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NATIONAL AERONAUTICS AND SPACE ADMINISTRATION

Technical Memorandum 33-787

Final Report- Apollo Experiment S-217 IRI Radar t, Study of Apollo Data

TENT S-21-7 N76-33230 (NASA-C:-- y 488U1) APOLLO EXPE - % ( IF/FADAF S T UDY CF hPO110 DATA Final F?port fJet Propulsion Lab.) 2C p HC $3.50 C3CL 22t Unclas G3/12 07367

JET PROPULSION LABORATORY ^56789^1 CALIFORNIA INSTITUTE OF TECHNOLOGY ^ C PASADENA, CALIFORNIA

October 1, 1976 ^P mil' a W. I

NATIONAL AERONAUTICS AND SPACE ADMINISTRATION

Technical Memorandum 33-787

Final Report- Apollo Experiment S-217 IRI Radar Study of Apollo Data

Thomas W. Thompson, Principal Investigator Jet Propulsion Laboratory

Coinvestigators: Henry J. Moore and Gerald G. Schaber United States Geological Survey

Richard W. Shorthill University of Utah Research lnstittte

Ewen A. Whitaker Lunar and Planetary Laboratory. University of Arizona

Stanley H. Zisk NEROC Haystack Observatory

JET PROPULSION L A B O R A T O R Y CALIFORNIA INSTITUTE OF TECHNOLOGY PASADENA, CALIFORNIA

October 1, 1976 Preface

The %work described in this report was performed by the University of Utah Research Institute, the Aerospace Division of the Boeing Company, and the NEROC Haystack Observatory, all under the cognizance of the Space Sciences Division of the Jet Propulsion Laboratory.

1PL TECHNICAL MEMORANDUM 33-787

t Acknowledgments

Personnel from the Astrogeology Branch of the United States Geologic Survey provided many useful inputs to our studies. Their contributions are best noted by thanking the following co-authors: H. Masursky, the 52 crater paper and the Apollo 15 and 16 landing site papers; Michael Carr, the Apollo 15 landing site paper; Daniel Milton, the Apollo 16 landing site paper; Keith Howard, the Mare Serenitatis paper; Carol Ann Hodges and Donald Wilhelms, the Aristarchus Plateau paper.

G. L. Tyler of Stanford provided many useful inputs to our studies; he is a co- author of the 52 crater paper, the Mare Serenitatis paper, and the compilations along the Apollo bistatic radar tracks.

Three of our co-investigators were funded by the following sources: H. Moore and G. Schaber were funded under Apollo Experiment S-222, which was performed by the Branch of Astrogeologic Studies of the United States Geological Survey, with Dr. Henry J. Moore as the Principal Investigator. Ewen Whitaker of the lunar and Planetary Laboratory, University of Arizona, Tucson, Arizona, was funded by NASA Grant NSG-7014. Mr. Whitaker provided the color-difference photography, which is particularly critical for the interpretation of surface chemistry.

iv Contents

I. Introduction 1

A. Background 1 B. Work Performed in S-217 Experiment 1 C. Future Work 2

11. Data Sets 3

III. Results 4 A. The Initial Study of 52 Craters . 4 B. The Apollo 15 Landing Site at Hadley Rille 5 C. The Apollo 16 Landing Site at Descartes 5 D. The Apollo 17 Landing Site at Taurus-Littrow 6 E. Mare Serenitatis 7 F. Imbrium Flows 8 G. Aristarchus Plateau 9 H. Factor Analysis Studies 10 I. Other Studies 12

IV. Summary and Concluding Remarks 12

Appendix. Lunar Data Set Manipulations at the Image Processing Laboratory at JPL 13

References 16

Tables

1. Study areas of the S-217 team 2 2. Surface conditions inferred from infrared and radar observations 8 3. Mare Serenitatis surface types defined by remote sensing data 9 4. Results of R-mode factor analysis on Mare Serenitatis data 10

Figures

1. Cooperative study areas of the S-217 and S-222 Experiment Teams 2

JPL TECHNICAL MEMORANDUM 33 -787 v w i

2. Data sets for the S-217 Experiment: 70-cm polarized and depolarized radar echoes 4 3. Data sets for the S-217 Experiment: infrared eclipse temperatures and full-Moon albedo 5 4. Data sets for the S-217 Experiment: color-difference photography and full-Moon albedo 6 5. Data sets for the S-217 Experiment: 3.8-cm polarized and depolarized radar maps . 7 6. Eight surface units in Mare Serenitatis determined by a factor and cluster analysis 11 A-1. Overview of image processing of lunar data at JPL's Image Processing Laboratory 13 t. A-2. Example of a lunar data set in the latitude-longitude format: full-Moon albedo also shown in Fig. 4 14 A-3. Example of lunar data set in the Mercator Projection: 70-cm radar echoes also shown in Fig. 2 15

A-4. Example of lunar data transformed to Lunar Aeronauticai (hart Projection: 70-cm depolarized data of the Aristarchus Plateau 16

c vi JPL TECHNICAL MEMORANDUM 33-787 a Abstract

This is the final report on Apollo Experiment S-217, /R and Radar Study of Apollo Data, an experiment using Earth-based remote-sensing radar, infrared eclipse, and color-difference data to deduce surface properties not visible in Apollo photography. The Earth-based data provided information on the small-scale (centimeter-sized) blockiness and on the surface chemical composition (titanium and iron contents) of the lunar surface. These deduced surface properties complemented the new Apollo photography, leading to refined geologic interpretations of the lunar surface. joint studies were conducted with Apollo Experiment S-222 (Photogeology) on a number of lunar areas. Results of these joint studies appear in the open literature. The work performed under Apollo Experiment S-217 is summarized in this report.

