Deep water search for jet could turn on robot subs

Apr 02, 2014 by Adam Geller
An autonomous underwater vehicle (AUV) sits on the wharf at naval base HMAS Stirling in Perth, Australia, ready to be fitted to the Australian warship Ocean Shield to aid in the search for missing Malaysia Airlines Flight MH370, Sunday, March 30, 2014. The Australian Maritime Safety Authority, which oversees the search, said the ship will be equipped with a black box detector—the U.S. Navy's Towed Pinger Locator—and the AUV, as well as other acoustic detection equipment. (AP Photo/Rob Griffith)

Two miles down or more and darker than night, the ocean becomes a particularly challenging place for human searchers.

If the wreckage of a missing Malaysian airliner rests somewhere in the Indian Ocean's depths, then investigators will likely need to entrust the hunt at least partly to robot submarines and the scientists who deploy them to scan remote swaths of the seafloor.

Such unmanned subs, called or AUVs, played a critical role in locating the carcass of a lost Air France jet in 2011, two years after it crashed in the middle of the south Atlantic. The find allowed searchers to recover the black boxes that revealed the malfunctions behind the tragedy.

That search keyed off critical information: The search area for the Air France jet was much smaller than that for Malaysia Airlines Flight 370, and the first pieces of wreckage were recovered within days of the crash. Even then, it required two years and four deep water search missions before a team from the Woods Hole Oceanographic Institution, using an AUV equipped with side-scan sonar, located the jet about 12,800 feet (3,900 meters) underwater.

"Air France 447 is a bit different from Malaysian Air 370 in that we had a few more clues to work with," said Dave Gallo, who led the search team from Woods Hole, located on Massachusetts' Cape Cod. The independent research institution has offered its services to investigators but has not been asked to join the current search effort.

Before unmanned subs can be sent down to look for the Malaysian jet, the search zone must be narrowed considerably. The size of the search area changes daily because of factors such as currents; on Wednesday it was 221,000 square kilometers (85,000 square miles).

But if investigators can zero in on an approximate crash location, they will likely turn to AUVs to begin the methodical task of tracking back and forth across miles of ocean floor in search of anomalies that might be wreckage.

"I like to think of it as mowing the lawn. You want to cover every bit of it," Gallo said.

"You need a little bit of luck and a lot of prayer that the oceans are going to cooperate, and then off you go."

The unmanned subs used by the Woods Hole team were developed as tools to research and monitor relatively shallow coastal waters, measuring variables like salinity and temperature over wide areas for hours on end. But AUVs are increasingly harnessed to perform some of the most demanding underwater jobs.

Australian Defense ship Ocean Shield is docked at naval base HMAS Stirling while being fitted with an autonomous underwater vehicle (AUV) and towed pinger locator to aid in the search for missing Malaysia Airlines Flight MH370, Sunday, March 30, 2014, in Perth, Australia. It will still take three to four days for the ship to reach the search zone—an area roughly the size of Poland about 1,850 kilometers (1,150 miles) to the west of Australia (AP Photo/Rob Griffith)

The U.S. Navy uses them to search for underwater mines because they can stay below the surface of even very cold water much longer than any diver, without the worry of exposing a human to danger. Energy companies employ unmanned subs to survey the floor at underwater drill sites.

In 2009, California's Waitt Institute sent down a pair of AUVs that surveyed more than 2,000 square miles of South Pacific ocean bottom over 72 days in an unsuccessful search for Amelia Earhart's plane.

The area off western Australia where search planes and aircraft are looking for the Malaysian jet slopes from about 2,600 feet (800 meters) to about 9,800 feet (3,000 meters) deep. But part of the zone drops into the narrow Diamantina trench, about 19,000 feet (5,800 meters) down.

"Let's hope the wreck debris has not landed over this escarpment. It's a long way to the bottom," said Robin Beaman, a marine geologist at Australia's James Cook University.

Australian Defense ship Ocean Shield is docked at naval base HMAS Stirling while being fitted with an autonomous underwater vehicle (AUV) and towed pinger locator to aid in the search for missing Malaysia Airlines Flight MH370, Sunday, March 30, 2014, in Perth, Australia. It will still take three to four days for the ship to reach the search zone—an area roughly the size of Poland about 1,850 kilometers (1,150 miles) to the west of Australia (AP Photo/Rob Griffith)

The U.S. Navy last week sent a Bluefin-21 autonomous sub to Australia to prepare for an eventual deep water search. That sub can dive to about 14,800 feet (4,500 meters). The largest unmanned subs used by Woods Hole researchers are built to reach depths of about 19,700 feet (6,000 meters).

