Malaysia's defense minister announced Wednesday evening that
Airbus Defense and Space, Europe's main commercial satellite company, had
forwarded images taken on Sunday of 122 objects floating southwest of Australia
and said that his country had asked Australia to check if they were debris from
the missing Malaysia Airlines Flight 370.
While the objects might turn out to be unrelated to the
aircraft, Defense Minister Hishammuddin Hussein said, "This is still the
most credible lead that we have."
The objects are up to 23 meters (75 feet) in length, and are
visible through gaps in clouds over an area of 400 square kilometers (154
square miles), he said. Some of the objects are bright, he noted without
elaboration. Metal objects that had recently entered the ocean might be
reflective.Malaysia forwarded the information to Australia on Wednesday. It is
unclear if the floating objects can be checked before dark or if an inspection
check may need to wait until Thursday, Hishammuddin added.
The floating objects are 2,557 kilometers (1,589 miles)
southwest of Perth.
If the debris turns out to be from the missing plane, the
next step would be to figure out how far it might have drifted from where the
aircraft might have splashed down, so as to begin an undersea search,
Hishammuddin said.
The U.S. Navy has sent an undersea listening device and a
sonar device. But each needs to be towed far underwater behind a ship traveling
scarcely faster than a person walking on land.
The listening device can pick up the data recorders' signals
if it comes within a mile of them but the signals will go silent within a
couple weeks anyway. The sonar will work even after the data recorders go
silent, but needs to be even closer to detect wreckage on the seabed.
Finding floating debris would help provide closure for the
families and friends of the passengers and crew, but may prove of limited use
in locating the data recorders on the bottom of the ocean, oceanographers
cautioned. Debris could have drifted hundreds of miles in the 18 days since the
plane disappeared, said Jianping Gan, an oceanographer at the Hong Kong
University of Science and Technology who has done research aboard a Chinese
icebreaker in the waters around Antarctica.
"Even if you've got floating material, if it has been
floating for two and a half weeks, it's not going to have much relation to the
wreckage" on the seabed, said Jason Ali, an earth sciences professor at
Hong Kong University who has studied currents in the Indian Ocean.
Michael Purcell, a senior engineer at the Woods Hole
Oceanographic Institution in Massachusetts, who led two underwater search
expeditions for the wreck of Air France Flight 447 in 2010 and 2011, said the
current search zone for Flight 370 was far more remote than the location of the
Air France wreckage and that the seas and weather conditions were known to be
considerably rougher.
"That can slow down your progress considerably, because
it makes it more difficult to operate, to get the vehicles in and out of the
water," and bad weather can mean days of waiting to resume the search,
Purcell said.
Purcell estimated that there were fewer than a dozen
underwater search vehicles in the world equipped with the sonar and imaging
technology required for a deep water search of this scale. These are operated
by a handful of private companies and oceanographic institutes as well as by
the U.S. Navy, he said.
Purcell said one advantage was that the sea floor in the
southern Indian Ocean was relatively flat compared with the highly varied
terrain of the mid-Atlantic. The depth of the water is comparable, however, at
more than 10,000 feet.
Military submarines have sophisticated equipment for
listening for ships or other submarines. But unlike towed sonar like the
Bluefin-21, which the U.S. Navy is sending and which can descend to 14,700
feet, or a towed pinger detector, which can plunge 20,000 feet, military
submarines are designed to operate within a few hundred feet of the surface.
That limits their ability to detect pings from far below the
surface in water of different densities, moving at different speeds and at
different temperatures.
For now, aircraft from Australia and other countries have
been looking in an area the size of the western and southwestern United States
where the plane is believed to have disappeared after its last signals to a
satellite. They have not extended the search to all the places where debris
might have drifted. But because the area of the aircraft's disappearance is so
far from land, roughly a four-hour flight in each direction, planes can only
spend a couple of hours searching.
Because of the distance, only about 4 percent of the
probable impact area was searched by aircraft on Monday, for example, and no
searching was possible on Tuesday because of bad weather. The search resumed
Wednesday.
Making matters worse, oceanographers said, is that currents
in the southern Indian Ocean are less well understood than in more heavily
trafficked seas. A violent storm on Tuesday, one of many in the region as the
southern hemisphere's winter approaches and days become shorter, has further
churned the waters. Any debris that stuck up out of the water will have been
pushed by the wind in directions that may be different from prevailing
currents.
"With any wind, it'll act like a sail," Ali said.Waves
may also have pushed objects in unpredictable directions, making it hard to
calculate the movements of any debris that might be found based on prevailing
ocean currents.
Even finding the data recorders, although extremely
difficult, may not be enough. The cockpit voice recorder only stores the two
most recent hours of sounds in the cockpit before the aircraft ceases
operating. Investigators have been most interested in why the plane turned
around over the Gulf of Thailand roughly seven hours before it is believed to
have run out of fuel over the southern Indian Ocean.
The separate data recorder for various aircraft instruments
and controls would have saved information from the plane's sharp turn, but
might not reveal the intent of whoever was in the cockpit if the turn was
deliberate, as the Malaysian authorities have suggested.
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