farouk el-baz and ron evans - report on apollo 17 "sea of serenity" observations

8/8/2019 Farouk El-Baz and Ron Evans - Report on Apollo 17 "Sea Of Serenity" observations.

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Observat ions o f Mare S e re n i t a t i s from l u n a r o r b i tand t h e i r i n t e rp r e t at i o n

FAROUKEL-BAZNational Air and Space Museum

Smi thsonian In st i t u t i o n , Washington, D.C. 20560

andR, E, EVARS

Astronaut OfficeJohnson Space Cmter, Houston, Texas 770W

Abstract : Visual obse rvat i ons of calm di ffe rences of S e r e n i t a t i s marc

m a t e r i a l s fmn o r b i t ca rr pl em n t photography an d o m e m t e l y set.s&

data . T h e l i g h t tan g r a y i n n e r f i l l of t h ? S e r e n i t a t i s b a s in i s

younger than the dark blue gray annulus; the l a t t e r c o n ti nu es i n t o a nd

a p p e ar s t o b e contesrporaneous w i th t h e f i l l of Mare i r a n q u i 1l i a t i s .

!&re r idge s occur in bo th t h e inne r bas in f i l l and t he dark annulus o f

S e r e n i t a t i s . R id ge s a r e i n t e r p r e t e d a s th e r e s u l t o f s t r u c t u r a l d e fo r-

mation and up-doming a f t e r th e so l id i f i ca t io n o fthe basa l t i c l avas .

On the sou theas te rn rim o f the S e r e n i t a t i s b a s i n i s t h e d a r k e s t

blue gray u n i t wi th in which Apollo17 landed. Highland massifs surround-

in g th is u n i t have unstable s lopes which are be1 ieved t o b e t h e r e s u l to f l o c a l i ze d t e c t o n i c a c t i v i t y . On the sou thwes t rim o f t h e b a si n a r e

t h e d a r k t a n t o brown g ra y m n t l n g m a t e r ia l s of the Sr r lp ic ius Gal lus

Formation. Farther west on the rim are dark b lue g ray pa tches which

resemble th e mare mate rfa l o f th e Seren i t a t i s da rk annulus.

( N A S A - Ti - 1 - 7 0 2 0 9 ) O B S E B V I T I O W S OF HARE H74-29245SERENITATIS F R O B i U H A R O b B I T A N D THEIR

I u r E w a E Ta r x o a ( N A S A ) 1 8 p H C $4.00 CSCL 038 UaclasG3/30 1 5 9 8 2


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INTRODUCTION

The o b j e c t i v e of visual observation f r o m lunar orbit to complement

photography and other remotely sensed datawas successful l y fu l f i l ed

on Apol l o 17 . Because th e Apollo 17 ground coverage duplicated about 80%

of t h a t of Apollo 15, much was known abou tthe overflown ar ea s- For this

reason emphasis was placed on the study o f co lor tones of 1unar surface

u n i t s and on thc de ta i l s of smal l scale featurn - A se l ec t ion of the

carnsents made while i n l u n a r o r b i t w i l l appmr in the A p l l o 17 P r e l i l r i -

nary Science R c p a r t (Eratrt a& EI-hz, 1973). This paper s m r i z e s

t h e o r b i t a l obsewaticm r e l a t i n g to ekrt Setmitat5 s- Pho-logic

in te rp mt a t fon s a re inc luded t o confi rmthese observations and to po in t

out their geological s ignif icance.

COLOR B O U W I E S1

The mare f i l l o f t h e Sereni ta t i s bas in has long beem knarrn .b

disp lay u n i t s w i t h d i ff e re n t a lbedo cha rac t e r i s t i c s . I t includes s a r r

of the darkest ( low albedo) u n i t s on t h e Moon (Pohn and Wildcy, 1970;

El-Baz, 1972a). There is co rre la tio n be- the albedo unit? and c o l o r units

detected by special photographic and photoelectricmethods

(Mitake.,1972; S t m , 1972).

An at tewpt was nud. on Apotlo 17 to discern the c o l o r bounbrfes

and to e luc ida te the i r re la t ionships to o the r no tab le color d i f f v

i n adjacent maria. The impottance of t h i s stems frrn grwndtmth data

which i n d ic a t es t h a t c o l o r d i f f n m c e s reflect ccmpesftionrl v a r i a t i o l ~ s ;


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e-g . , the darker and bluer th e mare, th e more titanium in the b a s a l t .

The A p o llo 11 and 17 s i t e s a r e bo th loca ted i n dark mare units; the mare

basal ts of both s i te s , a s estab l ished by numerous inv est i ga tor s , a r e

re la t iv el y r ic h in t i tanium (Strom, 1972).

