The Linux-based Bluefin-21 automated mini-sub now leading the search for Malaysia Airlines Flight 370 may need to be pushed beyond its 2.8 mile depth limit.



The massive, 40-day air and sea search for the missing Malaysia Airlines Flight 370 has now come down to this: one 16-foot, autonomous yellow submarine that runs on Linux.

The Bluefin-21 automated underwater vehicle (AUV) from Bluefin Robotics is now seen as the best hope for locating the wreckage of the plane, which is estimated to be in a 600 square mile area 1,400 miles west of Perth, Australia. If the sub can identify the black box within the wreckage, we may find the answer to why the plane abruptly changed course toward the empty expanses of the Indian Ocean, as well as the ultimate fate of the plane’s 227 passengers and 12 crew members.







Bluefin-21

(click image to enlarge)



The Bluefin-21 was loaned out by the U.S. Navy to an Australian Defense Vessel (ADV) called Ocean Shield that is leading the hunt under the guidance of UK-based Bluewater Recoveries. The search area was recently reduced in size thanks to some pings that were recorded from what may be Flight 370’s black box. The pings have gone silent, presumably because the black box has now exhausted its battery power, so the search is continuing via direct underwater observation.

The Bluefin-21 was chosen for its autonomous operation and hardened hull, which enables dives as deep as 2.8 miles, easily handling the bulk of the search area. Earlier this week on one of its first dives at the search site, the sub was forced to skip over an area that was a bit deeper than that. However, an April 17 USA Today report says the Bluefin-21 operators may choose to override the failsafe that prevents descents further than 4500 meters to approach closer to three miles. This move would pose a “small but acceptable level of risk,” according to the ADV operators.







Bluefin-21 in action

(click images to enlarge)



According to the story, as well as the Australian government’s Joint Agency Coordination Centre , earlier estimates that the sub would take 6-8 weeks to survey the area was incorrect. The new estimate is said to be less than that.

The Bluefin-21 navigates in a straight line about 150 feet above the sea floor at 2-3 knots, using side-scan sonar to build a high resolution 3D map of the searched area. If an object of interest is detected, with the help of onboard algorithms that differentiate between natural and man-made shapes, the sub switches to camera mode. Photographing in the undersea darkness requires proximity of 15 feet of the object.

In any 24 hour period, the Bluefin-21 can search for 16 hours. The other time is split up by diving and surfacing, as well as downloading data to on-ship computers via an Ethernet cable.

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The Bluefin-21 is used by the Navy for mine detection. Like other Bluefin UAVs, it has been used in applications including anti-terrorism surveillance, oceanography, and archaeology.

MIT spinoff Bluefin Robotics confirmed to Linux.com that like its smaller cousin the Bluefin-9, the Bluefin-21 runs Linux on multiple Pentium processors. In the Bluefin-21 product page, there are details on payload and other aspects. including the availability of GPS, RF, Iridium, and strobe communications. However, there are few details on the computer.



Bluefin-9

The presence of Linux in the smaller Bluefin-9, which is designed for 200-meter dives for harbor surveillance, was revealed by RTI, which makes the communications middleware [PDF] for the sub. The sub’s embedded Linux computer communicates with a Windows-based computer on the surface ship, but is intended to operate autonomously.

Last summer, a presentation stack appeared on the web that unveiled a Bluefin Robotics plan for a new version of the Bluefin-9 [PDF]. The updated model can dive to 300 meters, and offers some of the more advanced features found on the Bluefin-21, including modular free-flooded payload and swappable sensor payloads.

The updated Bluefin-9 is further equipped with gigabit Ethernet port and switch, as well as a 128GB SSD. It also adds a mechanism to integrate third-party computers to the sub’s COTS carrier board via a USB connection. It’s currently said to be configured to support an unstated Gumstix module. This may well be the Linux-ready DuoVerdo COM, such as the one found on the recently announced Gumstix AeroCore control board for micro-helicopters and other tiny drones.