JPL TECHNICAL MEMORANDUM 33-787 Final Report: Apollo Experiment S-217 IR/ Radar Study of Apollo Data

I. Introduction Moon, chaired by Eugene Simmons of M.L'T., and held at the Lunar Science Institute in July 1969, immediately The Apollo 1•:xperinuenl S-217, MIRtular Studies of hollowing maul's first landing oil Moon. Our first study Apollo Data, one of the Apollo Photo-Data Analysis concentrated oil thermal, radar. and geologic interpre- Experiments, concentrated oil use of remote-sensing tation of 52 craters (Ref. 1). This initial effort, which (primarily Earth-based) observations of the Moon to showed that the infrared and radar data complemented determine surface properties not inherentl y assn t iated the geologic interpretation of it range of the lunar crater with photograph y. An important accomplishment vial the types, led to the S-217 experiment proposal and the work Photogc•olovy. joint studies with Apollo Experiment S-222, that is reported here. The geologic interpretation of lunar features was enhanced by knowledge of surface conditions deduced from B. Work Performed in S-217 Experiment the remote, nonphotographic• sensors. The photogeologic• interpretations similarly enhanced understanding of the The work performed ill S-217 experiment (anti iu remote sensed data. Apollo Experiment S-217 started in the cooperative effort with the S-222 experiment June 1972 and ran until the sprin, of 1976. extended that first study to other areas of the Moon, focusing on the Apollo landing sites. Interpretations of the A. Background Apollo 15 landing site at Hadley Rille and the Apollo 16 The lunar surface became the suhiec•t of intense sttdv in landing site at the Descartes have been reported in Refs. 2 the 1960s, with the advent of space: flight. The manned and :3. A remote sensing analysis of the Apollo 17 lamdint; landings and surface samplings of the Apollo missions site at "Taurus-Littrow and the entire Mare Serenitatis were the c•ulinination of it series of space flights from the hasin have also been reported (Refs. -1.:5, and 6). Ranger and Lunar Orbiter photographic missions to the Surve y or surface-sampling missions. Scientific interest Ill to the Apollo landing sites, selected areas of kept ill with these space ad%auu•es. the Moon were studied because of their unusual geology and remote sensing signatures. The unitlue radar and color The initial focus for the S-217 work was provided by the signatures of the lava flows in Mare Inihiinnt were Sy mposium oil Geoph ysical Interpretation of the discussed by Schaller, et al., (Ref. 7), while the unusual

1PL TECHNICAL MENIORAND11M 13 7S:

I- i APOLLO 15 LANDING SITE IMBRIUM HADLEY RILLE FLOWS —

ARISTARCHUS APOLLO 17 PLATEAU LANDING SITE TAURUS-LITTROW

_ APOLLO 16 MARE LANDING SI7E SERENITATIS DESCARTES

Fig. 1. Cooperative study areas of the S-217 and S-222 Experiment Teems

Table 1. StuJy areas o f the S•217 Team 111). \ stud y of the techt► iyues of factor and cluster analysis applied to lunar data sets was performed by Shorthill, et Area Latitude Longitude Reference al., ;Ref. I I ,. Figure I shows the areas studied b\ I lic combined S-217/S-222 teams. Tabic 1 ;ununarizes thi A1x)IIo 15 landing 20*N to 28 1 N 0° to 8°E 18 joint .turf areas. site at lfadley Rille y Apollo 16 landing 7•S to 12 1 S I t°F, to 19*L 2,3 site at Dt-wartes C. Future Work Apollo 17 landing 181N to 22 • N 28 °E to 32 , F 6 site at I'mirns-Litt row The coik petiiiinied timid \pollo Lxperinw.it S-217 Man . ScIvilitatis 111°N to 40°N 11• to 35°F. 1. 5, 2I showed that Earth-based and orbital observations of the Innar surface can indeed be correlated with more The linbrinniFlows 16°N to 48 • N I1°1t'to38°\V 7 conventional visual photogeologic data to better under- 'I'hc Aristarchus 20*N to 32 • N all°\\' to 58 , %V 8 stand the geology, surface properties, .uul chemistry of an Plateau extraterrestrial bod y . During S-217, we started with Correlations along 9,10 analysis of the Apollo landing sites where in situ Apollo histatic radar he y E, measurements and returned sample data were available, and extrapolated such data to other scientificall y interesting; (but unsampled) regions of the moon. Much work remote-sensing signatures of the Aristarchus Plateau have needs to Ise dame Hith regard to extending the retnttte been studied in great detail L% %isk, ei al., (Ref. ,ti \ISO, sensing data synthesis teclinirlues developed dun ing S-217 radar. iofriocd, and color-difference data were compared (and S-222) to other lunar areas of interest. Examples of with the \Imllo 15 and Ifi histatic radar data rRefs. 9 and possible research topics for the near future arc:

2 JPL TECHNICAL MEMORANDUM 33-787 "_cPRODUCIBILITY OF THE , I(A IAL PAGE IS POOR I Analysis of the unique low radar reflectivity along the northern rim of the 1 ►nhrium Basin? \That is the observed around the outer rims of a niuulx •r of large geologic significance of the subtle color differences that lunar craters of diverse age e.g., Aristillus, Cassini, appear in eastern Mare Tr wIiiillitatis? Plato, Aristoles). Such lm% r.ular reflective rings may represent variations in physical and/or chemical 'I'he need to stmiv areas away from the Apollo tracks properties of materials ejected front depth during has already been demonstrated by our stuck• of the the individual cratering events. Ari••t.arclius Plateau and a recent study of Mare Ifuniorun by Pieters, et al., (Ref. 12). Study of areas away from the (2) Spectral reflectivit y data and color composite Apollo tracks is necessary to provide it basis for photographs of the lunar surface have revealed orals interpretation of Lunar Polar Orbiter data. When the a very few extremel y reel surface features. One of unar Polar Orbiter becomes a realit y, our attention %%ill these features is the Cruithuisen domes located :35 N focus on the global lunar problems. Mod 40'\%'. These domes have long been thought to

