; program management; personnel and related costs, including uniforms or allowances therefor, as authorized by sections 5901 and 5902 of title 5, United States Code; travel expenses; purchase and hire of passenger motor vehicles; and purchase, lease, charter, maintenance, and operation of mission and administrative aircraft, $1,205,000,000, to remain available until September 30, 2025: Provided, That $227,000,000 shall be for On-orbit Servicing, Assembly, and Manufacturing 1: Provided further, That $110,000,000 shall be for the development, production, and demonstration of a nuclear thermal propulsion system, of which not less than $45,000,000 shall be for reactor development, not less than $45,000,000 shall be for fuel materials development, and not less than $20,000,000 shall be for non-nuclear systems development and acquisition planning: Provided further, That, not later than 180 days after the enactment of this Act, the National Aeronautics and Space Administration shall provide a plan for the design of a flight demonstration. EXPLORATION For necessary expenses, not otherwise provided for, in the conduct and support of Artemis Campaign Development activities, including research, development, operations, support, and services; maintenance and repair, facility planning and design; space flight, spacecraft control, and communications activities; program management; personnel and related costs, including uniforms or allowances therefor, as authorized by sections 5901 and 5902 of title 5, United States Code; travel expenses; purchase and hire of passenger motor vehicles