It's the single-biggest question hanging over the Bath-Brunswick area:  What will become of Brunswick Naval Air Station when the Navy leaves little more than a year from now? Steve Levesque is working on that as head of the Midcoast Regional Redevelopment Authority. Levesque also worked on the redevelopment of Loring Air Force Base in northern Maine.  Levesque works in a small building just beyond the security gate at the Maine entrance to the base, which is where he and MPBN's Morning Edition host Irwin Gratz sat down for a talk, part of which you'll hear today and the rest next Monday.  They began with the -- for now -- closed airfield.