New Images Illuminate the Titanic


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Refined views of Titanic's bow (modeled) offer a comprehensiveness of detail never seen before. April 2012 issue of National Geographic Magazine. COPYRIGHT© 2012 RMS TITANIC, INC; Produced by AIVL, Woods Hole Oceanographic Institution; National Geographic Magazine

When the RMS Titanic left port from England 100 years ago, it was hailed as one of the most advanced vessels shipbuilders had ever produced, making the subsequent sinking all the more sensational. The first comprehensive map of the Titanic's underwater crash site, published in the April issue of National Geographic magazine, now may help experts answer some longstanding questions about the mystery of how such a ship could be punctured by an iceberg and sink so fast.

The mapping was done in a 2010 expedition to the wreck led by National Geographic, Woods Hole Oceanographic Institution, and the Waitt Institute of Discovery, La Jolla, CA. The three-dimensional map of a roughly 15-square-mile area was pieced together by engineers and scientists using remote- and autonomous-operated-vehicles working at 12,600-ft depths and fitted with sidescan sonar systems and cameras. For the first time, viewers can look at the wreck site as if the ocean were removed.

Remarkable Images

"The data is really pretty remarkable," says Michael Purcell, a senior research engineer at Woods Hole, who led the team that developed the autonomous underwater vehicles (AUVs), two Remus 6000s capable of diving to depths of 6,000 m. "This map gives information we've never had. It's a new capability to look at the wreck and give marine archaeologists and others a fresh look."

 
April 2012 cover of National Geographic
Image credit: National Geographic

To map the site, researchers used the Remus vehicles in tandem, "mowing the lawn" in a grid over a 3 x 5-square-mile area, using low-resolution sonar equipment. That was followed by high-resolution sonar used in mapping a smaller area that contains the wreck, roughly 1 x 2 square miles, or about the size of midtown Manhattan. After that, researchers used a remotely operated underwater vehicle (ROV) fitted with high-definition cameras to photograph debris-rich areas highlighted by the AUVs.

Going into the project, "We did not have a feel for how [the wreck] was laid out on the sea floor," says Purcell. "The AUVs were able to do that."

Close to Bottom

Purcell says the vehicles operated about 10 m above the sea floor, not getting too close to the main pieces of the wreck, the stern and the bow, which are separated by about 1,970 ft. He says the Remus 6000s followed a planned track "very accurately," swimming in rows about 5 m apart and working with transponders placed on the seafloor. They took overlapping images as they returned, swimming the tracks of the grid.

 
With her rudder cleaving the sand and two propeller blades peeking from the murk, Titanic's mangled stern rests on the abyssal plain, 1,970 feet south of the more photographed bow. This optical mosaic combines 300 high-resolution images taken on a 2010 expedition and published in April 2012 issue of National Geographic Magazine. COPYRIGHT© 2012 RMS TITANIC, INC; Produced by AIVL, Woods Hole Oceanographic Institution

This was not the first time underwater robots and submersibles had visited the site. It was first discovered in 1985 by explorer Robert Ballard. But earlier visits only recorded portions of the wreck, bringing disparate images and information back to the surface.

The high-resolution imaging came from a modified commercial ROV owned by Phoenix International, Largo, MD. Woods Hole scientists and technicians reworked the power system, telemetry, lighting, cameras, and flotation system and turned it into what is probably one of the world's best underwater, close-up, optical survey vehicles, says Bill Lange, head of Woods Hole's Advanced Imaging and Visualization Laboratory. Optical imaging was developed by Waitt researchers, he says.

But the project's biggest advancement was "to fuse sonar and optical data into a refined image," says Lange. "It is a hybrid of acoustical and optical mosaics. I am at a loss as to where this has been done to this degree [elsewhere]," he says.

Two Years in the Making

Lange says some real-time image processing was done on site while the underwater robots were working. But most of the enhancement was done at the lab after the cruise. There, scientists took the processed sonar images and the navigation data and reprocessed them to ensure accuracy. "Reprocessing the navigation data is critical" in searching for a specific area," he says. "For instance, it's important to know how straight the survey lines are."

Ethereal views of Titanic's bow offer a comprehensiveness of detail never seen before. The optical mosaics each consist of 1,500 high-resolution images rectified using sonar data, from April 2012 issue of National Geographic Magazine. COPYRIGHT© 2012 RMS TITANIC, INC; Produced by AIVL, Woods Hole Oceanographic Institution; National Geographic Magazine

The navigation and sonar images were then enhanced with 3-D imaging taken by the Phoenix ROV. Operators were reluctant to use the Remus robots close to the wreck, but the ROV was able to get close and move about the large pieces on the ocean floor. Those images "make it a lot easier to interpret [the wreck] and place it on a map," says Lange.

Besides the map, some of the most impressive images were put together from data taken by the twin Remus machines cruising over the top of the hulks, producing composite images of the entire bow and stern sections. Similar images were also produced in profile.

The work enhances efforts by the National Oceanic and Atmospheric Administration and the National Parks Service to develop a site formation plan in hopes of explaining how the ship broke apart, partly through where the pieces landed on the ocean floor. It also goes to continuing efforts to preserve the site as a cultural heritage site.

For the scientists at Woods Hole, the mapping and imaging is the latest remarkable success in underwater technology. The Remus used for the Titanic mapping was used in searching and locating Air France Flight 447, which crashed in the Atlantic Ocean in 2009.

It is a hybrid of acoustical and optical mosaics. I am at a loss as to where this has been done to this degree [elsewhere].

Bill Lange, head of Woods Hole's Advanced Imaging and Visualization Laboratory

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April 2012

by John Kosowatz, Senior Editor, ASME.org