Early in the morning of April 15, 1912, the world's largest ocean liner slipped beneath the icy waves of the North Atlantic, carrying 1,500 people to their graves. For decades, the shipwreck remained hidden - but how did they find the Titanic?
Treasure hunters searched for the ocean liner for years, hoping to find valuable items that sank with the Titanic. But in 1985, oceanographer Robert Ballard successfully found the Titanic on a scientific mission. Or, at least, that's what he told the press. The mission was "strictly scientific," one scientist told The New York Times in 1985. In fact, the search for the Titanic was actually a cover story for a secret Cold War mission.
Ballard discovered the ship's final resting place using a new technology: an undersea robot that could sweep the seafloor for weeks, transmitting pictures to a team of scientists on the surface. The US Navy funded the technology not to find the Titanic but to search for two sunken nuclear submarines. For decades, Ballard provided the perfect cover for the secret mission.
Robert Ballard spent years earning doctoral degrees in marine geology and geophysics. He helped design a manned submersible named Alvin to explore the deep sea. Ballard also helped discover the first hydrothermal vents in the Pacific.
But for Ballard, his life goal was discovering the wreckage of the Titanic.
“I always wanted to find the Titanic," Ballard said. "That was a Mt. Everest in my world - one of those mountains that had never been climbed.”
In the 1980s, Ballard had a chance to search for the Titanic and he partnered with a surprising group: the US Navy.
The Navy had no interest in finding the Titanic - but they did want to find two submarines that sank in the 1960s.
The USS Thresher and the USS Scorpion both went down in the North Atlantic - and both carried powerful nuclear reactors. The Navy wanted to know whether the Soviets had shot down the subs and whether their nuclear material remained 15,000 feet under the sea.
In the early 1980s, Robert Ballard asked the Navy to fund the Argo, which could take pictures at a depth of 20,000 feet. To Ballard, the Argo would allow him to finally find the Titanic. But the Navy saw another purpose for the robot. It could photograph the nuclear subs. The Navy agreed to secretly fund the project - if Ballard could map the sunken subs.
In 1985, Robert Ballard set out on a covert Cold War mission to find a sunken submarine. But publicly, Ballard said he was simply looking for the Titanic.
After he found the wreckage of the USS Scorpion, Ballard had just 12 days left in his mission to find the Titanic. To search for the sunken ocean liner, Ballard teamed up with the French Research Institute, which scouted the area where Ballard believed the Titanic sank more than 70 years earlier.
However, the French research team had spent five weeks trawling the sea without finding anything. Ballard would have only a fraction of that time to locate the Titanic.
Locating the Titanic posed an enormous challenge because no one knew exactly where the ocean liner struck the fateful iceberg.
Around 11:45 pm on April 14, 1912, the Titanic collided with an iceberg. But the ocean liner's last fixed position had been recorded four hours earlier. When the Titanic sent out a distress call, it only gave an inexact position. The estimate, based on the last fixed position, the ship's direction, and the distance the crew assumed the ship had covered, wasn't exact enough to pinpoint the location.
In addition, no one knew exactly how far the ship moved after making impact.
As a result, decades of searching for the Titanic wreckage turned up nothing until Ballard's 1985 expedition.