Searchers can also use tethered submersibles, towed by ships from cable that allows for real-time data transmission to the surface and a continuous supply of power to the vehicle. But it is a very slow process. AUVs can scan a larger area more quickly, without being affected by conditions on the surface. But they must be brought back to the surface to recharge, and for researchers to download and analyze their data.

Even so, they are much better suited to the job of deep water search than any manned sub, whose descents are limited by air, light and power, as well as safety concerns, said William Sager, a professor of marine geophysics at the University of Houston.

Sager recalled that in 2000, when he climbed aboard a sub and ventured 5,600 feet (1,700 meters) down to the bottom of the Gulf of Mexico, all those factors limited time on the sea floor to just four hours, moving at a crawl. A researcher looking out a porthole into even the clearest water with a very bright light can't see beyond 100 feet, he said.

Unmanned subs are far more flexible. When Woods Hole engineers built their first REMUS 6000 sub a little more than a decade ago, they tested it off the Bahamas by driving it down a trench the scale of the Grand Canyon, said Chris von Alt, who led the team that developed the craft and then co-founded Hydroid Inc., the Massachusetts manufacturer of the subs.

An autonomous underwater vehicle (AUV) sits on the wharf at naval base HMAS Stirling in Perth, Australia, ready to be fitted to the Australian warship Ocean Shield to aid in the search for missing Malaysia Airlines Flight MH370, Sunday, March 30, 2014. The Australian Maritime Safety Authority, which oversees the search, said the ship will be equipped with a black box detector—the U.S. Navy's Towed Pinger Locator—and the AUV, as well as other acoustic detection equipment. (AP Photo/Rob Griffith)

The REMUS sub—nearly 13 long, 1,900 pounds and mustard yellow—is equipped with sonar that can be programmed to capture images of vast stretches of seafloor and the objects resting there. Powered by a lithium battery, the unmanned subs stay below the surface for 20 to 24 hours. Scientists on the surface are now able to modify instructions to the sub via an acoustic link that allows them to look at bits of data gathered by the vehicle, von Alt said.

But they don't know what the sub has found until it surfaces and its data is fully downloaded to a computer.

The task requires patience and, for researchers whose livelihoods are focused on ocean life, a willingness to harness their expertise in a grim but necessary pursuit of answers.

"That's why you do it," von Alt said. "One of (the reasons) is, 'Why did it happen?' But the other is to get closure for the families who have suffered through the tragedy."

Explore further: Seabed of jet hunt zone mostly flat with one trench (Update)

5 /5 (2 votes)
add to favorites email to friend print save as pdf

Related Stories

New Malaysia plane search area turns up objects

Mar 28, 2014

Australian officials moved the search area for the lost Malaysian jetliner 1,100 kilometers (680 miles) to the northeast Friday following a new analysis of radar data, and planes quickly found multiple objects ...

Flight 370 search shifts after new look at data

Mar 29, 2014

Three weeks into the mystery of Flight 370, investigators relying on newly analyzed satellite data shifted the search zone yet again, focusing on a swath of Indian Ocean where better conditions could help ...

WHOI-led team locates Air France wreckage

Apr 05, 2011

A search team led by the Woods Hole Oceanographic Institution (WHOI) has located the wreckage of Air France Flight 447 some 3,900 meters, or nearly 2.5 miles, below the surface of the Atlantic Ocean off Brazil’s ...

China demands Malaysia turn over satellite data

Mar 25, 2014

China demanded that Malaysia turn over the satellite data used to conclude that a Malaysia Airlines jetliner had crashed in the southern Indian Ocean killing everyone on board, as gale-force winds and heavy ...

WHOI conducts latest search for Air France Flight 447

Mar 28, 2011

The Woods Hole Oceanographic Institution (WHOI) is again teaming with French authorities to renew the international search for the deep-sea wreck site of Air France Flight 447 and to retrieve the flight recorders ...

Recommended for you

US official: Auto safety agency under review

19 hours ago

Transportation officials are reviewing the "safety culture" of the U.S. agency that oversees auto recalls, a senior Obama administration official said Friday. The National Highway Traffic Safety Administration has been criticized ...

Christian Bale to play Apple's Steve Jobs

Oct 23, 2014

Oscar-winner Christian Bale—best known for his star turn as Batman in the blockbuster "Dark Knight" films—will play Apple co-founder Steve Jobs in an upcoming biopic.

How to find a submarine

Oct 23, 2014

Das Boot, The Hunt for Red October, The Bedford Incident, We Dive At Dawn: films based on submariners' experience reflect the tense and unusual nature of undersea warfare – where it is often not how well ...

Government ups air bag warning to 7.8M vehicles (Update)

Oct 22, 2014

The U.S. government is now urging owners of nearly 8 million cars and trucks to have the air bags repaired because of potential danger to drivers and passengers. But the effort is being complicated by confusing ...

User comments : 0