I seem to recall once reading that LC39 was designed to accomodate up to four pads. Pads C and D were never built because there was not the need. Does anyone know where they would have been located? Are those areas still free? Could they be constructed if there ever proved a need?
Additional pads would have been located north of the existing pads in a line up the beach. The fourth pad was basically a vague notion, but the third pad was planned. Some of the warning signage around the area reflected that and the crawlerway to pad B has a little stub where it would have continued north. Interestingly, originally the pads would have been lettered north to south making the current pad A, pad C.
Nothing has been built up there so technically they could build the pad, but it is unlikely a vehicle large enough to need Complex 39 will ever have the flight rate to justify it.