World War II combat pilots have been lost at the bottom of the Pacific
ocean for nearly 70 years. Now autonomous robots have been deployed to
find them.
By Andy Isaacson
 n a bright morning in mid-March, Pat Scannon stands on the deck of a
40-foot catamaran looking for an airplane hidden in the waters of
Palau’s western lagoon. A limestone ridge thick with vegetation juts
into the cloudless blue sky behind him. His quick-dry clothing, coupled
with a red bandanna knotted around his neck, befits Scannon’s role as an
amateur archaeologist. He has spent the past 20 years making annual
wreck-hunting trips to Palau, about 500 miles from the Philippines, to
find aircraft that had been shot down during one of World War II’s
fiercest battles—planes that may still be holding their pilots. His
organization, BentProp Project, works to repatriate their remains to the
U.S. To guide the search, Scannon ordinarily relies on interviews with
Palauan elders, military records, and maps hand-drawn after the war. But
on this trip, he has a new tool at his disposal.

Two technicians in a nearby Boston Whaler cradle a small,
torpedo-shaped craft, then lower it into the water. Scannon watches as
its nose tilts down and its rear propeller pushes it beneath the
surface. Out of sight, the autonomous underwater vehicle (AUV), an
oceanographic workhorse called a Remus, begins gliding through the
lagoon in a pattern that resembles the long, linear passes of a mowed
lawn. From roughly 10 feet above the seafloor, its side-scan sonar sends
out acoustic waves that build a two-­dimensional map. The strength of
the reflected waves also helps distinguish metal from mud or coral.

For a group like BentProp, the use of advanced oceanographic
instruments is a huge technological leap forward and one it couldn’t
afford on its own. The vehicles come from the University of California,
San Diego’s Scripps Institution of Oceanography and the University of
Delaware, which received a grant from the U.S. Office of Naval Research.
The funding enables oceanographers to test new technologies while
helping BentProp locate World War II airmen—an effort they named Project
Recover.

The lead scientist is Eric Terrill, director of the Scripps Coastal
Observing Research and Development Center. Board shorts and sandals make
the athletic oceanographer look more surfer than scientist­—he even
brought a board on the research vessel for what he calls “wave
sampling.” For the past few years, Terrill’s team has used a Remus to
study the ocean circulation around Palau.

“Historically, on unmanned underwater platforms, you might spend the
better part of your experimental time just ensuring the sensors were
functioning, tracking the vehicle navigation, and charging batteries,”
he says. “The systems now have matured to where we can run them hard,
like outboard motors. The oceanographic community is engineering new
sensors for them and having them do smarter things during their
searches.”

When Terrill and Scannon met through a mutual friend on the island, a
collaboration seemed natural. BentProp could find planes in a tricky
marine environment—with steep terrain, fast currents, and coral
heads—while Scripps tested circulation models and advanced imaging
systems. “If we’re able to use those techniques on natural environments,
there’s nothing to say we can’t apply it to the man-made objects on the
seafloor,” Terrill says.

Scripps and the University of Delaware shipped 60 packages of
equipment to Palau, including underwater vehicles, cameras, various
types of sonar, and, for aerial surveys, an autonomous hexacopter drone
that had been rebuilt to survive sea spray and aquatic landings. The
mangroves growing along the shore around Palau are so dense that
aluminum wreckage from aircraft has been found sitting on top of the
tree canopy about 30 feet up.

This year, Scannon has his eye on a major prize: a B-24 that he
believes had been shot down in Palau’s western reef. With the
oceanographers’ help, he hopes, BentProp could find it. “On land our
major technology was a machete, and underwater it was scuba tanks,” he
says. “The ability to extend our mission is, like, I don’t know how to
describe it. It’s like starting out walking, and suddenly you’re in a
supersonic jet.”
 By the 1920s, Palau had grown into a thriving Japanese port for goods
and services en route across the Pacific. Recognizing the strategic
location, Japan established an airfield there, and after World War II
broke out, it began to shore up its defenses—building hundreds of
bunkers and caves to defend the islands from an American attack­.
General MacArthur, who wanted to secure islands to the east as he
prepared to invade the Philippines, ordered that attack in 1944. The
U.S. began with a furious air campaign that was designed to knock out
Japanese vessels clustered in Palau’s western lagoon and adjacent
harbors, and clear the way for an amphibious assault.
 That September, the U.S. Marines landed on the island of Peleliu.
Although they ultimately won that battle, it came at a terrible cost:
10,000 Japanese and 1,700 Americans were killed in action—the highest
casualty rate of World War II’s Pacific Theater. And between the
beginning of the air campaign and the end of the war, BentProp
estimates, 200 U.S. aircraft were shot down inside Palau’s barrier reef.
Some 40 to 50 planes and 70 to 80 airmen have never been recovered.
Scannon, a medical doctor and founder of a biotechnology company, first
visited Palau in 1993 as a recreational scuba diver. He came with a
group looking for a Japanese naval vessel that had been sunk by George
H.W. Bush, who flew torpedo bombers during the war. After the group
found it, Scannon hired a local guide to take him to other wreck sites,
where he eventually discovered the wing of a B-24. When he researched
Palau’s history at home, he realized there must be many more planes in
ruins around the islands. “Palauans knew of them but didn’t know
anything about them,” he says. He was particularly gripped by the
thought that many airmen couldn’t have survived the impact. “These
people died defending us,” he says. “And they deserve to be honored and,
if possible, brought home.”

