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IN REPLY REFER TO: UN I TED STATES DEPARTMENT OF THE INTERIOR GEOLOGICAL SURVEY Center of Astrogeology 601 East Cedar Avenue Flagsta.ff, Arizona 86001 November 30, 1971 Memorar1dum To Noel Hinr~ers, Chairman, ad hoc Site Selection Group, A,p_ollo 17 From William R. Muehlberger, Principal Investigator, s~059 Apoll~ Field Geology Investigations Subject: Candidate Apollo 17 landing sites The attached memorandum presents a summary of the recommen_ded sites for Apoilo 17'by. the.photogeologic mappers of the U.S. Geol6gical Survey and my group of Co-investigator's. Please consider this as our basic input to.your ad hoc site selection. group. You will note thaf Alphousus is third on our list--actually it is on the list only because it had b~en a candidate site for Apollo 17 }' c during the Apollo 16 deliberations. None of our group voted for it as their first choice in the slate of three sites herein presented. Littrow highlands was a bare majority over Gassendi; we would be pleased with either side for the Apollo 17 landing site. if·there is further information that we can contribute to your deliberations, please let me know and I'll get it to you. c .. "' . November 30, 1971 ·'· o. APOLLO FIELD GEOLOGY INVESTIGATIONS (S-059) EXPERIMENT GROUP RECOMMENDATIONS FOR APOLLO 17 LANDING SITES R<~;tionale a11c1 Recommemdations ·, Rationale The Apollo 17 mi·ssion to the moon will be 'the culmination and must provide the optim~l realization of the first stage of.man's sci"entific exp-loration of the moon. Our knowle·dge of the maori derived from the preceding Apollo mi~sions has grown with sufficient order~iness and comprehensiveness to indicate unambiguously that the m.a'jor unexplored region. of the moon is the ancient uplands crust. A site which p_rovides for an effective examination and sampling of the materials from this i ' ! ' type of lunar region will actually permit the completion.. of a sound, if skeletal, reference framework for all future geological exploration 0 of the moon. This.cai:l be suJTI.marized·in the following table, which ten~atively estimates the contributions to fundamental ge_ological questions about the moon derived from each of the Apollo missions. The table makes it equally clear that we will not really complete the exploration of the moon with the Apollo program. In our consideration of sites for Apollo· 17, we have been guided by the thesis that information on the earlier (earliest?) phases of lunar evolution deserves the highest priority. We have surveyed sit·es in terms of the practical (operational) considerations which will permit us to effectively observe and sample desirable ancient materials. \ . With the assigriment of a geologist-astronaut to this mission, NASA, in fact, has made it possible to invoke the most discriminating obser- vations, and therefore, the most effective sampling approach possible at this point in the sampling program. ·-- -- -~-~- ·-· -:~--:-;---"":-:-"----------:- --~--------~------~ ~-- -· ··- ... ;;.,. 'j c··/' A Preliminary Evaluation of the Contributions of the Apollo Missions to the - Geologic Knowledge of the Moon 11 12 14 15 16 17 - Early Lunar Hi.story m m M? ? E Old Crus·t~l and Interior Materials M? ? E Major Basin Formation (>250 'km) and Mascons m m M M E Highland Crustal Evolution m M M E Mare Fillings M M M D Large Craters and their J,lroducts (>40 km) m ,. E Post-Mare Internal History m M M ? E Regolith Evolution M M m" M M? D and Interactions with Extra- C: lunar Environments M m m M M? D Present Interior, Physical and Chemical State m m M M M? E Lunar Heterogeneity m M m ? E M = major contribution m·= significant but limited contribution E = essential D desirable, but not as urgent 2 n.'.; \sj. There are four basic approaches to the problem of obtaining samples of old apd deeBlY buried rock materials: 1. Utilize ejecta blankets of very large and fresh impact craters; 2;· Sample material in the central peaks of large craters; 3. Identify arid sample suitable crater walls and other structural scarps w•hich are r~la.tively un,I!lantled; 4. Search volcanic vents for fragments of deep cr~st torn from the walls l:ly explosive activity • . These approaches are· listed in decreasing order of our estimate of successful yield in a short-{erm mission. Characte:ds.tic exampfes of each tyve of site are 1) Tycho; 2) Copernicus, Gassendi, and Petavius; 3) Litt:row highlands.and Davy; 4) Littrow hi~hlands; Davy, and Alphonsus. 0 Lack of available suitable phot?graphy and/or flight operational constraints rule out Tycho and other comparable sites in the highlands for utilization of the first approach. We have considered, therefore, sites in terms of the three other 9-pproaches. He. have selected three candidate ·sites for consideration from the following sites: Ahulfeda crater chain Littrow highlands Alphonsus Maraldi region Censorinus Marius Hills . Copernicus central peaks Proclus region Crisium, western margin Rima Bode Davy/Ptolemaeus Theophilus central peaks · Gassendi Tycho Hyginus rille ··------- -~.---------·--· · ·· .· ------,~~-,-, ::':"'·.