As shown in Figure 1, Mare S e r e n i t a t i s d i s p la y s tw, major albedo

un it s. The inn* f i l l of t he ba sin i s charac te r ized by a higher albedo \-

than t h a t of th e darker anmrlus, The lat* was p n v i c w r l y be1 i e d o

be the younger of the trio u n i t s (Cam, 1966; Mil helms aA d M h u l e y, 1 9 7 1;

El-Baz, 1972a; and others). As w i l l be shown below, Apollo 17 prwided

cont ra ry evidence, U m , u ~ h v is u al o b s e r v a t i o ~ s nd o r b i t a l photogram, --- - -t h a t the l i g h t e r c o l d inner f i l l i s younger than the dark wmlus,

In a d d i t i o n t o t h e dark annulus within t h e basin t h e r e d ark er

areas on the southeas te rn and southwestern par t s o f th e bas in ' srim.

Refering t o th ese c o lo r dif fer en ces , th e CI4P madethe following carncrrt

during the Apollo 17 mission: "To me t h e Moon has a l o t more c o l o r than

I had been le d t o be1 ieve. (P rio r t o th e mission) I had th e imprtss ion

tha t every th ing was t h e same color. Tha t i s f a r frwm being true,"

In the followi-ng discussion the regions o f easter n, southern and

wes te rn Seren i ta t i s w i l l be t rea ted separa te ly.

A. Eas t e rn Se ren i t a t i s

The dark m a t d a l on t h e southeastern rim of t he S e m i t a t i s b asin

(Fig. 2) is dark gray w i t ! a b l u i s h t i n t . During the mission, the CMP

s t a t e d t h a t i t is s i m i l a r i n c o l o r t o t h e dark f l o o r f i l l o f M am id i Crater

t o t h e e a s t . A t both l o c a l i t i e s , he a l s o not ed t h e p m e n c e of b lu i sh

gray blocks around larger cr~lterr; .g., the 300-600 m craters c l u s t e r e d


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in the A p o ll o 1 7 la n d in g s i t e a r e a ( F i g . 3 ) .

P r i o r t o Apol l o 17 , pho togeo log ic inve s t iga t io ns sugges ted t h a tthe

darker u n i t i s r e l a t i v e l y young (e.g. , l -Baz, 1972a). This was based

pr imar i ly on the smooth appearance of the s u r f a c e . In a d d i t i o n , the

premise t h a t t h e bl ue r maria a r e yourlger (Whitaker, 1972), the r e l a t i v e l y

1ow numb= of craters w i t h i n the dark uni t (Gree ley and Gault , 1973) , and

the p r o b a b i l i t y of the presence o f a source o f a p y m c l a s t i c m t l a i n

the fonn o f v o l c a n i c vents or c i n d a coms i n the area (El-Bar and Yerdcn,

1972), also suggested that the darker u n i t i s r e l a t i v e l y yatmg- EartR-

based raQr and I R rhrrticr (Thapsorr et, a l , 1973) a l so the

i n t e r p r e t a t i o n o f a n w w s w l l y smoth sur face , which s m t s a law

c r a t e r densi ty and t h e r e f o r e a r e l a t i v e l y young surface.

Age d a t i n g m u i t s i n d i c a t e that the basa l t s o f tht Taurus/Littmul and ing s i t e a r e similar i n a ge t o t h e A p ol lo 11 b a s a l t s , about 3.7 b, y .

01 d (Te ra et. a1 , 973). The dark c c l o r is pmbably due to the high

t i a n i m c o n te n t of t h e b a sa lts (Stram, 1972) and /or a laoderate arnourrt -of dark g lass beads a n d f r a g ~ l e n t s n the s o i l samples. There i s a l s o

p h o t o g r a p h i c e v i d e m e t h a t the mare materf a1 on t h e so uth ea st rim of

Mare Se re n i ta t i s i s embayed by, an d t h e r e f o r e o l d e r t h an , the dark annulus

m a t e r i a l s ( F i g . 2).

8. S o u t h m S e m i a ~ s

Perhaps the sharpest demrrcatfcm betmen the kK, major u n i t s o f

S e r e n i t a t i s i s i n the sou- part of the basin north o f the- c r a m

P l i n i u s (Fig. 4) and b l a u s . Matevials of the o u t e r anmius are dark

blue gray i n color, w i t h a slight t amtsh kmrr. The amre i n the $me?

p a r t o f t h e b a s h i s l i g h t tan gray.r'


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As shown in Figure 4 , the mare of the d a r k annulus i s more textured

(with small sc a le undulations and numerous ar cu at e r i 1 es and 1 neaments)

and has more craters per u n i t area than the mare of the inner basin. The

superposition relationships a re a1 so clea r: R i 11 es and other depressions

i n the older annulus are encroached and flooded by the 1 ghter and younger

u n i t . The braad a u r t ridge whichis

a relat ively y o u ~ g ea tureis

a l so

confined to the 1 ght-colored unit.

