Voyage to the bottom of the sea

On 31 May 2009 a unique and versatile hybrid vehicle dived 10,902m below the surface of the Pacific Ocean to the bottom of the ´Challenger Deep´ in the Mariana Trench. The Nereus is only the third vehicle ever to have descended this far - to the deepest part of the world´s oceans. The revolutionary unmanned craft was designed by engineers at Woods Hole Oceanographic Institute (WHOI) in Massachusetts on a budget of only $6m. Nereus is set to open up the exploration of the extreme depths to science, and its design concept will have extensive repercussions on ´conventional´ ROV design in the oil and gas and military sectors. Project manager and principal developer Andy Bowen talked to E&T about what makes it special. Its hybrid nature means that Nereus can be operated as a pre-programmed, free-flying autonomous underwater vehicle (AUV) to survey broad areas. Conversion into its tethered, piloted ROV (remotely-operated vehicle) mode only takes six hours and allows it to inspect specific areas of interest identified in the flyby. This makes it especially flexible and versatile. Freed of the constraints of heavy steel cables, with a robot like Nereus we can now explore virtually anywhere in the ocean.