~,::-·~~'"'"" ~"""~·-·r·- -c-• -~J ... , ._.,_,..... _7__ .,_..., ___ , ------·-. •-•·,•--~-·· ~ --:-" ---· ·- "' " ---- ··:··":. ~ . ··~· ,'>~.··~:.;:,. ~.~···· ~-, ~' -·:.-~. "·. ,, • -~ • ' '• Recommendations Our candidate list in order for Apollo 17 sites: 1. Littrow highlands 2. Gassendi ce~tral peaks 3. Alphonsus Littrow highlands and Gassendi are roughly equal- in our voting, and.provide two very at~ractive sites from scientific considerat:ions. \ "' . The final group of three includes Alphonsus, because _it was a named candidate site for Apollo 17 during the Apollo 16 site selection ·deliberation. None of our worldng group favored it. We would prefer Tycho, Copernicus, or Davy/Ptolemaeus from our rejected list over .. Alphonsus. We stress, however, the great potential yield from Littrow . G. or Gassendi . We consider that a major advantage.of.these two sites is their geographic separation from the central region of the nearside of the moon. Our previous explorations have been limited in their ability to establish the general nature·of crustal and interior heterogeneity on the moon. Apollo 15 orbital science results emphasize this important q~estion~ Littrow, and particularly Gassendi, offer outstanding sites where surface exploration, geophysical studies, and orbital science can yield enormous additional coverage of lunar geological characteristics. () 4 -·- ,, ... -:----"~---:- -::· ···--. --· ~- __ ., .... , .. -:-·-·:-- ·:- -~- ~ - ------- ··'-""'"'·•.,._:-- o. Littrow highlands site Geology The Littrow highlands site lies among the mountainous regions of [ the southeastern' riril of the S~renitatis basin. It is about 750 km east of Apollo 15 site and about the same distance north of Apollo 11. Old lunar highland material fo~Uis bright steepsided_ massifs accessible immediately north and south of' the site. The landing site itself is . ' underlain by young, very dark mantling material, presumably of pyro- clastic origin. An additional type of material within LRV reach of the site is a· ·widespread lunar unit, chara.cterized by· closely spaced domical .hills. Mare material is also accessib:)..e. Tl1•.' primary goals of a mission to thi.s site would ' be to observe and sample these four units as well as several distinctive features in the area--a w~iri~le ridge that crosses west of the site and a landslide 1or debris flow that lies at the foot of the southern massif. Samples from the mission will provide age and compositional data on a typical part of the highlands away from the Imbrium basin, and on volcanic material generated in the late stag~s of lunar evolution. The old highland material th'at forms the north and south massifs should _consist of ancient crustal rock including possibly ejecta of the nearby basins; The massifs stand unusually high, possibly because of repeated uplift as the result of the Tranquillitati~ and Imbrium impacts as well as the Serehitatis--the massifs appear to be along rings of all three basins. Material of the massifs, including blocks, could favorably be sampled at a spectacular debris flow or landslide 5 ... ·~ ., . ·•.' r C'• that projects_ northw8:rd from the. south massif, as- Hell as from blocks in t~ius flanking both massifs. An additional bright rugged unit is present in the vicinity of the s:i,te and as far east as the Crisium basin ri.m. The unit consists of1 closely packed rounded hills resembling kernels of a corn cob, ' and could have formed either through 1) fracturing of ancient high- -/ - ~- ... land terrane (probably Tranquillitatis, Crisium, and Serenitatis basin ejecta)~ or 2) by viscous terra volcanism. The unit is tound in many parts of the moon and ground observation of its form and feature as ( well as samples for analysis 1vould be a valuable contribution, whether it is an ejecta blankJt or·a new type of terra volcanic rock. The l closely packed hills could be sampled at their base, southeast of the site. Dark material, some of it among the darkest on the moon, covers I 'the flat terrain among and adjacent to the massifs and closely pack~d hills. The material is a smooth, sparsely cratered mantling deposit that covers mare material underlying the flat terrain and extensive tracts- of the high adjacent massifs and closely packed hills. The dark deposit is probably a young (Copernican) pyroclastic blanket. It and the underlying material could be sampled at several small craters near the landing site and from a scarp-tidge that crosses west of the site. The Littrmv site is more favorable for sampling highland material th~n most of the other sites proposed, and uniquely favorable for sampling young volcanic material. The massifs, which have-blocky 6 -_,..-----·-:; .. ,. ·- . ~- --- ...,---~---.---,---~--- ···-:.··"""":'" ---------- -- .. ··----------·-,-- ------- ., IP .. ·.. slopes, ~re clearly part of the Serenitatis b~sin rim (and probably part of other basin r{ngs). This cbntrast~ with Alphonsus, for example, \vhete the geologic conte~t of the underlying material excavated ' by AlphonS"\-lS and incor'porated in its walls' is unclear.
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