represent very sillc•ic• volcanic- materials. A detailed ^% The synthesis of lunar dat:► will have to deal ith larger evaluation of spectral re(1ec•tivity data and photogeo- voliinnes of more diverse measurements. Future systematic logic data of these features would be of significant treatments of these Larger volumes of data will require interest. No such silic•ic• materials were sampled by more sophisticated mathematical techniques of statistical any of the lunar landing missions. analysis. The factor/ cluster analysis that was proven by 3) The correlation of radar reflec•tivily and color with the S-217 stud y of Mare Serenitatis with four data sets mappable flow scarps in Mare lrnbritim during S-217 needs to he applied to other hurcr areas with more data was extremely rewarding, hot still poorl y understood sets. with regard to the phvsic•al processes involved. The joint work with geologists proved valuable in into ipreting lunar surface conditions. Future synthesis of The modulation of remotely sensed data by surface lunar data should rely heavily upon the geologic • mapping chemistry needs further study. The correlation of greatly expertise that has been built up for the Surveyor, Lunar reduced radar bac•ksc•atter with blue snare color ill 'share Orbiter, and Apollo missions. Imbrium is seen to Ire reversed in the case of the Aristarc hus Plateau area where the correlation of weak radar return is front it red surface. The inference has been that a highl y absorbing surface material with elevated iron-titanium content is responsible for the high radar II. Data Sets absorption while diverse valence states of titanium and The S-217 work was primarily an interpretation of iron ions in glasses (black glass-orange glass) is responsible existing data sets (no new data were produced by this for the color changes. This interpretation needs further experiment). Most reports and scientific articles produced investigation where similar correlations exist in other lunar by the joint S-217/S-222 teams contain s ections describing areas. The low radar return/red color correlation appears these data sets. restricted (on the lunar nearside hemisphere) to regions of dark mantle of probable pryoc•lastic• origin and extreme !wo prime data sets are the 3.R-c•m and 70-cnn radar age (3.75 billion years). Other low-alhedo regions such as maps of the Moon (Refs. 13, 14, and 15). Other pri ►ne data the llaemus Mountains an(] the Sulpicius Gallus region sets are the infrared eclipse maps (Ref. 16) and the color (eastern edge of Mare Serenitatis) need to be examined difference photography of Whitaker (Rcf. 17). All of tli-se further using all remote sensing data currentl y available. data are shown in Figs. 2, 3, 1, and 5. all of these r'sata sets Spectral reflectivity, and high-resolution rentaneot mag- were also converted to digital formats by the Image netization (1-2 km) data from Limar Polar Orbiter should Processing Laboratory (fil l, at the Jet Propulsion provide additional valuable information regarding the Laboratory, as descrilx•d in the Appendix. chemistry of these deposits. The data sets above emphasize surface properties Other questions remains unanswered. For example, what complementary to the Apollo photography. The 3.8-cm is the physical significance of the bright, fuzzy spots in the and 70-cm radar maps emphasize surface roughness with 3.8-c•un naps that were noted as surface type II in our 52 centi ►neter scales, slopes, and surface electrical losses. 'I'll(- crater paper y What is the geological significant,(, of the infrared eclipse maps emphasize surface hlockiness. The surface properties that caused the unusual color and radar color-difference photographs emphasize surface chemical scattering aromid crater Plato and in the highlands that lie composition.

1PL TECHNICAL MEMORANDUM 33787 (a) (b)

r ^z

-4r f n - ILI Tit

VT iSr ^ ^ . M S • y a

Fig. 2. Data sets for the 5-217 Experiment: 70-cm polarized and depolarized radar echoes (provided by T. W. Thompson; see Ref. 15)

III. Results Institute). The major results of this study are summarized in Table 2; the article states: Our prime objective was to interpret various remote- sensed Innar data sets to augment the knowledge gained Between IOW and 20( g ) infrared (eclipse) and from Apollo orbital photography. "I he problem was radar anomalies have been mapped on the attacked by interpreting remotely-sensed data sets for the nearside hemisphere of the Moon. A study of areas surrounding, the Apollos 15, 16, and 17 landing sites. 52 of these anomalies indicates that most are In addition, three larger areas—Mare Serenitatis, the related to impact craters and that the nature Inibriun( Flows, and the Aristarchus Plateau—were of the infrared and radar responses is compati- studied.'I'he Mare Serenitatis basin provided a subject for ble with it previousl y developed geologic cluster and factor analysis, a recent sophisticated statistical model of crater aging processes. The youngest technique first applied to lunar data. craters are pronounced thermal and radar anomalies; that is, they have enhanced eclipse temperatures and are strong radar scatterers. 'lo present this sunuuar y coherently, the descriptions of these studies will be given in the following order: the With increasing crater age, the associated paper on the 52 craters will be discussed first because it thenual and radar responses become progres- sets the stage for the S-217 experiment; the Apollo landing sivel y less noticeable until thev assume values sites will he discussed second; third, the larger areas will for the average lunar surface. 'I'he lasl type of he discussed—Mare Serenitatis. imbriun( Flows, and the anomaly to disappear is radar enhancement at Aristarchus Plateau. longer wavelengths. A few craters, however, have infrared and radar behaviors not pre- A. The Initial Study of 52 Craters dicted by the aging model. One previously unknown feature—a field strewn with centime- The initial study of 52 craters (Ref. 1), was conducted in ter-sized rock fragments—has been identified 1969 and 1970 at the S ymposium for the Geophysical by this technique of comparing maps at the Interpretation of the Moon (held at the Lunar Science infrared, radar. and visual wavelengths.

f TROD UCIBILITY uF THE JPL TECHNICAL MEMORANDUM 33-787 IG(NAI, PAGE IS POOR Fig. 3. Data sets for the S-217 Experiment: infrared eclipse temperatures and full-Moon albedo (provided by R. W. Shorthdl: see Ref. 16)

