51st Lunar and Planetary Science Conference (2020) 2234.pdf

GEOLOGIC CONTEXT OF APOLLO 17 STATION 3 FROM RECENT REMOTE SENSING DATASETS: IMPLICATIONS FOR THE APOLLO NEXT GENERATION SAMPLE ANALYSIS (ANGSA) DOUBLE CORE TUBE SAMPLES 73001/73002. N. E. Petro1, S. Valencia1, H. H. Schmitt2, D. Moriarty1, D. M. H. Baker1, C. Shearer3, B. Jolliff4. 1Solar System Exploration Division, NASA Goddard Space Flight Center, Greenbelt, MD 20771, 2University of Wisconsin, P. O. Box 90730, Albuquerque NM 87199, 3Dept. of Earth and Planetary Science, Institute of Meteoritics, University of New Mexico, Albuquerque, NM 87131; Lunar and Planetary Institute, Houston TX 77058. 4Dept. Earth & Planetary Sciences and the McDonnell Center for Space Science, Washington University in St. Louis, MO 63130. (Noah.E.Petro@nasa.gov)

Introduction: The Apollo Next Generation Sample m-chi deconvolution [6], Diviner regolith properties [7], Analysis Program (ANGSA) enables an unprecedented and M3 compositional data enable assessments of what opportunity to study “pristine” samples with 21st century may be in the double drive tube, specifically the as-of-yet analytical techniques [1]. One of the ANGSA samples, unstudied core sample (73001). 73002/73001- a double drive tube from Apollo 17 Station Mini-RF: Radar data is valuable for assessing regolith 3 (S3), was collected at surface expression of the Lee- properties of the upper ~1m of the lunar surface. The m- Lincoln Scarp and within a massive avalanche deposit chi deconvolution enables us to assess the scattering (Fig.1) [2]. Here we use multiple datasets available in the properties of the regolith and, given the area sampled PDS from the Lunar Reconnaissance Orbiter (LRO) during Apollo 17, compare regolith properties across mission as well as compositional data from the Moon Taurus–Littrow Valley (Fig. 2). The S3 regolith scattering Mineralogy Mapper (M3) to provide a geologic context properties appear to result from coherent fragments larger for these unique samples. We also use samples collected than ~12.6 cm (wavelength of the Mini-RF S-band data). at S3 to constrain regolith components. Both a double bounce (indicating rocks or a rough surface) and volume scattering component occur at S3. These data for the light mantle suggest abundant rocks or indurated regolith fragments [4] within the upper meter of the deposit.

Figure 1. LRO Camera Narrow Angle Camera view of light mantle deposits, showing the older (at right) and younger (at left) deposits. Location of S3 marked by red box, Station 4 with a blue box. Phase angle for the image is 19.47º. Image ID is M124369214. Geologic Context from Recent Observations:

While a companion abstract discusses the in situ context Figure 2. Mini-RF m-chi deconvolution of the Taurus-Littrow Valley, for the samples from S3 [3], with the suite of modern red box marks the location of S3. The m-chi color composite comprises remote sensing datasets we place those observations into R=double bounce G=volume scattering B=single bounce. a regional context. Analyses of recent data demonstrated Diviner: Thermophysical measurements of the lunar the importance of these new views in interpreting the regolith provide important constraints on the vertical and geologic context of the Apollo 17 landing site [4]. lateral variability of the regolith within the upper ~10 cm. Relevant to S3 has been the identification of at least two Relevant to the double drive tube, the upper portion of the distinct “light mantle” deposits (Fig. 1), one of which may core (73002) sampled to a depth of ~22 cm and contains be related to Tycho secondary craters or to the Lee- no fragments >2 cm within the upper 10 cm [8]. A map of Lincoln fault [4, 5]. Other datasets, namely the Mini-RF the density structure of the regolith [7] (Fig. 3) suggests 51st Lunar and Planetary Science Conference (2020) 2234.pdf

