The Secretary of each military department may establish such advisory committees and panels as are necessary for the research and development activities of his department and may employ such part-time advisers as he considers necessary to carry out those activities.

A person who serves as a member of such a committee or panel may not be paid for that service while holding another position or office under the United States for which he receives compensation. Other members and part-time advisers shall (except as otherwise specifically authorized by law) serve without compensation for such service.