The good news is that robotic submarine Bluefin-21 completed another successful deep-sea mission. Unfortunately, it found no "contacts of interest" in the search for missing Malaysia Airlines Flight MH370. According to Australia's Joint Agency Coordination Center, which is coordinating the search, the autonomous underwater vehicle has covered 42.5 square miles of the search area thus far.
The underwater drone uses side sonar to create high-resolution 3-D images of the seafloor. The search area is located on the not previously mapped Zenith Plateau. According to Reuters, it is likely covered in a sludge called "foraminiferal ooze" made of microscopic organisms. Each of Bluefin's missions is around 24 hours long -- 16 of those hours are spent scanning the bottom of the Indian Ocean for any debris. If it finds anything of note, the submarine can swap into camera mode and take images of the debris.
Bluefin's first two missions were cut short; one was due to depths below the AUV's programmed 2.8 mile limit, the other was due to technical issues. Problems were eventually resolved and according to the Joint Agency Coordination Center, Bluefin-21 is currently on mission five.
The AUV deep-ocean search began earlier this week; previously searchers were using a U.S. Navy black box detector towed by the Australian ship Ocean Shield. The Ocean Shield was able to pick up four "pings" that were consistent with black box signals. Planes' black boxes are equipped with two recorders, one for voices in the cockpit and the other for data. If found, these recorders could give investigators insight into what caused the plane to veer off course and end in the Indian Ocean. Each recorder is also furnished with a beacon that goes off when it makes contact with water. Unfortunately, these beacons only have a battery life of 30 days.
Investigators were hoping to pick up more "pings," but after a week it was suspected that the black box beacons' batteries had died. With the four signals, however, investigators were able to further narrow the search area, which is located around 1,400 miles northwest of Perth, Australia.
In the meantime, the search for floating debris has now entered its 42nd day -- with no physical evidence found. According to CBS News retired Air Chief Marshal Angus Houston, who is heading up the multinational search, the visual search will be ending within days.
Malaysia's Minister of Defense Hishamuddin Hussein said the visual search would extend through Easter weekend, but after that investigators would need to regroup. "There will come a time when we need to regroup and reconsider," he told reporters. "But in any event, the search will always continue. It's just a matter of approach."
Flight MH370 has been missing since March 8. The plane and 239 people on board never made it to its Beijing destination. Much mystery (and even some far-flung conspiracy theories) have surrounded the plane's disappearance. Early into the flight the plane's communication transponders went out and the plane dramatically diverted from its flight plan, heading west. Investigators are still unsure why the plane flew off course and ended in the Indian Ocean.