28. Geological Observations From Lunar Orbit 
R. E. Evans^ and Farouk El-BaJ? 
Visual observations from orbit were first con- 
?dered as a mission objective on Apollo 15. The 
concept and means of achieving the objective are 
described in reference 28-1, and summaries of the 
results have been published (refs. 28-2 to 28-4). 
Observations were also made from the command 
module (CM) during the Apollo 16 mission, and the 
results provided additional data which complemented 
the photographs and the geochemical remote sensing 
(refs. 28-5 and 28-6). 
As on previous missions, the Apollo 17 crew (the 
command module pilot (CMP) in particular) was 
trained during a 2-yr period before the flight for the 
task of making the observations. During this training, 
the CMP conducted simulations of the task by 
studying aerial photographs of geologically complex 
regions in the United States and by flying over these 
regions to make on-the-scene interpretations. 
Because the Apollo 17 groundtracks repeated 
approximately 80 percent of the lunar surface area 
previously overflown on Apollo 15, much was already 
knovra about the features in question. For this 
reason, emphasis was largely placed on color tones of 
geologic units and details of small-scale features. 
Observations were made from the CM windows 
without disturbing the operations of the scientific 
instrument module. The tools available were limited 
to a booklet of graphics (some of which are shown 
here as examples), a pair of lO-power binoculars, a 
reference color wheel, two hand-held cameras (Hassel- 
blad and Nikon), and voice-recording equipment. 
The Apollo 17 crew made observations from orbit 
of 14 lunar surface areas (fig. 28-1). As shown in 
table 28-1, four of these targets were not formally 
scheduled in the flight plan. A brief summary of 
^NASA Lyndon B. Johnson Space Center. 
''National Air and Space Museum, Smithsonian Institu- 
tion. 
visual observations during the Apollo 17 lunar orbit 
has been recently published (ref. 28-7). 
The following paragraphs give detailed descrip- 
tions of the observation sites arranged from east to 
west as they are numbered in figure 28-1; some of the 
sites are grouped together for convenience. Excerpts 
from the Apollo 17 real-time air-to-ground transcript 
are given after editing for clarity. The edited quota- 
tions are followed by identification of the source of 
the statement (e.g., CMP, command module pilot; 
LMP, lunar module pilot; and CDR, commander) and 
the lunar revolution (rev) during which the observa- 
tion was made. By consulting figure 28-1, the reader 
may check the Sun elevation angle at the time the 
observation was made. The terminators of revolution 
1 (at long. 152? W and 29? E) shift westward one 
lunar degree for each additional revolution; the 
terminators of revolution 75 (at long. 134? E and 
45? W) shift eastward for each preceding revolution. 
KOROLEV, GAGARIN, AND PASTEUR 
The largest light-plains-f?lled basin that was over- 
flown on Apollo 17 is Korolev. This double-ring basin 
is approximately 450 km in diameter and a few 
kilometers deep (fig. 28-2). Its interior is filled with a 
generally smooth but intensely cratered light albedo 
unit that resembles the Cayley Formation mapped on 
the near side of the Moon and presumably sampled 
during the Apollo 16 mission to the Descartes 
highlands. The origin of the Cayley Formation 
remains enigmatic. 
On Apollo 17, the sites Korolev, Gagarin, and 
Pasteur were studied from orbit to examine the 
detailed characteristics of the light plains fill. The 
smoothness of that fill was most striking: 
We all had an opportunity to look at Korolev, at a very 
low grazing Sun. One of the striking things was the extreme 
absence of relief; the very smooth surface that existed in 
Korolev, independent, of course, of the craters that penetrate 
28-2 APOLLO 17 PRELIMINARY SCIENCE REPORT 
50 ? Revi 
terminator 
60 ao       20       0 
w  ?    1 
20 40         60         80 
Longitude, deg 
100 120 MO        160 
E 
IBO 
.   1  . W   '     1 ?   1  ? 
1. 
2. 
3. 
4. 
5. 
Korolev 
Aitken 
Gagarin 
Tsiolkovsky 
Al-Khwarizmi 
(formerly Arabia) 
6. Pasteur 
7. Mare Smythii 
8. Crisium-Serenitatis 
9. Landing site 
10.   D-Caldera 
U. 
12. 
13. 
14. 
Copernicus 
Euler hills 
Reiner 7 
Post-TEI view 
*-^ 
: 
^ 
*^ 
t ^ 
j 
160 
FIGURE 28-1.-Index map of ApoUo 17 visual observation targets. The groundtracks for the first and 
last (75th) lunar revolutions are shown on the far side by vertical lines; the end points of the tracks 
on the near side delineate terminators of the respective revolutions. The dashed vertical line near 
longitude 95? W indicates the limit of earthshine illumination. The horizon limits enclose the 
maximum area of visibility from the CM windows throughout the mission. 
its surface. And there was a ring in the floor next to the wall, 
about maybe one-sixth of a crater radius, that was somewhat 
brighter at the low grazing Sun, suggesting it may have had a 
different slope. And I believe I am correct in saying that the 
inner floor may be slightly raised. (LMP, rev 1) 
Light plains materials were also observed and 
described in smaller craters west of Korolev: 
There is a sequence of different kinds of crater filling on 
the far side, and I think that, as the orbital stay progresses, 
we may be able to pin down the relative age relationships and 
the characteristics of those crater-filling episodes. Whether 
they are single episodes that happen in a variety of craters or 
whether they are a function of the age and characteristics of 
the craters in which you find them is not clear right now. But 
they seem to form fairly distinct groupings of crater fiU 
materials. (LMP, rev 5) 
This indicates that there appears to be several 
generations of light plains fill rather than nil from a 
single event. This is confirmed by the orbital photo- 
graphs of the area around Aitken Crater (part B of 
sec. 32). Some of the units observed and photo- 
graphed on Apollo 17 appear to be even smoother 
than mare surfaces (fig. 28-3): 
TABLE 28-I.-Z,wi of Apollo 17 Visual 
Observation Targets 
Target 
Copernicus 
Landing site 
Aitken 
Al-Khwarizmi 
(formerly Arabia) 
Crisium-Serenitatis 
Reiner y 
D-Caldera 
Mare Smythii 
Tsiolkovsky 
Euler hiUs 
Korolev 
Gagarin 
Pasteur 
Post-TEI areas 
Coordinates 
10?N,20? W 
20? N, 30? E 
15? S, 173? E 
1? N, 130? to 95? E 
15?N, 55?Eto20?N, 
25? E 
8? N, 58? W 
18?N,5?E 
4? S, 95? to 80? E 
20? S, 132? to 125? E 
18? N, 25? to 35? W 
5? S, 155? to 172? W 
20? S, 153? to 145? E 
12? S, 115? to 100? E 
''N/A 
Revolution 
1,28 
15,40,62 
27 
27 
27 
28 
40 
62 
64 
^73, 74 
?2to5 
?55, 61 to 63 
^55,61 to 63 
?'N/A 
?Target not nominally scheduled in flight plan. 
''N/A = not applicable. 
GEOLOGICAL OBSERVATIONS FROM LUNAR ORBIT 28-3 
One of those crater fill units that you also see in 
depressions other than craters is a very smooth, light, 
plains-forming material. And it is, although cratered, when 
you see it at the terminator, it is smoother than the mare; 
that is, it does not seem to have the swell, the sea swell 
characteristics or ridges or any other features other than the 
craters superimposed on it. (LMP, rev 5) 
An observation that I think is significant is that most of 
the 30-km craters on the far side of the Moon seem to be 
fairly fresh. By fresh, I mean you do not have any real 
definite ray pattern to them, but streaked, 45? slope on the 
crater walls. On the bottom of the crater is a flat floor, or 
sometimes there is a domical type (domed up) floor. And the 
domical floor does not resemble anything like what slumped 
down the sides. (CMP, rev 27) 
Few additional comments were made during the 
flight concerning the light plains materials. However, 
apart from the aforementioned characteristics, little 
could be added that would resolve the problem of 
their origin: 
Pasteur and Hubert make a pair of big craters that we 
spent some time studying... Both appear to be very old, 
much older than Tsiolkovsky and they have a plains-forming 
fill, very flat looking at this distance, and very Ught colored. 
It is an event on the Moon of which we have relatively Uttle 
understanding at this time, but possibly the Apollo 16 
results, when they are fully known, through the analysis of 
the samples and other data, may shed some light on that 
event. (LMP, post-transearth-injection (TEI)) 
? '  ' ?'? S'il'     . ?   'S ? {"     ' ' 
;^fvy^^ 
FIGURE 28-2.-Korolev basin: a double-ringed, light-plains- 
f?lled, 450-km-diameter crater. The right edge of the 
photograph coincides with the far-side terminator of the 
first lunar revolution of Apollo 17 (Lunar Orbiter I frame 
35-M). 
FIGURE 28-3.?Smooth light plains fill in an irregular structure near Sniadecki Crater on the lunar far 
side(AS17-151-23191). 
APOLLO 17 PRELIMINARY SCIENCE REPORT 
Examine the interior of crater Aitkeri with emphasis an the following: ^^^^^^^^^^^^^^^^ 
1. Albedo, textures, and structures of the dark floor fil!; compare with floors of ^L^rrounding craters, 
!. Noture of ligfif swirls in the southwest quadront of the floor. 
3. Structures and rock exposures on the central peak, and possible !avo morks." 
FIGURE 28-4.-Example of onboard graphics in support of visual observations from lunar orbit. This 
Zond 8 metric photograph of Aitken Crater (150 km in diameter) represents the same view of the 
crater as that seen by the Apollo 17 crew. 
GEOLOGICAL OBSERVATIONS FROM LUNAR ORBIT 
AITKEN 
Aitken Crater, 150 km in diameter, is one of the 
few craters that display a dark mare-like floor. 
Observations were made to better understand the 
crater and its surroundings, the dark floor material, 
and the many interesting small-scale features in the 
floor (fig. 28-4). 
The rim crest of Aitken Crater is very sharp and its 
secondary crater chains are distinct. However, it was 
not possible from the available photographs to 
establish without doubt whether or not the rim 
deposits are brighter than the surrounding highlands. 
When the CMP was queried about this particular 
aspect, he repHed: 
The rim deposits are a little bit brighter than the 
surrounding area. Where you would put it [place the crater in 
the lunar stratigraphie time scale] is probably early 
Eratosthenian. It is definitely not Copernican because I 
cannot see, at least at that low Sun, I cannot see any rays 
around it. But probably Eratosthenian-or somewhere in that 
area-because of the fresh slumping; it is not subdued at all. 
The walls of the crater themselves are not subdued. They are 
fairly fresh, but not as fresh as to be Copernican. And it 
seems to me like it was brighter at the higher Sun angles 
around there [on earlier revs], which indicates that there 
would still be some remnants of a bright rim around it. 
On the side of crater Aitken, there are no visible rays that 
I can see at this low Sun angle. There is definitely a mare 
floor in there. It is a dark, low-albedo-type flat floor with 
swirls in it; no definite [topographic] expression to the 
swirls. One thing that is quite apparent is a flow scarp in the 
northeast corner, coming out of a little cloverleaf-like area. I 
am going to have to look the next pass over it to see if the 
south domical structure that is in there is breached. And I 
cannot tell whether the material is flowing to the east out of 
that domical structure or if it is flowing into the domical 
structure. (CMP, rev 27) 
When the CMP was queried at that time whether 
or not he was able to distinguish high lava marks on 
the lower part of the crater wall, he replied: 
The lava mark is what I would call a lava scarp in the 
northeast corner. There are some lava marks along the central 
peak. They are not nearly as apparent as the one up in the 
northeast corner. In the northeast comer is definitely a flow 
front, a lava flow front, that [laps up against] the older 
interior wall of the crater. (CMP, rev 27) 
Some of the craters in the floor of Aitken, 
informally named on Apollo 17 the "cloverleaf 
cluster," display domical structures of unknown 
origin (fig. 28-5). An attempt was made to determine 
whether information could be gathered relative to the 
t   ? .>}< 
FIGURE 28-5.-Cluster of small craters (4 to 8 km in 
diameter) in the floor of Aitken Crater. Note the interior 
domical structures, the breaches in the walls, and the 
ridges and scarps in the dark floor material Oower right) 
(ApoUo 17 panoramic camera frame AS17-1915). 
color tone and the detailed characteristics of these 
domes: 
The color of the domes in Aitken, although these colors 
are hard to visualize, is essentia?v the same as the surround- 
ing material around [the crater]. Maybe a little bit lighter, a 
little bit lighter than the surrounding material. Of course, it is 
definitely lighter than the floor. The floor itself, is 
[somewhat] tan. (CMP, rev 27) 
... at the cloverleaf cluster in Aitken [part B of sec. 32]. 
