Rescuers trying to find a submersible that disappeared on a dive to the wreckage of the Titanic are not only racing the clock as the sub’s oxygen supplies dwindle — they are also battling a harsh and unforgiving environment more akin to outer space than most places on Earth.
“It’s pitch black down there. It’s freezing cold. The seabed is mud, and it’s undulating. You can’t see your hand in front of your face,” historian and Titanic expert Tim Maltin said in an interview with NBC News Now. “It’s really a bit like being an astronaut going into space.”
The deep-diving 22-feet submersible, operated by OceanGate Expeditions, vanished Sunday with five passengers on board, setting off a frantic rescue mission over a stretch of the North Atlantic Ocean roughly 400 miles off the coast of Newfoundland, Canada.
But unlike space, humanity's presence deep in the world's oceans is minimal, and the technology for search-and-recovery missions is limited.
Coast Guard officials estimated Tuesday afternoon that there was “about 40 hours of breathable air left” on the missing vessel. The Coast Guard is working with the Navy and Canadian partners in the search, and some civilian research vessels are also rushing to the site to volunteer their efforts as well. The French government on Tuesday said it will send a ship with a deep-diving vessel onboard to assist the search-and-rescue operation, as reported by Reuters.
Follow live updates about the missing Titanic sub here
The sub’s oxygen supply is the most pressing factor in the search, but it’s hardly the only challenge, said Jamie Pringle, a professor of forensic geosciences at Keele University in the United Kingdom.
Scouring such extreme depths is challenging because the seafloor is more rugged than land, he said. The remains of the Titanic, which sank more than a century ago, settled at a depth of around 12,500 feet.
“The bottom of the ocean is not flat — there are lots of hills and canyons,” Pringle said, adding that if the submersible is stranded on the seafloor, it’s going to be “really difficult” to locate it there.
Even searching in and around the wreckage of the Titanic is tricky because it’s such an expansive site, he said. Coast Guard officials said Tuesday that the search has been focused on an area of the North Atlantic roughly the size of the state of Connecticut.
A full-size digital scan of the Titanic’s remains, released last month, revealed that the ship’s two main pieces are about 2,000 feet apart and surrounded by debris.
These kinds of rescue efforts are also challenging because very few vessels and instruments are able to work at such extreme ocean depths.
“They have to be designed to withstand those depths and the pressure,” Pringle said.
At the depth of the Titanic wreck, the pressure would be around 400 times greater than at sea level, according to the Woods Hole Oceanographic Institution.
Some nuclear-powered military submarines are capable of diving up to 1,600 feet, but most modern subs operate at much shallower depths.
"Not too many things can go that deep," said Henry Hargrove, a senior analyst at the Rand Corp., who served in the U.S. Navy for 11 years.
Rescuers have deployed several C-130 aircraft to conduct aerial surveys of the site, and sonar buoys that can pick up signals to a depth of 13,000 feet are also being used to search underwater.
Pringle said, however, that sonar systems typically need to sweep at greater depths to detect something as small as a submersible within the huge debris field of the Titanic.
“If you’re using a sonar system [at the surface], your footprint is going to be quite big because it’s high above the sea floor,” he said. “The lower down it goes, the smaller the footprint and you have a better chance of finding something.”
Pringle said it's difficult to speculate about what went wrong aboard the missing submersible but added that there could be additional challenges even if it is found soon.
It’s unclear, for instance, if a rescue craft capable of reaching such depths of the ocean can be deployed in time — or how the stranded craft could be retrieved.
Submersibles like the ones used by OceanGate Expeditions usually don’t have mechanisms on their hulls that another vessel can lock onto for a submarine-to-submarine rescue, Pringle said.
For those onboard, there’s likely not much they can do but try to remain calm and conserve oxygen, Hargrove said.
“But it’s very challenging for people to stay calm, especially in this kind of situation,” he said. “At that depth there aren’t very many rescue options. When you’re disconnected from the ship above, you’re by yourself.”