C. Western S e m i b t i s

The dark blue gray mare aoter ial of the Serewi tatis annulus i s

exposed i n the western part near Sulpicius Gallus Crater, an d the otpsum

continues northward i n a broad zone beyad the point of merger-of Mare

Serenitatis and Mare Imbriunr. Another dark u n i t is exposed i n the a m

of the Sulpiciu s Gallus Ri ll es on t he western rim of the Seren i ta t i s

basin. T h i s u n i t has a dark brownish t i n t . I t appears t o f i l l v a l l e y s

and thinly mantle wnall h i l l s between th e Haemus Mountains, whose tops

a re not mantled, The color and texture of th is u n i t d i f f e r from those of

other terra mantliog materials farther to the west, which fonn s m t h and

f l a t patches of blue-gray mate rials (Fig. 5 ) .

The Sulpicius Gallus Rilles themelves are located i n a dark brownishgray u n i t that appears to mantle the rim materials of the S e m i t a t i s

basin. This u n i t has been mapped as t h e Sulpicius Gallus F o m t f a n (Caw,

1966). I t i s i n this area that several craters, probibly o f impact

ori gin , and ir re gu la r elongate depressions of unknom, ori gin , have a rust-

colored or orange t i n t . Since the same t i n t was o b s w e d from or b i t on

the n o r t h fla nk of Shorty Crate r (Evans and El-Bat, 1973), i t is reasonable


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to assume that t h e o ra ng e c o l o r s a t b oth l o c a l i t i e s a r e ca us edby the

presence of o range- t in ted glass beads which may be e i t h e r v o lcan ic o r

impact i n o r i g i n .

MARE R I D G E S

One major system o f wrinkle ridges , and several s ubsid iary ridges

occur i n Mare S e m i t a t i s . The major circular system occurs within the

1 g h t e r colored inner mare n m k r i a l o f S e m i t a t i s . The subs id iary ridges

t h a t a r e either subparal lel to tha major r idge syst tm o r r a d i a l t o i t ,

occur i n both un i t s o f Hare Serwri ta t is .

O n e prcmimt subsidiary ridge is i n the eastcrn part of k n

Seren i t a t i s . A p a r t o f t h i s ridge unusually laps up a g a i m t tho south-

western corner o f the f looded cra ter t e Monier (Fig. 6). I t c on tin ue s

to the south as a bruad r id ge , w ith sh ar p d is co ntin uo us e s c a m t snear

i t s borders. This charac ter i s t ic i s also cmmn along the inajor ridge

system (Fig. 6).

Figure 4 i l l u s t r a t e s an example of a radial subsidiary r idge. As is

comnon, there are no crosscut re la t ionships w i t h the main circular ridge,

and both appear to have formed contemporaneously. In this p a r t i c u l a r

example, the r idge abuts a g a i m t the older mare mater ia l tha tf o m the

dark annulus near the rim of Sereni ta t i s . There a r e ~ O W ~ Y W ,ases where

subsidiary r idges u t d throupk th. darker annulus, such a s i n the south-

eastern corner o f Rare S e r e n i t a t is ( ~ 1 - B a t , 1972a)-

In most cases, Mcrr I s c lea r ev idcma of cor re l a t ion between the

S e r e n i t a t i s mare r idges and fault systems in and a m m i the basin ( ~ l - ~ a z ,

1972a). I t was pr rv ia r s ly s h El-Bat, 1972b) that r e l a t t v e l y yo-


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nare flows i n southwestern Mare Imbr ium are pushed upward by r idges o f

substantial elevation, which suggests that t h e r idges a r e younger than the

flows. This and sup erpo sition o f ridg es on mare m at eri als of S e r e n i t a t i s

i n d i c a t e t h a t t h e r id g e s a r e f o n d a f t e r t h e emplacement and s o l i d i f i c a t i o n

o f t h e l a v a f i l l . The r idge s a re be s t exp la ined by th rus t in g up o f t he

s o l i d m a t e r ia l s ,n i th the excq t ic r r r o f a fen m a l l e x t ru s io n s and f l ow l i k e,f e a t u m that wee p m k b l y f l u i d i n the eastern part of the S m f a t i s

r i d g e systes (Strum, 1972).