The southern domical crater of the cloverleaf has a breach on 
APOLLO 17 PRELIMINARY SCIENCE REPORT 
the east side.. . The domical structures themselves are 
younger than the floor... Also, the texture is a coarser 
texture than the floor itself. In other words, the floor, to me, 
is kind of a standard flat mare floor. And I have to compare 
the texture of the domical hiUs to what I would imagine is 
some of the dacite flows that I have seen out in California, 
the heavy viscous-type flows. . . Well, I am pretty sure they 
have got to be volcanic in origin. (CMP, rev 28) 
TSIOLKOVSKY 
The 200-km crater Tsiolkovsky was studied 
thoroughly on the Apollo 15 mission, and the results 
of these observations are available in references 28-1 
and 28-4. On Apollo 17, further study was made of 
the crater and its many interesting features, especially 
the flow-like units on the northeast part of the crater 
rim (fig. 28-6 and 28-7). 
The visual of Tsiolkovsky is hopefully pretty much 
recorded on the recorder. In summary, I concentrated 
primarily on the flow up in the northeast corner. To me, that 
particular piece in the crater on picture Tsiolkovsky, 4 of 5 
[fig. 28-7(a)]. The piece that is down in the crater is on the 
right-hand side of the page, [must have been] in somewhat of 
a molten state. It looks hke it is a landsUde that has S?d down 
the wall of the crater and was detached from the molten 
material, the rough-looking material that's on the rim of the 
crater Tsiolkovsky. (CMP, rev 64) 
A similar flow unit occurs on the southern rim of 
the crater Tsiolkovsky. This unit apparently origi- 
nated at a graben bounded by two parallel faults on 
the rim and flowed into the crater Waterman (ref 
28-1). The two units were thought to be similar in 
nature: 
The flow that goes down into Waterman ... I did not get 
a chance to look at until I got to the west of it. .. But the 
material that is in the floor of the crater Waterman is the 
same type of material as that in the little flow on the 
northeast corner. (CMP, rev 64) 
The lineated unit on the northwest rim of 
Tsiolkovsky Crater was interpreted as a landsUde on 
Apollo 15. One of the problems was the fact that 
there appeared to be a larger crater population on 
that unit than on the older floor materials of Fermi 
Crater (ref. 28-1). More information was required to 
fully understand this and the detailed characteristics 
of these small craters: 
In the first observation of the mass of material that goes 
out into the crater Fermi, it looks hke there is a whole bunch 
of craters in there that are essentially rimless. However, on 
close examination with the binoculars, I could not see any 
that did not have at least a shght indication of a rim. The 
rims were essentially very subdued. They extended out to 
about a half a crater diameter; and these are the craters in the 
FIGURE 28-6.-Tsiolkovsky Crater (200 km in diameter) and its surroundings (Lunar Orbiter III frame 
121-M). 
GEOLOGICAL OBSERVATIONS FROM LUNAR ORBIT 28-7 
TSIOLKOVSKY (4 OF 5) 
m 
EKomine the flow unit on the northeast rim of Ts?o?kovsky? 
1. Look far a sourte (Frottures or vents). 
2. Compore it with; 
o. the iark floor moteria!. 
br rtie light iloor ploirs, 
?^j;^ the ?mooth potches on the wall terrncas. 
FIGURE 28-7.-Rim deposits of Tsiolkovsky Crater as seen on Apollo 17 onboard graphics compared 
to Apollo 17 photograph of a flow unit, (a) Hummocky rim deposits of Tsiolkovsky Crater as 
depicted on the onboard graphics in support of Apollo 17 visual observations. 
28-8 APOLLO 17 PRELIMINARY SCIENCE REPORT 
FIGURE 28-7.-Concluded, (b) Flow unit on the northeast rim of Tsiolkovsky Crater (background) as 
seen from orbit during Apollo 17. Note that the material appears to have flowed downslope into 
the crater in foreground (AS17-151-23212). 
500- to 1000-m size. I did not get a chance to look at them, 
looking straight down the craters, to see if there was any type 
of a structure in the bottoms. But I get the impression that 
they primarily all look like cones, with no flat bottoms at all. 
(CMP, rev 64) 
It was visually confirmed on the Apollo 17 
mission that the floor of Tsiolkovsky is filled with 
basalt-like mare material. The central peak was also 
described in much the same way as on Apollo 15, 
including the sightings of large block fields atop and 
near the base of the peaks. Marks on the central peak 
indicating a "high lava mark" were also sighted in two 
places: 
There seems to be high lava marks around the western and 
northern sides of the central peak. For some reason, it is not 
evident or visible on the south side of the central peak. Also, 
there seems to be high lava marks on the raised portion of the 
floor on the contact between the dark material on the floor 
and the lighter, rough-looking unit on the northern side of 
the crater. (CMP, rev 64) 
AL-KHWARIZMI (FORMERLY ARABIA) 
An old and subdued multi-ringed basin, centered 
at latitude 2? N and longitude 120? E, was discovered 
on the Apollo 16 photographs (ref. 28-8). The name 
Arabia was recommended for the basin to the 
Committee on Nomenclature of the International 
Astronomical Union (lAU). After discussions con- 
cerning the newly adopted rules of the lAU, the name 
Al-Khwarizmi was substituted (ref. 28-9). However, 
the previously recommended name of Arabia was 
used on the Apollo 17 mission, during which the 
basin rings as well as the light-colored swirls in its 
northern part (fig. 28-8) were studied. 
Basin Rings 
You can see the topographic rise in the Saenger area, 
especially. It is a little bit higher to the west of Saenger than 
to the east. But you can still see a general rise in that area. 
GEOLOGICAL OBSERVATIONS FROM LUNAR ORBIT 28-9 
FIGURE 28-8.-The extensive field of light-colored swirls in the northern part of thfc Al-Khwarizmi 
(formerly Arabia) basin (top) and in the northern part of Mare Marginis (bottom). 
You get a kind of a hint of the second ring of Arabia. (CMP, 
rev 29) 
Examinations of the old and subdued rings of the 
basin resulted in observation of interesting small-scale 
features on the western part of the second ring, near 
Saenger Crater (fig. 28-8): 
In some of the Eratosthenian craters around Saenger, you 
can still have a little bit of a hint of layering, or broken-up 
APOLLO 17 PRELIMINARY SCIENCE REPORT 
different-colored material at the top of all these craters. 
(CMP, rev 27) 
Near Abul W?fa on the first ring of Arabia, there is [a 
crater that should be] on the panoramic camera photographs. 
Look for a small crater just to the east of Abul W?fa, about 
200 to 400 m in diameter. And there is a black strip right on 
the western wall, going down the western wall of the crater. 
It doesTiot look like that strip extends beyond the rim at all; 
just down inside the crater wall. (CMP, rev 29) 
This is the first time I have really been able to see that 
first ring of Arabia. And it shows up as, the way the Sun is 
shining on the darn thing, it shows up as a bright-I'll be 
darned! That is amazing! It shows up as a bright ring, just like 
we got it drawn on the map. You know, I get a brighter 
albedo all the way around to the top of the ring. (CMP, rev 
40) 
Visibility of the basin rings was enhanced by the 
decrease in Sun elevation angles. As shown in the 
previous quotations, only the western part of the 
second ring was visible during most of the mission. 
However, as the Sun elevation angle decreased, the 
eastern part was clearly visible, especially post-TEI: 
Also, be advised the inner ring of the basin Arabia is quite 
visible. It looks like there is a shallow depression outside the 
inner ring and when you get up at this altitude right around 
Saenger, it looks like a raised-up plateau crossing Saenger. 
And, also, in the vicinity of King-King is almost going into 
the terminator now, well, it is 10? or 15? from the 
terminator-you can see a little bit of a raised-up plateau, 
that takes in the crater King and goes about a crater diameter 
and a half or maybe two diameters to the south, and a crater 
and a half to the north of King. (CMP, post-TEI) 
Light-Colored Swirls 
The light-colored sinuous markings in the north- 
ern part of Arabia form part of a large field that 
extends westward into Mare Marginis (ref. 28-10). 
The nature of these swirls is not well understood, and 
observations from orbit at varying Sun elevation 
angles were made in an effort to better characterize 
them: 
We are abeam of Al-Biruni and coming up on Goddaid 
and Marginis right now. Al-Biruni has got variations in its 
floor, variations in albedo. It ahnost looks like a pattern as if 
water were flowing on a beach-it is that irregular. Not in 
great areas, but in small areas around on the southern side, 
and the part that looks like it is a water-washing pattern is of 
a much lighter albedo, although I cannot see any real source 
for it. The texture, however, looks about the same. (LMP, rev 
2) 
And [more on] the question of these irregular swirls that 
we have in Mare Marginis, and we are looking just north of 
Neper now. In the mare, there just is no visible reUef. 
Although there seem to be some sinuous systematics anjrway 
to the distribution. Like, having a very dark area associated 
with the light area. And that dark area is darker than the 
[sunounding] mare. I think the pictures will show that. 
Now, in the highlands, however, the light albedo areas, which 
are very comparable, that appear to be swirl-Uke patterns of 
the same type, seem to be associated with a crest of crater 
ridges and other high points. We are right over a concentra- 
tion of these now in the northern part of Marginis, where the 
rule is that the light areas are associated with either 
symmetrically around a much darker area than the normal 
mare, or on one side, and in this case, generally the south 
side. That rule is very clear. And that also seems to hold in 
the far side where there was a slightly darker region between 
areas of light-colored swirls. (LMP, rev 2) 
Houston, there seem to be two general kinds of ray 
patterns: those associated with a lot of secondaries and those 
that have no visible secondaries. And that is independent, 
yet, from the irregular light-colored areas we have been 
calling swirls. There is a lot more of that light-colored 
swirl-like inegular material, or discoloration, or whatever you 
want to call it, in the far-side highlands, particularly as we 
approach Marginis, than I have previously gathered from the 
available photography. (LMP, rev 3) 
Let me reiterate something that 1 have been watching this 
revolution; that is this relationship of the light-colored or 
light-gray swirl patterns on the surface to associated patterns 
or parallel patterns that are darker than the average of the 
surrounding area. And this is true both in Mare Marginis and 
in most cases on the far side. Although these are very 
irregular patterns, there is roughly a concentric zoning of 
dark to light within an intermediate albedo surface. There are 
variations on that theme; sometimes you do not get the 
symmetry quite as good, but it is common enough that I 
think it is worth noting. (LMP, rev 5) 
Later during the mission, the CMP made addi- 
tional observations of this extensive swirl field. The 
alternating bands of dark and light were obvious 
despite the variation in Sun elevation angle. When he 
was queried about the swirls west of the crater Abul 
W?fa (fig. 28-8), he stated: 
Yes, I really saw them that time. And where the swirls 
really show up is about a crater diameter from Firsov, crater 
diameter to the east. And 1 talked about it on the tape. But, 
basically, they are kind of concentric swirls in that area, with 
light and dark [bands]. And the contrast between the light 
and dark is something tremendous. The dark is not a mare 
dark, but a tan that comes real close to it. (CMP, rev 29) 
You could really see the swirls in Marginis; [I am] trying 
to compare them with the same type of swirls back there in 
Arabia... But in the case of Marginis, there is a crater 
[Goddard] just in the northwest quarter .. . That is what is 
causing all the swirls going across Marginis ... There is a dark 
gray, and the swirls seem to be around the dark-gray areas. 