This work established infrared eclipse temperatures and a fine-grained, deep regolith over the Appennine back- radar maps as indicators of surface properties, and slope, consistent with a deposit of fine-grained material. complemented geologic interpretation of the photogra- Examination of the remote sensing signatures of the crater phy. This first paper also led to a good working Hadley C argues for an unusual geology for the crater. relationship where lunar synthesis took place in a workshop atmosphere and publication of scientific articles In concluding this study, Zisk, et al., (Ref. 18), noted was the primary output of the work, and led further to the that "useful geologic information can he drawn from S-217 proposal and the suhsequent work reported here. Earth-hased radar and infrared studies of the lunar surface since the measured quantities are strongly influenced by B. The Apollo 15 Landing Site at Hadley Rille stnuc•t-;re on a scale nnuc•h finer than basic instnlniental Our attention was focused on the Apollo landing sites resol l t ion. •' for the obvious reason that man landed there and could This study of the Apollo 15 landing site was cornpleted bring back ground-truth information about the h ►nar surface. The question asked was how the remote sensing before the S-217 experiment was funded. However, this data would agree with the astronauts findings? Our report study is described here because it and the 52 crater paper on the Apollo 15 landing site at Hadley Rille was given by laid the groundwork for the stud y of other Apollo landing Zisk, et al., (Ref. 18), who studied the area hounded by sites when S-217 was funded. 20'N and 28'N latitude and (1` and WE longitude. C. The Apollo 16 Landing Site at Descartes The infrared, radar, and photographic evidence indi- Work on the Apollo 16 landing site is reported in cated that the Appennine crest could be interpreted as a companion papers by Zisk, et al., (Ref. 3), and by Zisk and smooth, dense surface with a dielectric constant near 4.0, Moore (Ref. 2) in the Apollo 16 Preliminary Science And with no ►core than the average-surface and near- Report (Ref. 19). The first article interpreted an area ,urfac•e rocks of centimeter sire. These surface conditions hounded by IT F, and ME longitude and by 7'S and I I'S .ire consistent with the geologic interpretation twat these latitude, surrounding the Apollo 16 landing site at 8`59'S, mountains are very old. The remote sensing data suggests 15 '11AV. This work concentrated on two questions: (1) is

JPL TECHNICAL MEMORANDUM 33-787 Fig. 4. Data sets for the 5-217 Experiment: color-difference photography and full Moon albedo (provided by E. A. Whitaker; see Ref. 17)

there a physical difference between the Cayley and the first opportunity to test li-nothesized correlation Descartes geologic units? and (2) what is the nature of the between block frequencies and radar h.,, kscattering." bright units of the material of the Descartes Mountains? (her work showed that sm,al differences in the 70-cm radar bac•kscatter between the Cayley and Descartes formations D. The Apollo 17 Landing Sil? at Taurus-Littrow suggested that the Cayley regolith is relatively free of meter-sized Loulders to depths of 15 meters, which is the Studies of the Apollo 1i landing site and Mare estimated thickness of the regolith at this landing site. A Serenitatis were reported by Moore and %isk (Ref. 6) and study of the remote sensing, data and the Apollo by Thompson, et al., (Ref. 5) in the .Apollo 17 Preliminary photography of the bright Descartes region (between Science Report ( Ref. 21). craters Descartes C and Dollond E) suggest that this is an asymmetrical ejecta mass with it different chemistry and a lower electrical loss. The Apollo photography with its The earl y work trying to relate radar backscatter to higher resolution provided the evidence that the bright surface hlockiness was reported by Zisk and Moore (Ref. Descartes region was due to bright crater ejecta rather 2) for the Apollo 16 landing site. B y the tinie that Apollo than a young volcanic deposit as suggested earlier by Head 17 had landed, more correlations between radar backsc•at- and Goetz (Ref. 20). ter and surface hlockiness were carried out. Apollo 17 surface photograph y produced more data, c•ulcninating in the report cited above. It is interesting to note that /isk 'The Apollo 16 landing site provided another study by and Moore conclude that "comparison between echoes at 'Z.isk and Moore where 3.8-cm radar echo strength was thy- kpollo 16 and Apollo 17 landing site supports the c•onrpared with surface block counts from surface postulate that factors other than small fragments and photographs (Ref. 2). They conclude that "substantial blocks produce differences in depolarized radar echo v%." improvement in the prediction of surface and near surface 1 his postulate was tested further in studies of the larger hlockiness can be achieved b y using Earth-based radar areas, where many more radar scattering differences arc measurement." 'they note that . the Apollo 16 inission was explained b% differences in surface chemistry.

JPL TECHNICAL MEMORANDUM 33-787

s v r

+9 y ,^ -

^i„ • fa

AL^^.

Fig. 3. Data sets for the S-217 Experiment: 3.8-cm polarized and depolarized radar maps (provided by S. H. Zisk; see Ref. 14)

E. Mare Serenitatis the most part, these surface types agree with geologic units derived from the interpretation of orbital photogra- Our attention to Mare Serenitatis was drawn by its phy. The remotely-sensed data "see" surface types II and proximity to the Apollo 17 landing site at Taurus-Littrow W in the flat mare surface, the only indication of physical and by its unusual radar and color-difference signatures. differences between eastern and western Mare Serenitatis. The study of Mare Serenitatis differs from the landing-site In other cases, thc• remotely-sensed data do not see studies in several aspects. 'File area bounded by 10° and differences between certain geologic units. This illustrates 40'N latitude and by 0` and WE longitude, was much the complementary nature of the geologic interpretation larger. The radar and infrared data were augmented b% and the determination 4 surface properties deduced from color-difference photography that made a crucial differ- the remotely-sensed data. ence in the interpretation. A primary conclusion of the Mare Serenitatis work is The remotely-sensed data for Mare Serenitatis permit- that differences in surface chemistry are apparent in the ted a separation of surface types as shown in Table 3. For remotely-sensed data. The radar backscatter from Mare

JPL TECHNICAL MEMORANDUM 33787 7 ' RODUCII31MY OF THE IGMAI. PAGE IS POOR. Ta0e 2. Surface conditions inferred from infrared and radar observations

Infrared "s-col 70-cm Geologic later ( eclipse radar radar Inferred surface Occurrence agint model te•ngierature) enhanevolent enhancement

No No No Normal distribution of rocks, old Asymptotic surface, Most common undisturbed surface provides basis for definition of anomalies: widespread

I Yes Yes Yes Excess number of centimeter- and Predicted for recent Common incter-sized rocks cratering event

I I Yes Yes No Excess number of centimeter-sized Behavior not predicted (:onnnon Woks only: a very young and proba- bh small feature

III No No Yes Older crater covered with a few meters Predicted for cratering Common of regolith event of moderate age

I\' Ycs No Yes Excess nom her of nieter-sized surface Behavior not predicted Bare rocks

V Yes No No Excess number of smooth surface rocks Behavior not predicted Hare much larger than meter-size, or smooth bare rock surface VI No Yes Yes Upper layer of regolith rough on Behavior not predicted Bare centimeter and meter scale but no excess of bare surface rocks VII No Yes No Upper Dyer top of regolith rocky on Behavior not predicted Rare centimeter scale but no excess of bare surfaco locks: possibly, an excess number of surface rocks in 1- to 5-cm size range

-Modified froin Table I of Ref. 1.

