The Secretary of Defense is authorized, in his discretion, to transfer to the Secretary of the Army or the Secretary of the Navy, and to retransfer from either of such Secretaries to the other or to the Secretary of the Air Force, all, or any part of, the authority granted by sections 501 and 502 of this title; and, in connection with any such transfer or retransfer, to transfer all or any part of the funds available for the establishment and support of the joint long-range proving ground for guided missiles and other weapons. The Secretary of Defense is further authorized to permit, to the extent that he may deem appropriate, the Secretaries of the Army, the Navy, and the Air Force to contribute, with or without reimbursement, to the establishment and support of the joint long-range proving ground for guided missiles authorized by this chapter, by the loan, assignment, or transfer of personnel, supplies, equipment, and services.