Advancing Lunar And Solar System Science And Exploration Through A Lunar Sample Return Campaign [Updated]

Clive Neal
Abstract Title: 
Advancing Lunar And Solar System Science And Exploration Through A Lunar Sample Return Campaign [Updated]
Abstract Type: 
Abstract Body: 
Introduction: There have been 11 missions to the Moon this century from 5 different space agencies, 10 of which have been orbital. Significant global datasets show our lunar sample collection is not representative [1]. Decadal Survey (DS) [2]: South Pole-Aitken (SPA) Basin Sample Return has been a named New Frontiers class mission in the last two DSs [2,3]. The current DS [2] states (p. 133) that important science questions can be addressed by sample return. It is pres-ently thought that sample return missions are difficult under the conventional Discovery mission line, but recent developments in commercial lunar capabilities (e.g., [4]), demonstrate a new, innovative lunar science and exploration program could be initiated. Sample Return Targets: Available orbital data al-lows targeted lunar sample return missions to be pro-posed that address DS science and exploration goals. Multiple targets are identified in Fig. 1a,b; these are examples for the sample types that will greatly ad-vance our understanding of the Moon and the inner Solar System. Such sites will need to be assessed in terms of landing safety. Olivine/Orthopyroxene- and Spinel-rich lithologies (OOS) were discovered using M3 data [5,6]. These are not well represented in the current sample collection (Apollo and Luna, as well as lunar meteorites). “Impact Melt/Basin, Young Craters” locations would return impact melts for dating from young and old basins to constrain the impact history of the inner Solar System. Felsic locations have been identified from orbital da-tasets (silica-rich, high Th abundances, distinct peak in thermal emission near 8µm or the Christiansen feature [7,8]). Young Igneous samples include young basalts defined by crater counts [9], and proposed irregular mare patches [10]. These young basalts have important im-plications for understanding the composition of the mantle and the thermal evolution of the Moon. Sam-pling of Farside Mare Basalts will also address these science issues. Pyroclastic Deposits are critical for understanding the volatile budget of the lunar interior and their potential for in situ resource utilization (ISRU) [11-14]. Hydrogen (volatile) Deposits are shown by orbital data to be present in and around some permanently shaded regions (PSRs) [15]. Such materials could con-tain ancient materials that address Solar System sci-ence questions (building blocks of life, source signa-ture of inner Solar System volatiles, etc.). Defining the nature, distribution, and accessibility will be important for ISRU enabling human exploration. Deep Crust & Mantle can be sampled around central peaks and deep areas within SPA or around Mare Crisium. A sample of the deep crust and/or the upper mantle will constrain the Apollo geophysical data and the more capable Lunar Geophysical Network, a New Frontiers mission for the NF-5 call later this decade [2]. Farside Crust. Comparing these samples with Apollo, Luna and lunar meteorite highlands lithologies is im-portant for understanding crustal heterogeneity. It will also test if ferroan anorthosites are the dominant crus-tal lithology, as predicted from the LMO hypothesis. Outcrop Sampling: None of the samples in the collec-tion were collected from unequivocal in situ outcrops. Properly oriented samples are required from various terrains and of different ages to truly test the whether the Moon ever established a core dynamo [16]. Technology Development. Sample return has be-come a next step for studying many planetary bodies (Moon, Mars, asteroids). For the return of rock and regolith samples, very little technology development is needed. However, cryogenic sampling, return, and curation will require investment. A New Exploration Paradigm: Private companies are developing surface exploration capabilities, includ-ing sample return. Using these emerging capabilities could enable NASA to access the surface more rapidly, and on a more regular basis, as a customer. A dedicat-ed Lunar Science & Exploration Program (LSEP) Of-fice could be established that involves the lunar com-munity and industrial partners in mission planning and flight opportunities, providing tremendous opportunity for exploration advances. Since a regular cadence of missions to the Moon would be required for private commercial companies to build a business case, an opportunity now exists to change the paradigm of planetary science and exploration to implement an affordable lunar robotic program. A focused lunar program would allow NASA to be a regular customer while developing new capabilities and implementing at least some of the objectives listed in [17,18]. References: [1] Giguere T.A. et al. (2000) MaPS 35, 193. [2] Vision & Voyages for Planetary Science in the Dec-ade 2013-2022 (2013) 399 pp. [3] New Frontiers in the Solar System (2003) 248 pp. [4] Moon Express Sample Return Capability. [5] Pieters C. et al. (2011) JGR 116, doi:10.1029/2010JE 003727. [6] Pieters et al. (2014) Am. Min. 99, 1893. [7] Murcray F. et al. (1970) JGR, 75, 2671. [8] Salisbury J. et al. (1970) JGR, 75, 2671. . [9] Hiesinger H. et al. (2010) JGR 115, 10.1029/ 2009JE003380. [10] Braden S. et al. (2014) Nat. Geosci., 7, 787. [14] Rutherford M.J. et al. (1976) PLSC 7, 1723 [11] Green D. et al. (1975) PLSC 6, 871. [12] Saal A. et al. (2008) Nat. 454, 192. [13] Hauri E. et al. (2011) Sci. 333, 213. [14] Milliken & Li (2017) Nat. Geosci. 10, 561. [15] Mitrofanov I.G. et al. (2010) Sci. 330, 483. [16] Garrick-Bethell I. et al. (2009) Sci. 323, 356. [17] NRC Scientific Context for the Exploration of the Moon. [18] The LEAG Lunar Exploration Roadmap.
S.J Lawrence, 2ARES, NASA-Johnson Space Center, Houston TX 77058, USA (