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Mapping the Apollo 17 landing site area based on LunarReconnaissance Orbiter Camera images and Apollosurface photography
I. Haase,1 J. Oberst,1,2 F. Scholten,2 M. Wählisch,2 P. Gläser,1 I. Karachevtseva,3
and M. S. Robinson4
Received 28 July 2011; revised 29 March 2012; accepted 1 April 2012; published 15 May 2012.
 Newly acquired high resolution Lunar Reconnaissance Orbiter Camera (LROC)images allow accurate determination of the coordinates of Apollo hardware, samplingstations, and photographic viewpoints. In particular, the positions from where the Apollo17 astronauts recorded panoramic image series, at the so-called “traverse stations”,were precisely determined for traverse path reconstruction. We analyzed observationsmade in Apollo surface photography as well as orthorectified orbital images (0.5 m/pixel)and Digital Terrain Models (DTMs) (1.5 m/pixel and 100 m/pixel) derived from LROCNarrow Angle Camera (NAC) and Wide Angle Camera (WAC) images. Key featurescaptured in the Apollo panoramic sequences were identified in LROC NAC orthoimages.Angular directions of these features were measured in the panoramic images and fitted tothe NAC orthoimage by applying least squares techniques. As a result, we obtained thesurface panoramic camera positions to within 50 cm. At the same time, the cameraorientations, North azimuth angles and distances to nearby features of interest werealso determined. Here, initial results are shown for traverse station 1 (northwest ofSteno Crater) as well as the Apollo Lunar Surface Experiment Package (ALSEP) area.
Citation: Haase, I., J. Oberst, F. Scholten, M. Wählisch, P. Gläser, I. Karachevtseva, and M. S. Robinson (2012), Mappingthe Apollo 17 landing site area based on Lunar Reconnaissance Orbiter Camera images and Apollo surface photography,J. Geophys. Res., 117, E00H20, doi:10.1029/2011JE003908.
 During the nominal phase of the Lunar Reconnais-sance Orbiter (LRO) mission the Lunar ReconnaissanceOrbiter Camera (LROC) acquired images from a near-circular50 � 15 km polar orbit [Vondrak et al., 2010]. The LROCsystem consists of a Wide Angle Camera (WAC) and twoidentical Narrow Angle Cameras (NACs) and providesglobal (75 m/pixel) multispectral coverage as well as high-resolution (0.5 m/pixel) monochrome close-up views of theMoon, respectively [Robinson et al., 2010]. Stereo imageswith substantial overlap are acquired from adjacent orbitsproviding the means to derive Digital Terrain Models (DTMs)and orthoimages.
 These high-level topographic data products represent adetailed depiction of the Moon and are of great value toongoing science and exploration analyses. Furthermore, thequalitative and quantitative progress in acquisition and pro-cessing of remote sensing data also allows reanalysis andinterpretation of data returned from previous lunar missions,e.g. from Apollo landings. Returned rock samples, astronautobservations, in-situ measurements, and surface photogra-phy represent an invaluable and unique record of a non-terrestrial surface. Until now, however, our knowledge of thecoordinates of sampling sites and instrument locations relieson estimates from surface images and astronaut descriptions. Accurately tying these unique surface photographs to
modern high-resolution image maps and DTMs not onlyenables realistic, multisource and multidimensional datavisualization, but also improves the geologic and cartographiccontext of the features captured in the historic “on site”imagery. Precise geometric reconstruction of the moment ofimage acquisition (camera position and orientation) is indis-pensable for accurate identification and mapping of samplesites, ALSEP components, surface features, and topographycaptured in Apollo images. This study focuses on the Apollo 17 landing site,
which is located along the south-eastern rim of the Sereni-tatis basin. This last Apollo lunar mission is characterized bythe longest traverse path (30 km), the most recorded images(>2,200), and the largest sample mass returned (nearly
1Department of Planetary Geodesy, Institute for Geodesy andGeoinformation Sciences, Technical University of Berlin, Berlin, Germany.
2Institute of Planetary Research, German Aerospace Center, Berlin,Germany.
