; (B) fees and royalties collected by the Administrator or the ISS management entity under subsections (a) and (b); and (C) donations or contributions designated to support authorized activities. (4) Rule of construction Amounts available to the Administrator under this subsection shall be in addition to amounts otherwise made available for the purpose described in paragraph (2). (d) Definitions The terms used in this section have the meanings given the terms in section 20150. . (c) Conforming amendment The table of sections for chapter 201 of title 51, United States Code, as amended by sections 213 and 214, is further amended by inserting after the item relating to section 20151 the following: 20152. Royalties and other payments received for designated activities. . 216. Steppingstone approach to exploration (a) In general Section 70504 of title 51, United States Code, is amended to read as follows: 70504. Steppingstone approach to exploration (a) In general The Administrator, in sustainable steps, may conduct missions to intermediate destinations, such as the Moon, in accordance with section 20302(b), and on a timetable determined by the availability of funding, in order to achieve the objective of human exploration of Mars specified in section 202(b)(5) of the National Aeronautics and Space Administration Authorization Act of 2010 ( 42 U.S.C. 18312(b)(5) ), if the Administrator— (1) determines that each such mission demonstrates or advances a technology or operational concept that will enable human missions to Mars; and (2) incorporates each such mission into the human exploration roadmap under section 432 of the National Aeronautics and Space Administration Transition Authorization Act of 2017 ( Public Law 115–10