The research submarine Alvin is about to leave active research for an 18-month upgrade and overhaul.
It has been in operation for 46 years, doing both scientific research in the deep ocean while remaining available to conduct deep-water missions for the U.S. Navy. Some of these missions are public, such as the search for, and ultimate recovery of a nuclear bomb in the waters off Palomares, Spain in 1966. Others remain classified.
Most recently, Alvin has been conducting research on the effects of the Gulf oil spill.
Alvin will return to service in 2012.
Image courtesy of NOAA.