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Remote Sensing

Titanic: the optics of undersea discovery

Underwater camera systems and sensors have advanced steadily since the wreckage was discovered in 1985.
12 April 2012, SPIE Newsroom. DOI: 10.1117/2.2201204.01

In 1985, RMS Titanic, in pitch blackness two miles deep in the Atlantic, was first spotted by a towed camera sending up a TV image in simple black and white. It was live, sharp and sensational. And it opened a chapter in oceanography and optics that's still unfolding in an era of 3D, high-definition and wide-angle deep-sea images, including submersible 3D microscopes.

The feat, overcoming obstacles like pressure and marine snow, connected the crew of about 70 on the 244-foot oceanographic research vessel Knorr with the quiet scene on the ocean floor, a tribute to underwater explorer Robert Ballard and his team.

Mir 2 on the bridge of Titanic (Emory Kristof/National Geographic Stock)

Mir 2 lights expose the bronze telemotor once used to operate the steering gear on the bridge of the RMS Titanic. Click to enlarge (Emory Kristof/National Geographic Stock).

Now, fast forward to 2012.

Just days before the 100th anniversary of the April 15 sinking of the Titanic, a colleague of Ballard, Dwight Coleman, was in Rhode Island watching color images fed by a robot exploring the Gulf of Mexico, and observed, "Well, that's a crab." By contrast to Ballard's awesome discovery, it was an ordinary day for Coleman, a research scientist at the University of Rhode Island and Director of the university's Inner Space Center, which creates real-time connectivity, or telepresence, between scientists on shore and remotely operated vehicle systems on research ships.

The people who helped to shape the new era should take a bow. 

One of them is Bill Lange. He was looking at the screen on the Knorr that night in 1985 when he shouted, "It's a boiler!" and the word "boiler" echoed as celebrations began. The Titanic had been sighted, 73 years after it sank. Later Lange started the unit at Woods Hole Oceanographic Institution (WHOI) called the Advanced Imaging and Visualization Laboratory.  "We had to put together a better underwater camcorder that could deliver," he said. "If something was not available, we needed to build it."  Over a 30-year stretch, Lange has been designing ways to improve deep-sea images. "We've gone from low-quality color cams to broadcast quality.  It's a great leap. We've just gotten better and better."

Video monitor showing Titanic wreckage. (Simon Mills by arrangement with the Lone Wolf Documentary Group, ME)

Video monitor showing Titanic wreckage. Click to enlarge (Simon Mills by arrangement with the Lone Wolf Documentary Group, ME).

Another pioneer is Jules Jaffe. He was an assistant scientist at Woods Hole in 1985, bringing a background in image processing from Silicon Valley. Now he runs the Jaffe Laboratory for Underwater Imaging at Scripps Institution of Oceanography at the University of California, San Diego.  "The genius of Ballard is that he knew how to use light to take pictures in the deepest ocean," Jaffe recalled.  "Before that people were using a 35-mm camera system to survey hydrothermal beds but there was no real-time telemetry. You would just send it down, tow it around like a dog on a chain, bring it up and develop the pictures, and that's what you saw, half a day later." With Ballard's system, "You drove around on the surface, watching TV."

Yet another pioneer is Dwight Coleman, the seagoing oceanographer who has worked with Ballard for 12 years and 20 expeditions. Among the challenges at Titanic's depth is enormous pressure, 5,283 pounds per square inch at 12,000 feet. "It's like an elephant on your thumb," Coleman said. "We use titanium housings with special glass lenses and seals to withstand it." At sea, steel-armored cables today have three fiber-optic cables and copper for power, Coleman said. He works with engineers who custom-design the cameras, with the work done by Insite Pacific Inc. (Solana Beach,  CA). For lighting, today's systems use two 1,200-watt HMI (hydrargyrum medium-arc iodide) lamps with electronic ballast to eliminate flicker (see image below). Seeing things under water is like driving in a fog bank; turn on your brights and all you see is fog. Thus a car's fog lights are set low.  On later trips to Titanic, lights and camera have been on separate vehicles, reducing fog, or backscatter. "We are creative in many ways," Coleman said.

1200-Watt HMI light from DeepSea Power & Light

A 1200W HMI light of the type used on Titanic missions, from DeepSea Power & Light (San Diego, CA).

The 1985 Milestone

In 1985, most optical surveys were carried out by submersibles that towed sleds with strobe lights, film cameras modified to work at up to 6,000 meters, and limited wide-area imaging.  "It was very simplistic," Lange said. The strobes fired, triggered by the camera lens. Images were taken every 20 seconds.  After 20 hours, the vehicle was recovered, the film was processed and analyzed. "You got to see where you had been a day or so before," Lange said.

The Ballard group at Woods Hole engineered a live TV feed to the surface. The cameras were fixed on an aluminum sled called the Argo, about 15 feet long, 4 feet high and 4 feet wide, with 35-mm cameras and a side-scan sonar.  The sled was attached by RG8 armored coaxial cable. The technological milestone was that the Argo could deliver sonar and a channel of black-and-white video live, while taking 35-mm still pictures.

