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. In addition,
the dark matefial of the Li.tttow region is younger and far more
extensiv_g thCI.Jl th~ dark de:posits of the Alphonsus crater. Furthermore,
' the pronounced mantling character of the Littrow material suggests that
it formed as a pyroclastic and thus may contain remnant volatiles.
The perenitatis region, like Alphonsus, has been the site of numerous
I . reporte1d transiEmt events. Another possibility includes the presence
\ of deep~s~ated crustal or interior rock fragments explosively derived ' from the volcanic. vents. C) Landing Area and Possible Traverses
The proposed landing site is located on a fla't dark embayment
between two bright massifs. • Three possible traverses have been laid
out that reach the feet of the massifs, a landslide or debris flow
from the southern massif, a hill made up of closely packed domes,
and a wrinkle ridge that crosses the embayment and debris flow.
The first proposed traverse ·extends south of the landing site.
It crosses dark mantling material of the embayment to the head of the
debris flov7 at its junction with the steep ta~us slope of the south
massif. From there it crosses east to the foot of a hill made up of
' ' the light-colored close-packed dome materi~l. The traverse then
returns in a northwesterly direction to the landing site, p_assing / c·. around the rinis of several craters that have excavated into mare
mateFial underlying the dark pyroclastic ~nit.
7 .., )• CI The second traverse, which is the shortest of t_he three, extends north and east of the site to and along the base of the northern
massif, then east to apother·hill of close packed domes, and return
via another crater cut in botfi the dark deposit and ~nderlying mare
material.
The third traverse has been :J..aid out to extend \vest from the
landing site across the northern part of the debris flow from the
sdrithern massif. It crosses the intersection 6f the frOnt of the
debris flow and the wrinkle ridge, and then extends west and north
across' the dark pyroclastic deposit .to the northern massif. It ! . crosses.back to the east along the intersection of the wrinkle ridge
and the northern massif and continues east along the foot of the
~as~if talus slope before turning.south to the landing site.
8
'.,:. p;;-, \.(__j Gassendi site
Geology
Gassep.di, in the southwestern quadrant of the near side of the
moon; is a 120 km diameter crater straddling the north rim of the
Mare Humortim Basin.- It lies about 700km southwest of the Apollo 12
site in Oceanus Procellarum and 1800 l~ southwest of the Apollo 16
Descartes site.
The 500 km diameter Humorum Basin has clearly defined scarps and
has a sizeable positive gravity anomaly (Masqori.). It is older than
the Orientale, Imbrium, and Crisium~ The ejecta from the basin is - I probably on the order 'of 1 :km thick under the. center of the later
crater Gassendi. Both the Hare Humorum Basin and the ' crater Gassendi · ' are pre-Imbrian in age. C} -Tn~ main objec~ive would be to sample material from the central
peaks. From terrestrial analogues, this material would have come
from depths of up to abou_t 1/10 of the crater diameter or possibly
as much as 10 km. This is several times the depth of material exposed
on a crater 'wall. Blocks at the base of the central ~eak should be
uniquely ascribable to a source beneath the crater.
We are fully confident that uplifted old, deep crustal material
will b~found in the central peak. There are, howeyer, widely held
alternate hypotheses, and the simple fact of sampling along the base
of a central peak will drastically ~educe the range of hypotheses on
the origin of large lunar craters.
(
. ·---'"':":"' . ._ .. _... The proposed landing site is near the south base of the western
cluster of central peaks. Boulder fields on the peqks are especially
abundant in this area. Study of terrestrial craters indicates that
these rocks in the central p~ak should vary from lightly to intensely
shocked; they should not be multiply brecciated and are probably
intensely brecciated only locally. A t~averse along the base of the
peak· in this area is in a directio:n radial. to the probably structural
center· of the peak-complex. If, as in terrestrial analogues, the strata
are steeply dipping, theh several kilometers of rock layers could be sampled.
Further, small domical.hills are possibly part of. an original I hummocky crater floor~ Blocks on the summit of one dome suggest
that the regolith is not extraordinarily thick. Elsewhere' on the
\ level surfaces the regoli-th may be upwards of 25 m in thickness. c ) Several linear rilles--grabens--are present in the area. The walls
are generally subdued, but block fields and possible outcrops are
I accessible wh~re two of these rilles intersect.