3State University of Geodesy and Cartography, Moscow, Russia.4School of Earth and Space Exploration, Arizona State University,
Tempe, Arizona, USA.
Corresponding author: I. Haase, Department of Planetary Geodesy,H12, Technical University of Berlin, Str. des 17. Juni 135, D-10623 Berlin,Germany. ([email protected])
Copyright 2012 by the American Geophysical Union.0148-0227/12/2011JE003908
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120 kg) [Wolfe et al., 1981]. We used panoramic imagestaken by the astronauts during their three Extra-VehicularActivities (EVAs), which then and now served as the primeresource for the determination of astronaut positions. Basedon high-resolution 0.5 m/pixel LROC orthoimages we obtainprecise selenocentric body-fixed coordinates of astronaut andsurface feature positions. Like all LRO archival data thesecoordinates are given in the Mean Earth/Polar Axis (ME)Reference System, with the z-axis being the mean rotationalpole and with the prime meridian (0� longitude) defined bythe mean Earth direction [NASA, 2008].
2. Image Data Sets
2.1. LROC WAC DTM
 The LROC WAC is a multispectral camera with twoseparate optics for the visible (VIS) and ultraviolet (UV)spectrum, imaging onto different sections of the same CCDarray (1,024 � 1,024 pixel). Two bandpass filters in theultraviolet (321, 360 nm) and five filters in the visible (415,566, 604, 643, 689 nm) subdivide the array into seven sub-frames of 16 lines (summed to 4) and 14 lines, respectively[Robinson et al., 2010]. The WAC instantaneous field-of-view (IFOV) is
5.15 arcmin for the VIS optics. From 50 km orbit altitudethis results in a ground resolution of about 75 m/pixel. Whenoperated in the seven-band (color) imaging mode, only thecentral 704 pixels/line of the visible bands are read out. Theground track swath of a WAC color image is typically about60 km wide and 300 km long, depending on the orbital betaangle. Within one month, the WAC provides near completecoverage of the Moon. From images taken under differentlighting conditions a global 100 m/pixel basemap wasderived, suitable for morphological studies [Speyerer et al.,2011]. Additionally, a near-global 100 m/pixel DTM, called
the Global Lunar DTM 100 m or GLD100, was derived fromabout 69,000 stereo models from one visible band (604 nm).High quality stereo observations (33� stereo angle and 52%
overlap at the equator) are provided by images from adjacentorbits, as well as between images taken on consecutivemonths. GLD100’s mean vertical accuracy was quantita-tively compared with the Lunar Orbiter Laser Altimeter(LOLA) [Smith et al., 2011] global altimetric map; the ver-tical match between the two data sets is better than 20 m (formore details, see Scholten et al. ). In this study a 75 km � 75 km subset of the GLD100
covering the Taurus-Littrow Valley, including the hills andmassifs surrounding the Apollo 17 landing site, was used forinitial positioning purposes.
2.2. LROC NAC DTM and Orthoimages
 From 50 km orbit altitude LROC NAC images have apixel scale of 0.5 m, which allows meter-scale assessment ofregions explored by the astronauts. Both LROC mono-chrome CCD line-scan imagers, NAC-L and NAC-R, arealigned side-by-side with a small overlap to provide a widerfield-of-view (FOV) of two by 2.85� in the cross-trackdirection. A combined NAC-L/R-mosaic covers a groundtrack swath of about 5 km and typically 26 km in length. To acquire stereo images from adjacent orbits, LRO is