The swirls are a Ught tan. The swirls in Marginis... seem to 
be emanating essentially radially from that bright crater, 
going out across the mare. (CMP, rev 38) 
The newly found association between the swirls 
GEOLOGICAL OBSERVATIONS FROM LUNAR ORBIT 28-11 
and the darker bands added a new dimension of 
mystery to the problem. The relationship between 
the physical presence of a small crater on the rim of 
Goddard and a portion of the swirl field in Mare 
Marginis did not resolve the original problem: that of 
the lack of identifiable features that may have caused 
the surface brightening. Alteration of the surface 
material by gases escaping from the lunar interior had 
been suggested as a possible cause (ref. 28-11). 
MARE SMYTH 11 
Mare Smythii is a relatively old circular basin on 
the eastern limb of the Moon. The basin is charac- 
terized by several discrete units with different albedo 
and textural patterns. The mare also contains a 
unique population of multi-ringed craters, some of 
which are polygonal in outline (fig. 28-9). The 
objective of making observations of Mare Smythii 
from orbit on Apollo 17 was to study the multi- 
ringed craters to determine their probable origin: 
On the crater to the north of the Wright Brothers, the 
slope of the walls is steep, probably 45? on the inside. It is a 
gradual slope on the outside, slipping away from the crater. 
There is no apparent albedo difference in the ?jecta or 
patterned annulus around the crater itself, and we are looking 
specifically at the one to the northwest of the Wright 
Brothers now. There is a definite mare flow that is inundated, 
and it is a different color and has a light albedo to it now. It 
is kind of a grayish tan. It is a light-grayish-tan material that 
has flowed, and-I cannot tell?it almost looks like it is flowed 
down to the crater. There is an impact crater right in the 
breach in the wall, which has nothing to do with the flow 
itself. The material in the inner crater-in these double-ring 
structures down there?is comparable to the hummocky, 
bumpy-looking-type stuff that is not really the mare; not the 
smooth mare of Smythii, but the other part of the mare of 
Smyth?. (CMP, rev 62) 
The walls [of the multi-ringed craters] are not delta- 
shaped at all. The one directly north [of the Wright Brothers 
(fig. 28-9)] we will say is 12 o'clock; the other one is 1 
o'clock; and then a 2-o'clock crater. The I-o'clock crater, as 
it looks to me, has a high lava mark around the outer ring of 
the crater itself. The one at 12 o'clock is the one I was 
talking about, has the breach on it with the later impact, the 
small impact crater on it. And without the binoculars I could 
not tell flow direction, whether they were flowing into the 
double-ring basin from that mare patch on the outside or vice 
versa, so I am going to try to check that out the next time 
around. (CMP, rev 62) 
The crater just above the "rev 62" line in figure 
28-9 displays a multi-ring structure. From the center 
of the structure to the inner ring, the surface slopes 
upward at 15? to 20?. On the outside ofthat ring, the 
surface drops steeply, at about 45?. (Paraphrased 
from CMP, rev 64) 
I still want to talk a little bit about these polygonal craters 
and Smythii. The one right above revolution 62 has kind of 
an inundated old depression there with a mare, very smooth 
mare floor, with two old craters. And that is definitely a 
younger flow than whatever made the polygonal crater-like 
depression. Right above the 'rev 62' number [fig. 28-9]. The 
thing that bothers me about that is that they look like if you 
threw a rock in the mud, and you get a wave or a ripple going 
out from there. In other words, you have got a high 
wavefront going out from a circular direction with a slight 
sloping up to that wavefront. That is on the inner ring of the 
thing. The outer ring, of course, is a typical ring that you get 
from an impact-type operation. It looked like the rough- 
looking floors of those ring basins essentially have the same 
albedo, the same characteristics, as the rougher-looking floor 
in Mare Smythii itself. (CMP, rev 66) 
Rims on the Wright Brothers crater pair have a struc- 
ture similar to that of the crater above the "rev 62" 
line in figure 28-9. A cross section of the rim would dis- 
play a steep outer slope (as much as 45?) and a lower 
inner slope (approximately 20?), a configuration oppo- 
site to that of the majority of craters. The western por- 
tion of one of these craters is an exception in that the 
rim is almost delta-shaped; that is, it has the same slope 
inside and outside the crater. (Paraphrased from CMP, 
rev 73) 
CRISIUM-SERENITATIS 
As illustrated previously, much emphasis was 
placed on color tones of the observed features. As a 
result of Earth-based studies of the near side of the 
Moon, the lunar surface units had been mapped as 
red, intermediate, and blue (fig. 28-10) depending on 
their response to the solar spectrum. These color 
units appear to correlate with compositional varia- 
tions (ref. 28-12). Visual study of actual colors of 
representative areas was expected to help in inter- 
preting the color variations and in extrapolating to 
other areas of the Moon. 
The region designated 8 in figure 28-1 was 
considered of high priority in the discussion of the 
colors of the surface units. The region encompasses 
the western half of Mare Crisium through the eastern 
part of Mare Serenitatis. At one time, the CMP 
commented: 
To me, the Moon has got a lot more color than I had been 
led to believe. I kind of had the impression that everything 
was the same color. That is far from being true. 
This being the case, the area of observation was 
28-12 APOLLO 17 PRELIMINARY SCIENCE REPORT 
MARESMYTHll il of It 
Study the muit?-rmged craters in Mare Smythri with porticuiar attention to: 
?   1. Symmetrl of crater rijn slopes.       I 
2. Breaching of wails and resulting lectures (flow irr or out?) 
3. inter-crater units and their reiationships to the croter rims (impoct ?jecta^ volcanic deposits, etc.] 
FIGURE 28-9.-Numerous multi-ringed craters in Mare Smythii on the eastern limb of the Moon were 
the object of visual observation from orbit. Rim materials of these craters were compared to the 
hummocky units in the southern part of the basin. 
GEOLOGICAL OBSERVATIONS FROM LUNAR ORBIT 28-13 
Color differences in the lunar maria 
[Em        ^        ^ 
Blue Intermediate Red 
FIGURE 28-10.-Generallzed map of color differences in the 
lunar maria (r?f. 28-12, p. 199). 
extended, in real time, both to the east (to include 
eastern Mare Crisium, fig. 28-11) and to the west (to 
include the western rim of Mare Serenitatis, fig. 
28-11). For clarity, the region will be divided into 
seven segments in the following discussion. 
Mare Crisium 
Some patches in Mare Crisium appear to have 
lower albedo than the rest of the mare. Boundaries 
between these units are difficult to draw, based on 
available photographs. Also, the relationship between 
the discontinuous circumbasin mare-ridge system and 
these units was not clear. The CMP was asked to 
study these relationships within the basin and report 
on the color tone of the mare materials: 
I am looking at the eastern edge of Crisium now. As you 
come across there, it looks a little bit darker; I keep seeing 
browns all the time up here instead of gray tones. Maybe that 
is just the way I interpret them. They have kind of a 
brownish tint to them, and it is a darker brown than south of 
the ridge system there. (CMP, rev 27) 
The CMP noted that the crater Condorcet H on 
the southeastern rim of Crisium displays an unusual 
diamond-shaped floor; he also noted a probable 
landslide in the adjacent Condorcet A Crater (fig. 
28-12): 
I am just now passing that crater I took a picture of on 
the last time [Condorcet H]. And instead of having around 
bottom, it has a diamond-shaped fill in the bottom. And the 
diamond, itself, is about one-half of the crater diameter. 
(CMP, rev 27) 
Condorcet A [appears to have] a landslide on it. And it 
does not look like a crater on the side of the wall, on the 
northwest wall of the crater ... The area is oval or ellipse 
shaped. Of course, the top of the ellipse is toward the top of 
FIGURE 28-11.-Lunar near-side region encompassing Mare Crisium (right) and Mare Serenitatis (left). 
Note the albedo boundaries in both maria (AS 13-60-8696). 
28-14 APOLLO 17 PRELIMINARY SCIENCE REPORT 
FIGURE 28-12.-On the eastern rim of Mare Crisium, a 
landslide was described in Condorcet A Crater, and a 
diamond-shaped floor was found in a fairly fresh crater 
(arrow) near Condorcet H (AS17-149-22787). 
the crater. And it looks like almost a flow out of the bottom 
of the ellipse, which is about a fourth of the way up from the 
bottom of the crater ... The hole or the slope or the slide, or 
whatever you want to call it, down through there, is maybe 
one-eighth of the crater diameter. And the floor area is only 
just a real small portion of one-eighth size .. . There were some 
lineaments in the area; and, again, they are vertical-type 
lineaments downslope. (CMP, rev 28) 
Picard Crater 
Picard Crater, 30 km in diameter, is located in 
western Mare Crisium and displays a somewhat dark 
rim (fig. 28-13). Although the crater appears to be 
younger than the surrounding mare material, there 
are no rays and crater chains associated with its 
relatively smooth ?jecta blanket. Detailed study of its 
characteristics from orbit was planned to aid in 
deciphering its origin. The similar, but smaller, Peirce 
Crater to the north was also studied for the same 
reason. The most obvious first question was related to 
the color of their rim deposits relative to the 
surrounding mare: 
All those dark and light albedo changes around Picard and 
Peirce are not obvious at this particular angle yet. There is 
some hint of them... We are just about over the top of 
Picard; and the rim materials, which go out about a third of a 
crater diameter, as near as I can tell, are distinctly darker but 
not by much. They are more gray than the gray tan, or 
tannish gray of the rest of the mare. (LMP, rev 1) 
Coming up at Picard now. Looking at it, a little bit from a 
distance, there is a darker albedo that goes about one-half a 
crater diameter. And then, on top of that darker albedo, it 
FIGURE   28-13.-Picard  Crater  in  western Mare Crisium 
(AS17-150-23038). 
only goes out maybe a fourth of a crater diameter, there is a 
lighter-type material that seems to be covering it up. The 
lighter-type material though only goes in a generally westerly, 
from the south around to the west side and then from the 
northeast around to the northwest side, and it leaves the dark 
material draping down on the east side of Picard. 
You can pretty well carry a light layer in the top portion 
of the wall all the way around to that part where the light 
part stops. And then you come to a dark layer again. And 
then, as you continue around from the west to go to the 
north side, it is a little bit in shadow on the east side, so I 
cannot tell for sure whether that light layer is in there or not. 
But starting on the south side, going around to the west 
again, you can see a layer of dark material, although there 
does not seem to be a change in the slope or the inner wall of 
the crater. 
Just below the dark layer, there is a change in slope a little 
bit. It maintains that slope all the way down to the crater 
floor, where you get into the slump blocks. And then in the 
center of the crater, it looks like a mare-like fill with, I am 
about to lose sight of it again, something comparable to a 
central peak in it. (CMP, rev 24) 
When queried as to whether or not the Crisium 
mare ridge system corresponds to the color boundary, 
and if not, does the ridge cross any color boundaries, 
the CMP stated: 
This ridge system is running east and west down here. The 
color boundary is not nearly as apparent in Crisium as it is in 
Serenitatis, except that right under me right now, there is a 
GEOLOGICAL OBSERVATIONS FROM LUNAR ORBIT 
subdued crater with a southern part of a ridge. The ridge runs 
east-west, and it looks like we have got a flow coming out of 
it... The zero-phase point is following me right along here in 
Crisium, so I get a different color straight out from the 
window than I do out from the edge of it. So I think that is 
going to influence my thinking. 
You can see some of the rays from the crater Proclus have 
spread out all the way across here. And they completely 
cover up the ridge system, so I cannot see any color 
distinction on the western edge of Crisium. (CMP, rev 27) 
On the following revolution, the color tones 
around and within Picard Crater were again and more 
fully described: 
Sure hope that color difference shows up in Picard.. . 
