time. One of the pilots might glance up (or down) at just the right angle, and catch a glimpse of a strange black shape against the waves, or a small winged silhouette against the night sky.

Silva knew she shouldn’t be thinking such thoughts, but this was the part she hated. The waiting. The proverbial calm before the proverbial goddamned storm. That frozen eternity of inaction, where every second seemed to draw itself out to an edge as keen as a razor, and there was nothing to do but dwell on the endless list of things that could go wrong.

On the tactical display, the symbols for Towers and Gerrardwere well into the deepening reds of the Chinese radar coverage now. The probability of detection readout said 88.1 / 17.6. There was nearly a one-in-five chance they’d be spotted, and the numbers were still climbing.

Splitting the difference between best-case and worst-case for the areas of uncertainty, the Chinese destroyers were a little over 40 nautical miles away. They were well within Harpoon range, but Silva knew from the pre-mission briefing that Captain Bowie intended to close another three miles before launching the strike.

Like most American surface combatants, the Towers carried only eight Harpoon anti-ship missiles. The USS Donald Gerrard carried eight as well. That only allowed four Harpoons per target, and the Chinese warships were supposed to have good anti-missile defenses.

Bowie wanted to be close enough to press the attack with naval gunfire, in case the limited inventory of Harpoons was not enough to guarantee a kill.

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