slewed up to 30� off nadir to either side in the across-trackdirection. For stereo image processing we used an LROC-adapted version of the German Aerospace Center (DLR)photogrammetric processing system, which has operation-ally been applied to Mars Express High-Resolution StereoCamera (HRSC) data [Gwinner et al., 2009] and other stereoimagery. This system is characterized by area-based imagematching within stereo model overlap, 3D forward rayintersection, and a final interpolation of a DTM grid. Twostereo pairs from different mission phases were used togenerate high-resolution NAC DTMs of the Apollo 17landing site, providing elevations with a relative accuracy ofa few decimeter. LRO was initially placed in an elliptical orbit (45–
190 km altitude) for a three months commissioning phase.From this orbit LROC obtained a 1.4 m scale stereo set(M104311715L/R, M104318871L/R) of the Apollo 17 land-ing site. This stereo pair (12� stereo angle, 80% overlap) wasused to generate a 4.0 m raster DTM [Oberst et al., 2010],which covers the area traversed by the astronauts. The DTMranges from 30.425�E to 30.910�E in longitude and from18.762�N to 21.143�N in latitude, including parts of theNorth, East, and South Massifs. From the nominal mission phase, a 0.5 meter pixel
scale stereo pair (M113751661L/R, M113758461L/R)providing a stereo angle of 35� was used to generate a1.5 m/pixel raster DTM. This stereo model covers an area of3.2 km � 3.2 km in the vicinity of the landing site, includingthe ALSEP area, station 1, and station 9 (see white outlinesin Figure 1). To assess the relative accuracy of this DTM,ten, evenly distributed LOLA tracks (2,206 height observa-tions) containing altimetric crossover solutions [Mazaricoet al., 2011] were accurately registered to the DTM[Gläser et al., 2010]. It showed a standard deviation of theelevation differences of the LOLA profiles and thecorresponding DTM elevations of �40 cm on average, aftera mean vertical offset of 37.7 m had been accounted for byshifting down the NAC DTM. Based on these DTMs, the NAC images of the land-
ing site were orthorectified maintaining their original image
Figure 1. Apollo 17 Landing Site. The astronauts’ traversepath and stations (extracted from the historic traverse map)within Taurus-Littrow Valley were superimposed onto anLROC NAC orthomosaic (M104318871L/R) for approxi-mate positioning purposes. The white box outlines thedimension of the NAC DTM and orthomosaic (0.5 m/pixelresolution and about (3.2 km)2 in size), which was used foraccurate astronaut positioning.
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ground scales. We chose (azimuthal) stereographic mapprojection, placing the origin at the approximate position ofthe astronaut, respectively, to preserve directions from theorigin of the map. The ALSEP’s radio transmitter, which is housed in
the central station, served as the control point for accuratereferencing of the orthoimages. The central station, whichcould be identified in the images, is one of the nine mostaccurately known positions on the Moon. Along with fourlaser ranging retro-reflectors (LRRR) and four other radiotransmitters, it constitutes the ME-reference frame on thelunar surface. Their positions were determined from preciseEarth-based measurements, i.e. Lunar Laser Ranging (LLR;ongoing experiment with increasing accuracies) and VeryLong Baseline Interferometry (VLBI). VLBI observations onradio transmission from the five ALSEPs, monitored between1972 and 1974, resulted in relative coordinates with uncer-tainties of about 10 m horizontally and about 30 m vertically[King et al., 1976]. Absolute ME-coordinates of the ALSEPtransmitters were determined by tying the VLBI network tothe LRRRs, which have absolute accuracies of about 1 m.So far, the most accurate estimate of ME-coordinates of theApollo 17 ALSEP transmitter (20.19209�N, 30.76492�E)was given by Davies and Colvin .