The floor of Gassendi apparently. has been uplifted~ producing
the linear rilles (grabens) and making the central peaks as high as
the crater rim. A ring of mare occurs iii a crescent-shaped zone
along the south and low side of the warped crater floor--along the
Humorum Basin margin. The crater floor may have been isostatically
uplifted as are terrestrial craters of similar size, .e.g., the Lake
Manicouagan structure in central Quebec, Canada. If this hypothesis
is true, then Gassendi should not have a negative gravity anomaly.
Ptolemaeus, a similar sized craterrin the center of the moon do~s.
10 ,.
r· cI This difference would. indicate that the crust underlying Gassendi
may have been mor·e mobile at the time of its formation than the crust
in the central part of the moon.
The greatest benefit of the Ga~sendi site.is its distance from
the Imqrium Ba:siri. It is the most remote of.any site proposed. A
further benefit is that this site maximizes returns from the orbital
science package. Th.e flight path would allow photography, laser
altimetry, IR radiometry, ancl EM sounder scans· to extend. westward
acros~.the face of the moon to the centra;L portion of Mare Orientale--
the youngest, multi-ringed impact basin on the moon. Intensive study i of this feature would furnish important insights into· this major I .. modifying process of the post-accretion history of the moon. 0 Landing Area and Possible Traverses
Two sites, one on either side of the north-trending rille that
reaches the base of the western cluster of central peaks, can be
recommended. Both are on smoothed terrain (young volcanic material);
from either the base of the central peaks. can be explored with only
a 2-3 km drive.each way; and a variety 'of crat~r floor types and the
rifles can be inspected.
For each site, one EVA should be mainly devoted to the central·
peak region.
. . For the eastern site, a second EVA could range eastward to inspect
the heavily cratered region between the·central peak ranges and the
volcanic-appearing domes. For the western site, a second EVA could
11 ~ C_/' be devoted· to ranging northwest~vard to several large (l.,.-2 km diarileter)
c~aters that could give a sampiing in depth of the crater floor'·
mate:i:"ials.
For each site, a third ~VA could be devoted to a study of the
rilles.
Tne traverse experiments would have a variety of features and
structures to assist in giving three dimensional solutions: shape
of central peak, gJ;adient'S at edge of Hare Humorum, thickn,esses and·
variation of ~nits in the crater floor.
' •.
0
12 Alphonsus, west wall
Geology
Alphonsus is a large (115 km), old (pre-Imbrian) crater in the
no.r.tJ:n·lest.~rn part of. the central highlands, close to the eastern margin ! of Mate Ntibiuto.. Major basins occur on three sides and Alphonsus is
sandwiched in time between the ,)earliest and youngest basins. It is
j~st west of the Descartes Plateau area, presumed to consist of con-
strut donal· volcanics. Immediately to the north is the large, flat
1~. floored crater; Ptoiomaeus, which is older than Alphortsus; to the ~outh
are the craters Arzachel and Alpetragius, both younger th~:m Alphonsus.
Alphonsus is typic"'!-1 of marty upland craters, having a flat,
heavily cratered floor, a central peak, and a broad spar.sely cratered
and subdu1ed rim. Less· typical features are a network of intersecting
straight ·rilles cutting the floor and dark halo craters centered at
the intersections and bends in these rilles.
Alphonsus \.Jas formed after the oldest large frontside basins
but before the youngest (Imbrium). Consequently, the surface into
which the crater Alphonsus ~vas punched con·sisted of old crust, overlain
by successive ejecta blankets from the earlier basins Tranquillitatis,
south Imbrium, possibly Nubium, and ejecta from the large, nearby
old craters Arzachel. and Albategnius. Hence, a thick blanket of
ejecta existed on top of the' older crust at the time of formation on
Alphonsus. During the cratering event itself, presumably an.impact,
part of this section was disturbed-~so deeper parts of it would be
exposed on the ove·rturned crater rim; some uplifted ·in the central ( peaks (perhaps as much as 10 to 20 km).
13 ,...... ·
I Sub·sequent to the formqtion of the crater, ejecta from Imbrium
(Fra Mauro, perqaps about 50 to 100 rri in thickness} and from the moderate-
sized but nearby craters, Arzachel and Alpetragius, was deposi:ted,over
the Alphonsus area; and also, the crater floor was filled with Cayley
plains-forming materials. The/floor was cracked and the late stage
dark halo craters, emplaced· along the rifts probably as volatile-rich
(maar-type) volcanoes, ejected fine-grained materials (based on the
~egion being dark to 3.8 em radar).
Specific. features of intere.st in Alphonsus include the central
peak, the crate.r wall, the crater floor and its straight rilles, the 1
last stage volcanism (dark halo craters), and reports of transient
phenomena.