Serenitatis correlates very well with color throughout the The Mare Serenitatis study area also provided an area basin. However, radar-backscatter differences expected for testing factor analysis as described later in Subsection from different aged surfaces do not appear. Thus, III-H. chemical composition is a major controlling factor in radar backscatter for this area of the moon.

F. Imbrium Flows

The Mare Serenitatis work also concluded that the The Imbrium Flows have provided another study using remote-sensed data are useful for predicting lunar surface the Apollo photography and the remotely-sensed data. conditions beyond the areas covered by Apollo orbital Our attention to this area was drawn by remarkably sharp photography. For example, the Mare Serenitatis study radar-scatter and color-difference boundaries that appear area included the LeMonnier Crater, the landing site of in central Mare Imbrium. Lunokhod II (a surface sampler). Also, the southern rim of Mare Serenitatis has the same signatures as the Apollo 11 landing site in Mare Tranyuillitatis. This suggests that the An early report by Schaber (Refs. 22 and 23) concen- surface conditions and surface chemistry in southern Mare trated on the geologic interpretation of Apollo orbital Serenitatis are the same as those observed for the Apollo photography and identified the Euler P dome as the 11 surface samples (collected some 40O to 5W kilometers source of several late lava extrusions. A second report by to the south). Schaber, et al., (Ref. 7) concentrated on the interpretation

8 JPL TECHNICAL MEMORANDUM 33-787

f r Table 3. Mare Serenitatis surface types defined by remote sensing data (modified from Table 33-1 of Ref. 5)

Infrared eclipse Inferred Color Alhedo Hadar temperature chemistry I = bluest 1 = darkest I = strongest 1 = coolest I = highest in Surface t%pe 4 = reddest 4 = brightest 3 = weakest 2 = warmest titanium and iron I = lowest in titanium and iron

(1) Southeast rim and Aare 1 2 3 2 1 Tran(lnilitatis ( 11 1 Kortbwest Aare 2 4 2 2 2 Serenitatis i Ill) :Northeast rim, Southwest 3 3 3 2 3 rim, !dare Serenitatis t IV Eastern basin floor, 'Hare 4 4 1 2 4 Serenitatis l Montes Ilaemus 4 1 3 1 4

of Apollo photography and the radar, infrared, and color- G. Aristarchus Plateau difference data. This second report concluded: The Aristarchus Plateau provided another area where the interpretation of the Apollo photograph y was Earth-based 3.8-cm and 70-cm polarized (1) augmented by the remotel y-sensed infrared, rad. r, -!^a and depolarized radar return front color-difference data. Our attention to this area wa,, drawn Imbrium decreases in average intensit y front by its very unusual red color, low radar scatter, in(] low the old red to younger blue Inihrinm age infrared eclipse temperatures. Also, the Aristarchus region surfaces and also decreases from the oldest to had very unusual orbital geoc •hemical results and is often youngest Eratosthenian surface, all of the blue mentioned as the scene of transient events. The work on spectral type. the Aristarchus Plateau is tieing prepared for publication by 7.isk, et al., i Ref. 8). (2) This reduced radar bac •kscatter from the red to the hlne Mare surfaces is attributed to ts Plateau were increased radar absorption in the latter, The surface conditions oil Aristarc•h► resulting, at least indirectl y , front deduced front the collection of the remotely-sensed data, titanium and/or iron content in the basalts and lunar orbital photograph,\, lunar orbital geoc•hemic•al overlying rc,,,olitli. The important physical/ experiments, and surface sampling experience. The chemical parameter may be increased concen- sy nthesis of these data indicate that: trations of disseminated (FeTio 3) iLnenfte opayues in it deeper than normal ,dassy (l) 'The Aristarchus Plateau is most likely nuuiticd by a regolith. p y roclastic• material. which is fine grained with relativel y few rocks of size material greater than In 3) Titanium calihrttion of Earth-based radar cm. hackscatter maps should provide a pow,crful new tool for limar geochemical and geologic (2) The pli\sical and chemical characteristics of this mapping as well as providing it means for mantle material resemble tlhc orange ,,lass heads preliminar y geological and geochemic •al analy found at Short y crater durii -, the Apoll„ 17 surface •atter maps. -sis of Garth-haled Venus backsc samipling.

JPL TECHNICAL MEMORANDUM 33-787 9

f 1 (3) The thickness of the block-free mantle must Ile Table 4 Results of R-mode factor analysis on Mare Serenitatis data between 50 and W) in hased on geologic interpretation of Apollo photographs and the physical explanations of the weak infrared and radar Factor No. F1 112 F3 strengths. Experiment (4) This mantle oil Aristarc •hus Plateau was depos- Color difference ited Ixfore the adjacent Eratosthenean Maria were photography 0.281 0.7 25 0.628 extruded, based primarily oil interpretation of 70-cm radar Apollo photography. ( polarized) 0.906 —0.305 —0.013 70-cm radar 0.948 —0.083 —11.05() One of the striking results front this synthesis and depolarized interpretation of the Aristarc•hus Plateau data is that Albedo 0.196 0.7,6 —0.598 meaningful interpretations can Ile made for areas very r,'f+ variance distant from the lunar sampling sites. The Aristarc•hus accounted Plateau is more than 1.500 kilt from the nearest Apollo for by each factor 45.91 30.67 18.87 landing site and some 24011 kilt from the Apollo 17 Linding site where the orange glass beads were found.

