The Bin Laden Plot

Harrison was the last to climb aboard his RHIB, as was Khalila into hers. The outboard engines were already running, but barely audible. Their position updated on Keller’s handheld GPS display, then he shifted the outboard into gear and pointed the RHIB toward their insertion point on Failaka Island. Senior Chief Burkhardt’s RHIB followed.

46 ALVIN

Alvin descended through the darkness, continuing its trek toward the ocean floor nine thousand feet below the water’s surface. Inside the submersible, it was quiet at first, the only sound being the hum of the carbon dioxide scrubbers purifying the air, until Hillsley turned on music, which was now playing softly in the background. The external lights were kept off during the descent, saving the vehicle’s battery power until they reached the bottom. What they were searching for hadn’t been fully explained to Hillsley — and wasn’t going to be — although Christine wondered if he had deduced the reason for their mission. After all, bin Laden’s burial in the Arabian Sea was public knowledge.

If Hillsley suspected, he didn’t let on, spending the time instead monitoring Alvin’s equipment, including its scrubbers and oxygen bleed, ensuring the air inside the sphere was properly maintained. Everything was functioning properly, and Hillsley eventually struck up a conversation, during which Christine learned a great deal about Alvin and the fascinating sea life surrounding them.

The first two hundred meters of their descent was through the euphotic zone, also called the sunlight layer, where enough light penetrated the water to support photosynthesis and where the majority of aquatic organisms lived. The light outside faded, becoming greenish at first, gradually transitioning to dark blue. After ten minutes, they entered the dysphotic or twilight zone, where only a small amount of light penetrated, and Christine watched as numerous glowing bioluminescent animals floated past Alvin’s portholes.

Darkness then closed in as Alvin entered the aphotic — or midnight — zone, devoid of natural light. Inside the submersible, the only light came from blinking LEDs built into the sophisticated electronics. Outside the submersible, occasional greenish flashes were emitted by small fluorescent marine animals disturbed by Alvin’s descent through their realm.

It was cold inside the sphere; the temperature had plummeted due to the near-freezing seawater surrounding them. A chill set in, and Christine put on a sweater and pair of jogging pants she had borrowed from one of the crew members aboard Atlantis, following the advice of Alvin’s operations officer.

As they descended, Hillsley monitored Alvin’s sonar display for the sonic beacon in bin Laden’s body bag. To conserve power, the beacon emitted a pulse only once every hour. The pulse had been detected by the sonar equipment aboard Atlantis, so they knew it was functioning and they were in the right spot. Still, even a small angular error in a nine-thousand-foot descent could place Alvin far from their objective once it reached the ocean bottom.

About halfway down, Hillsley picked up a pulse from the beacon and made a slight adjustment in their downward trajectory, energizing one of Alvin’s seven thrusters for a few seconds.

As predicted, it took ninety minutes to complete the descent. As they approached the ocean bottom, Hillsley turned off the music and energized additional equipment, including its external lights, illuminating a flat, featureless, sediment-covered bottom out to a range of about thirty feet.

Christine peered out one of the five viewports; there were three in the forward portion of the sphere, each about seventeen inches in diameter, with a smaller, twelve-inch-diameter portal on each side. Additionally, there were three small displays mounted to the equipment racks, connected to cameras mounted to Alvin’s exterior.

Hillsley set Alvin to hover ten feet above the ocean floor. While they awaited the next sonic pulse from bin Laden’s body bag, they searched the immediate area, doing a slow spin at their current location. Hillsley examined the results from three different sonars: two seafloor profilers, plus a dual-frequency scanner that could detect objects buried down to forty feet beneath the ocean floor.

About the time they finished searching their current location, Alvin received another ping from the sonic beacon, coming from a bearing of zero-one-one. Hillsley set Alvin to the northerly course, proceeding slowly. Although the submersible was capable of a speedy two knots, Hillsley explained that they typically cruised along the bottom at only one-half knot to preserve battery power. As they traveled toward the object, Christine directed Hillsley to de-energize Alvin’s cameras. She wanted no recording of what was about to occur.