As the Argo was towed ("flown" was Ballard's fanciful word) back and forth, it used an ultra-light-sensitive video camera with a silicon-intensified tube, or SIT, placed in water-tight housings. "It had good sensitivity for very dim conditions," Jaffe said.

In the Titanic search, Ballard collaborated with a French team using sonar. (The approach is powerful. Jaffe recalled that in 2011 a Remus 6000 underwater vehicle used sonar imagery to locate the wreckage of Air France 447, lost in the Atlantic in 2009 about 2.5 miles deep.) Sonar can see about 300 meters. "You can map everything all around an area and look for an anomaly, and that becomes your target," Jaffe said. "Then you go back with an optical imaging system and verify it."

But in the Titanic search, the French survey of the ocean floor didn't come up with much. "Their system didn't work well," Jaffe said. "They did see something, maybe some aberration. They kept mapping, and at the end of three weeks, they had no idea where the Titanic was."

Ballard then started mapping in the same places, Jaffe said, switching from sonar to visual monitoring.  "And after five to seven days or so, they run over this 20-foot boiler," he said. Most accounts, Jaffe said, remain a mix of legend and reality. "The reality is, Ballard's team ran over a boiler on the fifth to seventh day. They found it." And that showed that acoustic monitoring systems can't approach the fidelity or clarity of a good imaging system, Jaffe said.

Submersible Hercules exploring the deep (University of Rhode Island)

Remotely operated vehicle Hercules exploring the deep. Equipped with a sensor array consisting of a pressure/depth sensor, altimeter, and Doppler, Hercules can conduct a variety of precision documentation functions. Click to enlarge (University of Rhode Island).

Mir submersible (Simon Mills by arrangement with the Lone Wolf Documentary Group, ME)

One of the Mir submersibles featured in James Cameron's 1997 movie Titanic, currently slated to give tourist dives to the site. The Mirs were chartered by the Lone Wolf Documentary Group in August 2005 for a History Channel project. The cameras were supplied by WHOI. Click to enlarge (Simon Mills by arrangement with the Lone Wolf Documentary Group, ME).

The Future

Since 1985, researchers have been improving the optical performance of deep-sea camera systems. Starting in the late 80s, cameras have used optically corrected domes. "There was no need to do any lens correction," Lange said. "The lens and the view ports were coupled so they worked very efficiently."

The sensors have been constantly improving. In 1985, systems did one color with internal recording. By the 1990s, they were able to do produce broadcast-quality images of Titanic.  "We improved the lighting technology, the telemetry systems, the optics," Lange said. "From there we went on to 3D, and 3D HD, and even ultra-high-definition imaging systems."

"All of the 3D modeling, the mapping work, that's really set a whole new level of detail," Lange said. The breakthroughs have applications in both deep-sea mapping and documentary film making.

For example, Lange's lab can take the systems in a large Sony studio HD camera and redesign it to fit in a six-inch cylinder for deep-sea use. "We redo the power supply, the telemetry, the optics. We can take a sensor as good as the best used in broadcasting and modify it to work in the deep sea. That involves reprogramming the color response tables."

Lange's lab has come up with small high-resolution 2D and 3D cameras that can fit in the palm of your hand and work over 60 miles of cable.  "We have a symbiotic relationship," Lange said. "We pair science with the needs of filmmakers."

Lowering a camera into the water off the coast of Greece (Simon Mills by arrangement with the Lone Wolf Documentary Group, ME)

Lowering a camera into the water off the coast of Greece during the exploration of the Britannic, sister ship to Titanic that was sunk during World War I. Click to enlarge (Simon Mills by arrangement with the Lone Wolf Documentary Group, ME).

On another frontier, the Jaffe lab is working on submersible tools to study the microscopic creatures between the surface and the ocean floor. He received a $1 million grant from the W. M. Keck Foundation to create a 3D video rate underwater microscope to count - but more interestingly, observe - the behavior of organisms as small as tens of microns that make up 90 percent of the biomass of the oceans. (See SPIE Newsroom video: Jules Jaffe's photonic tools explore the secrets of the ocean.)

Lange's lab is also working with the National Park Service and the National Oceanographic and Atmospheric Administration's marine archaeologists to turn the data from the Titanic site into an archaeological site plan.  "We want policymakers to understand the size and condition of the site so they can better protect it," Lange said.  His lab is working on converting 3D deep-sea cameras to produce images with the size and resolution of the Imax motion picture standards.

"Our goal for 3D camera systems is to put the public's mind in the deep sea, to make the technology seem transparent, with high-resolution sensors, better color, stereoscopic imaging," Lange said. "We want there to be no technology barriers to the public, and no distractions for a person doing quantitative analysis of the imagery."

(Research for this article was contributed by Eryn Burkhart, a graduate student at the University of California, Santa Barbara.)