Navy research submersible finishes $41 million retrofit

Nature : In 1964 the US Navy commissioned the DSV Alvin, a small, manned research submarine. Since its launch, Alvin has been responsible for several major discoveries such as ecosystems powered by hydrothermal vents instead of sunlight. In 2011, after making observations of the Deepwater Horizon oil spill , the vessel began a $41 million retrofit that has just been completed. On 25 May, Alvin will leave Woods Hole Oceanographic Institution in Massachusetts for a series of certification cruises off the coast of Oregon. Its upgrades include a larger sphere with extra windows and cameras for human occupants, longer manipulator arms, and a larger sample collection container. The new titanium sphere is capable of reaching depths of 6500 m, but the craft will still be limited to its previous maximum depth of 4500 m because its lead-acid batteries are not suitable for the lower mark. Susan Humphries, who was in charge of the retrofit, hopes that lithium-ion batteries will soon be safe enough to be added during regular maintenance in the next 5 years.