2.3. Apollo 17 Surface Photography
 The Apollo 17 astronauts G. Cernan and H. Schmitttook more than 2,200 photographs to document and supporttheir scientific investigations of the landing site and alongtraverses. The astronauts explored the valley with a battery-powered Lunar Roving Vehicle (LRV) enabling them toextend the range of their surface activities. They visited thebases of the South Massif (EVA 2) and the North Massif(EVA 3), covering a distance of about 30 km in total. Sev-eral sampling stops along their traverse path were includedto collect lunar material to return to Earth. At nine pre-planned, major sampling stops at geo-
logically interesting sites, the so-called “traverse stations”,the astronauts performed systematic documentary and pan-oramic photography [Wolfe et al., 1981].2.3.1. Hasselblad Panoramas The Apollo 17 astronauts used two modified Hassel-
blad electric data cameras (60 mm focal length, 70 mm film)while performing EVAs. The cameras were typically attachedto the chest of the astronauts’ spacesuits while they werephotographing. To enable photogrammetric measurements,these cameras were accurately calibrated and contained high-precision reseau plates, i.e. a glass plate situated immediatelyin front of the film plane with 25 measuring crosses etched at10 mm intervals [Kammerer, 1973]. The astronauts acquired single frames, partial panor-
amas, full panoramas, and stereo pairs along their traversepath and at sample stations to aid in post-flight geologicalanalysis. Additional pictures were taken to illustrate deploy-ment of the ALSEP and for other operational purposes[Batson et al., 1981]. A complete index list of all surface andorbital photographs taken during the Apollo 17 missioncan be found in the Apollo 17 Photo Index [NASA, 1974].Furthermore, many of the pictures taken on the lunar sur-face were digitized by the Johnson Space Center (JSC).Starting in 2004 they scanned the well preserved, originalHasselblad films at 4,096 � 4,096 pixels per image. At
reduced image sizes of 2,340 � 2,350 pixels and along withsupplemental information such as time of image acquisitionstated as Ground Elapsed Time (GET; corrected for thedelay in launch), these scans are available to the generalpublic, e.g. from the Apollo Lunar Surface Journal (ALSJ)(http://www.hq.nasa.gov/alsj/frame.html). This study concentrates on full 360� Hasselblad
panoramas, which were routinely recorded at each of thetraverse stations and at the ALSEP area. The panoramasequences were achieved by slightly turning and changingthe aiming direction of the camera each time a picture wastaken, providing a 360� view from a single point. (Comment:Because the camera was attached to the front of the space suitthe focal point is assumed to have moved in circle rather thanabout a point.) A complete panorama mosaic consists of atleast 15 overlapping individual frames. Assembled panor-amas are available from the ALSJ or the Apollo Image Atlas(http://www.lpi.usra.edu/resources/apollopanoramas/).2.3.2. Apollo Traverses Maps From Apollo Era Up to the present-day the most widely known recon-
struction of the astronaut traverse path is the Apollo 17 Tra-verses Lunar Photomap (scale 1:25,000) published by theDefense Mapping Agency Topographic Center (DMATC) in1975. Based on the Hasselblad panoramas taken at thetraverse stations the traditional surveying method of three-point resection was used to locate the camera positions on aphotograph from the orbit of the Apollo capsule. Thereforeazimuth angles of three or more surface features, which wereidentified in the panorama as well as on the vertical photo-graph, were measured in the panorama and plotted on tracingpaper as lines radiating from one point. The tracing paper wasthen placed over the image map so that each ray intersected theappropriate feature. The point from which the lines radiatedwas identified as a panorama station [Batson et al., 1981]. All 9 traverse stations were mapped using this
method, the accuracy was estimated to be better than 10 m.Detailed data from Very Long Baseline Interferometry(VLBI) provided by Salzberg  was used to fill thegaps between the astronauts’ stops, i.e. to map the tracks ofthe LRV between the previously located traverse stations. The lateral accuracy of this historic image map is
relatively low, as the photograph from Apollo orbit had notbeen orthorectified. For example, a comparison of thecoordinates of the Lunar Module (LM) derived from thetraverse map to the ones given by Davies and Colvin reveals an error of 59 arcsec in latitude and 48 arcsec inlongitude. This corresponds to a mean positional error of theLM of about 625 m.
3. Precise Positioning of Apollo 17Panorama Stations
 Our improved positioning of the Apollo astronautlocations was based on measurements from the Hasselbladpanoramas in conjunction with LROC NAC orthoimages.Similar to Apollo era analyses, as described in section 2.3.2,the panoramas provided direction angles to three or more lunarlandmarks, such as large boulders, crater rims, or anthropo-genic objects. Then, the same features were identified in LROC
NAC orthoimages, providing their positions with respect tothe ME-reference frame. Feature identification was
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facilitated by superimposing contour lines on the ortho-image. It helped to isolate the appropriate features correctlyby limiting the number of potential matches to the onesrealistically visible from the astronaut’s point of view. By a weighted least squares adjustment the observed
network of angular directions was optimally fitted to theidentified features (reference points) in the LROC NACorthoimage. As a result, we obtain the most probable loca-tion of the astronaut while taking the images, as well as astatistical assessment of the accuracy, that was achieved. Thefunctional model of this resection adjustment is given by thefundamental direction observation equation (1).