HIGHtAIIDUNITS

Highland o r terra u n i t s that s u m m d the l an d in g s i t e (both m s s i f

u n i t s and s c u lp t ur e d h i l l s ) c o n s t i t u t e th e b e s t exposures o f S e r m i t a t f s

r i m mater ia l s . They were studied from o r b i t and canpared t o m a t e r i a l s

s ur ro u nd in g C r i s i m and I m b r i m b a si ns .

Mass if un i t s s um un din g the Taurus -Li ttron v a l l e y haw an unusual ly

high albedo- A c o n c e n t ra t i o n o f b l o c k s o c u v s on the tops of the massifs

th a t i s matched on ly on the tops o f ce n t ra l peaks of re la t i v e ly f resh

cra te : ; uch as Ts io lk ov sk y. E vide nce o f downslope m o v ~ tf m a t e ri a l

in cl u d in g numerous trac ks o f downward moving blocks (Fig. 7) suggests

t h a t t h t m a ss if s have u n s t a b le s lo pe s. The l i g h t m a n tl e i n t h e l a n d in g

s i t e area (Fig. 3) i s b e li ev e d t o be a l a n d s l i d e t h a t o r i g i n a t e d from

South Massf 8 (El-Baz, 1972a).

Massif un i t s o f comparable s i t e su r rounding Mare Cris ium and Mare

Imbrium do not show similar features, a1 hough both C r i s fwr an d Inrbrim

basins a re be l ieved t o be younger thnn the S e m i t a t f s basin (Wilheirm

and McCauley, 1971). Block exposures and d ow mlo pe m v e m n t of m a t e r i a l


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on th e Serenitatis massifs ma y hav? been triggered by relatively recent

tectcnic a c t i v i t y in the area; one possibit ity is the te ctonic move ment

that Formed the Scarp (F ig . 3).

The Sculp tured H i l l s have a lower albedo than that of the naassifs

("intermediate betweerr that of the massifs and the dark mantle"), and are

1 ght gray i n color. These h i l l s which dawimte the terrain north andeast of the landing site a m are h e l i e m i to be of differ ent w i # n

from h i l l y units surrounding H m ? Crisiu, although \both g i v e #e

so-called corn-on- t lmob appwsnce at h igh Sun elevation ;npla, -

sculpturing i s belf to b ar, mhmced by acc t# i r t t oa ef 91.k

materials i n grooves bekrrar the highland hf ll s.

The lo w a1 bedo material which forms the dark annulus of H a r e Sercrri-

t a t i s has the same color and albedo as the f i l l o f mot o f Ham Tranquil-

l i t a t i s . Thfs i s suppurted by sim ila rit ies i n chewistry and i n c r ys t al l i -

zation age of the Apollo 17 and Apollo 11 mare basalts. Mare material of

th e dark annulus ahears t o be flooded by and therefore older than the

1 ghter mare fill n the inner part of the Sw en it at is basin.

To sumnari ze the colors o f t)re mare units o f S e m f t e t f s as o & s m e d

fm orbit : The i n n u f i l l of the basin i s l i g h t tan gray; the ate

annulus f s dark blue gray; the Taurrrs-Littrtm valley where the Apt3110 17

LE( landed i s a darker blue gray; the S ul pi ci ut Gallur F o m t i o ~ s dark

tan to brown gray a d ttte n ur e l i ke p a t c h babem th. Ha an8

Apennine llountaim an, i k e tJte rmvlur r t i k 4 a l s . dark blub ray.


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T h e s e c o l o r ~ h a r a c t e r i s t i c s r e i m p o r t a n t i n extrapola t i ny ground-

t r u t h d a t a t o l a rg e r areas of the Moon, as wel l as in the i n t e r p r e t a t i o n

o f results of both Earth-based and orbital geochemical and geophysical

remote sensing.

A c i rc u l a r major r idge system i s loca ted in the l i g h t i n n er mare

f i l l of S e r en i t a t i s . Subsid ia ry r i dges , both subpa ra l l e land r a d i a l t o

the v a j o r s y st em occur in both the l i g h t inner mare and i n the d w k anrrrrlus,

b u t n one a pp e ar t o b e d i r e c t l y r e l a t e d t o t h e l ava ex t ru s ioa , The r i dges

are p robably d u e to s t ru c t ur a l d e f o m t i o t : a f t e r the s o l i d i f f c a t i o n o f the

mare lavas.