There is black material now you get on up here, the darker 
tannish-gray material covers essentially from the east all the 
way around to the south. It goes outside the rim as well as 
inside the rim. It drapes o>^i the rim. That cannot be a 
shadow effect. (CMP, rev 28) 
Additional details of the crater and its surround- 
ings were also obtained on later revolutions: 
You know you could, even as the zero phase went right 
across Picard, you could still see the darkness on the east 
from 9 o'clock around to 6 o'clock, if north is zero. And if 
north is zero as you look at the crater, then over about 1 
o'clock there is some kind of a fault zone in the side of the 
rim, and that is another spot where the dark material drapes 
down into the rim and also outside of the rim. And then you 
have that same type of impression at about 11 o'clock. You 
have got a black streak going down inside the rim, and then it 
widens out going toward a little crater outside of the rim. 
(CMP, rev 36) 
In the eastern wall of Picard-I am looking at it with the 
binoculars now-you can definitely see the first part of it up 
there has some vertical escarpments along the edge. And the 
vertical escarpments are in irregular layers, just like you 
would suspect if you eroded out a bunch of lava layers. In 
other words, they are discontinuous, but they are kind of 
intermingled along, and they go about a third of the way 
down from the top of the rim, down to where the talus starts 
sliding into the crater. (CMP, rev 40) 
At a Sun angle of 50? to 55? (rev 50), the crater 
Picard still displays a dark halo. The dark halo 
appears slightly smaller, extending perhaps to one 
crater diameter, and is less distinct. (Paraphrased 
from CMP, rev 50) 
Western Crisium 
In the western part of the Crisium basin, observa- 
tions were made of (1) the dark-halo craters in the 
mare fill and (2) the rim materials as displayed in 
massif units and in the ?jecta blanket, including 
Proclus Crater and its bright rays. 
Small, dark-halo craters in Mare Crisium.?The 
mare surface northwest of Yerkes Crater includes 
several dark-halo craters (fig. 28-14). Some of these 
display smooth rim deposits and are beheved to be 
volcanic in origin (ref. 28-13), and others have 
hummocky ?jecta blankets and are probably pro- 
duced by impact. The following observations were 
made from orbit during the Apollo 17 mission. 
West of Yerkes, there is a real small crater I am looking at 
with the binoculars. And the reason it stands out is because it 
is a fresh crater and yet there is a dark halo all the way 
around it. And it is also dark down on the inside of it. I still 
FIGURE 28-14.-Dark-halo craters in western Mare Crisium. 
The ?jecta blanket of the circled crater was described as 
having an orange-tinted color (AS17-150-23044). 
APOLLO 17 PRELIMINARY SCIENCE REPORT 
do not have a feeling for the relative size of things. I will try 
to get that one on the next pass. (CMP, rev 24) 
All these dark-halo craters by Yerkes! The one that is 
farthest to the south looks like an impact-type crater. In 
other words, you have a definite ?jecta blanket around it. 
The one that is hard to look at is in the middle of the field, 
but I think it is probably the second one down from the top. 
It has rounded ridges, and a rounded rim. The ?jecta pattern 
or the dark halo is about twice the crater diameter. And it is 
either a highly eroded impact-type crater, or it is a 
volcanic-type structure. And, to rae, it does not look like a 
highly eroded impact one. (CMP, rev 40) 
The rays and ?jecta blanket surrounding the 
bright-rayed crater in the area (fig. 28-14) were 
described as orange in color. The crater was compared 
to others in the Taurus-Littrow landing site and in the 
Sulpicius Gallus area (as discussed in the following 
paragraphs). 
In the north, east, and west quadrants of that little crater, 
there is very clearly an orange pattern, an orange color to the 
?jecta. The other quadrant is a lighter color, a light gray. 
(LMP, rev 64) 
In addition to the orange-tinted ?jecta, blocks 
with a greenish hue were observed around impact 
craters in western Crisium. These observations may be 
important in establishing the importance and distribu- 
tion of colored glasses collected on Apollo missions 
11, 15, and 17. 
I get the impression that these bright ones, see the bright 
one right down there in front of us [fig. 28-14], have a dark 
greenish-black or blackish-green [color], yes, a green cast to 
the rocks. The big blocks that are laying around in the crater 
and also the ones that are down in the bottom, a greenish 
cast to them. (CMP, rev 64) 
Houston, we are just passing over a little polygonal crater 
that is maybe 15 km in diameter. It, again, has that dark 
greenish-black rock that is collected down at the bottom of 
it, and you also see it streaking down the side of it. But, I 
think one of the most significant features about the crater 
itself is that it has a swirl, and this looks like swirls rather 
than rays. It has a swirl pattern, radial from that most recent 
impact. (CMP, rev 66) 
Rim materials of the Crisium Basin.?The sharp- 
ness of the massif units that ring the circular basins is 
one of the factors to be considered in deducing the 
relative age of the basin. The mountain rings of large 
circular basins and those of Imbrium were compared 
during the flight, based on what is known about their 
positions in the lunar stratigraphie sequence (ref. 
24-14). The following are selected comments that 
compare Crisium with other overflown basins: 
While we are in a relatively quiet period, we are going to 
make a few comments about some of the things tnat cross 
the two big basins that we are getting very famiUal with, 
actually, three: Smythii, Crisium, and Serenitatis. [The 
obvious features are] the degradation of the walls of the 
major ring and the lack of any obvious blanket structures, in 
contrast to Imbrium and Orientale, which we have also had a 
pretty good look at. That contrast is quite striking. 
The fronts of the major ring in Crisium are strikingly 
different from those of the Apennines in their general slopes; 
sharpness of topographical features; and in any appearance of 
having even a hint of boulder fields on their slopes like we 
observed, say, on the South Massif, anything like that. At 
least Serenitatis massifs seem to locally show fairly major 
boulder fields on their flanks. And I have not seen any 
around Crisium yet. 
A crater, a fresh crater in the mare or a fresh crater in the 
rim area will have boulders, do not misunderstand me. But the 
front faces, the ring front faces, do not have boulders that 1 
can see. And I think boulders are pretty obvious when they 
are there. We have seen them well defined on the central 
peaks of Tsiolkovsky, and I think any time you have a major 
boulder field, you can see it with the binoculars. (LMP, rev 
62) 
Proclus Crater, 35 km in diameter, was studied 
during Apollo 15, and its ray-excluded zone was 
attributed to shadowing at the time of impact (ref. 
28-1). The rays of Proclus were studied during Apollo 
17 to determine whether or not there is any similarity 
in appearance between those rays and the swirls of 
light-colored markings discussed in the section on 
Arabia: 
I am looking north along Crisium, and there is Picard and 
Peirce. And you get the same pattern that looks like a swirl. 
The same type of albedo as a swirl with light places and dark 
places. The only difference being that you can definitely tell 
that these are ?jecta from Proclus because the pattern is 
somewhat radial to Proclus itself. And then you have the 
same thing; there is a crater up on the north rim of Crisium, 
just outside of it is a 50-km crater. And it is a very bright 
one. And there the rays cross the Proclus swirls or rays. Here 
you have to definitely call them rays instead of swirls, and 
yet they look the same way. And the only distinction is that 
in Crisium they go essentially radial. They have a direction to 
them, whereas the ones over there in Marginis and next to 
Firsov do not have any particular direction to them. (CMP, 
rev 38) 
On Apollo 17, an effort was made to study the 
unit in which Proclus Crater is located and to 
compare that unit to other hilly terra units in the 
vicinity of the Serenitatis and Imbrium basins. 
There is a crater just on the west rim of Crisium, [with a] 
relatively fresh rim, fairly crisp rim, but no strong ray 
pattern. There is no ray pattern apparent at all. It looks like 
it predates the plains material around it, since they come 
GEOLOGICAL OBSERVATIONS FROM LUNAR ORBIT 
right up to the edge of the crater in one spot. That is 
[Proclus] ! (LMP, rev 1) 
The highlands look essentially the same as you pass from 
Crisium on across to Fertility. Again, they look so much like 
the Sculptured Hills... What I am referring to are the 
highlands bordering Crisium, in all of them you do see a 
definite radial pattern upslope and downslope, from the 
center of Crisium. But none of the lineaments look like Fra 
Mauro [the Fra Mauro Formation, bordering the Imbrium 
basin]. (CMP, rev 62) 
Getting into areas that resemble, in their surface texture, 
the Sculptured Hills of the Taurus-Littrow landing area. Here 
we are just passing Proclus, so it is in the ray-excluded zone 
of Proclus where there is a mare surface projecting up into 
tenain that looks like Sculptured Hills. And that mare has a 
distinct bluish-gray color, in contrast to the regolith associ- 
ated with the Sculptured Hills, between the Hills at least, 
which is a brown, let us call it a tannish gray. Quite a sharp 
color hue contrast to my eyes, at any rate. (LMP, rev 63) 
Macrobius A Area 
West of Macrobius Crater and especially in the 
vicinity of Macrobius A are several small cone-shaped 
craters that display dark halos (fig. 28-15). The 
Apollo 17 crew was asked to study these craters from 
orbit to determine whether they are volcanic cinder- 
cone-like features, or impact craters that excavated 
dark material from beneath a lighter mantle: 
Next to Macrobius A, there is a dark halo crater, a very 
small one. And it does not have the appearance of a 
hummocky crater rim to it, at all. It looks like the material 
just kind of spreads out all over the area, but it does not have 
a hummocky appearance to it. I am going to take a look at 
that again when I come back around. On the other side, there 
is a small mound down in the bottom of the crater, also. It is 
a dome-shaped structure in the bottom of that small crater. It 
is right next to J-3, north of J-3 [fig. 28-15]. (CMP, rev 15) 
I was looking at the dark rimmed craters, and some of 
them have what I would call an ?jecta pattern around them; 
and the others just have kind of a raised rim with no apparent 
blocks. The one to the southwest of that hill by Yerkes looks 
like it has an ?jecta pattern around it with blocks. 
I was looking for any dark-halo craters in this area that 
might be sticking through the Proclus rays. You compare on 
either side of the Proclus ray, and the same size crater... 
You get the same albedo of ray material from the small 
craters in either case ... 
The two dark craters, the one just north of Macrobius A, 
and also north of J-3, that is the one that has the dark mound 
around it, it has got a small dome down in the center. It does 
not have any ?jecta pattern around it; no rays, no nothing. 
To me, that sure looks like a cinder cone. The dark halo 
around it goes out for at least a crater and a half diameter. 
The raised dome down in the center of the crater is about a 
fourth of a crater diameter. And there are no rays. (CMP, rev 
27) 
The CMP at this point characterized the color of 
the dark-halo craters near Macrobius A as similar to 
that of Maraldi and the landing site; he characterized 
the color as "dark tannish gray." (Paraphrased from 
CMP, rev 27) 
Maraldi Area 
Before Apollo 17, the origin of the Sculptured 
Hills on the eastern rim of the Serenitatis basin was 
not fully understood. One of the possibilities was a 
volcanic, constructional origin (ref. 28-15), and the 
example usually given was the dome-shaped, isolated 
structure Maraldi y (fig. 28-16). An objective of the 
Crisium-Serenitatis visual observations was to determ- 
ine the nature of that structure. 
From the t<ictures of Maraldi % it looked to me like it 
might have been a volcanic dome of some kind. Now when 
you look at it and compare it with the rest of the 
sunounding material, it looks just like any of the other 
Sculptured Hills. The domical structures on it are the same 
type of material that carries on through south of Maraldi. 
(CMP, rev 17) 
The floor material of Maraldi Crater east of Mare 
Serenitatis was also studied from orbit, and some 
interesting color tones were discovered and later 
compared to materials in the Taurus-Littrow landing 
site and on the western rim of Mare Serenitatis. 
It looks like maybe some kind of a mare fill has come in 
and filled up Maraldi itself. You can see flow Unes, going 
down into Maraldi from Tranquillitatis. The impact craters 
inside Maraldi have a definite bluish tint to the halo that 
comes out as opposed to the bright or the white-type craters. 
