South Pole-Aitken Basin Sample Return and eXploration (SPARX) Science Definition Team Report

Sample return from the Moon’s South Pole-Aitken Basin (SPA) has been recognized as the highest priority lunar science mission for well over two decades, appearing as a recommended New Frontiers class mission in the two previous Planetary Science Decadal Survey documents (2003–2012 New Frontiers, 2013–2022 Visions & Voyages), and as a prioritized mission for the Lunar Discovery and Exploration Program (LDEP) in the 2023–2032 Origins, Worlds, and Life Decadal Survey (OWL). The South Pole-Aitken basin presents the ideal target destination to test nearly 60 years of lunar science hypotheses owing to a unique combination of its size, antiquity, and location on the lunar farside. Despite the recognized importance of SPA science, past sample return mission designs have been challenged by a combination of cost and technology.

This report defines science goals and objectives for a South Pole-Aitken Basin Sample Return and eXploration (SPARX) mission, the in situ and terrestrial laboratory measurements required for the completion of these objectives, and the lithologies, sample properties, and masses of samples that must be returned for the required measurements. This report also explores a range of potential mission implementation and programmatic architectures for achieving various levels of the SPARX science objectives, including a full range of mobility options, commercial capabilities, the role of astronauts, and the potential for multi-landing campaign-style science. From these investigations, the SPARX SDT has developed a baseline mission concept for a long- distance rover that would collect samples and conduct science at 21 locations across SPA before rendezvousing with Artemis astronauts for sample return. The proposed baseline mission includes a traverse design that can accomplish the SPARX science goals, optimizes the programmatic understanding of the implementation space, and fits within the cost guidance provided by NASA.

The return of samples from the Moon by the Apollo missions revolutionized not only our understanding of the Moon but also established the foundational lens through which we view the formation and evolution of the Solar System. And yet, as the field of planetary science has continued to evolve, with missions across the Solar System, comparative studies between planetary surfaces, and the re-examination of Apollo samples for a new generation, gaps in these initial models have begun to appear. The time is now, for a new generation of sample return, to address critical questions of Solar System and planetary formation, once again using the Moon as an archetype with scientific implications that will ripple across the rest of the Solar System.