Dij þ vij ¼ Azij þ wi ¼ arctan xj � xiyj � yi
� �þ wi ð1Þ
Dij .. angular direction from the astronaut’s position I to asurface feature J (observation)
uij .. residual in the observed angleAzij .. North azimuth of a surface feature Jwi .. orientation angle toward North (unknown)
xi, yi .. coordinates of the astronaut’s position I (unknown)xj, yj .. coordinates of a surface feature J (treated as
 Every single angular direction Dij measured in a pan-orama yields one observation equation, setting up an over-determined, nonlinear equation system. Furthermore, thecoordinates of the reference points were treated as unknownquantities and were integrated as additional observations.This enabled the detection of possible gross errors and pro-vided corrections and accuracies for all coordinates of thenetwork. For the definition of the datum we used all of the
reference points, placing no external constraints on the mea-sured angles (free network adjustment). To apply a weightedleast squares adjustment we assigned standard deviations tothe angular measurements (�0.4�) and the orthoimage coor-dinates (�1 m). Equation (1) was linearized and solved using a first-
order Taylor series approximation, which required initialapproximations for the unknowns (astronaut position, ori-entation angle, and reference point positions). Two differentmethods, described in section 3.2, were used to acquire theseinitial values.
Figure 2. Angular Measurements in Panorama. Angular directions from traverse station 1 to targets atthe horizon were derived from the assembled, so-called ‘Station 1 B&W Pan’ (AS17-136-20744 to20776, source: ALSJ website), providing a view greater than 360�. The observed angles were used forapproximate positioning within GLD100 (see also Figure 3). The targets’ initials are used as acronyms,as listed in Table 1.
Table 1. GLD100 Derived Positions of (Selected) Summits of theApollo 17 Site
Name Longitude (�E) Latitude (�N) Heighta (m)
Family Mountain (fm) 29.785 20.346 �321Peak E-n (pEn) 29.851 20.491 �1162Hill F (hF) 30.348 20.371 �1720North Massif (nm) 30.886 20.596 �582East Massif (em) 31.229 19.589 �308Bear Mountain (bm) 30.767 19.986 �2358South Massif (sm) 30.373 20.018 �213
aElevations are referred to a zero vertical datum of the mean lunar radiusof 1,737.4 km [Archinal et al., 2011].
Figure 3. Initial Positioning of Traverse Station 1. Thiscolor-coded subset of GLD100 (75 km � 75 km) displaysthe Taurus-Littrow Valley (image center) surrounded bythe North (nm), East (em), and South (sm) Massifs. The ori-gin of the network of angular directions (see Figure 2) desig-nates the approximate position of station 1. Elevations arereferred to the mean lunar radius of 1,737.4 km [Archinalet al., 2011].
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3.1. Analysis of Hasselblad Panoramas
 We used assembled panoramas from the ALSJ, whichdisplayed views of slightly more than 360�. This had thebeneficial effect that some features were displayed twice atthe vertical image borders. By setting the horizontal distance(number of pixels) between those features to 360� we accu-rately determined the horizontal IFOV for each panorama weused. This allowed us to derive angles from the panorama. In the case of geometric inconsistencies in these
panoramas, e.g. duplications within adjacent pixels, or if theavailable panorama proved to be too distorted, we used theoriginal single frames. Knowledge of the camera focal length(60 mm) in conjunction with the nominal reseau positions inthe digitized images, we determined the horizontal resolutionand the FOV of each frame; the average scale was 1,144 pixelsper inch and a FOV of 46.8� (≈ 0.02�/pixel). Angles measured within the overlapping areas of the
single frames showed small differences, up to 1�–2�. Thesedifferences are caused by the camera’s attachment to theastronauts’ chest, causing small changes in perspective fromimage-to-image. These discrepancies were adjusted within theleast squares adjustment, incorporating all measured angles.