Those have more of a darkish bluish tint to them. Oddly 
enough, that is the same type of bluish tinge that I see right 
in the landing site right now. In the Pentagon Complex, 
MOCR shows up that same type of a bluish tint. (CMP, rev 
17) 
Again, the fresh craters in Maraldi still look kind of bluish 
to me, not as much as they did yesterday, but they still have 
a bluish tint to them from the reflection of the Sun. In other 
words, they are fresh craters and one of them is about the 
size of M(X!R, and the other one is about the size of 
Sherlock or Camelot. (CMP, rev 27) 
Houston, even at the high Sun angle here, the ?jecta of the 
four or five recent craters around Maraldi, still are bluish 
gray, light bluish gray. The floor of the crater Maraldi is 
essentially a darker gray today, I guess, than anything. And 
the ?jecta patterns on that are the same albedo and color 
distinctions as the ones in the landing site. (CMP, rev 74) 
When he was asked to compare the floor fill of 
Maraldi to that of the light plains materials in Maraldi 
E, the CMP replied: 
APOLLO 17 PRELIMINARY SCIENCE REPORT 
FIGURE 28-15.-Dark-halo craters near Macrobius A and B Craters (Apollo 15 metric camera frame 
AS15-557). 
The floor fill in Maraldi is definitely a darker color. The 
Bght plains in Maraldi E are the light-tan material. And the 
floor of Maraldi looks just like the landing site. (CMP, rev 27) 
Mare Serenitatis 
As an additional tool for the extrapolation of 
ground-truth data, observations were made of the 
relationship  of the  dark  material in the Taurus- 
Littrow landing site and the dark annulus of Mare 
Serenitatis (fig. 28-11). The following discussion will 
start with the eastern border of Mare Serenitatis, 
followed by observations of the color/stratigraphic 
units in the southern part of the mare. Detailed 
descriptions of the landing site area itself are given 
under a separate heading of this report. 
Eastern Mare Serenitatis.?It was previously stated 
GEOLOGICAL OBSERVATIONS FROM LUNAR ORBIT 28-19 
CRISIUM-SERENITATIS (5 of 5) 
1. CompOfi the floor fill of Moroldi to tighl plains in Marcldi t- 
2. Compare tfie olbedo, iexture ond structure of Moroldi "y to tfiose of the iculptyrsd hills, 
3. EscomW tfi? floor of Vftr?vios A old comport the dotnical fiifls to tfiost rn the ffoor of the croter Aitkcfi. 
FIGURE 28-16.-Apollo 17 onboard graphic in support of visual observations of the Maraldi Crater 
area. 
that the dark fill of Maraldi resembles that in the 
landing site area including a few craters with a bluish 
tint. The dark materials of the Taurus-Littrow area 
appear in photographs to continue into the Sereni- 
tatis basin and show intricate relationships with the 
mare  ridges in  the  dark  annulus.  The  following 
APOLLO 17 PRELIMINARY SCIENCE REPORT 
observations are descriptions of these relationships as 
seen from orbit. 
Right now, I am looking at the tidge system around the 
annulus of Serenitatis. And the dark material stops before 
you get to the crater that sticks into the eastern edge of 
Serenitatis. (CMP, rev 27) 
The dark annulus around Serenitatis, as you look north, 
and I am kind of looking back, that dark has no continuity 
with the ridges at all. It [the color boundary] goes right 
down the middle of the ridges. As you look directly west of 
Littrow, the wrinkle ridge is there, and you have the dark 
tannish gray. And then you get out to the light tan of the 
Mare Serenitatis itself. (CMP, rev 35) 
I am looking out of window 2 now, and you can 
definitely get three different color units: You have the light 
tan of Serenitatis; and then you have the darker annulus that 
stops somewhere in about the middle of the two ridge 
systems that go around; and then you come down south in 
the landing site area and the two dark units change. The 
landing site area is a darker gray. (CMP, rev 38) 
The same color differences were amplified and 
more fully described at higher Sun angles (25? 
higher): 
This is not a good viewing attitude at all, but we get a few 
isolated views that may be worth commenting on. The 
contrast, to my eye anyway, between the three color units 
around the landing site is a medium bluish gray to gray for 
the dark mantle; a light blue gray for the annulus around 
Serenitatis; and then, a tan gray for Mare Serenitatis proper. 
The light-blue-gray annulus is also the locus of most of the 
circumferential grabens, that Serenitatis is noted for, in that 
area. And that is nothing new! But, in one place, there is a 
very subdued, flooded crater which seems to control a 
circular projection of the light blue gray out over the tan-gray 
mare. Most of the major wrinkle ridge system of Serenitatis, 
of course, is outside the annulus of blue gray, except locally, 
and one of those places was to the west of the Taurus- 
Littrow site. Although that wrinkle ridge system does, in the 
southern portions of Serenitatis, cross the contact between 
the light blue gray and the tan gray. 
The impression I have had by looking at all the mare 
wrinkle ridge systems is that they are a late feature. They, at 
least at low Sun, and sometimes even at high Sun, they have 
very sharply defined ridges with steep slopes on either side 
that, in general, give me the impression that they are 
constructional, possibly associated with some thrusting move- 
ment. (LMP, rev 62) 
Southern Mare Serenitatis.?An interesting obser- 
vation was made of apparent layering in Dawes Crater 
(fig. 28-17) that is related to the units in southern 
Mare Serenitatis and their color boundaries: 
The crater Dawes has, starting from the top going down 
the rim, a light-tan layer; it is a concentric layer all the way 
around. And then you come into a lighter one, almost Uke on 
the hUls all around the landing site. The first layer goes down 
maybe about a third of the depth; and then the white 
FIGURE 28-17.-Layering in Dawes Crater on the south- 
eastern corner of Mare Serenitatis as seen from lunar orbit 
(AS17-150-23066). 
concentric layer, in the western wa?, goes down to not quite 
half of the distance from the top of the rim down to the 
bottom. The lower portion, a little better than a half, is kind 
of a tatmish gray. It is all streaked. And the bottom of the 
crater itself is filled with, oddly enough, the same color of 
material as that lying around the edges of the crater. It has 
some radial rings, which give an indication of a subsidence of 
some kind, or of sliding downhUl. That is really the first 
crater where I have been able to see any sort of layering in 
the walls. Now the first layer on the north side and also on 
the south side, in the dark-brownish layer of the thing, you 
can see parts that are jagged. In other words, there is a slight 
change in slope. That looks like it is a very steep slope, which 
would indicate that it is a fairly compacted type of material 
in the first layer. And then the slope changes in the white 
layer on down a little bit more. And the white layer seems to 
sort of maintain the same slope as the dark-gray layer. (CMP, 
rev 39) 
At higher Sun angles and to another observer, the 
sequence of layers in the w^alls of Dawes Crater 
suggested overturning of strata: 
In Dawes, I think you can see the overturned [units]. The 
rim materials are made up of the brownish-gray material, and 
the walls underneath these are the bluish gray, which is the 
age relationship suggested by topography; that would be the 
lower unit is forming the rim, with inverted stratigraphy. 
(LMP, rev 62) 
Layering was also noted in segments of the Rimae 
Menelaus that appear to have raised rims when 
observed at low Sun elevation angles: 
Those rilles to the north of [Menelaus], there is a bunch 
of them crisscrossing. One is right on the edge of the 
Serenitatis basin. But they have got slightly raised rims 
around the edges. You can see some layering down inside the 
rUle itself, in the one that runs in the east-west direction. 
(CMP, rev 15) 
GEOLOGICAL OBSERVATIONS FROM LUNAR ORBIT 
The color boundaries in southern Mare Serenitatis, 
particularly north of Menelaus Crater (fig. 28-18), 
received much discussion throughout the mission. 
The following observations were made of this area: 
When I take a look at it from this angle, the ?jecta from 
Plinius covers up the rilles and the annulus around Sereni- 
tatis . .. Now, we are getting into a relatively low Sun. And 
Serenitatis is a lot lighter colored than the light tan, to me. 
At this low Sun, you look out into Tranquillitatis, across 
Plinius, and that turns out to be the same kind of gray tan, it 
is darker. .. There is a definite color difference between 
them [Tranquillitatis and Serenitatis]. And it almost looks as 
if the color from TranquiUitatis extends on over, or kind of 
drapes over the edge, and covers up part of Serenitatis. 
We are at the same Sun angle, and there is no doubt about 
it from Tacquet on up to Menelaus, there is a group of smaU 
rilles and those rilles have ejected material, around and over 
the rilles; not impact-type ?jecta. It has got to be a volcanic 
?jecta of some kind. It is a darker brown than the tan of 
Serenitatis. (CMP, rev 28) 
Going to come across the Tacquet area again, and there is 
a bright crater, a recent crater, in that dark annulus in the 
southern part of Serenitatis. It shows up again as that kind of 
a blue-gray brightness, as opposed to the tannish brightness 
of the bright craters in Serenitatis. There is still no apparent 
color tone or differentiation in the wrinkle ridge in this part 
of it. The only differentiation is that it looks like south of 
Tacquet you get the same color tone on over into TranquiUi- 
tatis as you get between Tacquet and Menelaus. (CMP, rev 
35) 
Looking at Menelaus, you can see where the dark edge of 
Serenitatis goes through the crater. And, the north wall is 
quite distinctly grayer, let us say bluish gray, than the south 
wall, which is very light gray in the talus. My guess is that it is 
a very nearly vertical contact at that point. (LMP, rev 66) 
Sulpicius Gallus Area 
The dark mantling materials on the western rim of 
the Serenitatis basin are more varied and perhaps 
more complex than on the southeastern rim. Mater- 
ials of the dark mare annulus in southern Serenitatis 
appear to be overlain by younger mare materials that 
also postdate the dark mantling units of the.Sulpicius 
Gallus area on the western rim of Serenitatis. These 
rough and textured materials are to be contrasted 
with the patches of dark units between Montes 
Haemus and Montes Apenninus to the west (fig. 
28-19). The objective of this observation was to 
compare these units to the Serenitatis mare materials, 
with emphasis on the color tones. (This task was 
added to planned observations in real time.) 
When we are coming around the dark annulus, follow it 
around, by Menelaus and Tacquet, it seems to change colors a 
little bit when we get up to the Sulpicius Gallus. I guess the 
FIGURE 28-18.?Contact between two mare units in south- 
ern Mare Serenitatis. The older and darker unit near the 
rim of Menelaus Crater Qower edge) displays rougher 
topography; the younger and lighter unit contains a broad 
wrinkle ridge (AS17-150-23069). 
only thing you can say is that the southern part there, in the 
Tacquet region, has a more of a bluish tint. And, then to me, 
this has more of a brownish tint to it when you get to the 
Sulpicius Gallus region. 
I am just passing Menelaus ... and Sulpicius Gallus is just 
now coming up. I think the Sun angle has a lot to do with 
that, because this whole Sulpicius Gallus region looks kind of 
brownish to me. I will have to check that when the Sun gets a 
little bit higher. (CMP, rev 24) 
I am just passing over Sulpicius Gallus, now. And just 
beyond Sulpicius Gallus, you got a gentle slope of the massif 
coming down and then it changes slope a little bit. And that 
might be what we have at one time or another called the high 
water mark, but I believe that is just a talus change in the 
slope. But as soon as you cross that area, we have a dark-tan 
material that essentially covers the highland. It is a hum- 
mocky material. There are a few rilles just north of Sulpicius 
Gallus; those rilles, again, have the dark-tan material on them. 
(CMP, rev 36) 
28-22 APOLLO 17 PRELIMINARY SCIENCE REPORT 
FIGURE 28-19.?Oblique view looking westward from the dark mantling deposits on the western rim 
of Mare Serenitatis. Rimae Sulpicius GaUus are in the lower right corner; D-Caldera (circled) is near 
the upper left edge of the photograph (AS17-153-23572). 
As will be discussed later, the CMP noted an 
orange zone on the northeast rim of Shorty Crater. 
Ejecta blankets of several craters of comparable size 
and larger also displayed an orange color. Referring to 
these craters later in the mission, the LMP added: 
Ron says that he already commented on those, and they 
look very obvious to me .. . [The color] is a light orange, in 
contrast to the brown gray of the dark mantle in the vicinity 
of Sulpicius Callus. There is a good one right down there. 
