Thanks to recent advances in technology, marine archaeologists are finally able to make a full 3D map of the world's most famous shipwreck more than 25 years after its discovery.
RMS Titanic will never be raised from her resting place two and a half miles down. She can however be raised virtually for all to explore thanks to a new 3D map. April will see the first release of a 'virtual' Titanic, an enormously detailed interactive 3D map that will allow those of us who cannot afford $60,000 for a submersible dive an experience similar to diving down two and a half miles to the wreck itself.
A full century on, Titanic continues to fascinate as a tale of hubris and disaster, and it seems incredible that the site has not been rigorously mapped since its discovery by Robert Ballard in 1985. The reason is simple: it was impossible. The suite of technologies required to do it to marine archaeological standards at great depth has just not been available. James Delgado, chief scientist and principal archaeologist on the Titanic mapping project at the US National Oceanic and Atmospheric Administration federal agency (NOAA) explains why: "Ideally we would have done this after Ballard discovered the site. But we had no GPS, no GIS systems to hold the surface support vessel stationary, and no autonomous underwater robots. We also lacked the vast computing power required to stitch together the terabytes of data."
Beginning the scan
Portions of the wreck were relatively well known, especially the bow section, but no comprehensive and systematic approach had ever been attempted.The detailed mapping took place on a 2010 expedition sponsored by salvor RMS Titanic Inc, and co-led by David Gallo, special projects director at Massachusetts-based Woods Hole Oceanographic Institute (WHOI). At an estimated cost of $5m, the expedition team used two REMUS 6000 Autonomous Underwater Vehicles (AUVs) owned by the Waitt's Institute for Discovery and operated by Woods Hole.
First, a series of deep-ocean transponders were deployed on to the seabed to enable the AUVs to navigate accurately. The vehicles communicated with these via sonar, and cross referencing allowed the robots to determine their own position. The initial survey required the AUVs to swim over a 10-square-mile area to identify areas of specific interest for inspection. In a series of 18-hour dives the bright yellow robots, named Ginger and Mary Ann, scanned the sea floor in spaced lanes, criss-crossing the area, or 'mowing the lawn', as Delgado calls it, before surfacing to report their findings to the mother ship. From the preliminary survey it was clear that over 50 per cent of the shipwreck site was totally unknown and had never been explored.
The first sweep of the site was conducted using sidescan sonar mounted on the AUVs, placing the wreck in the context of the general geology of the seabed. Sub-bottom profilers enabled penetration of the sea floor as parts of the superstructure are submerged in the sediment. These were needed to characterise the state of the bow section, which is buried up to 20m into the sediment.
Simultaneously, downward facing digital'cameras synced'> with strobes firing 10m above the seafloor, fired from the underside of the AUVs and generated what Gallo calls a 'Google Earth' type view of the site. Once the main areas of interest had been identified by the AUVs using the sonar sensors, the modified Remora ROV, a remotely operated vehicle piloted from the mother ship was sent down to join the AUVs. This small robot was attached to the ship by three miles of fibre optic cable and transmitted advanced live 3D imagery to the team to form the bulk of the data that will be launched online.
Gallo says: "To have two AUVs and an ROV in the water, two and a half miles down, was brand new." The three robots added to the complexity but greatly enhanced the efficient use of ship time, which was especially important since two consecutive hurricanes, Danielle and Earl, caused the team to abandon the site for over a week.
Completing the picture
Bill Lange is a key member of the mapping team and a research specialist and head of the advanced imaging and visualisation lab at WHOI. He was on watch as the original team searched for the wreck during the 1985 expedition. "After seeing nothing but fish for weeks, we started to see objects from the debris field and had a bit of a debate as to when to wake up Ballard. From there on, the rest is history. We were a ship full of engineers and scientists and everyone was excited by the discovery, but nothing prepared us for the world reaction," he says.
Lange is responsible for the gathering and processing of all the visual data gathered by eight cameras deployed on the wreck both on the AUVs and on the tethered ROV. Everything from 2D cameras and HD video to'3D IMAX cameras were deployed to bring the site to life in high definition. Lange's work has been key in the intervening two years since the expedition, post-processing and integrating the sonar maps with visual and geological data. Individual images are stitched together in a mosaicking process to create large-scale, almost panoramic views of the wreck.
"We have an image of everything. That's what's important," says Lange. "This has never been done before in the deep sea. Some of the images capture huge boilers and engines seemingly frozen in time as they rise from the ocean bottom." The completed map will show close-ups of the many artefacts, and wide-angle, high-altitude views of the bow, stern and the large object field to the east of the stern.
The imagery is so good that Delgado is certain that the map generated from the 2010 expedition will allow on-going archaeological investigations of the site.
"What we now have is a clear idea of what caused the transition from ship to shipwreck in a forensic sense," says Delgado. "The visualisations show us everything from a tea cup to a crab on the hull."
His team's job has been to categorise and assign coordinates to every object. The 5,500 objects to be auctioned in April represent a fraction of 1'per cent of what has been found. Delgado likens it to a airline crash investigation. The very first underwater archaeology only took place 50 years ago.
Dave Conlin, chief of the US National Parks Service, Submerged Resources Centre in Colorado, is a marine archaeologist and is part of the team analysing the cruise data and contributed to the design of the research objectives for the mission. He says: "The idea that Titanic ruptured, spewing objects over the sea floor, is incorrect. Millions of artefacts remain inside the structure in a tremendous state of preservation and open up the possibility for further research."
Delgado has a keen interest in those who did not survive the sinking, especially those third class, steerage passengers and the crew, about whom relatively little is known. "Future study of their baggage, which is likely to have survived more or less intact, would give us a better sense of those people, enabling us to give voice to those who were seemingly erased from history or silenced by the events of that night, and the cold dark waters of the North Atlantic.
"Titanic was a short-lived, floating community that ended suddenly and with as well preserved a record as Pompeii." There are no plans for future expeditions but Delgado feels we need to know more about the basic oceanographic conditions prevailing at the site, more sediment and corrosion studies, and a better understanding of the environmental factors. These might answer key archaeological questions regarding change and the nature of preservation at the site, and could help in the exploration of other, more historically important, older shipwrecks.
As for the much discussed imminent demise of the wreck under the onslaught of rust-munching bacteria, Conlin says: "The wreck has been degrading gradually over the past 100 years. There is no evidence to support a dramatic change in the environmental conditions which would change this. The wreck is a very complex structure made up of many different materials and is sure to be around for many years to come."
Materials scientist and metallurgist Tim Foecke of the National Institute of Standards and Technology agrees: "We have been studying the steel recovered from the wreck extensively. The bacterial colonies, called 'rusticles', are changing the environment on the hull, but the ship is rusting at a rate expected for being in seawater. The excitement comes because the wreck is in a deterioration midlife crisis. Things are starting to collapse, and in a couple of decades it will have folded in upon itself and will stabilise again, and in a century or so will reach its final state, an iron ore deposit."
Cynics might speculate that the hype about the wreck's rapid deterioration is timed to coincide with the upcoming auction, but it is clear that the ship can still exert a strong fascination. "Titanic is the Mount Everest of underwater archaeology, the most famous shipwreck on the planet, and it's been a terrific privilege to have been part of a very talented team," says Conlin.