All of the ships involved in the search for the missing Titan submersible are now in place, including one carrying a robot that can dive to 6,000 m (19,600 ft).
Maritime traffic in the area of the Titanic wreck in the North Atlantic shows the ship is in position as the race against time draws to a close.
The submersible, which went missing on Sunday, is expected to run out of oxygen at noon UK time today.
Titanic number search – follow real-time updates
Ships heading to the search area Thursday morning included the French research vessel Atalante, which is carrying a deep-sea robot called Victor 6000.
It has a remote-controlled arm that can cut cables and perform other maneuvers to free trapped ships – and its 6,000m dive capability means it can go deeper than the Titanic itself.
The famous wreck to which the Titan went is located at a water depth of approximately 3,810 meters (12,500 feet).
Operated by a crew of 25, the Victor 6000 “can work non-stop for up to 72 hours,” says Olivier Lefort of Ifremer, the French state-run research institute that operates the robot.
“Victor was able to visually explore with all the video equipment he had,” said Mr Lefort of the team that discovered the Titanic wreck in 1985.
“It’s also equipped with a manipulator arm that can be used to free the sub, for example by cutting a cable or something blocking it at the bottom.”
How “ROV” joined the search
Victor wasn’t the only remotely operated vehicle (ROV) called in since the Titan went missing on Sunday.
Some of the first responding ships brought others to the scene earlier this week.
As the name suggests, they are then operated remotely from surface ships. Most are equipped with cameras and lights to send live images back to the ship.
The Canadian vessel Horizon Arctic deployed the ROV that had reached the seafloor in search of the submersible, with the Victor 6000 not far behind.
Their search focused on areas where sonobuoys picked up the sound.
These devices are designed to use sonar to locate underwater objects and are deployed by Canadian P-3 aircraft.
Once deployed, inflatables with radio transmitters are placed on the surface, while equipment for detecting noise is strung along wires and lowered below the surface.
While officials said an investigation into the impact they heard was negative, experts said sonobuoys remained critical to narrowing the search.
Sonobuoys and their role in the Titan search explained
Underwater noises in the hunt for Titan – what do they mean for the search?
While ROVs can’t lift Titan to the surface on their own, they can help hook it to a boat on the surface.
To recover the sub, the search team has access to the Fly Away Deep Sea Salvage System (Fadoss), which arrived on the Horizon Arctic on Thursday along with several other ships.
Its winches and cables are long enough to pull something like a submersible to the surface, and it has a deep-sea lifting capacity of up to 27,200kg.