\The Bluefin-21 underwater drone is hoisted back on board the Australian Defense Vessel Ocean Shield after successful buoyancy testing in the Indian Ocean on April 1.
Underwater drones equipped with side-scan sonar equipment are about to join the search for Malaysian Airlines Flight 370, as the hunt for the missing plane prepares to enter its third month.
The new drones are expected to hit the water in one or two months, according to CNN. The Bluefin-21, a different type of underwater drone, has been scanning the ocean floor since last month for debris that might have come from the plane, and will continue to do so over the next month. However, the search now requires devices that are capable of diving further than the Bluefin-21's 2.8-mile limit, CNN reported.
The Bluefin-21 is 21 inches in diameter, 16 feet long and weighs about 1,650 pounds. It used sonar to scan about 154 square miles of underwater terrain at a cost of around $40,000 per day. So far, it's found nothing.
In addition to finding pieces of Flight 370, the new drones will be tasked with widening the search area, and mapping swaths of the ocean floor that have never before been mapped, according to NBC.
Side-scan sonar equipment will be key in the mapping effort. The drones will travel close to the ocean floor and beam sound waves at the earth from side-to-side, covering a wider area than if they could only blast the area directly below them. Side-scan sonar is designed to find items at the bottom of the ocean, according to the National Oceanic and Atmospheric Administration.
Flight 370 disappeared over the Indian Ocean in March during a flight that carried 239 passengers from Kuala Lumpur to Beijing. The plane has not yet been recovered.