; (2) to the maximum extent practicable, encourage reusability and sustainability of systems developed; (3) ensure availability of 1 or more lunar polar science payloads for a demonstration mission; and (4) to the maximum extent practicable, offer existing capabilities and assets of NASA centers to support these partnerships. 202. Space launch system configurations (a) Mobile launch platform The Administrator is authorized to maintain 2 operational mobile launch platforms to enable the launch of multiple configurations of the Space Launch System. (b) Exploration upper stage To meet the capability requirements under section 302(c)(2) of the National Aeronautics and Space Administration Authorization Act of 2010 ( 42 U.S.C. 18322(c)(2) ), the Administrator shall continue development of the Exploration Upper Stage for the Space Launch System with a scheduled availability sufficient for use on the third launch of the Space Launch System. (c) Briefing Not later than 90 days after the date of the enactment of this Act, the Administrator shall brief the appropriate committees of Congress on the development and scheduled availability of the Exploration Upper Stage for the third launch of the Space Launch System. (d) Main propulsion test article To meet the requirements under section 302(c)(3) of the National Aeronautics and Space Administration Authorization Act of 2010 ( 42 U.S.C. 18322(c)(3) ), the Administrator shall— (1) immediately on completion of the first full-duration integrated core stage test of the Space Launch System, initiate development of a main propulsion test article for the integrated core stage propulsion elements of the Space Launch System; (2) not later than 180 days after the date of the enactment of this Act, submit to the appropriate committees of Congress a detailed plan for the development and operation of such main propulsion test article