CosmoELEMENTS ELEMENTS AUGUST 2019 286 THE APOLLO SAMPLE COLLECTION: 50 YEARS OF SOLAR SYSTEM INSIGHT R. A. Zeigler 1 , A. B. Mosie 2 , C. Corrigan 3 , L. J. Costello 4 , J. J. Kent 2 , C. H. Krysher 5 , L. A. Watts 6 , and F. M. McCubbin 1 DOI: 10.2113/gselements.15.4.286 OVERVIEW The Apollo program was the seminal moment in modern human history and the crowning technological achievement of the 20 th century. In addition to the obvious historical, cultural, and technological signifi- cance of the Apollo program, scientific results from the Apollo lunar samples have had a lasting impact on a range of scientific fields, none more so than on the fields of planetary science and cosmochem- istry. Over the past five decades, studies of these lunar samples have yielded significant insights into planetary bodies throughout the solar system. Despite the Apollo samples being a static collection, recent and ongoing studies continue to make new significant discoveries. Here, we will discuss the collection, curation, and study of the Apollo lunar samples and look forward to some expected new developments in the coming years. BACKGROUND The Astromaterials Acquisition and Curation Office at NASA’s Johnson Space Center (hereafter JSC curation) is the past, present, and future home of all of NASA’s astromaterial sample collections (Allen et al. 2011). Our primary goals are to maintain the long-term integrity of the samples and ensure that the samples are distributed for scientific study in a fair, timely, and responsible manner. This maximizes the scientific return on each sample. The JSC curation currently houses all, or part of, nine different astromaterial sample collections, with two more sample- return missions underway: (1) Apollo program samples (1969); (2) Luna program samples (1972); (3) Antarctic meteorites (1976); (4) cosmic dust particles (1981); (5) Microparticle Impact Collection (1985); (6) Genesis solar wind atoms (2004); (7) Stardust comet Wild-2 particles (2006); (8) Stardust interstellar particles (2006); (9) Japan’s JAXA Hayabusa asteroid Itokawa particles (2010); (10) JAXA’s Hayabusa2 asteroid Ryugu particles (2021); (11) OSIRIS REx asteroid Bennu particles (2023). Additionally, JSC curation houses some combination of space-exposed hardware, contamination knowledge samples, and spacecraft material coupons for all NASA-led sample-return missions, including ongoing sample- return missions like OSIRIS-REx and Mars 2020. Each sample collection and/or affiliated witness materials are housed in dedicated clean rooms tailored to the requirements of that sample collection. APOLLO SAMPLES From 1969 to 1972, the Apollo mission astronauts collected 382 kg of rock, regolith, and core samples from six geologically diverse locations on the Moon (FIG. 1). Because of the dexterity, adaptability, and real- time decision-making ability that astronauts provide, the Apollo samples span an incredible range of sample types, including the following: large rock samples (e.g., the 11.7 kg sample 61016); multiple rocks chipped from large boulders (e.g., 76235/55/75/95 from Boulder 1, Station 6, Apollo 17 mission); bulk surface, trenched, and shaded lunar soils (e.g., 1 Astromaterials Acquisition and Curation Office NASA Johnson Space Center Houston, TX, USA E-mail: ryan.a.zeigler@nasa.gov 2 GeoControl Systems Inc., Jacobs JETS Contract, NASA/JSC 3 Smithsonian Institution, National Museum of Natural History, Department of Mineral Sciences, 10th and Constitution Ave NW, Washington DC 4 Jacobs Engineering, Jacobs JETS Contract, NASA/JSC 5 HX5, Jacobs JETS Contract, NASA/JSC 6 Barrios Technology, Jacobs JETS Contract, NASA/JSC 60500, 61220, and 69920/40/60, respectively); multiple 30–60 cm drive tubes and deep drill core samples up to ~3 meters in depth which preserved regolith stratigraphy; and several different types of special vacuum-sealed regolith and drive tube samples. In the 50 years since the Apollo samples were collected, there have been 3,195 unique lunar sample requests. These have come from over 500 different principal investigators in >15 different countries. The total number of samples allocated is not precisely known at this time, since pre-database records (before 1984) have not yet been fully digitized, but a conservative estimate is that >50,000 Apollo samples have been allocated over the past 50 years (FIG. 2). Although demand for lunar samples has waxed and waned over the years (Lunar pun!), studies of the samples have continued as new scientists and new instruments push the boundaries of what can be done with the samples. Currently, 145 active lunar principal investigators are studying >8,000 samples in fields as disparate as biology, medicine, astronomy, engineering, material science, chemistry, and (of course) geology. DISCUSSION Studies of the Apollo samples, both early and more recent, continue to yield significant insights into the formation, evolution, and maturation of the Earth–Moon system, as well as many other planetary bodies in both the inner and outer solar system. A comprehensive listing of significant results from the study of Apollo samples is not possible here. However, we have listed below a subset of results that highlight the wide-ranging, long-lasting, and diverse nature of studies of Apollo samples. (1) The Moon formed from the debris of a giant impact between the proto-Earth and a large bolide early in the solar system’s FIGURE 1 Astronaut Alan Bean, Apollo 12 lunar module pilot, holding a “special environmental sample container” containing a lunar regolith sample that was sealed under vacuum for return to Earth. CREDIT: NASA IMAGE NUMBER AS12-49-7278 FIGURE 2 The number of Apollo sample requests and Apollo sample allocations per year since 1984. This represents about 50% of the total requests made since 1969. Downloaded from http://pubs.geoscienceworld.org/msa/elements/article-pdf/15/4/286/4804188/gselements-15-4-286.pdf by guest on 05 October 2022