Rescuers trying to save the missing Titanic submersible should commission the equipment that recovered the Apollo 11 engines in 2013, a longtime submersible diver and maritime lawyer urged authorities.
David Concannon, an adviser to the submersible's operator, OceanGate Expeditions, made a Tuesday evening Facebook post calling for the new gear.
"This is the type of equipment that needs to be on site but is not on site," Concannon wrote.
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Apollo 11 was the first spaceflight that landed humans on the moon.
Concannon, who's run multiple deep-sea expeditions and helped to recover artifacts from the Titanic, oversaw the recovery of the Apollo engines under Bezos Expeditions, which was created by Amazon founder Jeff Bezos.
According to Concannon's account of the 2013 expedition, his crew used two remotely-operated vehicles, or ROVs, that could operate at a depth of 16,000 feet. Both were developed by Schilling, a robotics company.
At least one of these was fitted with high-definition underwater imaging and lightning systems, per Concannon.
Footage of Concannon's team recovering an engine shows an ROV on the deep ocean floor, using twin metal arms to push aside sand and attach a cable to the engine.
Rescuers will likely require an ROV with similar capabilities if they aim to retrieve the missing submersible, which disappeared on Sunday afternoon on its way to the Titanic wreck some 13,000 feet beneath surface level. If the vessel is intact and still underwater, it's most likely to be sitting on the ocean floor.
With the crushing pressure at that depth, only an unmanned vehicle can hook the submersible so it can be hauled to the surface. A French ship, the Atalante, was dispatched to the Titanic wreck site with a robot that can operate at a depth of 20,000 feet and manipulate objects.
As of Wednesday evening, maritime data shows the Atalante has reached or is close to the search area.
But any hope of rescue still hinges on whether the submersible, called the Titan, is intact, and whether it can be found by Thursday afternoon Eastern Time - when the vessel's life support is expected to run out.
Officials will also need a lift system that can carry the submersible, which weighs 23,000 pounds, per OceanGate's statistics.
Meanwhile, Concannon has been aggressively championing optimism for the survival of the five people on the Titan.
He accused US officials on Tuesday of a lackluster response and a delay in rescue efforts, saying he was met with out-of-office email replies when trying to contact key decision-makers.
"The same group, the experts, that did the advanced survey of the Titanic last year - they are mobilized," Concannon told NewsNation. "They're sitting on the tarmac, ready to go. We have a ship off Newfoundland that is ready to take them to the site."
Five people were on board the Titan when it went missing: OceanGate CEO Stockton Rush, French explorer Paul-Henri Nargeolet, British adventurer and billionaire Hamish Harding, and British-Pakstiani businessman Shahzada Dawood and his 19-year-old son, Suleman.