Retrieved from Bluefin.com
The disappearance of the Malaysian Air flight MH370 on March 8, 2014, resulted in a multi national search and recovery effort.  On January 6, 2015, the total search area spanned over 14,000 square kilometers. (Jamieson, 2015)  The tools utilized to search for the missing aircraft included manned aircraft including C-130, P-3, and helicopters, towed ping detector arrays, and a U.S. Navy Bluefin-21 Unmanned Underwater Vehicle (UUV).  “While scouring the bottom of the ocean, the Bluefin-21 dove to crushing depths of 5,000 meters, said Jeff Smith, chief operating officer of the Bluefin Robotics Corp., a wholly-owned subsidiary of Battelle. That was deeper than any other Bluefin-21 had reached before, he said.” (Tadjdeh, 2014)
The Bluefin21 is an electrically powered modular UUV with an endurance of 25 hours and a depth rating of 14,763 ft. (Bluefin Robotics Corporation, 2015) Its standard  sensor payload is as follows:
·      Proprioceptive sensors:
o   Fault detection: monitor system status and report faults to operator.
o   Leak detection: alert operator of internal leaks that would threaten the UUV
o   Internal Pressure sensor: detect changes in internal pressure of UUV to monitor system health
·      Exteroceptive sensors
o   INS (Internal Navigation System): provides location data for navigation.
o   DVL (Doppler Velocity Logger): provide positioning data by measuring water velocity and acoustic echo intensity. (Teledyne RD Instruments, 2013)
o   SVS (Sound Velocity Sensor): measure speed of sound in water.
o   GPS (Global Positioning System): provides positioning information.
o   Iridium: satellite communication positioning.
o   EdgeTech 2200-M 120/410 kHz side scan sonar: “This modular unit can be configured, based on the customers’ application, to collect side scan sonar imagery, sub-bottom profiles and bathymetric data, singly or in concert with one another.” (EdgeTech, 2015)
o   EdgeTech DW-216 sub-bottom profiler: utilized to generate high-resolution images of the sub-bottom stratigraphy. (EdgeTech, 2015)
o   Reson 7125 400 kHz multibeam echosounder: creates image of the seabed.
The Bluefin21 can support multiple configurations due to its modular design.  These configurations are dependent on the underwater vehicle; having longer mission duration and being able to support more powerful sensors could enhance the UUV.  The operating depth of the Bluefin21 can also affect its effectiveness.  The first mission trying to locate flight MH370 had to be aborted 10 hours ahead of schedule since the depth exceeded the UUV’s rating.  “However, the sonar imaging becomes less effective as the scan depth increases. There are small portions of the current search area where the actual depth may exceed the charted depth.” (News.Com.Au, 2014)
One interesting approach to the utilization of UUVs for search and rescue is the cooperative integration between UUVs and Unmanned Air Vehicles (UAVs).  The UAVs can be deployed as an immediate response to the search effort; being airborne they can cover a large expanse of water to look for obvious signs or the target or debris.  Recent developments in LIDAR technology can forecast the utilization of such sensor payloads on UAVs for underwater exploration.  “Researchers have developed a proof-of-concept LIDAR prototype that improves the speed and accuracy of ocean scans and – unlike current systems – allows the collection and transmission of data in real time for production of high resolution 3-D images.” (Toensmeir, 204)  Data captured by the UAVs will assist in the deployment of UUVs in better-defined search grids.
Unmanned maritime systems have the advantage, over their manned counterparts, of being able to operate closer to the seabed for a longer duration. Being unmanned, UUVs do not need life support systems that would increase the overall system complexity and place a higher demand on the power source.  This benefit allows the UUV to be more effective by being able to utilize a lower power sensor payload for a longer duration, closed to the seabed.  Being able to operate for a longer duration in lower depths also means that the UUV could be more effective by not being affected by surface weather.
UUVs are a natural progression in the development of unmanned systems.  They operate in environments that require manned counterparts to have elaborate life support systems.  They excel in long duration missions and have the ability to carry a more diverse sensor payload.  An added benefit of UUVs is their cost as compared to manned units.  UUVs can be launched and recovered and a faster rate than manned crafts.  More powerful and efficient sensor technology and power units will result in a broader application of UUVs.


References

Bluefin Robotics Corporation. (2015). Bluefin-21. Retrieved January 25, 2015, from Bluefin Robotics Corporation: http://www.bluefinrobotics.com/assets/Downloads/ Bluefin-21-Product-Sheet.pdf
Bluefin Robotics Corporation. (2015). Sensor Integration. Retrieved January 25, 2015, from Bluefin Robotics Corporation: http://www.bluefinrobotics.com/technology /sensor-integration/
EdgeTech. (2015). 2200 and 2205 AUV/ROV Sonars. Retrieved January 25, 2015, from EdgeTech: http://www.edgetech.com/products/auv-rov-sonar/2200-2205-auv-rov-sonar/#productTab2
EdgeTech. (2015). Sub-bottom Profiling. Retrieved January 25, 2015, from EdgeTech: http://www.edgetech.com/products/sub-bottom-profiling/
Jamieson, A. (2015, January 7). Missing MH370: Search Will Prioritize Finding Jet's Black Boxes. Retrieved January 25, 2015, from NBC News: http://www.nbcnews.com/storyline/missing-jet/missing-mh370-search-will-prioritize-finding-jets-black-boxes-n281231
News.Com.Au. (2014, April 16). Malaysia Airlines flight MH370: If Bluefin-21 fails in search what next. Retrieved January 25, 2015, from News.Com.Au: http://www.news.com.au/travel/travel-updates/malaysia-airlines-flight-mh370-if-bluefin21-fails-in-search-what-next/story-fnizu68q-1226885624059
Tadjdeh, Y. (2014). As Technology Matures, New Roles Emerge for Underwater Drones. National Defense , 99 (730), 24-26.
Teledyne RD Instruments. (2013). Workhorse Navigator Doppler Velocity Log. Retrieved January 25, 2015, from Teledyne RD Instruments: http://www.rdinstruments.com/ navigator.aspx

Toensmeir, P. (204, December 15-22). Undersea Mapping. Aviation Week & Space Technology.