Based oil three synthetic variables (Fl, F2, and F3), a new set of svnthetic• observations was created and the H. Factor Analysis Studies results were clustered (Ref. 26). Figure 6 shows that the At the University of Utah and the Boeing Co., R. W. results of this clustering yielded eight surface units. Shorthill, W. J. Peeples and T. F. Greene (Boeing) studied the application of factor and cluster analysis techniques to The predominate cluster or surface unit in Serenitatis is nntltk,ariable lunar data sets. This work will he reported denoted as unit I. This unit delineates the central, high in a separate final report currentl y being prepared by R. alhedo, young unit of Serenitatis. Note that this unit W. Shorthill, et al., (Ref. 11.). appears to extend to the northeast into Locus Senutiorum Factor analysis was applied to the Mare Serenitatis and (Ref. 27). The second most predominate unit is labeled reported by Peeples and Shorthill (Ref. 24). Four data sets unit 2 and encompasses west central Mare Serenitatis. were used including 70-c•tn polarized and depolarized echo This unit is also detected oil eastern edge of the basin. strengths, alhcdo, and color difference. The observations The dark mottling material (Refs. 28 through :30) appears were sampled every lunar degree from 17.6°N to 37.6°N to correlate with unit 8 and is seen in the southwest latitude and 10.6`E to 29.6`E longitude for a total of 166 corner of the basin extending northward and also appears observations at 400 grid points. This grid covers approxi- to extend intermittentl y :round the northeast margin of mately 3250X) k1112 of lunar surface, all large enough the basin. to determine ^,%hether the cluster analysis would (Itiantita- tively define surface units the same way as the previous Unit :3, which represents it unit associated with the dark qualitative studies of Mare Serenitatis by Thompson, et annulus, is seen in the southwest, southeast, east, al., ( Ref. 5). northeast, north and northwest borders of the basin, thus almost c•ompletcl^ encircling the basin. Unit 4 occurs These four data sets were first analyzed using in R-more primaril y along the northern border of the basin where it factor analvsis (Ref. 25). The results are shown in Table 4, is intermixed with other units (predominately units 5 and which lists the principal factors and their components iu 8). Unit 6 appears in the SE corner with it small patch in terms of the four original variables. The three factors (F1, the S«' corner. This unit also appears in the extreme NW F2, and F3) retain 95.5 0% of the original data variance. corner of the basin. Unit 7 appears dominately in the SE Synthetic• variable Fl \vas dominated by results front quadrant of the basin with some material in the N«' 70-cnn polarized auul depolarised radar data, xkhile F2 was corner. dominated by the positive addition of the color difference data and albedo. F3 wits it positive component of color- difference data and a negative c•ontrihttion front albedo The similarity of this ncNk factor analysis \s ith the data. previous analysis is quite striking, except lh,tt out t luster

10 JPL TECHNICAL MEMORANDUM 33-787

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1PL TECHNICAL MEMOP.ANDUM 33 787

11 REPRODUCIBILITY OF THE ORI ANAL PAGE IS POOR

1 1

;;4 Analysis surface types show more of the detail in the chemistry (titanium and iron c•ontcat) can be n►appin" that is actually inherent in the data. We were deduced by complementary geologic interpretation .►hle to delineate (easily) eight surface types instead of the of Apollo photography and correlations between five types in the previous qualitative analysis. Earth-based infrared, radar, and color-difference mappings of the lunar surface. I. Other Studies (2) Much of the information in the Earth-based, Other studies were carried out under the S-217 remotely-sensed data pertains to surface properties experiment. Extensive correlations of photogeology with on scales too small to he observed in orbital remotely-sensed data along the Apollo 14, 15, and 16 photography. bistatic• radar tracks were carried out by Moore, et al.. Ref. 9) and Moore, et al., (Ref. 10). These correlations %^ ill (3) Much of our interpretation of any lunar area is based be reported in the final report on the 5-222 experiment to on extrapolation of surface sampling experience. he published b' the United States Geological Survey by (4) The geologic interpretation of orbital photography H.J. Moore. S.H. Zisk working with others at M.LT. and and the s'nthesis of remote sensing data are Brown University coauthored scientific articles on the complementary. The geologic interpretation often Lunar Black Spots (Ref. 31), Mare Humorum (Ref. 12), and limits our deductions of surface conditions from the lunar surface units (Ref. :32). remote sensing data; surface conditions deduced from the remote data often limits the geologic interpretations. IV. Summary and Concluding Remarks (5) Factor analysis, a modern statistical technique, successfully defined surface units from a complex, The results of the S-217 experiment indicate: in tilt data set. This technique defined (1) Physical properties of the lunar surface such as surface units that were not c,hvious by the visual small-scale (centimeter-sized) blockiness and surface overlay methods.

12 JPL TECHNICAL MEMORANDUM 33-787 Appc-;-, dix Lunar Data Set Manipulations at the Image Processing Laboratory at JPL

The Image Processing I aboratory k ill.) at the Jet Maps. Examples of the lunar data in the Mercator Propulsion Laborator y provided a valuable computer Projection are shown in Fig. A-3 and in Ref. 33. Another facilit y for manipulation and display of the Earth-based, IPI, prognun, MPXSYS, was written to transform the data remotely-sensed lunar data sets. An overview of the into orthographic projection, %%hic•h shows the Moon at processing at IPI, is given in Fig. A-l. Much of this IPI, mean libration. Examples of the data in this projection is processing was accomplished b y L,ymvt Lyon. given by Figs. 2, 3, and 4, and by the figures used in the Mare Serenitatis article (Ref. 5). A combination of 1108 There are six prime data sets stored in digital formats at computer programs and standard IPL subroutines was the IPL. These include digitized versions of color- used to transform the lunar data into the Lunar difference and full-Moon photographs (provided by Ewen Aeronautical Chart (LAC) Projections as shown in Fig. Whitaker), infrared eclipse temperatures and visible scans A-4. of the moon (provided by RAV. Shorthill), and 70-cm polarized and depolarized radar maps (provided by TAV. Thompson). The base data sets for these projections are the data in the latitude-longWide array. These base arrays were A convenient common projection for these data sets was obtained by several means. The 70-cm radar data was to arrange the data in a square arra y where the horizontal originally mapped to this latitude-longitude projection. and vertical position of a pixel (a picture element) was The infrared and visual data sets from HAV. Shorthill were proportional to latitude and longitude (see Fig. A-2). Once already digitized and the transformations front array the data was in this latitude-longitude format, it was easy position to latitude and longitude were already worked to transform the data to other map projections. An IPL out The color difference and full-Moon photographs program, MPMERC, was written to transform the data to provided by Ewen Whitaker were transformed to the base the Mercator Projections used for many Apollo Planning data set by a series of operations. First, the data were

