Robot Sub to Search Area 'New to Man' for Jet Search for pings called off after 6 days with no signal By Rob Quinn, Newser Staff Posted Apr 14, 2014 3:15 AM CDT 3 comments Comments The Bluefin-21 autonomous sub is hoisted back on board the Australian Defense Vessel Ocean Shield after successful buoyancy testing in the Indian Ocean,. (AP Photo/US Navy, Specialist 1st Class Peter D. Blair ) (Newser) – After six days with no fresh pings detected, the chief of the search for Malaysia Airlines Flight 370 says it's time to go underwater. The Bluefin-21 underwater autonomous vehicle will now be deployed to search for wreckage in an area defined by signals picked up last week that are believed to have been from the missing jet's data recorders, reports the BBC. Search chief Angus Houston says the robotic sub will be in a "reduced and manageable search area on the ocean floor" and, with the data recorders' batteries now almost certainly dead, efforts to detect pings will cease. On its first 24-hour mission, the Bluefin-21 will search an area of around 15 square miles, producing a high-resolution map of the sea floor, the Los Angeles Times reports. Houston warns, however, that the underwater search will be a "slow and painstaking process" with no guarantee of results. The area being searched, he says, is extremely deep—2.8 miles—and is largely unknown terrain "new to man." An oil slick detected on the surface of the area last night, meanwhile, is being analyzed and officials believe it didn't come from any of the search vessels, CNN reports.