So began Scannon’s quest. He returned to Palau for the next few years
by himself, chasing leads. Then in 1996, he formed BentProp and
recruited volunteers, roughly half of whom are retired and active-duty
military members, to help him search. Combing the jungle and surrounding
waters, they located debris from more than five dozen aircraft.

Last year, local spear fishermen diving on Palau’s western barrier
reef stumbled across one of the most impressive finds: an intact plane.
They alerted the owner of a dive shop, who passed photos of the wreck
along to BentProp. Scannon’s team eventually identified the plane as an
American Corsair. It had sustained some damage to its left forward wing
root, but the wing flaps were down, and the canopy had been locked open,
suggesting that the pilot had ditched. “It had been sitting there
unknown for 65 years,” Scannon says. “It gave us great hope that there
were other intact airplanes out here that no one has seen.”

BentProp calculates that eight American planes, including a B-24
bomber, remain hidden in Palau’s western lagoon. The B-24, in
particular, would be a tremendous discovery. It carried 10 to 11 men,
including a pilot and co-pilot, gunners, bombers, a radioman, and a
navigator. Of the four B-24s BentProp suspects were shot down near
Palau, two were found after the war. BentProp located a third in 2004;
the organization notified the Department of Defense’s Joint POW/MIA
Accounting Command, and the remains of the eight men onboard (three had
parachuted out, only to be apprehended and executed) were repatriated to
Arlington National Cemetery.

Mission photographs from World War II show the fourth, a Consolidated
B-24 Liberator, on a path toward the western lagoon. Two of its crew
had bailed out midair, landing in Malakal Harbor to the east, where the
Japanese took them into custody; the rest presumably went down with the
plane. “We have very, very good information about what heading they were
on during the bombing mission, and we have very good information about
what heading they took leaving,” Scannon says, on the deck of the
research vessel during this year’s expedition. “So bringing the two of
those together essentially brings you right here.”

The oceanographic team’s official command center in Palau is on the
second floor of the Coral Reef Research Foundation, but their unofficial
headquarters is an open-air bar called the Drop Off, originally built
for the production crew of CBS’s Survivor: Palau. Several days
into the expedition, they head there for dinner and order a round of
local Red Rooster beers. As they wait for their food, Mark Moline, an
oceanographer from the University of Delaware, opens a Toughbook laptop
and scrolls through sonar images produced by the Remus.

Grainy and reddish, the sonar images look like transmissions from
Mars. Some show deep scours; others, shadowy trenches. The team have
given the features names like Homer Simpson, Crying Baby, and
SpongeBob’s Grave. After identifying promising targets in scans, they
will have to investigate in person, diving to the various sites to
determine if the features are purely biological, like coral heads, or
actual wrecks.

Moline pauses on an image with an oblong shape. On closer inspection,
it seems to have intact wings and a tail. “We got a plane!” Moline
announces. Everyone springs up and huddles around the screen, snapping
photos with their phones. Their excitement attracts the attention of a
Japanese man dining at the other end of the long communal table, who
cranes his neck for a peek at the computer. Moline abruptly shuts the
laptop; World War II wrecks attract dive tourists and salvagers.

The next morning, at the coral-reef lab, Terrill debriefs Scannon and
the BentProp group. Paul Reuter, a Scripps programmer, projects Google
Earth onto a wall. Reuter had used an archival map of observed plane
crashes to mark Google Earth layers with known wreck sites; he then
added a layer with intriguing objects that had turned up in the sonar
images.

Terrill uses a laser pointer to indicate the newest find. “The hard
edges provide bright scatter,” he says. “There’s a long shadow here and
here.” He then shifts his pointer to a spherical object about 45 meters
away and wonders if it could be the pontoon of a floatplane.