Now, that one looks like a constructional cone that is 
orangish. And that is right out on a raised projection of the 
brown-gray dark mantle out onto the light-blue-gray annulus 
material. (LMP, rev 62) 
In addition to the constructional-appearing, 
orange-tinted craters and the many orange-colored 
blankets around small impact craters in the Sulpicius 
Gallus region, an elongate depression with orange- 
related colors was also discovered (flg. 28-20). 
There is a large gouge just south of the Sulpicius Gallus 
rille. The gouge is a rimless depression, and streaming down 
from the upper portion of that depression are not only our 
old friend the orange gray, but some would be a red brown 
gray, very clear coloration .. . There is another crater we will 
have to look at... There is a whole bunch of them down 
there... Yes, we are seeing an orange Moon now. In this 
whole dark mantle in here around Sulpicius Gallus there are 
scattered craters with a variety of orange to red-brown hues. 
And they aU, except for that large rimless depression, which 
looked as if it was exposing some layers which were 
streaming those colors, all the other craters seem to be small 
impacts that apparently are penetrating just far enough into 
the dark mantle material to tap this zone of orange to 
red-brown material. (LMP, rev 64) 
That rimless, V-shaped depression [fig. 28-20(b)] that had 
the streaked talus on it has a mottled rim area that has the 
orangjsh-tan or orangish-gray color as the spot. And it looked 
as if the more red-gray, red-brown-gray, if you will, material 
was lower in the section within the walls of the depression. 
This is a very steep-waUed depression, by the way. It has talus 
GEOLOGICAL OBSERVATIONS FROM LUNAR ORBIT 28-23 
FIGURE 28-20.-ApoUo 17 photographs of Sulpicius Gallus 
formation where orange-tinted material was observed 
during lunar orbit, (a) Two 0.5-km-diameter craters. The 
upper crater is an impact in the dark plain and exhibits 
orange-tinted ?jecta (AS17-148-22771). (b) Elongate de- 
pression, approximately 6 km long, showing orange-tinted 
walls (AS17-149-22880). For general setting, see figure 
28-19. 
streaming down the sides of it, and the coloration streams in 
this same direction. It looks as if there may be layers or 
roughly horizontal zones that have the coloration that we are 
seeing, which are forming the talus slopes down below them. 
(LMP, rev 65) 
These observations of the orange materials were 
also confirmed by the third crewmember: 
Just so you are fuUy aware, we are not sort of just leaning 
and getting colorblind up here, I tell you, the last one Jack 
was talking about [the small impact crater, fig. 28-20(a)] was 
not even subtle. Its entire ray pattern was this color material. 
with a definite contact between it and the dark material 
around it, and it had that orange-brown hue to it, without 
any question at all. (CDR, rev 64) 
LANDING SITE AREA 
The Taurus-Iittrow landing site on the south- 
eastern rim of Mare Serenitatis was studied from orbit 
for (1) regional characteristics that may reflect on the 
sampling area and (2) details of local structures that 
may help decipher the setting of explored sites. 
General Setting 
Observations from orbit began very early during 
the mission and continued throughout the orbital 
period. One of the more interesting problems was to 
see whether or not it is possible to define a source 
point for the landslide or white mantle on South 
Massif (figs. 28-21 and 28-22). The slide itself and the 
scarp that goes through it were obvious even at very 
low Sun elevation angles: 
With respect to the landing site, when I first had it in 
view, there was a clear lightening in the area of the light 
mantle. It was not sharply defined; but around the crater 
Lara and Nansen and to the west of the scarp, there was very 
clearly, slightly brighter reflectivity. (LMP, rev 2) 
I can now see down in through the shadow. I can see Bear 
Mountain. I cannot really make out the slide yet. Most of the 
North Massif is stiU in shadow due to the Sculptured 
H?ls .. . But, I did see some sort of albedo change that went 
across the canyon about in the vicinity of the scarp. (CDR, 
rev 2) 
You could really see a difference between South Massif 
and the mantle material through there. The mantle is not 
nearly as dark as it looks on the pictures, though. But South 
Massif, especially, looked whitish in color. I guess it is 
because the Sun was shining on it.. . You can see the slide 
and definitely see the scarp going across through there. (CMP, 
rev 3) 
I got the landing site. We are right over the top of it, and 
the scarp is fantastically detailed at this [Sun angle] . .. The 
light unit is very obviously mantling the area. The scarp is 
very detailed, and, so far, [I] could not see any structure in 
the massifs at all... From this altitude and with that low 
Sun, there is no question of the sharpness of the topographic 
features in the landing area. The scarp, and even some of the 
apparent backflow features, that is, apparent flows to the 
west in the light mantle area, were extremely sharp, even 
those fronts going west were sharp. It looked even more like 
a mare ridge than it ever did before. (LMP, rev 5) 
The scarp definitely cuts up through the North Massif. I 
cannot see a continuation into the South Massif at all. And it 
almost looks like a flow coming from the direction of Family 
Mountain, lapping up on the side of the North Massif. That is 
28-24 APOLLO 17 PRELIMINARY SCIENCE REPORT 
FIGURE  28-21.-ObBque view looking westward from  the Taurus-Littrow landing site. Arrow, 
showing the direction of flight, indicates the landing point (AS17-148-22770). 
the way it looks as you go on by it. I could not see anything 
that would lead you to believe that the slide area, so to 
speak, would come on across anything that would be the 
source ofthat slide area. (CMP, rev 15) 
As discussed in earlier sections of this report, 
blue-gray rocks were sampled at several localities in 
the landing site. The same color tone was described 
from lunar orbit in the vicinity of larger craters in the 
subfloor materials as well as on the sUde. 
You still get that same bluish tint from the area in the 
landing site. At station number 2, on the landslide, it is going 
to be a pretty good little depression there. (CMP, rev 24) 
Areas in the landing site where we now know there are 
extensive blocks of the subfloor material, particularly in the 
walls of the larger craters, I have the impression that those 
block fields, from this altitude, give a light bluish-gray 
appearance. (LMP, rev 66) 
Just north of the bright-rayed craters in the Littrow area, 
there are five craters, probably in the range of 500 to 
1000 m; and all five have the sequence of colors in the walls, 
from rim down, of a brown gray, blue gray, and then brown 
gray. They are all identical in that and quite clear. And that 
blue gray is comparable to the blue gray that is visible in the 
craters such as Sherlock in the landing area. (LMP, rev 72) 
The differences in albedo, color tone, and texture 
between the massif units and the Sculptured HiUs 
were obvious from orbital altitude both at low and 
high Sun elevation angles: 
I can see the landing site now quite well. The slide area 
definitely shows up. The South Massif seems to have the Sun 
shining right on the walls. I am looking for any type of 
layering, or anything like that, and cannot see anything. The 
big difference between the massif structures and the Sculp- 
tured Hills is that the massifs look like they have a steeper 
slope. And they do not seem to have that type of covering 
over them, like the Sculptured Hills do. (CMP, rev 15) 
The albedo differences are very definite: one is the dark 
mantle on the floor; one is the South and North Massifs; and 
the other is the Sculptured Hills. And the Sculptured Hills 
have a light-gray albedo between the Massifs and the dark 
mantle. This line is very evident and there is a definite break 
in slope that you can see between the South Massif and the 
white mantle out on the valley floor. (CDR, rev 62) 
To me, the Sculptured Hills incorporate the albedo both 
of the North Massif, or South Massif, and the mantle area and 
combine them to give you a generally in-between gray 
albedo, but the sculpturing is produced by the darker albedo 
that looks Uke the mantle, and the lighter albedo that looks 
like the massifs. (CMP, rev 62) 
GEOLOGICAL OBSERVATIONS FROM LUNAR ORBIT 28-25 
FIGURE 28-22.-Taurus-Littrow landing site. Note that the 
scarp displays mare ridge characteristics between the 
North Massif (top) and the South Massif (lower half); it 
also appears as a flow that laps up against the North 
Massif (AS17-150-23006). 
SHORTY CRATER 
Much excitement was generated during the mis- 
sion by the finding of orange soil on the rim of 
Shorty Crater (fig. 28-22). The CMP was asked, after 
the discovery, to determine whether the orange soil 
could be observed from orbit. An orange-tinted zone 
was described particularly on the north rim of 
Shorty. This finding also led to further concentration 
on craters of a similar size in western Mare Crisium, in 
the Littrow B area, and in the Sulpicius Callus area. 
The orange-tinted zone was obvious at inter- 
mediate Sun elevation angles (on rev 40) but harder 
to discern at high illumination (on rev 65): 
I have got Shorty in the picture. It is a sharper crater than 
any of them ... Did they find that orange stuff on the north 
side of it? ... I would say they just barely got into the 
[orange] stuff, then, because the north rim has mote of a tint 
of a different color to it. . . Would you believe an orangish 
tan through these binoculars? (CMP, rev 40) 
Through these glasses, Shorty still looks light tannish 
orange. And it does not come all the way down to the center 
of the crater. It is tangent to the north edge or perpendicular 
to the scarp. (CMP, rev 41) 
On Shorty, I stiU have that light-orangish-tan material. It 
is essentially perpendicular to the line of the sUde area there 
in the northern semicircle of the rim. (CMP, rev 62) 
My impression of Shorty from the other day, and also 
from seeing these craters that seem to have orange around 
them, they look very much like impact craters from orbit. At 
any rate, if that is an alteration phenomenon, it is being 
localized around the structure created by the impact. But in 
this latter case, it looks as if the impact itself penetrated into 
a zone of that color. (LMP, rev 64) 
The craters we are seeing around Sulpicius are very clearly 
orange gray and the whole, or at least most of the crater, is 
that way. We looked at Shorty today, and Ron said that even 
the little bit of orange that he saw the other day is not 
visible, and I agree with that. The amount of orange we saw 
on the surface certainly would not be comparable to what we 
are seeing around Sulpicius Gallus. .. And on a couple of 
quick scans, on previous revs, of the area, the dark mantle, 
near Littrow, I did not notice any obvious orange-gray 
craters. (LMP, rev 65) 
I still get a feeling that there is just a tinge of the orange 
or tannish orange around Shorty, looking at it with the 
binoculars. (CMP, rev 74) 
D-CALDERA 
The low hills between the Montes Haemus to the 
east and Montes Apenninus to the west are inter- 
spersed with patches of superposed dark material (fig. 
28-19). In one of these patches is a D-shaped 
depression (fig. 28-23) that was previously inter- 
preted as a volcanic caldera (r?f. 28-16). The struc- 
ture is unique, with no equivalent formations on the 
Moon. It was studied from orbit to further charac- 
terize its nature: 
FIGURE 28-23.-The D-shaped depression in the dark 
mantling material west of the Montes Haemus exhibits a 
Ught-blue-gray tint. A darker bluish tone is also exhibited 
in the crater in the lower left corner (AS17-152-23286). 
28-26 APOLLO 17 PRELIMINARY SCIENCE REPORT 
The EM?aldera is sure a depression. Like notliing I have 
ever seen before ... At this point, you get a dark tan, a 
mare-type material. And then it is a light gray down in the 
D-Caldera itself. But it is a light gray down inside. It has got 
bumps that stick up, and the bumps themselves... are light 
tan. Arid down between the bumps in the caldera is a rough, 
blocky, gray material. (CMP, rev 28) 
At higher Sun elevation angles, the floor of the 
depression was found to have a bluish tint to it that is 
also apparent in the Hasselblad color photographs. 
D-Caldera is sure fascinating. I wUl try and take a quick 
look with the binoculars on that one ... I hope the pictures 
wiU confirm a little bit of a topographic rise around the 
D-Caldera, just a slight one, and it is about half the width of 
the "D." And there seems tot be a raised, flat rim around it. 
