He had pitched his head forward in the standard safety posture and his only injuries were a series of painful welts where the straps dug into his shoulders. After taking a deep breath he unbuckled the harness and swivelled towards the workstation, his right hand pushed against the control panel to stop him sliding forward where the module had angled into the seabed.
To the left was a smaller monitor for the display of bathymetric data. As the numbers began to flicker he saw the depth gauge read a staggering 750 metres below sea level, a full hundred metres below the official maximum operating depth of the module. The base of the fault was far deeper than they had imagined, more than half a kilometre below the submerged ancient shoreline.
Jack switched on the sound navigation and ranging system and waited while the screen came to life. The active sonar transducer emitted a high-frequency narrowband pulse beam in a 360 degree vertical sweep to give a profile of the sea floor and any suspended objects up to the surface. During Seaquest’s run over the canyon two days previously they had established that the fault lay north-south, so he fixed the sonar trajectory east-west to give a cross-section of his position within the defile.
The speed of the beam meant the entire profile was visible on the monitor at once. The mottled green on either side showed where the canyon walls rose some four hundred metres apart. Near the top were jagged protrusions that narrowed the profile further still. The canyon bore all the characteristics of a horizontal tear fault, caused by plates in the earth’s crust wrenching apart rather than grinding sideways. It was a geological rarity that would have delighted Costas but was of more immediate concern to Jack because it compounded the gravity of his situation.
He realized his chances against surviving this far had been truly astronomical. If Seaquest had sunk only fifty metres west she would have impacted with the lip of the canyon, smashing him to oblivion well before the wreckage reached the sea floor far below.
He turned his attention to the base of the fault where the profiler showed a mass of light green, denoting hundreds of metres of sediment. Partway up was a horizontal line level with the apex of the sonar, a compacted layer which was the resting place for Seaquest. Above it a lighter scattering of colour denoting suspended sediment continued for at least twenty metres until the screen became clear, indicating open water.
Jack knew he was atop a drift of sediment at least as deep as the ocean above, immense quantities of silt derived from land run-off mixed with dead marine organisms, natural seabed clays, volcanic debris and brine from the Ice Age evaporation. It was continuously being added to by fallout from above and at any moment could swallow him up like quicksand. And if the quicksand did not get him, an avalanche could. The suspended silt above the wreckage was the result of a turbidity current. IMU scientists had monitored turbidity currents in the Atlantic cascading off the continental shelf at 100 kilometres an hour, carving out submarine canyons and depositing millions of tons of silt. Like snow avalanches, the shock wave from one could trigger another. If he was caught anywhere near an underwater displacement of such magnitude he would be doomed without hope of reprieve.
Even before he tried the engines he knew it was a forlorn hope. The erratic hum as he powered up the unit only confirmed that the water jets were clogged with silt and incapable of shifting the module from the grave it had dug itself. There was no way the IMU engineers could have anticipated that the first deployment of their brainchild would be under twenty metres of ooze at the bottom of an uncharted abyss.
His one remaining option was a double-lock chamber behind him that allowed divers to enter and exit. The casing above was enveloped in a swirling cloud of sediment which might still be sufficiently fluid for escape, though with each passing minute the chances were diminishing as more of the particulate matter came out of solution and buried the module ever deeper in a mass of compacted sediment.
After a final glance at the sonar profile to memorize its features, he made his way to the double-lock chamber. The retaining wheel turned easily and he stepped inside. There were two compartments, each little larger than a closet, the first an equipment storage and kitting-up room and the second the double-lock chamber itself. He pushed his way past a rack of E-suits and trimix regulators until he stood before a metallic monster that looked like something from a science-fiction B movie.
Once again Jack had reason to be grateful to Costas. With the command module as yet untested he had insisted on a one-atmosphere diving suit as a back-up, a measure Jack had only grudgingly accepted because of the extra time needed for installation. In the event he had helped to stow the suit inside the chamber so was closely familiar with the escape procedure they had devised.
He stepped onto the grid in front of the suit and unlocked the coupling ring, pivoting the helmet forward and exposing the control panel inside. After satisfying himself that all systems were operational, he disconnected the belts that secured it to the bulkhead and scanned the exterior to make sure the joints were all fully sealed.
Officially designated Autonomous Deep Sea Anthropod, the suit had more in common with submersibles like the Aquapod than conventional scuba equipment. The Mark 5 ADSA allowed solo penetrations to ocean depths in excess of four hundred metres. The life support system was a rebreather which injected oxygen while scrubbing carbon dioxide from exhaled air to provide safe breathing gas for up to forty-eight hours. Like earlier suits, the ADSA was pressure resistant with liquid-filled joints and an all-metal carapace, though the material used was titanium-reinforced high-tensile steel which gave an unprecedented pressure rating of 2,000 metres water depth.
The ADSA exemplified the great strides made by IMU in deep submersible technology. An ultrasonic multi-directional sonar fed a three-dimensional moving image into a snap-down headset, providing a virtual-reality navigation system in zero visibility. For mid-water mobility the suit was equipped with a computerized variable-buoyancy device and a vectored-thrust water-jet pack, a combination that gave the versatility of an astronaut on a space walk but without the need for a grounding tether.
After uncoupling the suit Jack stepped back into the main compartment and quickly backtracked to the weapons locker. From the top shelf he took a Beretta 9 millimetre handgun to replace the one confiscated by Aslan and shoved it into his flight suit. He then uncoupled an SA80-A2 assault rifle and grabbed three magazines. After slinging the rifle he extracted two small packages of Semtex plastic explosive, normally used for underwater demolition work, and two briefcase-sized boxes each containing a mesh of bubble mines and a detonator transceiver.
Back in the double-lock chamber he hooked the boxes to a pair of carabiners on the front of the ADSA and secured them with a retaining strap. He reached over and slid the rifle and magazines into a pouch under the control panel, the bull-pup SA80 fitting easily inside. After closing the hatch to the chamber and spinning the locking wheel he ascended the metal ladder and clambered into the suit. It was surprisingly spacious, providing room for him to withdraw his hands from the metal arms and operate the console controls. Despite its half-ton weight he was able to flex the leg joints and open and close the pincer-like hands. After checking the oxygen supply, he shut the dome and locked the neck seal, his body now encased in a self-contained life support system and the world outside the viewports suddenly remote and dispensable.