“If that’s intact, it tells me it was a low-speed impact, perhaps
ditching,” says Daniel O’Brien, a former skydiver and Hollywood stuntman
who now volunteers for BentProp. “My first impression is that’s a
Zero”—a long-range fighter aircraft. “There are rounded edges at the
tail. But if it is a floatplane, the only U.S. airplane it could be
would be amphibious. The shape looks like a Kingfisher.” Flip Colmer, a
former Navy pilot who now flies for Delta, also with BentProp, reaches
for the book Floatplanes in Action and begins flipping through color pictures.

The Kingfisher, O’Brien explains, was typically flown for observation
and to rescue downed pilots. “If they were in this deep, it would have
been on a risky endeavor. There weren’t anti-aircraft along the ridge.
But existing ships that were still moored had anti-aircraft. So for him
to come in and land here, it would have been to pick somebody up.”

During World War II, floatplanes in Palau often flew rescue
operations. As they scooped airmen from the water, another plane
provided cover overhead. BentProp knew that two Kingfishers on
reconnaissance missions had disappeared during the war, and the western
lagoon seemed the most likely location for them to have ended up. The
identification number painted on the plane’s exterior would have
degraded by now; to confirm the exact craft, divers would try to recover
a stamped metal plate riveted to the inside of the cockpit. “It’s our
holy grail,” O’Brien tells me.
Colmer cautions the group about jumping to conclusions. The Japanese
also flew seaplanes. “If there’s any primer left on the interior of the
cockpit—which will last longer than straight paint—that’s one way to
take a peek at it,” he says. U.S. airplanes used lime-green zinc
chromate; the Japanese had a red primer. The team will have to get a
close look.

Guided by GPS coordinates from the AUV, Pat Colin, director of the
Coral Reef Research Foundation, pilots the vessel across the lagoon to
the approximate location of the mystery plane. Then Terrill lowers a
device called an Echoscope over the side. As we creep along the surface,
an onboard computer displays 3-D images of the seafloor in real time.

While side-scan sonar provides a general impression of contours along
the bottom, it doesn’t directly measure the elevations of features. The
Echoscope, or multibeam volume imaging sonar, does, enabling
oceanographers to map topography accurately and in high enough
resolution to distinguish man-made objects. Terrill describes it as “the
oceanographic seafloor-mapping equivalent of ultrasound sonar used to
look inside the human body.” Using the two technologies in tandem helps
to narrow wide-area searches and then pick out targets from clutter on
the seafloor, so that human divers maximize their time at the correct
site.

With the boat now directly over the plane, the dive teams begin to
suit up. Terrill fills his scuba tank with nitrox to allow himself more
time to explore the aircraft 100 feet below. Shannon Scott, an engineer
from Scripps, descends with Terrill, Colmer, and O’Brien. He carries a
handheld sonar that displays acoustic images on an LCD screen, allowing
the divers to zero in on the floatplane even in five-foot visibility.
About 20 minutes later, O’Brien surfaces. “Well, it’s not a Kingfisher,”
he says
After descending to the plane, O’Brien noticed that the windscreen on
the cockpit was located behind the wing. In Kingfishers, it was
situated in front. He’d also detected a subtle distinction in the shape
of the fuselage near the tail.

I strap on a scuba tank and jump into the water with Scannon, who
wants to see for himself. We follow a rope line, pinching our noses on
the way down to equalize pressure, until we arrive at the fuselage. It
lays on a bed of thick sediment that our fins kick up into dusty clouds.
Long, gangly strands of black coral grow up and through the corroded
metal. The front motor and propellers have broken away from the body of
the plane, so that it now resembles a chewed-off cigar or the burnt end
of a firecracker. Scannon waves me over to the cockpit and places my
hand on the gun mount. It held a 7.7mm machine gun, Scannon later
explains to me, developed by the Japanese navy.

The next day, BentProp compares the aircraft in the western lagoon
with a hundred different vintage planes. Eventually, the team determines
that the wreck has all the characteristics of a Kawanishi E15K1 Shiun,
code-named Norm by the Allies. The high-speed reconnaissance floatplane
had a single engine, contra-rotating propellers, and a center pontoon
that could be jettisoned during an attack. It also had a flattened
beaver tail around the vertical stabilizer, an aft cockpit machine gun,
and no wing armaments. According to BentProp, the Japanese manufactured
nine prototypes; six were brought to Palau for combat testing, and all
were shot down by U.S. forces.