The color of the raised bumps down in the D-Caldera is the 
same as the sunoundtng material. The bumps that are raised 
up are smooth looking and the depression (floor material) is 
light bluish gray, very Ught bluish gray. (CMP, rev 36) 
There is nothing surrounding D-Caldera that looks any- 
thing like the silver-gray material that was depressed with 
respect to the surrounding terrain. (CMP, rev 40) 
Flow structures were also observed in the interior 
of the depression: 
I was looking at D-Caldera and you got a lobate flow front 
sticking down in the crazy thing. (CMP, rev 42) 
The light-blue-tinted materials observed in the 
D-Caldera were compared earlier to the somewhat 
darker tints of blue gray in the floor of Maraldi as 
well as in the Taurus-Littrow area. This comparison 
was also evident as the Sim elevation angle increased: 
Ron's D-Caldera?1 am just correlating apparent colors 
now, or hues-and the lighter-colored material there is 
comparable in hue to the subfloor color at the landing site. 
(LMP, rev 66) 
COPERNICUS 
Copernicus Crater was studied from orbit mainly 
in earthshine (flg. 28-24). In addition to details of the 
?jecta and interior, emphasis was placed on the 
central peaks and on a possible extension of the dark 
and blocky band that was observed in Lunar Orbiter 
II frame 162-H. Apparently, the viewing conditions 
were not adequate for this. Several other features of 
Copernicus were discussed throughout the orbital 
period of the flight: 
I have got a visual on Eratosthenes and Copernicus. They 
are obviously different age craters in this Ught. You can see 
the ray patterns of Copernicus moderately well. You can 
even tell that they do cross Eratosthenes... On the upper 
portion of the rim and on the benches, there are the dark 
spots of lower albedo material. They form linear patterns 
along the benches, although the topography is not too clear. 
But the dark spots are in arcuate linear anangement parallel 
to the rim. And they appear to be elongate along the radius 
of the crater [Copernicus]. 
Copernicus H is also very obvious as a dark-rimmed crater, 
relative to the albedo of the ?jecta blanket. And the 
northwest quadrant, which we mapped as a smooth floor 
material and somewhat darker albedo, is just as apparent 
here, although all the contrasts, of course, are less. The main 
thing that you can pick out in earthshine are albedo 
distinctions. (LMP, rev 1) 
Additional details of the dark zone in the southern 
wall of Copernicus were provided under faint earth- 
shine illumination conditions: 
On the south side of Copernicus, you can see albedos real 
well, and there is a dark area that extends maybe half a crater 
diameter to three-quarters of a crater diameter to the south, 
and it carries down the crater wall to the crater floor. And 
this is in the south maybe from about 4:30 to 7:30. And in 
the rest of the crater, all the way you can see light albedo. 
When asked if he was able to see any structure in 
the central peaks (both in earthshine and in sunlight), 
the LMP replied: 
No, I cannot... The central peaks do stand out, though, 
as a much lighter albedo area within the crater. It looks to me 
like the best thing you can do in earthshine is work with 
albedos. Knowing the general topography from earlier photo- 
graphy. (LMP, rev 1) 
And this is a good view of the central peaks, although 
from some distance; and, as Ron and I were discussing earlier, 
it is not at all clear that, in fact, that so-called dike does not 
come through as a unit that is clearly defined. (LMP, rev 65) 
The CMP also confirmed that the structure in the 
central peak could not be studied: 
I just got a real good view of Copernicus, but 1 am afraid I 
cannot help you out on that structure in the central peak. 
Just a little too dark. (CMP, rev 4) 
1 was looking at it through the binoculars last time, and I 
could not really see anything that was really defined as 
coming on through there. (CMP, rev 65) 
Dark deposits both to the southeast (Copernicus 
CD area) and north (Montes Carpatus) were described 
from orbit. The relationships of these deposits to 
other units on the Moon have been previously 
discussed (ref. 28-13). 
One of the things that we mapped on the southeast and 
south rim of Copernicus were dark-albedo areas within the 
?jecta. And those are apparent here very clearly. (LMP, rev 1) 
And some of the dark-halo craters that we mapped 
originally on the north portion of the ?jecta blanket, which 
were similar to Copernicus H, are very clearly darker halo, or 
have darker blankets around them than the ?jecta blanket 
from Copernicus. (LMP, rev 65) 
GEOLOGICAL OBSERVATIONS FROM LUNAR ORBIT 28-27 
FIGURE 28-24.-Oblique view looking southward from Copernicus Crater (AS17-151-23265). 
One of the questions we asked ourselves years ago, when 
we mapped the Copernicus area, was were we really seeing 
dark mantling deposits on some of the massifs of the 
Carpathians, and looking at it obhquely here, some of those 
areas that we have mapped as dark mantling are distinctly 
brownish gray versus the normal tan gray of most of the 
Carpathians. It looks like it is about the same 
color?extrapolating?as the dark mantle around Sulpicius 
and Taurus-Littrow. (LMP, rev 73) 
EULER AREA 
Near the end of the mission, very httle time was 
available for observing some of the interesting fea- 
tures in the Euler area. Many structures believed to be 
volcanic occur to the south of Euler Crater (f?g. 
28-25), including what seems to be a main source of 
some of the Imbrium lava flows (ref. 28-17). There 
appears to be a color boundary within the walls of 
Euler itself as observed from orbit: 
The lower part of Euler is blue gray, and the upper is a 
very light gray, from the talus slope up to the rim. (LMP, rev 
66) 
Large boulders were observed on the central peaks 
of Euler. The observation was made possible by the 
low Sun illumination angle. 
I can just start to see the peaks of Euler now. The tops of 
them are exposed in the sunlight, and it looks like there are 
massive quantities of large boulders on the peaks. (CDR, rev 
66) 
A chain of low-rimmed structures and collapse 
depressions forms a semicircle due west of Euler P 
(fig. 28-25). These landforms were interpreted as 
being extrusive, volcanic in origin: 
That is my little [C] crater chain down there. Looks like a 
cinder cone chain. (CMP, rev 66) 
As seen in figure 28-25, there are numerous 
sinuous rilles and arcuate depressions in the area. 
There appears to be intricate relationships between 
28-28 APOLLO 17 PRELIMINARY SCIENCE REPORT 
?"?V.-  ? 
FIGURE 28-25.-Portion of Lunar Orbiter IV frame 133-H showing the southern part of Mare 
Imbrium, south of Euler Crater (30 km in diameter). 
the rilles and the mare ridges and other scarps as      have been able, over the last day, to find rilles that clearly 
described by the LMP- ^?^^ *"** separate portions of ridges. And ridges that clearly 
I might summarize my impression of the rilles in the 
vicinity of Euler and their relationship to the mare ridges. I 
cross and partially buiy rilles. And in another third case, a 
riUe that appears to be leveed, that is, have flat banks on 
either side, but near the end of it, it transitions into a mare 
GEOLOGICAL OBSERVATIONS FROM LUNAR ORBIT 
ridge, very clearly. It looks as if, to me, that the rille and 
ridge problem in here is just one of repetitive compression 
and extension v/ithin the surficial flows of the Imbrium 
basin. And that, possibly during the compressive stages, there 
were extrusions locally along the ridge system; but in the 
main part, the ridge systems represent, I think, a doming. It 
looks like just a doming of the mare surface except for these 
local ridge-like extrusions. 
I might also add that the rules, to me, seem to be made up 
of zigzag straight-line segments rather than being truly 
sinuous. They appear sinuous because of the rounding of the 
corners, but my impression is that they are really made up of 
straight-line segments. (LMP, rev 73) 
REINERT 
Reiner y remains one of the most enigmatic 
structures on the Moon. It is similar in gross 
characteristics to the light-colored swirls discussed 
under the heading entitled "Al-Khwarizmi (Formerly 
Arabia)." However, it is only one feature with no 
obvious source. Even if the swirls near the eastern 
limb of the Moon are interpreted as unusual ray 
materials, the Reiner y structure is harder to interpret 
because of its shape (?g. 28-26) and the complete 
lack of association mth any impact structures. 
Observations from orbit during ApoUo 17 added 
details that do not solve the problem but may add to 
the constraints on the theories of origin: 
I am able to see some of the Reiner y materials, and it is 
awful hard to say more than just the fact there is a very clear 
light-colored pattern off to the north of our position. (LMP, 
rev 1) 
[The brightness of] Reiner y from here almost looks like 
?jecta from a crater ... The y itself is dark ... Zero phase is 
going right through it right now; it did not blot out the dark 
at all... The only light-colored stuff that you can see is right 
around Reiner y itself. And intermixed within that is the 
dark. It is a dark annulus, except the annulus is on the inside 
of the white. And it looks Uke-I do not know if your eyes 
deceive you in this darkness or not-but the light-colored 
stuff is raised up with respect to the dark. 
The light material around it... does not look like a ray. 
In other words, it does not thin out in different parts like a 
ray does. (CMP, rev 28) 
I was trying to think if there was anything I could add to 
the Reiner y observation. I am right over the light-albedo 
material that goes between Reiner and Reiner y. It is kind of 
crooked; it goes for a little ways, and then it breaks off in 
another direction. So, it does not look like a straight ray at 
all. 
Looking right down on Reiner now, and you sure have 
that dark annulus. The lighter-albedo stuff is essentially in 
the middle of it, is about half of the width, and it is lighter 
on the outside than it is on the inside. 
It is very hard to see any great topographic expression to 
it.   The  reason  I  say  that is because it blends in with 
everything. (CMP, rev 36) 
MISCELLANEOUS OBSERVATIONS 
Flashes of Light 
On the first lunar revolution, the LMP reported 
seeing a flash of light north of Grimaldi Crater 
(21:11:09 G.m.t. on Dec. 10). It is interesting to note 
that this is the same area where the CMP during 
Apollo 16 also reported seeing "a flash of bright 
light" (Riccioli). The following descriptions were 
made during Apollo 17 orbit: 
Hey, I just saw a flash on the lunar surface! It was just out 
there north of Grimaldi. You might see if you got anything 
on your seismometers, although a small impact probably 
would give a fair amount of visible light. It was a bright Uttle 
flash near the crater at the north edge of Grimaldi; the fairly 
sharp one to the north [small crater north of Grimaldi B] is 
where there was just a thin streak of light. (LMP, rev 1) 
On-the following day, the CMP also reported 
seeing a flash, this time near the rim of Mare 
Orientale (22:28:27 G.m.t. on Dec. 11): 
Hey! You know, you will never believe it. I am right over 
the edge of Orientale. I just looked down and saw a light 
flash myself. Right at the end of the rille that is on the east 
of Orientale. (CMP, rev 14) 
Visibility in Earthshine 
The Earth disk was almost full at the beginning of 
the orbital period, and light reflected from the Sun 
by the Earth to the Moon was enough to study 
features on the surface but not in great detail. 
Following are some comments on the Hghting condi- 
tions: 
There is no question that right at the terminator you pick 
up relief that you normally would not believe is there in the 
mare. I remember Bill Anders talking about the appearance 
of a sea swell within the mare itself and that is certainly 
clearly shown right at the terminator. Unless you start to see 
the shadows from all the very small craters that otherwise do 
not show up as much more than just little depressions, if 
that. (LMP, rev 1) 
Kepler ray pattern is very striking in this Ught; an 
anastomosing series or bands which only average being radial. 
In most cases, they are a Uttle off radial, but by joining 
together, they give you a general radial pattern... Once 
again, albedo differences are very clear, such as the distinc- 
tion between the wall or brighter wall materials and the rim 
which is brighter than the surrounding mare. (LMP, rev 
1) 
28-30 APOLLO 17 PRELIMINARY SCIENCE REPORT 
FIGURE 28-26.-North-looking Lunar Oibiter oblique view of the Reiner 7 structure in western 
Oceanus Procellaium. 