3.2. Initial Camera Positioning
 The determination of an astronaut position using leastsquares techniques requires adequate initial values for theunknowns: position and the angular orientation towardNorth. Regarding values for initial orientation, ephemerisdata and time of acquisition were used. By means of the solarazimuth angle measured from the Hasselblad panorama, thecomplete network of angles was pre-oriented toward North. Initial coordinates for the unknown camera position
were determined in two steps by visual alignment. As arough, first approximation, we took advantage of the historic
traverse map by semi-transparently overlaying it onto anLROC NAC orthoimage. The traverse map layer was thendistorted to match projection and size of the orthoimage (seeFigure 1). The locations of the depicted traverse stationswere used as a first approximation for the camera position,which was further refined in a second step. Depending onthe different stations, this coarse approximation came asclose as 20–40 m to our final, least squares adjusted results. For surface images with no position information we
followed a different initial control method. Directions totargets on the horizon, e.g. to local peaks and the summits ofadjacent mountains, as well as to the Sun were measured inan assembled 360�-panorama taken at traverse station 1 (seeFigure 2). This network of angles was plotted on a carto-graphic reconstruction of the subset of the 100 m rasterDTM GLD100. To facilitate the identification and posi-tioning procedure, heights were represented by colors andcontour lines to clearly display the local topography. Addi-tionally, the positions of the summits were derived from theDTM (see Table 1) and labeled with crosses. Visually fittingthe network of angles to the GLD100 model provided a first,100-m-scale approximation for the location of traverse sta-tion 1 (see Figure 3). The initial, first order camera positions were further
refined by ties to the LROC NAC images. The observeddirections to features in the vicinity were plotted onto theLROC NAC orthoimage using the approximate values for
Table 2. Used Acronyms
Station Acronym Feature
ALSEP r1-r5 rocks 1–5rdb rock “double”rG3 rock next to Geophone 3
(ALSEP instrument)cs central station (ALSEP instrument)cr right crater rimGR Geophone RockLM Lunar ModuleRTG Radioisotope Thermoelectric
GeneratorStation 1 r6-r8 rocks 6–8
LM Lunar Moduleboulder 20773 a boulder named after Hasselblad
Figure 4. Angular Directions To Prominent Features (‘Geo 3 Pan’). An assembled version of the ‘Geo 3Pan’ (AS17-147-22544 to 22562, source: ALSJ website), which was taken about 11 m from the GeophoneRock (GR), was used for accurate astronaut positioning at the ALSEP station. For this, angular directionsto prominent features were measured (see Table 2 for the use of acronyms).
Figure 5. Network of Directions (‘Geo 3 Pan’). Resultsfrom visual fits of the observed network of angular direc-tions to the appropriate features in the LROC NAC ortho-image (M113758461R) provide approximate coordinates ofthe unknown astronaut position (origin of the network) atthe ALSEP station. See Table 2 for the use of acronymsand Table 4 for azimuth angles and distances.
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position and North azimuth. The network of angles was then“moved and turned” on the orthoimage until its location, byvisual inspection, best matched the appropriate features. Thecoordinates of the origin of the network of directions servedas starting values for the least squares adjustment.
4.1. ALSEP Area
 The precise positions of two panorama stations nearthe ALSEP were determined. Both pans were recorded byH. Schmitt during EVA 1 (12 December 1972), capturing theALSEP instruments, Geophone Rock, the LM, and otherlandmarks, each from a different perspective. Standing between the Geophone Rock and the Geo-
phone 3 instrument (part of the seismic sounding experiment),the first color panorama ‘Geo 3 Pan’ was taken at about03:33 UTC (120:40 GET) consisting of frames AS17-147-22544 to -22562 [Wolfe et al., 1981]. An assembled version of‘Geo 3 Pan’ from ALSJ was used to measure angular direc-tions to 10 features, such as the Geophone Rock, a crater rim, arock next to the Geophone 3 instrument, and six other rocks(see Figure 4; for the use of acronyms, see Table 2). The
Figure 7. Adjusted Azimuths (‘B&W ALSEP Pan’). Theadjusted North Azimuth vectors of the ‘B&W ALSEP Pan’were plotted on the LROC NAC orthoimage (M113758461R).They are radiating from the panorama station, which islocated at the northern edge of the ALSEP region. SeeTable 2 for the use of acronyms and Table 4 for azimuthangles and distances.
