Voyage to the Bottom of the Sea

By Eliza Strickland

NOTE: This is an overview of the entire article, which appeared in the March 2012 issue of the IEEE Sprctrum magazine.
Click here to read the entire article.

As the battered little boat slides down a 3-meter ocean swell into the next trough, Chris Welsh grits his teeth and peers out into the storm. Sheets of rain pummel the dark windows of the bridge, and a Micronesian sailor wrestles with the wheel. It’s past midnight on a July night and we’re bobbing over the almost 11 kilometers of water that fill the deepest abyss on Earth, the Mariana Trench. Welsh is leading a small party of engineers, scientists, and adventurers under the banner of Virgin Oceanic; they’ve chugged out here aboard a 20-year-old ferryboat to test some unmanned deep-diving probes. It’s the first step in what they hope will be a glorious high-tech adventure, in which a man – Welsh, specifically – will visit the bottom of the trench before the end of this year.

In comparison to the South Pole, the peak of Mt. Everest, and the moon, the bottom of the Mariana Trench has had the fewest visitors – precisely two. In 1960, U.S. Navy lieutenant Don Walsh and Swiss engineer Jacques Piccard rode down in a primitive vehicle called a bathyscaphe (essentially a small metal sphere attached to an enormous bag of buoyant gasoline). No one has been there since, although three unmanned vehicles took the plunge in the 1990s and 2000s.

So why is Chris Welsh planning to travel there? The answer begins with a half-finished submersible built by the radical sub designer Graham Hawkes, who creates what he calls “under- water flying machines.” In 2010, Welsh bought a sub that came with a grim history and three years’ worth of dust. Hawkes had been building the vehicle for Steve Fossett, a wealthy adventurer who wanted to add the record for the first solo Mariana Trench dive to his achievements in ballooning, fly- ing, and sailing. But in September 2007 Fossett took off in a single-engine plane from a ranch in Nevada and never came back. His bones were found a year later in the mountains of eastern California, near the wreckage of his crashed plane.

Later, when Welsh was inquiring about Fossett’s up-for-sale yacht, he learned that the boat had been modified to launch a sub from its deck and that the sub was also for sale. He’d never piloted a submersible before either, but once he saw the sub he was hooked.

At around US $10 million, the Mariana expedition is beyond the capacities of the lower order of rich people. So Welsh, who made his pile in real estate, approached Sir Richard Branson, the chairman of Virgin Group and No. 4 on Forbes’s list of British billionaires. Branson signed on, agreeing that Welsh would pilot the sub on the first Mariana Trench dive,while Branson will plunge the sub into another deep ocean trench. (The sub was, not coincidentally, named “Virgin Oceanic”.)

To make really deep probes, engineers have built autonomous underwater vehicles (AUVs) and remotely operated vehicles (ROVs). Just as space explorers have come to rely on rovers and unmanned probes to survey our solar system, oceanographers have chosen robotic vehicles and ocean observatories to be their proxies in the deep. But for true believers like Welsh and the Virgin Oceanic team behind him, there’s nothing like having a human brain down there to see, experience, think, and improvise.

Using exotic materials, these new marine trailblazers are promising to build vehicles that are much faster and cheaper than the old-style government models. Hawkes’s 5-meter-long sub, for example, is a far cry from the plump, pod-like submersibles operated by the world’s research institutions, which rely solely on ballast to descend straight down. Think of Hawkes’s machine as an underwater flyer, one whose stubby wings generate hydrodynamic forces to pull the vehicle down into the abyss rather than up into the air.

To survive the dive into the highest pressure environment on Earth, the sub is relying on an exotic material with exciting but untested capabilities. The carbon fiber material that forms the hull is some of the toughest stuff on Earth, but it’s never been used in quite this way before. The carbon fibers, which are wound around an epoxy matrix, are fantastically strong in tension when the pressure is applied from inside. But when external pressure causes compression, the material doesn’t have quite the same strength.

The pilot’s head will be within the pressure-resistant transparent dome on the front of the pressure hull. This will give him a much better view than researchers get in government subs, which sport just a couple of small portholes. Virgin Oceanic hired a company to make a dome out of a 1270-kg ingot of synthetic quartz. Then a company that makes lenses for NASA telescopes spent one year hollowing it out into a hemispherical shape. This new dome will be tested in a pressure chamber at Pennsylvania State University this spring.

The pilot (who is the sole occupant) will lie prone in the craft and grip the two joysticks that control both the thrust and the plane-type parts that allow the pilot to steer: ailerons in the wings and elevators and rudders in the tail. With a combination of the hydrodynamic forces and about 270 kg of ballast, the sub will get to the bottom of the Mariana Trench in 2 hours, leaving plenty of battery time for an exploration of the seafloor. Hawkes’s team began building the sub in 2005. The time was right to go for full-ocean depth. The team used light and powerful lithium-ion batteries developed by the auto industry for electric cars. The back half of the sub holds blocks of a buoyant material called syntactic foam, composed of hollow glass microspheres embedded in an epoxy matrix; the newest type of this material can stand up to the deepest sea pressures. Once the sub drops its ballast, that buoyant foam will bring the pilot home.