could find were bullet trains and American footballs. Both have
an elliptical profile. He worked from there, ultimately creating
something that looks like a huge pillow standing on its side.
Limiting Factor’s core is a titanium sphere flanked by specialized
foam cladding. To test the strength of this 3.5-inch-thick hull—to make
sure it would not implode at depth and kill Lahey’s golden ticket—
Triton sent it to Russia’s Krylov Institute, which has the only
full-ocean-depth pressure chamber on Earth large enough to fit it.
“It was kind of scraping down the sides as you lowered it in,” Ramsay
said. Krylov squeezed the submersible at nearly 1,400 atmospheres,
pressure equivalent to more than 20,000 pounds per square inch.
Electronics were another key concern for the battery-operated
craft, since a malfunction could result in a disastrous fire. To mini-
mize the number of holes in the hull, electrical engineer Tom Blades
set most of the circuitry outside the vessel. (Doing so also helped
keep the craft small.) Only a few mission- critical controls, such as
the ballast dropped to start the sub’s ascent, are hard-wired to a
switch through small openings in its shell.
Putting electronics on the exterior, though, required each piece to
have vast pressure tolerances: They had to work whether at sea level
or 11,000 meters. Microchips, which manufacturers test for speci-
fications such as temperature, aren’t pressure-rated. And there was
no such thing as a full-ocean-depth battery. “You have to design
everything to operate in 1 atmosphere and 1,100,” Vescovo explained.
“Imagine carrying a pound, and now imagine carrying 1,100 pounds.
Engineering-wise, it’s kind of what you’re doing.”
Triton collaborated with specialty suppliers to modify existing parts
and run intensive checks. “It is very much a research and development
project with a lot of testing still going on in the field,” Blades said.
To avoid regulatory headaches, Triton worked closely with Jonathan
Struwe, an engineer from Norway’s DNV-GL, one of only a few compa-
nies that certifies submersibles. Without its clearance, Limiting Factor
couldn’t get insurance or dive commercially. Struwe now calls the ves-
sel “the best-tested submersible in the world. Any single component
has been tested to a much higher pressure than the sub would ever see.”
By August 2018—after 26 months and about $30 million— Triton
was ready for ocean testing, and Vescovo took his first dives, to nearly
5,000 meters. He urged Lahey not to rush things if it meant sacri-
ficing safety, but by fall, everyone seemed confident enough in the
vessel to go forward. “A small team of really dedicated engineers
working 24/7 can accomplish extraordinary things,” Vescovo said.
Meanwhile, he needed a ship to tote the submersible around the
globe. Following the advice of expedition leader Rob McCallum and
skipper Stuart Buckle—who had captained James Cameron’s support
ship on the Challenger Deep expedition—Vescovo bought and refit
a retired Navy sub-hunting vessel (originally, USNS Indomitable) to
serve as a roving base. They added a crane to raise and lower Lim-
iting Factor, equipped wet and dry labs for the science, and updated
the onboard control room for sonar and other electronics (plus some
comfort upgrades for the crew). Vescovo named the 224-foot-long
ship Pressure Drop, another Banks-inspired moniker.
With both craft secured, the team turned to the most compli-
cated parts of the process: sub launch and recovery. Fred McLaren,POPSCI.COM•FALL 2019 53DEEP HORIZONS7
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Dive 2: Southern
Vescovo’s plunge made him
the first person ever to dive
the South Sandwich Trench.
It led to cartographic
discoveries, including a new
bottommost point and
underwater mountains more
than 4,000 feet tall. (He and
the mission crew will get to
name them.) —MRx 9
Burj
Khalifas