Pentagon leaders, including Defense Department acquisition chief Michael Duffey, are weighing options for the future GPS ground system--options that include a cancellation of the GPS Next Generation Operational Control System (OCX) by RTX [RTX]. "This is in the [Air Force] Secretary's [Troy Meink's] decision space, and he's gonna work it out through Secretary Duffey," Chief of Space Operations Gen. Chance Saltzman said at the Mitchell Institute for Aerospace Studies' spacepower forum on Wednesday in response to a question on the…