“It is time to go underwater.”

Since March 8 when Malaysia Airlines Flight 370 vanished with 239 people on board, investigators have been looking desperately for clues ranging from surface debris to transmissions which were thought to come from one or both of the black boxes on the international passenger flight. Those pings have since stopped.

38 days after the search began, investigators have announced a new phase in the operation.

Bluefin-21, a 16-foot, 1,650-pound underwater autonomous vehicle, was deployed into the Indian Ocean on Monday to search for wreckage from the plane using sonar that gathers data. Running on a 24-hour cycle, it dives 2 hours to reach the 2.8 mile deep seafloor, explores for 16 hours, then climbs another 2 hours back to the surface.

Once back above water, it takes 4 hours to download the data received (a high-resolution 3-D map of the floor) and prepare the Bluefin-21 for its next ocean floor dive.

“The whole key on these searches is you have to be methodical and persistent, and they can take quite a bit of time,” said David Kelly, president and chief executive of Bluefin Robotics, the company that makes the vessel.

But, even in this day and age, technology isn’t always as perfect as sometimes needed. Personnel aboard the Australian ship Ocean Shield have limited low bandwidth communication with Bluefin-21 while on its mission.

Charitha Pattiaratchi, a professor of oceanography at the University of Western Australia, said, “It doesn’t transfer any imagery or anything while it’s down there.”

In fact on Monday, the first day of the dive, the robot returned to Ocean Shield after only six hours because it began to exceed its maximum depth of 2.8 miles. For most people, even oceanographers, that is hard to comprehend. It’s like stacking approximately 12 Sears Towers on top of each other.

Comparing the depth zone of Indian Ocean :( RIP #MH370 pic.twitter.com/uHZVSuioa1

— Jalan2Liburan (@jalan2liburan) March 24, 2014

The Bluefin-21 will be searching an area of about 600 square miles at approximately 15 square miles a day (if there are no problems). The U.S. Navy says that the search of this area alone could take 6 weeks to 2 months.

In the meantime, families of those lost are still waiting for answers and, perhaps, a bit of closure.

Image via YouTube