Titanic submarine: Five unanswered questions surrounding the missing deep-sea explorer

A deep-sea faring submersible vessel that disappeared on an expedition to the Titanic wreckage site only has about 40 hours of oxygen left, US CoastGuard officials said on Tuesday afternoon.

The Titan, a five-person capacity vessel run by OceanGate Expeditions, vanished without a trace about 100 minutes after launching from the Polar Prince icebreaker research ship about 900 miles off the coast of Cape Cod on Sunday morning.

A sweeping search and rescue effort involving Canadian Boeing P-8 Poseidon and C-130 Hercules reconnaissance aircraft and underwater sonar buoys has failed to find any sign of the vessel, US CoastGuard Captain Jamie Frederick said in a briefing on Tuesday.

British billionaire explorer Hamish Harding and French diver Paul-Henri Nargeolet — known as Mr Titanic — are onboard, along with Pakistani businessman Shahzada Dawood and his 19-year-old son Sulaiman Dawood.

OceanGate Expeditions confirmed its CEO and founder Stockton Rush was the fifth person aboard on Tuesday.

More than 48 hours after the vessel vanished, many troubling questions remain.

Why did the submersible go offline?

The Titan uses two systems to communicate with its surface ship. Text messages can be sent back and forth, and safety pings are emitted every 15 minutes to indicate the sub’s location and that it is still functioning.

Both systems stopped working about an hour and 45 minutes after the Titan submerged on Sunday morning.

According to its website, OceanGate developed a Real Time Hull Health Monitoring (RTM) safety feature that assesses the integrity of the Titan’s hull throughout every dive.

The technology can likely gauge any weaknesses in the Titan’s carbon fibre hull and transmit the data to its five-person crew and the support ship on the surface.

The hull connects two titanium domes that are specifically built to withstand the extreme pressure from the weight of the water at 4,000m below sea level.

OceanGate Expeditions revealed earlier this month that Elon Musk’s Starlink satellite company was providing it with internet connection.

What could have happened to the Titan?

The sudden loss of contact by the Titan’s twin communications systems was an ominous sign, according to longtime tech journalist David Pogue, who travelled to the famous wreck site onboard the Titan in 2022.

“There are only two things that could mean. Either they lost all power or the ship developed a hull breach and it imploded instantly. Both of those are devastatingly hopeless,” Mr Pogue told CBC on Tuesday.

Alistair Greig, a professor of marine engineering at University College London, told the Associated Press that another possibility was a leak in the Titan’s pressure hull.

If the vessel had reached the ocean floor and couldn’t return on its own, “options are very limited,” he said.

“While the submersible might still be intact, if it is beyond the continental shelf, there are very few vessels that can get that deep, and certainly not divers.”

Underwater currents

Another possibility is the Titan came into contact with the wreckage of the Titanic, and became stuck or had its onboard systems disabled.

The period between entering the water and when it lost contact would roughly correspond to the length of time it would take to reach the wreckage site.

Former ABC News science editor Michael Guillen, who was the first journalist to visit the Titanic wreck site in 2000, shared his own near-death experience after the submersible he was in became caught in an underwater current.

Mr Guillen said a strong ocean rip pushed the vessel towards the Titanic’s 21-tonne propellers, and became wedged under its stern.

The crew of the Mir 1 submersible then frantically tried to reverse out, and appeared to collide with the famous shipwreck.

After 30 minutes of moving backward and forward, the crew eventually managed to free the vessel and return to the surface.

Mr Guillen later wrote in his 2021 memoir Believing is Seeing that he thought he was going to die.

The Canadian military has dropped sonar buoys into the water that would likely be able to detect distress signals made by the five-person crew, if they hadn’t been incapacitated.

What emergency options would the vessel have to float up?

The Titan had seven onboard backup systems to return it to the surface. These included “drop weights” of sandbags and lead pipes that would fall off in the event of an emergency and bring the vessel up to the surface using buoyancy.

The Titan was also equipped with an inflatable balloon that was designed to bring it back to the surface. One device is meant to work even if everyone aboard is rendered unconscious.

“If there was a power failure and/or communication failure, this might have happened, and the submersible would then be bobbing about on the surface waiting to be found,” Professor Grieg told the AP.

The US Coast Guard has said it is searching a vast 10,000sqm area, indicating that searchers believe the vessel may have resurfaced somewhere in the North Atlantic.

However, extensive search efforts have so far failed to yield any trace of the Titan.

Can the passengers be saved if the vessel is found?

David Concannon, an adviser to OceanGate Expeditions who was supposed to be on the latest expedition, said officials are working to source an unmanned vehicle that could reach the 4,000m depth.

The crushing pressure of the ocean at that extreme depth means that an unmanned vehicle such as a US Navy’s Curv-21 would realistically be the only vessel that could reach the missing submersible.

The Curv-21 can reach a depth of 20,000 feet and relay video, navigation and sonar data back to operators on the ocean surface via its fibre-optic “umbilical cord”, according to the US Navy.

French president Emmanuel Macron has also sent the research ship Atlante to assist in the search, CNN reported.

The ship is equipped with an underwater robot that can reach depths of 4,000 metres, and is expected to reach the site on Wednesday evening.

In 1973, two British sailors were rescued from a depth of 487m (1,600 ft) after becoming stranded in a six-foot steel ball.

The survivors had 12 minutes of oxygen remaining when they were finally pulled from the sea, according to the BBC.