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Back to the Challenger Deep

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Jacques Piccard (center) and Lieutenant Don Walsh (bottom) head down to the Mariana Trench inside the Trieste in 1960. Filmaker James Cameron made a return visit to the deepest piont in the ocean in March 2012. (Photo: NOAA)

On January 23, 1960, Jacques Piccard and a U.S. Navy officer, Lieutenant Don Walsh, made the first descent ever to the Challenger Deep, nearly 7 miles down in the Mariana Trench, the deepest place known in the ocean. It was frightening trip down, from rough seas into total darkness. At one point, as they were approaching the deepest point, they heard a load crack, which turned out to be the Plexiglas in the viewport cracking from the pressure of about 16,000 pounds per square inch. 

Later on the surface, having survived the trip and now lounging in the bathyscaphe Trieste, waiting for the tender to retrieve them, they wondered how long it would be before somebody repeated their adventure. They guessed maybe two years. They were only off by half a century. On March 25, 2012, filmmaker James Cameron performed a solo dive to the Challenger Deep in the vessel Deep Sea Challenger.

I was privileged to have a long phone conversation recently with Don Walsh, who was also a participant in the Cameron expedition. I asked what his role there was. "Oh, advisor, engineer...or ceremonial object," he responded with a flash of humor.

Lieutenant Walsh has long since become Dr. Walsh, with a Ph.D. in Oceanography. From 1975-1983, he was professor of Ocean Engineering at the University of Southern California, and since 1976, he has been president of his own consulting firm, International Maritime, Inc. 

Despite his impressive credentials, Walsh had no desire to replace Cameron as the pilot of the Deep Sea Challenger. He regarded Cameron as more than qualified, calling him "an intuitive engineer who knows the science." Cameron, of course, is no stranger to the ocean, having directed such epics as Titanic and The Abyss, in addition to the wildly popular Avatar. Cameron also co-produced the IMAX documentary Volcanoes of the Deep Sea, about hydrothermal vents, or as Walsh called them, "black smokers," around which an impressive variety of life forms have formed unique biological communities. 

The vents abound in the mid-ocean ridges. According to Walsh, this is where magma flow from the volcanoes forms new crust for the oceanic tectonic plates. Since the Earth is not expanding, as new crust is being continuously formed, it must also somewhere be folded back into the earth's mantle. This occurs at "subduction zones" in the ocean trenches. In the Mariana Trench, the denser Pacific plate is being shoved underneath the smaller Mariana plate. It takes about 200 million years for a portion of the crust to make the trip from the mid-Pacific to the Trench.

The main reason to visit the deep ocean trenches is that "We need to understand the mechanics of our planet," says Walsh. The friction between the plates is what causes devastating earthquakes, including the one that recently destroyed Fukushima, Japan, with the resultant nuclear catastrophe. The earthquake and tsunami of March 2011 was spawned in the Japan Trench.

There are no obvious easily-exploitable resources in the ocean trenches, which is probably why, like the moon, man has left them alone after the initial exploration. But there is life. Piccard and Walsh reported seeing a flatfish upon first arriving at bottom in the Challenger Deep, although many scientists still doubt that vertebrates can actually survive that deep. Snail fish (Pseudoliparis amblystomopsis) hold the record as the deepest fish recorded on camera. Shrimp-like crustaceans called amphipods sit in ocean deep and devour practically anything that drifts down from above. Sea cucumbers (holothurians) are probably the dominant life form in the trenches, thriving on organic material that they sift from the mud. Recently, giant multinucleated but single celled animals called Xenophiophores have been recently identified in the Marianas Trench by National Geographic researchers. These can reach 4 inches in diameter. 

In the April 12 issue of Science, Richard Lutz and Paul Falkowski discuss the potential biological riches of the deep ocean trenches. They point to the discovery of anaerobic bacteria called actinomycetes several kilometers deep in the South China Sea. Soil dwelling actinomycetes have given us streptomycin and other antibiotics. The challenges of living at great pressure and near freezing temperatures have forced organisms to develop unique biochemicals that might be basis for new pharmaceuticals or other valuable compounds.

One reason it has taken so long to return to the deep ocean is the lack of a suitable vehicle. The last bathyscaphe capable of venturing to the Challenger Deep was retired in 1977, according to Walsh. In these budget-restricted times, private industry is thankfully stepping into the gap left by governments. The Deep Sea Challenge project is underwritten by Rolex and the National Geographic Society, as well as through resources provided by Cameron, himself. The project required a vehicle that could safely transport a man to the ocean's deepest regions, a means of retrieving biologic and geologic samples, and of course, since James Cameron was to be the pilot, extraordinary lighting and photographic abilities, to make really great 3-D movies. The latter allows for more than just entertainment, however. Scientists should have the luxury of viewing details of underwater life and geology on 80 foot IMAX screens.

Unlike other submersibles, it is propelled through the water with its long axis pointed vertically. About 70 percent of the sub is filled with an epoxy resin syntactic foam (filled with glass microspheres) especially designed by engineer Ron Allum for the project. As in the Trieste, the single man crew compartment is in the shape of a sphere, the best geometry for resisting pressure. 

The sub is propelled downward through the use of steel weights. These are jettisoned at the bottom, allowing the sub to rise because of its lighter-than-water construction. Several fail-safe mechanisms insure that the weights do, in fact, release.

I asked Walsh if there would ever be a continuously-occupied deep ocean habitat, like that seen in Cameron's fictional Abyss. He was dubious, although he knew of shallow depth underwater hotels  that have been built for tourists. Very rich tourists, of course, have already spent time at the international space station. How many, I wonder, are ready to sign up for the Seven Mile Down Club? (current membership: two living, one (Piccard) deceased)

Author

Steven A. Edwards, Ph.D.

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