70-cm RADAR IR/VISIBLE COLOR. DIFFERENCE, DIGITAL TAPES DIGITAL TAPES FULL-MOON PHOTOS

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Fig, A-1. Overview of image processing of lunar data at JPL ' s Image Processing Laboratory

JPL TECHNICAL MEMORANDUM 33-787 13

1 Fig. A•2. Example of a lunar data set in the latitude—longitude format: full-Moon albedo also shown in Fig. 4 scanned to convert the data into digital formats. After this Other computer programs were developed at JP1, to scanning, the formulas for conversion of pixel position to accomplish a number of tasks peculiar to our S-217 work. latitude and longitude were computed by an 1108 A set of 1108 computer programs were developed to computer program GPAR. Program GPAR punches input select data for points along the Apollo bistatic radar sets. parameters for a standard IPL suhro utine GEOM, which This was used for the correlations along the radar tracks was used to convert the scanned data into the base set. reported by Moore, et al., (Ref. 9), and Moore, et al., (Ref. Although these manipulations of the color-difference and 10). .mother set of IPL programs was developed to full-Moon photos were more complicated than the other printout statistics for areas within an IPL data set. "These data sets, it left us with a powerful set of computer programs were used to generate the histograms that were programs that could convert any scanned lunar data sets reported by Scha per, Thompson, and 7.isk (Ref. 7). into a latitude-longitude array. This latitude-longitude Another set of 1108 and JPI, computer programs were array could he retransformed to the other standard map developed to redisplay the :3.8-cm radar maps at the IN, projections mentioned above. as shown in Fig. S.

JPL TECHNICAL MEMORANDUM 33-787 14 RMODUCIBILITY OF THE ORR ANAL PAGE IS POOR Fig. A-3. Example of lunar data set in the Mercator Projection: 70-cm radar echoes also shown in Fig. 2

JPL TECHNICAL MEMORANDUM 33.787 15 REPRODUCIBILITY OF THY, ORI( NAL PAGE IS POOR

r r Fig. A-4. Example of lunar data transformed to Lunar Aeronautical Chart Projection: 70-cm depolarized data of the Aristarchus Plateau

References

I. Thompson, T. fit'., Masursky, H., Shorthill, R. W., Tyler, G. L., and Zisk, S. I1., "A Comparison of bifrared, Radar, anal Geologic Mapping of lunar Craters," The .Noon, Vol. 10, No. 1, pp. 87-117, 1974.

2. Zisk, S. H., and Moore, II. J.,"Calibration of Radar Data from Apollo 16 Results, Part X of Photogeology," in Apollo 16 Preliminary Scienct, Report, NASA SP- 315, pp. 29-110 to 29-113. National Aeronautics and Space Administration, Washington, D. C., 1972.

3. Zisk, S. H., Masursky, H., Milton, 1). J., Schaber, G. G., Shorthill, 11. W., and Thompson, T. W., "Apollo 16 Landing Site: Sunimary of Earth-Based Remote Sensing Data, Part W of Photogeology," in Apollo 16 Preliminary Science Report, NASA SP-315, pp. 29-105 to 29-110. National Aeronautics and Space Administration, Washington. 1). C., 1972.

4. Thompson, T. W., Shorthill, K W.. Whitaker, E. A., and Zisk, S. H., "Mare Serenitatis: A Preliniivary Definition of Surface Units by Remote Observations," The Aloon, Vol. 9, pp. 89-96, 1974.

16 JPL TECHNICAL MEMORANDUM 33-787 5. Thompson, T. \\ ., Iloward. K. W., Shorthill. It. \v., 'Tyler, G. L, Zisk, S. H.. Whitaker. E. A., Schaber, G. G., and Moore. If. J.. "Remote Sensing of Mare Screnitatis. Part A of Remote Sensing and Photogra mmelric Stu ill Apollo 1; Prclimintury Science Report, NASA SP-:3:30, pp.33.3 to 1. National Aeronautics and Space Administration. Washington, 1). C., 197:3.

6. Moore, H. J., and 'Lisk, S. II.. "Calibration of Radar Data froru Apollo 17 and Othcr Mission Results, Part B Of Remote Sensing and Photogr,m inetric Studies," in Apollo 17 Preliminary Science Report, NASA SP-330, pp. 3:3-III to 33-17. National Aeronautics and Space Administration, Washington, l). C., 1973. 7. Schaber, G. (:., Thompson, T. W., and /.isk, S. II., "L•tva Flows in Mare Imbrium: Au Evaluation of Anomalousi Low Earth-Based Radar ReHectivitv," The Moort, Vol. 1:3, pp. :395-423, 1975. (Also in ('niter/ States Geological Surrey Interagency Report No. 64, December 1974.) S. Zisk, S. II.. (lodges. C. A.. Moore, f1. J., Shorthill. It. \\'., Thompson, 'I'. \\"., Whitaker, E. A., and Wilhelrns, 1). G., The Aristarcluts-Ilarbinger Region of the Moon: Surface Geology and histor y from Recent Itemote Sensing Observations," (in preparation).

9. Moore, If. J., Tyler, G. I... Boyce, J. M., Shorthill. It. W., '11hornpson. T. W., Walker, A. S., Wilhelms, D. E., \\'u, S. S. C., and '/.isk, S. I1.. Uorrclation of Photogeology and Remote Sensing Data alone tla, Apollo 11 Ri.stalie-Radar Ground Track; A Working Compendium, /'art 1. United States Geologic Survey Interagency Report: Astrogcology 80 (Open File Report 76-298).