Understanding the crater wall at Alphonsus is cr.l.10ial to under-
J 0 standing the potential of the site in fulfilling the primary goal
of the mission, i.e. sampling old crust. The inner part of the
original wall is d6-..vn--faulted by slumping, a characteristic feature
of large craters. The inne-r sets of these dowrt-faulted blocks are
probably buried by the Cayley fill (i.e. the original crater diameter
is unknown but less than the present diameter). The rocks exposed in
the upper part of the Alphonsus ejecta blanket would have originated
from the deepest layers excavated by the impact--possibly into the
primitive crust \vhich underlies the lowest basin ejecta (i.e. the
Tranquillity ejecta layer). As at Hadley-Apennine, the hope is that
talus accumulating at the base of the scarp would contain at least
some of this material. The Alphonsus crater wall, however~ differs
·~ i significantly from the Hadley (Apollo 15) scarp b,ecause the Alphonsus ( j
16
-· ------·~--~ .. --,?~------·~--~-~-~ ------~ . ·-·· -·-· '---·-- -- -~---.-- -~-, ------~-----:·.---. ·:·--.-·- wall is known to be blaneted by younger ejecta (the Fra Mauro, c·, / Ptolemaeus, and Alpetragius) and volcanics (Cayley and minor cont:rib)l"-
tion,s from the dark halo 'Craters). The total thickness of the blanket
over the. Alphonsus wall ii:; cert~inly me.asured in 10.' s of meters;·
possibly lOO's. This blanket accounts for the very subdued appearance
of the surface, the deep regolith and the lack of"blocks. In addition,
some observers feel the walls might even be covered by lava derived
frpm pools high on the,rim. Each of •these effects reduces· the
probabilities of obtaining significant numbers of samples of undoubted
anci~nt highlands. materials. ~
Landing areas and possible traverses
The proposed sites are near the west 111all of Alpho11sus, and adj acelit
to the dark halo craters. The principal specific objectives of the
site are: (1) obtain old upland rocks from the crater wall.; (2) to sample
the ejecta from the young volcanoes which cut the crater floor--and
possibly, to collect deep-seated xenolith rocks and mineral fragments;
(3) to sample the deposits blanketing the crater floor--i.e. the Cayley.
Two quite similar sites are available, one is north of th:e two
dark halo craters, the other south. Three traverses from the north
site would visit (a) Alphonsus scarp, (b) north d?,;_rk halo crater, and
(c) an impact crater in the crater floor, possibly penetrating the
Cayley. The traverses from the.southern site would visit (a) the
southern dark halo crater, (b) and (c) traverses to the so~th, both of
>vhich would visit the Alphonsus 'crater wall. c
17
_I ·,
·---·------=------·------~- .. -- ~---:----~----,·--- :- -·--- -- ~-:-·-. ~- .•. ------•. ;-' - --;---->-· •
Overall evaluation
The Alphonsus \vest ?ite at first examination offers ~he possibility
of sampling crustal r·ocks older than the oldest basins, volcar).ic rocks
representing c:r:-ater fill (mare filling), post-mare, poss.ibly de·ep-
seated volcanic rocks and the remote chance of finding deep-seated
xenol-iths in the maar-ejecta.
However, we feel the likelihood of clearly achieving important
' objectives, old rocks and xenoliths, is remote. Acc~ss t·o, old
crust (i.e. crust similar to Tycho highlands, which specifically means
primitive crust not buried under the complex ejecta blankets from the
major basins) must be acquired in the crater walls. But we believe a
thick blanket of ejecta covered the surface prior to thE! time Alphonsus
itself was formed. Furthermore other thick blankets of ejecta covered
it <.tfter the crater formed, including Imbrium ejecta, ejecta from
large nearby craters Arzachel and Alpetragius. Subsequent volcanic
rocks (Cayley) lap agairtst the base of the crater wall. Lack of :..._. visible blocks and the completely subdued topography make effective
geological study and sampling quite difficult and probably relatively
) unprofitable.