Figure 8. Adjusted Azimuths (‘Station 1 Pan’). The posi-tion of the astronaut while recording the ‘Station 1 Pan’(northwest of Steno Crater) is pinpointed by the originof the least squares adjusted network of North azimuthangles (plotted on a 0.5 m/pxl LROC NAC orthoimage(M113758461R)). See Table 2 for the use of acronyms andTable 5 for azimuth angles and distances.
Figure 6. Single Frame Measurements. In this sampleHasselblad frame (AS17-136-20704) of the ‘B&W ALSEPPan’ angles were measured between the central station (cs),a boulder (r2), a rock near the Geophone 3 instrument(rG3), and the Geophone Rock (GR).
Table 3. ME-Coordinates of Apollo 17 Panorama Stations
Panorama Name Longitude (�E) Latitude (�N) Relative Accuracy (m)
Geo 3 Pan 30.76516 20.19073 0.3B&W ALSEP Pan 30.76465 20.19247 0.4Station 1 B&W Pan 30.78620 20.15659 0.5
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panorama showed distortions of a few degrees right of Geo-phone Rock. Therefore, single frames were used to measurerelative angles within that area. Plotting the network of mea-sured angles on the LROC NAC orthoimage, immediatelyshowed high consistency between the observed angles and theappropriate features in the orthoimage (see Figure 5). Hence, asubsequent least squares adjustment only improved the initialcamera location in the order of a few decimeters. We obtained ME-coordinates of the camera location
of ‘Geo 3 Pan’ with a mean point error of 30 cm (relative),which is within the pixel size (see Table 3). At that spot,heavily disturbed regolith can be seen in the orthoimagerevealing activity of the astronaut. A black and white panorama, the so-called ‘B&W
ALSEP Pan’, was taken about a quarter of an hour later at03:49 UTC (120:56 GET), after changing the film maga-zines and walking 54 m in northwest direction crossing theALSEP area. It consists of frames AS17-136-20683 to�20710. The available panorama mosaics of the ‘B&WALSEP Pan’ had large geometric errors, so three singleframes (136–20701, �20703, �20704) were used instead(see Figure 6). From the combined least squares adjustmentcalculation, including13 measured angles to 8 different fea-tures, e.g. ALSEP’s central station and Radioisotope Ther-moelectric Generator (RTG) (see Figure 7; one target wasomitted for better viewing), we assessed the relative accu-racy of the adjusted camera location to be better than 40 cm.TheME-coordinates of both ALSEP panoramas, ‘Geo 3 Pan’and ‘B&W ALSEP Pan’, are listed in Table 3.
4.2. Traverse Station 1
 After deployment of the ALSEP instruments, thecrew drove about 1.2 km in southeast direction to their firstmajor sampling station. They stopped at the so-called “Sta-tion 1 Crater”, a small crater 12 m in diameter, which islocated about 185 m from the northwest rim of Steno Crater.At 05:26 UTC (122:33 GET), standing between the LRVand the southern rim of Station 1 Crater, H. Schmitt obtainedthe required station panorama (‘Station 1 B&W Pan’), whichincluded 33 frames: AS17-136-20744 to �20776.
 Four single frames (136–20752, �20754, �20772,�20774) were used to derive angular directions to 19 fea-tures such as large-size boulders, crater rims, and the LM(see Figure 8; for better presentation only selected featuresare included). The least squares adjusted position, located10 m from the southern rim of Station 1 Crater, has a relativeaccuracy of 0.5 m (see Table 3).