10. Moore, if. J., Tyler, G. L. Boyce, J. M. Shorthill. It. \\ Thompson , T. W., \\"ilhelms, U. E., \\'u. S. S. C., and %isk, S. I1., Correlation of I'Irotogeology and I{rrnote Sensing 1)ato Alow, the Apollo 11, 1.7, (nr(/ 16 Bistatic-Radar Ground Tracks: A Working Compendium. Part H . 1'nited States Geological Survey Interagenev Report: Astrogeology 80 (Open File Report 76-298). 11. Shorthill, It. W., Peeples. W. J., and Greene, T. F., Finial Reporl: Factor Arurlr/sis. (Part of S-217 studies, in preparation.) 12. Pieters, C., I lca d, J. W.. McCord, T. B., Adams, J. B., and '/.isk, S. If.. "Geochen► ical and Geophysical Units of Mare Ilmnorma: Definition Using Iteroote Sensing_ and Lunar Sample Information," in Pruccc(lingti of the Sixth Lunar Science Conference. (:eoehcrnical unrl ('osmoclt('mical Acto, pp. 2689- 2710, 1975. 1:3. Potengill. G. If., 'Lisk, S. I I., and 'l'hontpson, T. \V., ...fhe Mapping of Lunar Radar Scattering Characteristics." Tla • .11oo►t, Vol. 10, No. 1, pp.3-16, 1974. 14. %isk, S. 1L. Pettengill, G. II., ,u d Catuna, G. W_ "Iligh liesoluthn Radar Maps of the Lunar Surface at :3.8 cur Wavelength," 7'Ite .Moon. Vol. 10, No. 1, pp. 17- 1, 1974. 15. Thompson, T. W., "Atlas of Lunar Hadar Maps at 70 cm Wavelength." The Moon. Vol.10, tip). I. pp. 51-85, 1974. 16. Shorthill, It. W., "Infrared Was Charts of The Eclipsed Moon," Ili• .Noun. Vol. 7. pp. 22-45, 197:3. 17. Whitaker, E. A.. "Lunar Color Boundaries and their Relationship to Topographic Features: A Prchminary Stud.\.' The Moon, Vol. 4. pp. 52:3-530, 1972.

JPL TECHNICAL MEMORANDUM 33-787 17

1 1 18. 'Lisk, S. H., Carr, M. II., Masunks, H., Shorthill, It. W., and Thompson, T. W., "Lunar Appennine-fladley Region: Implications of Earth-Based Hadar and Infrared Measurements," Srirncr, Vol. 173, pp. 8018-812, 1971. 19. Apollo 16 Pre irninary Scirncc Report, NASA SP-315. National Aeronautics and Space Administration, Washington, 1). C.. 1972.

20. Head, J. W., and C:oeti. %. F. H., "Descarte Region: Evidence for Copernican- Age Vulcanism," Journal of Gcophysicwl lirsrarch. Vol. 77. No. S. pp. 13f38- 1374, 1972. 21. Apollo 1,- Preliminary Sc•ienec Report. NASA SP-:3:311. National Acronautic •s and Space Administration, Washington. 1). C., 197:3. 22. Sc•haber, G. G., "Eratosthenian Vulcanism in Mare linhimin: Source of youngest Lava Flows, Part E of Volcanic Studies," in Apollo 17 Prchminury Science Report, NASA SP-3311• pp. :30-17 to :30. National Avrunautic•s and Space Administration, Washington, 1). C., 1973. 23. Schaper, G. G. "Lava Floss hi Mare Inrbriuui: Geologic• Esaluatiun from Apollo Orbital Photographs. in Proceedin gs of. Fourth Lunar Srirnre Conti-rence, Georliciniral (ind Co.smoc •hi-mieul Arta, Supplement 4, Vol. I. pp. 73-92,1973. 24. Peeples, W. J., and Shorthill. R. W.. "Initial Besults of Factor .aid Cluster Analysis for Mare Serenitatis." presented at the 7th Lunar Science Conference, Lunar Science Institute, Ilouslon, Texas, 1976. 25. Gorsuch, R. 1.., Factor Analysis, W. B. Saunders Co., Philadelphia, Penn., 1974. 26. Anderberg, M. I3.. Cluster Analysis for Applic(itions. Academic Press, New York. 1973. 27. Schmitt, 11. If., "Lunar Mare Color Provinces as Observed on Apollo 17," Geology. Vol. 2, pp. 55-56, 1974. 28. Carr, M. If., "Geologic Map of Mare Serenitatis Region of the Moon, flap I489, U. S. Geological Survey, Washington, 1). C., 1966. 29. Scott, 1). H., Luc•chitta, B. K., and Carr, M. H., "Geologic Maps of the 'laurus- Littrow Region of the Moon," .Nap I-HINT, 1'. S. Geological Surve y , Washim-,ton, 1). C., 1972. 30. Luc•c•hitta, R. K., and Schmitt, II. II., "Orange Material in the Sulpic•ius Gallo. Formation at the Soutimestern Edge of Mare Serenitatis," Georhirn Cosmochim. Arta, Vol. :38, Supplement 5, pp. 22:3-2:3. 1, 1974. 31. Pieters, C., McCord, T. B., 'Lisk, S. H., Adams, J. B.. "Lunar Black Spots and the Nature of the Apollo 17 Landing Area," Journal of Geophysical Rrstwrch, Vol. 78, pp. 5867-5875, 1973. 32. Head, J., Pieters, C., McCord. T. B., Adams, J., and %isk, S. H., "Definition and Detailed Characterization of Lunar Surface Units V ying Remote Ohservation," in preparation for submission to Icarus. :3:3. Shorthill, It. W., Thompson, T. W., mid Zisk, S. H.. "Infrared and Ra(lar Maps of the Lunar Equatorial Region," 77je .Noon, \'of. 4, pp. .169-47:3, 1972.

i g JPL TECHNICAL MEMORANDUM 33-787 NASA- 1P'I -( ). t A C.0