1~ ,~
Brief statements of objectives for a few of the rejected sites
Tycho
. Tycho is the prime scientific site for the advancement of our
understanding of the pre-Imbrian moon. Tycho is iq the southern
highlands, the most primitive region which can be sampled on the near
-- ' side of the nioori. Tycho provides the geographic spread for large-scale
triangulation required for geophysical, celestiai mechanics, and
orbital experiments. The Tycho site contains rocks older than the
basin-ejecta blankets such as Fra Mauro. The formation of the crater
Tycho has freshly exposed some of the oldest and most primitive rocks
on" the nioon and, at the same time, has produced the mN: t youthful ext en- ~
sive surface visil··le on the ~ear side. Tycho exploration can yield more
significant limiting data on the nature and origin of the most ancient
materials and most\ recent processes on the lunar surface than any
other site on the near side of the moon. These data can be obtained
on nn LRV or walking ·mission using .available detailed p:hotographj.c '" ' I. covefage from Surveyor VII and from Lunar Orbiter photography. The
site is rejected for operational rather than scientific reasons.
Davy-Pto~e111aeus
The Davy-Ptolemaeus region offers a site with access to a steep
upland scarp at the base of the east wall of Davy crater. A rover
mission can successfully investigate two types of upland plains units,
the maar-like volcanoes of the Davy Rille, and may obtain samples
of deep-seated rock frQgments from the luriar interior, brought to c the surface by- the Davy crater chain (ten or more could be sampled
19 "1-~:l,, I .. ~· C' qn an LRV traverse). He· must emphasize that we consider this site to
be primarily a source of terra materials and only secondarily valuable
as an investigation of the Davy crater chain.
Site reject-ed because photographs will not be available until-
after Apollo 16.
Marius Hills
If the Apollo 16 and 17 missions to lunar terrae are successful,
our next priority is an investigation of younger mare volcanism. This
has major implications regarding the thermal state and the thermal
·history of the· planet. The Marius Hills volcanic complex near the
cehter of Oceanus Procellarum is one of the most concentrated and
varied arrays of younger volcanic features on the moon. ' The various \ well-defined volcanic forms indicate-major differences in magma C' viscosity, and suggest Marius Hills as an optimal site for /Studying
a range of possible mare magmatic differentiation products. Geological,
geochemical, and geophysical possibilities make this a first-order
objective for major data acquisition relative to the more recent
history of the moon.
Site rejected because it does not satisfy our highest scientific
priority and is accessible for only one day in each of two months
during the proposed Apollo 17 launch period.
Copernicus
Copernicus central peaks region may yield samples of' the lunar I interior from as much as 10-15 km from beneath Oceanus Procellarum.
II1 addition, it \·muld provide samples of relatively young shock-
() generated crater fill materials which are major constituents of the luri.ar
surface rocks. 20 S.ite rejected because samples would come from area that lies between
Apetui.irfe-Hadley (Apollo 15) and Fra Mauro (Apollo 14) landing areas.
It ·is a reasonable interpretation that ·a ray from Copernicus has been
sampled at the Apollo 12 site.
P:i:'oclus - \Vest Cr:lsium margin
Prbclus is a large fresh young impact crater on the western rim of
Mare Crisum basin. It allows samples to be collected from the Cris:Lum.
ejecta blanket and' the underlying Crisium ancient highlands.
' Proclus ejecta blanket site rejected because it lies at the edge
of the zone accessible to Apollo. A more desirable site is at the
contact of the mare filling of the Crisium basin and the western
basin walls. From this point, LRV traverses v.rould permit' sampling 0 of the Crisium mare, Crisium basin walL (Crisium ejecta blanket), and Proclus ray material (possibly highlands material from beneath
Crisium ejecta). Site rejected because •of the operational limits ) assigned for Apollo 17 landing sites.
(
~1 A ., ''' ' ' . ~ ' t. f• -~ c~I' Distrib~tion.:
:N. w. Hinners, Bellcomm Incorporated R. A. Petrone, NA.SA Headquarters A. j .'' Calia, MSC P. hT, Gast, MSC J. C. Zarcaro/ MSC E. t... Baudette, USGS M. H. Gai'r, USGS J. w. Head, Bellcomm Incorporated K. A. Howard, USGS Baerbel Lucchitta, USGS Harold Masursky, USGS T. R. Mc;Ge_tchil1, MIT D. J. Milton, USGS w. R. Muehlberger, USGS T. A. Mutch, USGS L. R. Page; USGS D. L. ·Peck, USG.$ L. T. Sil.ver, Cal tech s. R. Titley, USGS G. E. Ulrich, USGS J D. E. Wil}:l..elms, USGS E. w. Wolfe, USGS v. L. Freeman, 'USGS
. J. D. Strobell, Jr. ,USGS 0 J. F. McCaule.y, USGS N. J. Trask, USGS E. A. Cernan, MSC H. H. Schmitt, NSC R. A. ·.Parker, MSC
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