Though it isn’t an American plane, Scannon is pleased with the
discovery. “It’s a very unusual aircraft, one of the rarest
archaeological planes you will find,” he says. “And there’s a very high
likelihood that the remains are still on it.” BentProp alerts the
Palauan government, which will notify the Japanese embassy.

* * *
Of more than 60 aircraft BentProp has identified in Palau—half of
which are Japanese—the team has recovered just one metal plate stamped
with a serial number: that of the American Corsair discovered by the
spear fishermen. That plate revealed the Corsair’s story.

On November 21, 1944, a young Marine captain named Carroll McCullah
set off from the American airfield to finish off a Japanese vessel that
had been bombed earlier. On the way back, he and his wingman strafed
four Japanese ammunition dumps; an explosion at the last one sent
shrapnel into the oil cooler of his plane. McCullah placed a distress
call and made for the island’s western reef. Then he tightened his seat
belt, locked the canopy back, and turned off the plane’s engine switch.
Placing his left hand on the cockpit coaming, he braced for impact.
“There was no shock,” McCullah later wrote in a mission report. He
launched his life raft and swam across the reef, where a rescue aircraft
swept down to pick him up. For the rest of his life,
McCullah—who, after his rescue, went back to the base, had a brandy, and
then flew another mission the next day—retold the story of that
landing. “And many other ones,” his son, Patrick, told me by phone from
Florida, where McCullah lives (with dementia) at age 92. “His tales were
tall, but they were true.”

Today, McCullah’s plane rests intact on the seabed, with its nose up
against the edge of the reef, like a car driven up onto a curb and
abandoned. But time has turned the craft into a relic: corrosion has
gnawed at the metal, and the reef has crept into the propellers and the
engine; a large, bulbous coral head has taken up occupancy in the
cockpit. Originally painted blue, with a white star-and-bar symbol, the
aircraft has been scoured to bare aluminum.

Scripps wants to use its technology to document this chapter of the
Corsair’s story too, before it ends altogether. “We’re not only here to
find and detect underwater objects, but to get a snapshot of the state
of those objects that may be corroding or eroding away in time,” Terrill
says. “There’s a whole new field in trying to baseline-capture all the
detail we can about these historic artifacts. I’m calling it digital
preservation.”

Suzanne Finney, an American archaeologist working with Palau’s Bureau
of Arts and Culture, joins us for the 45-minute boat ride to the site
of the Corsair. Marine archeology rarely gets to benefit from such
advances, she says. “Most of the work I’ve done, you’ve got a tape
measure and some string and a dive slate and a pencil, and you’re taking
photographs and measurements by hand. And that’s what you do.” With
data from the robotic vehicles, Palau can add downed aircraft to an
inventory of the country’s rich underwater sites, something previously
unattainable for an office that can barely afford to buy gas for a boat.
“There are a lot of wrecks in water that’s inaccessible to diving,” she
says, “so you need remote-sensing equipment.” By the time the
expedition ends, the AUV has scanned 18.9 square kilometers of the
seafloor at slightly better than 10cm resolution, an area that would
have taken scuba divers a decade to explore. The sonar also revealed
what Terrill says could be a new species of coral.

When we reach the Corsair, engineers lower the Remus, now equipped
with GoPro HERO3 HD cameras, into the water, and it once again begins a
methodical sweep. Back in California, Terrill and his team will use the
thousands of captured images, plus hundreds of photos taken by human
divers, to build a 3-D reconstruction of the plane. Terrill is
beta-testing algorithms developed by Autodesk for the company’s new
cloud-based, reality-capture software, called ReCap; the software has
been designed to model aboveground areas like historic sites and factory
floors, and Terrill is evaluating how well it works in an aquatic
environment, where light is distorted. “Man-made structures underwater
are an ideal testbed for that,” he says. “If it pans out, it’ll be a
great archaeological tool to baseline a lot of these wrecks.”

Scientists and naval historians could use such technology to document
how wreck sites decay. Oceanographers and biologists studying living
structures such as coral reefs could also benefit from it; 3-D models
would enable them to detect how ocean acidification and events like
typhoons alter reefs over time. And, of course, Scannon hopes that one
day AUVs will lead him to his biggest find, the final B-24, so that a
perfect replica of it, too, can be recorded for posterity. For now, it
still lies somewhere in the lagoons surrounding Palau, concealed by
water and time.
Fonte:
 http://www.popsci.com/technology/article/2013-08/robotic-search-wwii-airmen
                                                                 Foto:  popsci.com

                                                 

                                                 Corsair and Diver:  Andy Isaacson

                                             

                                               Downed Corsair:  Andy Isaacson