Looking at Oceanus Procellarum. And now, up to the 
northwest, Grimaldi is starting to show up. A very obvious 
dark area within the highlands of that part of the Moon, and 
one of the darkest mare regions that we have seen on the 
Moon. It is comparable, at least in the photographs, to that 
of Tsiolkovsky. (LMP, rev 1) 
Amazing how much of the highlands to the west of 
Procellarum is still bright, and the contrast between fresh 
craters and the normal higliland is very obvious still in 
earthlight, particularly along the zero-phase point with 
respect to the Earth. (LMP, rev 1) 
This is a spectacular sight, you ought to take a look at 
Orientate. One of the largest fresh basins on the Moon. It still 
is probably 4 billion years old, or 3.8 at any rate, if our 
dating criteria aie any good. It has the outer Cordillera ring 
and the inner ring called the Rook Mountains, very nicely 
shown ... As we approach the terminator, the lighting is still 
excellent. Matter of fact, it appears brighter than what we 
were looking at over at Copernicus. Now, part of that may be 
we are seeing much sharper relief since the slopes, Earth- 
facing slopes, are nicely lit, and the backfacing slopes, of 
course, are in shadow. (LMP, rev 1) 
You can even see a horizon in earthshine out there. (LMP, 
rev 1) 
You sure can. You can see an earthlit horizon out there 
into the dark part of the Moon. (CDR, rev 1) 
I noticed there is even a lot of difference in earthshine 
and in the double umbra. You get in earthshine and it is hard 
to see the stars even if you do not have the Earth in 
there ... The double umbra on the back side of the Moon is 
even better than the simulator! (CMP, rev 14) 
Lineaments 
Much discussion about small-scale lineaments on 
lunar slopes followed the description and photo- 
graphs of the ones observed on Mons Hadley during 
the Apollo 15 mission. During Apollo 16, similar 
features were described in many regions of the Moon, 
on slopes as well as on flat surfaces (ref. 28-5). During 
Apollo 17, hneaments were observed and photo- 
graphed during the surface stay time; some were also 
described from lunar orbit: 
In a place where the Sun is just grazing the slope, it is a 
steep slope on the north rim of Crisium, I can see the 
horizontal lineaments that were such a controversy on 
[Apollo] 15 .. . There are some very steep slopes that just 
have grazing Sun on them now, and with the binoculars, you 
can see that horizontal lineation pattern. 
Also, on that lineation question, not only where the Sun 
grazes a slope do you see the horizontal lineations, but they 
GEOLOGICAL OBSERVATIONS FROM LUNAR ORBIT 
are at the southern end of the shadowed area on a slope. You 
get a couple other lineations showing up at least in a couple 
of places I saw. One would be parallel to the slope, that is 
aoss-contour, and the other was at an angle to that direction, 
say of about 30?. (LMP, rev 3) 
Craters 
Observations were made of various types of lunar 
craters. The first unplanned observation was that of 
Kopff Crater at latitude 17? S and longitude 90? W in 
Mare Orientale: 
Delta-rim crater-just as has been, I think, discussed in the 
literature?has no obvious ?jecta blanket around it, compared 
to other larger craters within the basin. We are directly over 
that crater right now. It is filled with mare, very smooth 
mare. Matter of fact, within that fill, I can see no craters. 
Getting very close to the Earth terminator, but you see good 
texture in the ?jecta blanket of the large crater in the north 
part of the inner basin of Orientale. The radial ridge and 
valley patterns are very clear; the concentric coarse hum- 
mocks near the rim are apparent; and you can even see the 
patterns of secondaries. (LMP, rev 1) 
Numerous craters on the far side display flat, 
somewhat dark floors; these floors are commonly 
domed in smaller craters. In larger and fresher craters 
(e.g., "The Bright One" in ref. 28-18), there are 
scarps and fronts indicative of fluid flow. During 
Apollo 17, the first impression of these features from 
orbit was that these floors were volcanic; however, 
the original melts were later (and after repeated 
observation) attributed to shock melting by impact. 
Fresh, rayless craters on the far side, probably 
Eratosthenian in age, all appear to have a mare-type 
or volcanic-type floor, suggesting the possibility that 
a liquid mantle existed during the Eratosthenian era 
and was penetrated by these craters. (Paraphrased 
from CMP, rev 48) 
I guess the feeling I was getting is that most of the 
[Eratosthenian] age craters all have some sort of a moimd, a 
domical structure, down in the bottom of the crater. Even 
the smaller ones, some of the 30- to 50-km-size class. And the 
flat floors look volcanic. Some of the bigger ones, of course, 
are volcanic, the lava flows on the floor of these big craters. 
(CMP, rev 48) 
While we are waiting for the site to come up again here, 
which seems to interest us every time we go over it, I think 
we sort of came to a general consensus on the problem of the 
smaller cone-shaped craters on the far side that have the little 
pool-like concentrations of material in the bottom. If you 
look at the freshest of those craters, there seems to be 
continuity between the streaks of very dark material that 
cover the walls and the rim of the fresh cone-shaped craters. 
As  the  crater  gets  older,  that  distinction  becomes  less 
obvious; however, the pool remains, and all you lose is the 
dark streaks on the rim and on the walls of the crater. I think 
we sort of suspect that the pool in the bottom of the fresh 
craters is just the concentrated impact melt that some of 
which stayed there during the impact and others drained 
back after the impact from the walls. And then, with time, 
that pool may be subdued some. The structures in it, the 
swirls and little domes in that pool, are subdued possibly not 
only by the impact but by debris, slides, and avalanches off 
the walls of the crater. (LMP, rev 64) 
Features of the large crater Archimedes (100-km 
diameter) were described in the context of lunar 
stratigraphy as seen within the Imbrium basin: 
Archimedes is one of those craters that, in the early days 
of the lunar mapping program, helped establish some of the 
fundamental age relationships between the various units that 
were visible in the Earth-based photographs. In this particular 
case, it related to the sequence of events that created 
Imbrium and then flooded it with mare. And Archimedes is 
completely circular and it is filled with mare. And it, in itself, 
is superimposed on one of the main benches of the Imbrium 
basin. Now, to have mare filling of approximately the same 
level in the vicinity of a large mare region is one of the things 
that has suggested to many people that rather than single 
sources for mare lavas, you have a multitude of sources in a 
very fractured lunar crust. The ultimate source at depth, 
though, is still certainly a subject of controversy. (LMP, rev 
62) 
Unique features of the elongate Messier Crater, 
which is believed to be the result of an oblique 
impact (flg. 28-27), were described from orbit by the 
CDR: 
It has got a very sharply raised Up, and it has got some 
very dark and rough rim deposits. It has also a very obvious 
FIGURE 28-27.-Part of Apollo 15 panoramic camera frame 
AS15-127 showing the elongate Messier Crater in Mare 
Fecunditatis. 
28-32 APOLLO 17 PRELIMINARY SCIENCE REPORT 
furrow, looks like it is elongated, generally to the east and 
west. I cannot tell, but because of the shape of it and because 
of those dark rim deposits, I am sure there must be a vent 
there somewhere, but it is too dark down in there. I cannot 
really see for sure whether there is one or not. But, if there is, 
I imagine it is pretty big. And I imagine the elongation was 
produced during the thrust of the initial dynamics, the 
formation by the impact. (CDR, rev 73) 
Finally, during the post-TEI television transmis- 
sion, the following statement was made by the LMP, 
summarizing the lunar surface history and pointing 
out the importance of that history to the study of the 
Earth: 
... basalt flows, that some 3 to 4 billion years ago, in 
round numbers, were erupted on the Moon and filled many 
of the low areas that existed at that time. Not an awful lot 
has happened to the Moon since, except for the impact 
craters, some of the younger ones, since 3 billion years ago, 
which is one of the reasons it becomes so interesting to man. 
It is the Moon's frozen period of history that we cannot 
recognize very readily on Earth because of the dynamic 
processes of mountain building and oceans and weathering 
that are taking place even at the present time. Understanding 
that early history of the Moon may mean an understanding 
of the early history of the Earth. And, I think we are weU on 
our way to a flrst-order understanding of that history as a 
result of the [Apollo] Program. (LMP, post-TEI) 
REFERENCES 
28-1. El-Baz, Farouk; and Worden, A. M.: Visual Observa- 
tions From Lunar Orbit. Sec. 25, Part A, of the Apollo 15 
Preliminary Science Report. NASA SP-289, 1972. 
28-2. Worden, A. M.; and El-Baz, Farouk: ApoUo 15 in 
Lunar Orbit: Significance of Visual Observations and 
Photography. The Moon, vol. 4, nos. 3/4, 1972, p. 535. 
28-3. El-Baz, Farouk; Worden, A. M.; and Brand, V. D.: 
Apollo 15 Observations. Lunar Science-Ill (Rev. abs. of 
papers presented at the Third Lunar Science Conference 
(Houston, Tex.), Jan. 10-13,1972), pp. 219-220. 
28-4. El-Baz, Farouk; Worden, A. M.; and Brand, V. D.: 
Astronaut Observations From Lunar Orbit and Their 
Geologic Significance. Proceedings of the Third Lunar 
Science Conference, vol. 1, MIT Press (Cambridge, Mass.), 
1972, pp. 85-104. 
28-5. Mattingly, T. K.; El-Baz, Farouk; and Laidley, Richard 
A.: Observations and Impressions From Lunar Orbit. Sec. 
28 of the Apollo 16 Preliml \ary Science Report. NASA 
SP-315, x972. 
28-6. Mattingly, T. K.; and El-Baz, Farouk: Impressions of 
the Lunar Highlands From the ApoUo 16 Command 
Module. Lunar Science IV (Abs. of papers presented at 
the Fourth Lunar Science Conference (Houston, Tex.), 
Mar. 5-8, 1973), pp. 513-514. 
28-7. Evans, R. E.; and El-Baz, Farouk: Visual Observations 
From Lunar Orbit on Apollo 17. Lunar Science IV (Abs. 
of papers presented at the Fourth Lunar Science Confer- 
ence (Houston, Tex.), Mar. 5-8, 1973), pp. 231-232. 
28-8. El-Baz, Farouk: Discovery of Two Lunar Features. 
Sec. 29, Part H, of the Apollo 16 Preliminary Science 
Report. NASA SP-315, 1972. 
28-9. El-Baz, Farouk: Al-Khwarizmi: A New-Found Basin on 
the Lunar Farside. Science, vol. 180, no. 4091, June 15, 
1973, pp. 1173-1176. 
28-10. El-Baz, Farouk: The Alhazen to Abul W?fa Swirl 
Belt: An Extensive Field of Light-Colored, Sinuous 
Markings. Sec. 29, Part T, of the Apollo 16 Preliminary 
Science Report. NASA SP-315, 1972. 
28-11. El-Baz, Farouk: Light-Colored Swirls in the Lunar 
Maria. The Moon, vol. 4, nos. 3/4, 1972, p. 531. 
28-12. Strom, R. G.: Lunar Mare Ridges, Rings and Volcanic 
Ring Complexes. The Moon: International Astronomical 
Union Symposium No. 47,1972, pp. 187-215. 
28-13. El-Baz, Farouk: The Lunar Dark Mantle: Its Distribu- 
tion and Geologic Significance. Lunar Science IV (Abs. of 
papers presented at the Fourth Lunar Science Conference 
(Houston, Tex.), Mar. 5-8, 1973), pp. 217-218. 
28-14. Wilhelms, D. E.; and McCauley, J. F.: Geologic Map 
of the Near Side of the Moon. U.S. Geol. Survey Misc. 
Geol. Inv. Map 1-703,1971. 
28-15. Wolfe, E. W.; Freeman, V. L.; Muehlberger, W. R.; 
Head, J. W.; Schmitt, H. H.; and Sevier, J. R.: Apollo 17 
Exploration at Taurus-Littrow. Geotimes, vol. 17, no. 11, 
1972, pp. 14-18. 
28-16. El-Baz, Farouk: Apollo 16 and 17 Lunar Orbital 
Photography. Lunar Science IV (Abs. of papers presented 
at the Fourth Lunar Science Conference (Houston, Tex.), 
Mar. 5-8, 1973), pp. 215-216. 
28-17. Schaber, Gerald G.: Lava Flows in Mare Imbrium: 
Geologic Evaluation From Apollo Orbital Photography. 
Lunar Science IV (Abs. of papers presented at the Fourth 
Lunar Science Conference (Houston, Tex.), Mar. 5-8, 
1973), pp. 653-654. 
28-18. El-Baz, Farouk; and Roosa, S. A.: Significant Results 
From Apollo 14 Lunar Orbital Photography. Proceedings 
of the Third Lunar Science Conference, vol. 1, MIT Press 
(Cambridge, Mass.), 1972, pp. 63-83.