For the first time since the hunt for missing Malaysia Airlines Flight 370 began, a submarine will be sent down to search the area where an Australian ship heard what could be pings from its black box.
The Ocean Shield, which detected two possible pings over the weekend, will launch an unmanned miniature submarine into the Indian Ocean. The sub uses sonar to make a map of the ocean floor, so if there is any debris down there, it will hopefully "see" it.
The first ping lasted over two hours before it was lost. The second lasted just 13 minutes. Angus Houston, who is in charge of the search, called the signals "a most promising lead, and in the search so far it's probably the best information we've had."
A Chinese ship, the Haixun 01, also said it detected possible pings, but the Ocean Shield is carrying much more sophisticated detection equipment. It is possible both ships heard the same signal. The ships are 300 nautical miles away from each other. A British search ship is now searching the area of the Haixun 01 with a deep-sea ping locator.
The frequency of the signal the Ocean Shield detected was 33.3 kHz -- not the 37.5 kHz the black box is supposed to emit. This can be explained, the AP said, as "the frequency of black boxes can drift in older equipment." Or it's not the black box.
The black box's batteries only last about 30 days. Today was the thirtieth day of the search.