The br ightness of the S e m i t a t i s massifs, the nuncraus blocks that

c m hem, th e t racks o f d t ~ ~ ~ - ~ r doving b locks , a s we ll a s t h e l and -

s l i d e t h a t is be l ieved t o have formed t h e 1 gh t man t le i n t h e Apo llo 17

l a n d i n g s i t e are b el ie v ed t o b e i n d i c a t io n s o f r e l a t i v e l y l a t e t e c t o n i c

movement. One p o s s i b i l i t y is the disp lacements tha t resu ltd i n the

formation of the Scarp, which i s probably older than the s l id* .


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REFERENCES

Carr M. H. (1966) Geologic map of the Mare Sereni ta t is region of the moon. U.S.

Geol . Surv. Misc. Geol. Inv. Map 1-489.

El-Bat F. (1972a) The cinder f i e l d o f the Taurus Mountains. In Apollo 15

Pre l m inary Scf m e Rcport NASA SP-289, pp. 25-67 t o 25-71.- -

El-Baz F. (1972b) Nm gralgfcal f i n d in g s i n A pa ll o 1 5l w r orbital photo--- --- - * - . .- . - -.i

g r a m Pmc. 3 r d ~ r S ~ .onf. Val, 1, pp. 39-61. :f

El-Baz f. a d ~ r r d m . #. . ~ I W Z )v i ~ ~t + m m 1- mt.

25-27.- - . -.- - - - . - - -- .-..--- . .Evans R. E. and El-Bat F. (1973) Geological observations fm lunar. o r b i t .

I n Apollo 15 Preliminary Science ReportNASA SF-330 ( i n press).. - . -I-- - . .-

Pohn H. A.' and U i c k y R. L. (1970) ~h&.electrfc-pkotogmphfc ~ a & f thc

nornral alb* of the m m . U.S. Geol. Suw. Prof . Papar 599-E.

Greeley R. and Gault 0. E. (1973) Crater frectumcy ,age determimtfarn f o r

th e proposed Apol lo 17 s i t e a t T i ~s- l i t t r aw. Ear th 8 Planet,

Sci. Let., Vol. 1%pp. 102-108.

S t r o m R . G. (1972) Lunar m a r e ridges, rin gs and volcan fc r i n g complexes.

In The fhm: I n t e rna t i ona l Asttbnonfcat Union, Sylrrp. No. 47

Runcorn 5. K. and U m y H. C. editors,pp. 187-215.

Tera F. Papanrs.-sim 0. A. and Uusserburg G. 3. (1973) A- l u w cataclym-.t

a t 1 3.95 R a d tm ~httGG--&--thc~GFct-&. I n Lunar SCI& IV.

Chamberlain J . M. and b t k i n s C. dl tm L w w Science Ins t i tu te ,

pp. 723-725.


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Thompson T. W . Shorthill R . W . lrlhitaker E . A. and Zisk S. H . (1973)

Complex origin o f Mare Serenitatis floor : Synthesis of remote

observations. I n Lunar Science IV . Chamberlain J. W . and

Watkins C . editors. Lunar Sclence Institute, pp. 726-727.

Whitaker E. A . (1972) Lunar color boundaries and their relationship to

topographic features: a p r e l i d w r y survey. TheHoon

Vol. 4,pp. 348-355.

Wilhelm D, E. and McCwley J . F. (1971) Geologfc map of the nearside o f

the moan. U.S. Geol. Sum. MSC. G-1. Inv. Map 1-703.


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Figure 5. Oblique view loo kin g westward of the western r i m deposfts of

the Sereni t a t is basin. The dark b lu e gray mat eria l o f the

Se ren i t a t i s annulus i s i n th e lower right corner. The Sulp ic ius

G a l i u s R i l l e s ( r i g h t edge) and t he u n i t i n t he n ear f i e l d are

t an t o brown gray i n color. This i s contrasted t o patches i n t he

background o f dark blue gray mare-1i

e mater ials . Apoll o 17Hassel bl ad f rar 153.23573 .

Figure 6. R i @ systenn o f eas tem Marc S e r m i t a t f s : top, p o r t io n o f the

su tn id fary r fdga system i n t h e dark annulus n# r the souUIwntcrn

r i m o f L g ' M a r i nC r a m ( I lpa l lo 17 Hasse lb lH frame 153-2-j;

bottom, po rt io n o f the major circular rid* s y s m s b i n g t!u!

sharp escarpments on both s ides o f th e broad r idg e (Apollo 17

Hassel b lad f ram 150-23021 ) .Figure 7. V i e w from the Taurus-Lit trow va l l ey o fNorth Massii" showing

boulders (some are c i rc1ed) tha t moved downslopa l e av ing conspi-

cuous tmdss- A@ lo 17 Hissel blad fraAs 147-22549.


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farouk el-baz and ron evans - report on apollo 17 "sea of serenity" observations

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