No submarine equipment of any kind existed that could survive the shock. Displays, computers, mountings, and life support equipment were expensive to re-engineer. Host needs – Weight, size, and center of gravity all were limited by what could be carried on the back of a . Life Support – The large number of passengers for the small submarine, the need for fully automated and self-controlling systems, and the long periods of submersion (days) presented serious challenges that could not be met with Commercial Off The Shelf (COTS) nor Government Off The Shelf (GOTS) systems. Existing systems used on large submarines required too much space and too much power. Existing systems on small submarines lacked capacity and the ease-of-use required for combat. Internal heating and cooling systems not usually needed for large submarines were needed for the smaller sub that would go into shallower warmer waters or colder surface waters. Navigation – Sonar systems developed for attack submarines, but needed for the shallow water maneuvers, were large, power hungry, and gave off excessive heat. Construction – Full nuclear sub shock, hull and piping requirements were imposed on the designers – nullifying the "off the shelf" design approaches requested by the government in earlier phases. To accommodate the larger piping and thicker hull, other systems had to be lightened. (Reference the GAO and RAND reports.) The pressure hull construction was HY-80 alloy steel (same as larger nuclear powered submarines) and the batteries were contained in separate titanium alloy pressure enclosures (14 total) which hung beneath the hull. The outer surfaces, control surfaces, nose, and tail were constructed of fiberglass composite to give the submersible a streamlined shape. The pressure hull consisted of three compartments; an operations compartment (forward) where the submersible was piloted and controlled; a diving lockout chamber (middle); and a troop transport compartment (aft) where special operations commandos and their equipment are transported. Cancellation In April 2006, the program for new submarines was canceled and Northrop Grumman notified of termination. The current submarine was still in development and in use until it was damaged in a "serious fire" in November 2008. , the cause of the fire has yet to be determined. Given the probable extent of fire and water damage (the mini-sub burned for six hours and remained sealed for two weeks) it was highly unlikely that the craft could be saved. Repair was expected to cost $237 million,