Finding the 22-foot-long Titan submersible, which went missing on June 18, is a desperate race against time. The craft, powered by four electric thrusters that move it at a maximum speed of 3 knots, lost contact with its surface vessel, the Polar Prince, around 105 minutes into a dive. The Titan was headed for the wreckage of the Titanic, roughly 375 nautical miles from Newfoundland, Canada. If the sub is still intact, those aboard have only two days of air left.
Five people are crammed into the craft: Stockton Rush, president and founder of OceanGate, the submarine exploration company that operates the sub; pilot Paul Nargeolet; British billionaire Hamish Harding; and Pakistani businessman Shahzada Dawood and his son Sulaiman. Because of Titan’s design, they can’t free themselves—they’re bolted into the craft from the outside. Rescuers therefore need to find them quickly, as even if they reach the surface they could still run out of oxygen.
“You know where you launched the submersible, you know the direction it would have been heading, and they had been tracking it for an hour and a half,” says Frank Owen, a former submarine officer and director of the Australian navy’s submarine escape and rescue project, who now works for sonar specialists Sonartech Atlas. But the hunt is still difficult—both because of the search area and the vagaries of the sea.
According to MarineTraffic data, at just before 9 am ET on June 20, more than 60 different vessels were circling sites off the coast of Nova Scotia looking for the submersible. These ships are scouring the sea surface. Alongside the boats, the US Coast Guard has sent two C-130 Hercules aircraft to look for the sub from the sky, alongside a Canadian C-130 and a P-3 airplane. “Aircraft will fly up and down legs, going back on each other, doing a grid search pattern, looking out for the submarine,” says Neville Yard, a submarine rescue expert who has experience with the UK’s Royal Navy and NATO, and who worked on the rescue operation of the Russian sub the Kursk in 2000.
The technology for finding a vessel on the surface is well known and proven, says Owen—ships and aircraft have infrared sensors, thermal vision, radar, and good old-fashioned eyesight at their disposal. However, the efficacy of these methods depends on the weather. “If it’s relatively calm, and [Titan] has been able to get to the surface, the submersible will have radar reflectors, radio transmitters, and strobe lights to assist in visual searches,” he says. “But it’s still difficult to find things on the surface—especially if it’s rough.” Yard agrees: “It’s like looking for a needle in a haystack,” he says. Even if you nail down where to look, “it’s still a lot of water to cover.”
But if Titan remains below water, the problems are magnified, says Owen. Some of the ships and one of the aircraft—the P8—are equipped with sonar, but the majority of these can only search within relatively shallow waters. Mohammed Sanhaji, a sonar and marine surveys expert, says that “sonar systems that image the seafloor acoustically” work to a depth of around 1.25 miles—or around half the depth of the Titanic wreck. Titan is designed to descend more than 2.5 miles below the surface—far beyond where most sonar can reach. “These sorts of systems aren’t very good for looking for something on the seabed,” says Owen.
To understand why, you have to look at how sonar works. The tech sends a beam of sound waves out into the water and looks for an echo back. The further that goes, the more the sound waves get refracted by pressure and temperature changes in the water. That makes the sonar less accurate in identifying objects beneath the surface.
And there are no viable alternatives. Under the sea there’s “no radar, no GPS,” wrote Eric Fusil, CEO of Odyssee Aus, an Australian company specializing in submarines, in a LinkedIn post discussing the hunt. Spotlights or laser beams also won’t work, says Fusil—they’re absorbed by the water within a few meters. This means rescue crews scouring the ocean floor need to get their sonar signals farther down toward where they think the submersible could be, either by adding submarines to the hunt or by lowering sonar devices down on cables.
The fact the sub was going to explore the wreckage of the Titanic also means there may be lots of false positives on any sonar scans. Any positive signals could be Titan—or part of the ship the expedition was going to explore.
A recent 3D scan of the Titanic wreckage conducted by Magellan Aerospace suggests that the remains of the sunken liner are spread over 15 square miles. Sweeping a field that big would take far more time than those aboard the Titan are expected to have. At a briefing on Tuesday afternoon, the US Coast Guard estimated the sub had 40 hours of oxygen left—which, if the case, means it would likely run out by Thursday morning ET.
It’s vital those aboard Titan stretch that oxygen supply as far as possible, says Owen. “The best thing they can do is lie down and go to sleep—especially the passengers, because they have no role to play,” he explains. During sleep we breathe more shallowly, using less oxygen and producing less carbon dioxide. But falling asleep is easier said than done if you’re potentially stuck 2.5 miles below the sea’s surface with no communication with the outside world.
Even if the vessel is found, that won’t necessarily stop the clock from ticking. If the Titan is on the seabed, it will need to be hauled to the surface. While Owen reckons the Polar Prince will have the equipment needed to hoist the vessel up from shallow water, it would require help if the Titan is deeper or tangled in an object, such as an underwater cable.
A remote operating vehicle could attach a line to the sub, and the vessel on the surface could use a fairly large deck crane to haul it up, Yard says. “I don’t know of any vessel that goes around with a crane and a winch wire 12,500 feet long,” he adds. “I don’t know of any readily available remote operating vehicles that have an umbilical that long, either.”
Recovery, if it comes to that, is possible. It just takes time. The equipment required would need to travel to a nearby port, be welded together, and then sail 370 nautical miles—which takes around a day and a half—to the site of the wreck. “All of that is eating into the days that are left,” says Owen. “Forty-eight hours have already been used. Time is against us.”
Updated 6-21-2023 11:15 am BST: The model of the Canadian airplane was corrected.
