By Claire Discenza
“This is the week of the 100th anniversary of the Titanic (sinking),” said Scripps Institution of Oceanography researcher Jules Jaffe to a packed foyer at the Birch Aquarium. “And I know a lot of people have come primarily to hear about my involvement in that.” At the Jeffrey B. Graham “Perspectives on Ocean Science” lecture on April 9, Jaffe gave the audience just that.
In his talk, “Underwater Imaging: From Titanic to the Tiny,” Jaffe reviewed the optical imaging systems he helped develop to explore everything from large undersea wrecks to miniscule microbes.
While Jaffe stressed the importance of studying the “little guys” of the ocean — the zooplankton, phytoplankton and microbes that make up the majority of marine biomass — he started his talk on a much grander scale.
Jaffe began by explaining how technology plays a role in the difficult task of finding a shipwreck. The strategy that explorers and scientists use to locate any undersea rubble involves two phases: an audio search followed by a visual search.
As sound can travel farther underwater than light, it is most efficient to start by sending high-frequency sonar pulses out into the ocean. By recording the returning sound waves after they have bounced off an object, or “contact,” researchers can make rough sonic images of the ocean floor.
When looking for something like the Titanic, researchers have to be thorough. “What you want to do is map a pattern with sonar to methodically go back and forth and find contacts that are potentially the Titanic,” Jaffe said. “We call it ‘mowing the lawn.’ ”
Jaffe showed a sonic image of one of these contacts, a fuzzy picture with a small speckling of dots in the center. “It turns out that inherent in the process of forming a sonic image is something called ‘speckle.’ It has to do with the fact that sound is almost like laser because it is very coherent. That means all the waves line up together,” he explained.
“You might look at that image and ask: ‘Oh my gosh, how did they figure out that was a wreck?’ It turns out that researchers cannot be sure this image is of anything of interest — instead, a sonic image simply gives a search team an inkling that there might be something out there. The team can then go back to search the contact visually with optical imaging. The optical imaging system uses what most of us know and love to do — to see.”
Jaffe helped design this optical imaging system that found the Titanic nearly 30 years ago. He got involved in maritime archaeology after a chance meeting with Robert Ballard.
“I meet this guy [Ballard], and I realize very quickly that he wants to be the most famous ocean explorer ever,” Jaffe reminisced. “He says to me: ‘I want to find the Titanic.’ And what do I think but ‘yeah right.’ So I was wrong.”
Jaffe helped Ballard understand the physics of deep-sea light propagation by working with the Visibility Lab at Scripps Institution of Oceanography, the world’s experts in underwater imaging at the time.
With Jaffe’s expertise, Ballard’s team built “Argo,” a submersible sled-mounted video camera that could be pulled along the bottom of the ocean floor for hours, sending live feed for researchers to examine in real time. After a first-pass sonar search in collaboration with the French oceanographic institute IFREMER, it was with Argo that Ballard was able to finally identify the remains of the Titanic.
“I didn’t go with Ballard on that trip, and in principle I don’t regret it,” said Jaffe, wistfully remembering the day Ballard found the wreck. “I wasn’t interested in finding the Titanic, I was interested in the technology.”
In the 25 years since the discovery of the Titanic, Jaffe has used optical technology to see much more than metal at the bottom of the ocean. Today, he develops instruments to study how squid vision is adapted to dark waters. “There are experts in underwater imaging,” Jaffe pointed out. “It just happens that they aren’t people, they’re animals.”
Jaffe’s team has also set up an autonomous profiler deep under the surface of the ocean. The profiler is fitted with cameras to take pictures of tiny micro-organisms, ranging in size from micrometers to inches. These images capture minute details that can only be seen in the wild and not in captive species, emphasizing the importance of studying these organisms in their natural habitats.
“One of my goals is to garner appreciation on your part of the smallest things in the ocean and to highlight how important they are in our global ecology,” Jaffe said. “I would be remiss as a scientist if part of my mission was not to enlighten people about things we find fascinating.”