Even though National Geographic Explorer-in-Residence James Cameron successfully piloted a submersible—the DEEPSEA CHALLENGER—on the first solo dive to the deepest known part of the Earth’s ocean on March 26, 2012, the expedition was not without difficulties. The preparation and descent, nearly 11 kilometers (7 miles) to the Mariana Trench’s Challenger Deep, presented challenges and unforeseen complications for DEEPSEA CHALLENGE engineers and scientists.
For instance, the sub’s arm started to lose power due to a hydraulic leak. This was not a major failure, but still caused Cameron to leave the ocean bottom earlier than anticipated.
Yet Cameron realizes these setbacks are essential to science and exploration.
“People think that when an experiment doesn’t give the result that the hypothesis stated going in, that it’s a failure,” he says. “It’s not a failure! It’s an opportunity to learn. You know, we just learned something even though it didn’t happen the way we thought. So it’s part of [the scientific method].”
Learning from the Past
While designing DEEPSEA CHALLENGER, Cameron and his crew looked at the problems other ocean explorers encountered on deep-sea missions. Specifically, they looked at the difficulties faced by retired U.S. Navy Capt. Don Walsh and Swiss oceanographer and engineer Jacques Piccard when they reached the Challenger Deep in 1960. On that mission, their vehicle—the bathyscaphe Trieste—kicked up so much sediment that they could barely see anything on the ocean floor. The silty situation forced the explorers to leave after just 20 minutes.
Cameron says he and his team designed the DEEPSEA CHALLENGER with the experiences of Walsh and Piccard in mind. They built the sub so the thrusts from its propellers would not stir up silt on the ocean floor. Cameron also realized he would have to pilot the sub in a way that would minimize its disruption of the seafloor.
During Walsh and Piccard’s 1960 descent, their sub’s window actually cracked due to the intense underwater pressure. Cameron and his team took this into account, and created glass-based syntactic foam that allowed the vehicle to compress under the ocean’s pressure.
“We knew that was going to be a problem on our sub,” Cameron says. “Our whole sub would shrink by 3 inches overall . . . It was 24 feet long, and it would get 3 inches shorter by the time it got to full ocean depth . . . [W]e had to design every fastener, every hole that a bolt went through had to be slightly oval in shape so that the bolt could move in the hole as everything shrank at a different rate . . . [T]he outer shell would shrink at a different rate than the frame underneath it . . . [T]he whole sub was sort of breathing in this organic way.”
Anticipating New Challenges
Cameron says planning for possible failures in any exploration is important. When he lost the ability to control the sub’s arm, for example, it was impossible to collect any more samples from the seafloor. Fortunately, the DEEPSEA CHALLENGE team had a contingency plan.
“I had already taken one sediment sample, so we had a sediment sample,” he says. “I did that the second I got to the bottom, just in case something like that had already happened. We think about all these things. We think about what the likely failures might be. Well, what if you have a hydraulic failure, and you can’t take a sample? Take the sample as soon as you get there. That was our plan. Just like when the Apollo astronauts landed on the Moon. The very first thing that they did was pick up a rock. . . . They call it a contingency sample.”
Before the DEEPSEA CHALLENGER takes another dive, Cameron and his crew will analyze all the difficulties they faced on the last expedition.
“We now have to go back and review what didn’t work in the technology,” he says. “Why did the machine not behave or not do what it was supposed to do? Sometimes it is simple—it’s weather, it’s sea state, something breaks. Sometimes it can be much less obvious—a problem in the electronics or maybe even a problem in the way that we’re operating the submersible. But you build on your knowledge . . . This last expedition was my eighth, so in the previous seven expeditions, I learned a lot and my team learned a lot about what technologies work and what doesn’t work.”
Cameron even sees some silver lining in the problems he encountered.
“You don’t know what the failures will be, but you can assume there will be failures throughout or on every dive,” he says. “A light will fail, a thruster motor will fail, and the hydraulics may have problems . . . You can’t do everything on one expedition. That would take all the fun out of it!”