that the light mantle, and the region near S3, is 73001/73002 were collected ~15 m from the rim of the homogenous and broadly similar to the regolith sampled small crater and likely samples the light-mantle [3]. during Apollo 17. In situ observations and rake samples, Rock Fragments: Nearly all rock fragments collected however, indicate greater similarity with the fine fraction from S3 are breccias similar to the South Massif breecias. of regolith on the North Massif [3]. Unlike what is These rocks are aphanitic to fine-grained impact melt observed by Mini-RF, the central cluster is distinct from breccias (IMBs) dominated by matrix materials. Lithic the light mantle deposit in the H-parameter (Fig. 3). clasts are composed of non-mare materials. Lithic clasts record multiple events from 3.9–>4.1 Ga [12-17]. Early interpretations were that these impact melt rocks must be remnants of the Serenitatis impact event [e.g., 18], but there have been challenges to this interpretation [e.g., 4, 19, 20]. Exposure and crater- frequency ages of the IMBs cluster may reflect the multiple stages of landslide deposits [4] with ages of 75- 86, 95-110, 160, and >190-270 myr [12-15]. Soils: Near-surface Station 3 soils were collected from a 10 cm deep trench dug on the rim of the Ballet crater. The trench soils exhibit a distinct marbling of light and Figure 3. Diviner H-parameter map of the Taurus-Littrow Valley, the darker gray material owing to varying agglutinate content location of S3 is marked in a red box, the landing site a black box [7, 9]. (i.e., maturity) [3, 21]. The soil samples are reflective of Moon Mineralogy Mapper: Compositional data from 3 the light mantle as breccia is the most common material M help in understanding what may have been incor- (≤62%), but also contain other fragments of interest porated into the avalanche deposit and sampled at S3 (Fig, including basalt (≤3.7%) and volcanic ash (≤7.0%). A 4). Knowing that there is slight compositional variability 3 companion abstract [22] provides a detailed evaluation of in the samples [10] collected at S3 (see below), the M samples from S3. data indicates that the light mantle is relatively Implications for 73001/73002: The ANGSA homogenous, compositionally similar to both the South program allows us to analyze previously unstudied lunar and North Massifs, and mineralogically distinct from the samples [1]. The Apollo 17 Station 3 double core tube central cluster/valley floor. However, at the summit of the sampled a ~70 cm deep section of the light mantle deposit. South Massif are exposures of potentially noritic Based on remote sensing data the regolith at Station 3 may materials, which may be related to breccias sampled at S3. have portions of decimeter sized indurated regolith within the upper meter but below the top ~7 cm which is relatively unconsolidated. However, there may be additional mafic fragments within the core samples, similar to the IMBs sampled at Ballet Crater, may be sourced from the blocks at the summit of the South Massif. Detailed analysis of the core, building on the micro-XCT scans already performed of 73002, will provide an excellent ground truth test for these remote observations and provide insight for the application of these datasets to planning future sample return missions. References: [1] Shearer, C. K., et al., (2019), LPSC,Abst. #1412. [2] Parker, R. A., et al., (1973) Apollo 17: Preliminary Science Report., SP-330, [3] Schmitt, H. H., (2020) These proceedings. [4] Schmitt, H. H., et al., (2017) Icarus, 298, 2-33. [5] Hahn, T. M., et al., (2019) LPSC, 1963. [6] Cahill, J. T. S., et al., (2014) Icarus, 243, 173-190. [7] Hayne, P. O., et al., (2017) Journal of Geophysical Research-Planets, 122, 2371-2400. [8] Butler, P., (1973) Lunar Sample Information Catalog: Apollo 17, MSC 03211. [9] http://bit.ly/35k6jEh [10] Wolfe, E. W., et al., (1981) The Geologic investigation of the Taurus-Littrow valley, Apollo 17 landing site, 45. [12] Phinney, D., et al., (1975) PLPSC, 2, Figure 4. Principal Components Analysis map of M3 data highlighting 1593-1608. [13] Turner, G. and P. H. Cadogan, (1975) PLPSC, 2, 1509- compositional variations across the Taurus-Littrow Valley overlain on 1538. [14] Staudacher, T., et al., (1977) LPSC, 8, 896. [15] Staudacher, LROC NAC images [4]. S3 is marked by a red box. T., et al., (1979) PLPSC, 1, 745-762. [16] Carlson, R. W. and G. W. Station 3 Sample Context: Station 3 soils and rock Lugmair, (1981) EPSL, 52, 227-238. [17] Grange, M. L., et al., (2009) GCA, 73, 3093-3107. [18] Dence, M. R., et al., (1976) PLPSC, 2, 1821- fragments were collected along the rim of a 10 m crater 1832. [19] Spudis, P. D. and G. Ryder, (1981), Multi-ring basins: (tentatively named Ballet) within the light-mantle Formation and Evolution,Abst. #133-148. [20] Spudis, P. D., et al., landside from the South Massif. Additionally, samples (2011) JGR-P, 116, E00H03. [21] Heiken, G. and D. S. McKay, (1974) PLPSC, 5, 843-860. [22] Jolliff, B.J. et al, (2020) These proceedings.