4.3. Mapping of Apollo 17 Landing Site Area
 Determining the exact position and orientation of thecamera allows measurement of precise coordinates of anyfeature within surface panorama – as long as it is resolved ina high-resolution orthoimage. Using LROC NAC imagesfrom the nominal 50 km orbit, object matching is limited tofeatures comparable in size (or larger) to the ground pixelscale of 0.5 m. Prominent objects captured in the surfacephotographs were located in the orthoimages and theiridentity was verified within a least squares fit. We deter-mined object positions relative to the camera locationby North azimuth and distance as well as their absoluteME-coordinates. Locations of selected features imaged inthe three panoramas used in this study, e.g. the LM, RTG,and the Geophone Rock, are listed in Tables 4 and 5. Theirrelative positional errors were assessed by the least squaresfit to be better than 25 cm.
5. Summary and Outlook
 High-resolution images (0.5 m/pixel) provided by theLRO mission allowed us to carry out a new, detailed carto-graphic investigation of the Apollo 17 landing site. As partof this mapping project we precisely determined positions onthe lunar surface from where astronauts obtained panoramicimages with their calibrated Hasselblad. The astronauts’ positions while taking two ALSEP
panoramas as well as a panorama at traverse station 1 weredetermined within 0.5 m (LROC NAC pixel size). For thispurpose, weighted least squares adjustment was applied tothe angular directions observed in assembled panoramamosaics or in the original Hasselblad frames. PreciseME-coordinates of the camera positions as well as theirindividual accuracies are presented. Additionally, prominentsurface features such as large boulders, crater rims, andastronaut equipment, e.g. the LM, the ALSEP central station,and RTG, captured in the Hasselblad images were identifiedin LROC NAC orthoimages. After the free network adjust-ment the relative point error of the adjusted features wereassessed to be better than 0.25 m. Selected object positionsare given as absolute ME-coordinates as well as relative tothe adjusted camera location by their North azimuth angleand distances.
Table 4. ALSEP Station: Adjusted Positions of Selected Features
Geo 3 pan r1 30.76548 20.19163 18.99 28.9cr 30.76615 20.19161 46.67 39.0LM 30.77176 20.19092 88.24 187.9r2 30.76636 20.18909 145.33 60.3rdb 30.76511 20.18848 180.94 68.1GR 30.76487 20.19047 226.41 11.2r3 30.76337 20.19138 291.35 54.5r4 30.76243 20.19331 315.25 110.4r5 30.76443 20.19234 337.10 53.1rG3 30.76511 20.19095 350.72 7.0
B&W ALSEP pan LM 30.77176 20.19092 103.13 207.5RTG 30.76505 20.19212 133.00 15.8r1 30.76548 20.19163 137.41 34.8cs 30.76492 20.19209 147.07 13.9r2 30.76636 20.18909 154.68 113.6rG3 30.76511 20.19095 164.16 48.0GR 30.76487 20.19047 174.23 61.0r3 30.76443 20.19234 237.23 7.6
Table 5. Station 1: Adjusted Positions of Selected Features
Station 1B&W Pan
r8 30.80011 20.18035 28.80 822.2boulder 20773 30.78308 20.15150 209.92 178.3r6 30.78188 20.15430 240.51 141.3LM 30.77176 20.19092 338.46 1119.2r7 30.78539 20.16601 355.41 286.4
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 Applying this technique to all of the 9 traversestations will enable creation of a new, digital Apollo 17Traverse Map based on half-meter-scale LROC imagery. Inthis context, the possibility of the positioning of singleframes or partial panoramas recorded by the astronauts alongtheir traverse path will be investigated, to provide additionalanchor points for mapping the VLBI-based tracks of theLRV. An improved cartographic framework of the landingsite supports further detailed exploration and scientificinvestigation of the Apollo EVAs and lunar surface opera-tions. Researchers will have the ability to derive accuratecoordinates of in-situ observations and rock samples,for cross-reference with complementary orbital data sets. So far, the identification and positioning of prominent
features is limited by the resolution of the orthoimage. Fur-ther analysis of stereo images or triplets, i.e. images of thesame object from two or three different astronaut positions,will allow for the integration of all suitable features to thenetwork adjustment, regardless of their sizes. By measuringtwo (or three) different networks of angular directions, fea-ture positions are determined by ray-intersection of theappropriate direction vectors. In addition, most recent LROCNAC images obtained from lowest altitudes of about 21 kmwill support our improved mapping of the landing site. Furthermore, the least squares adjustment of angles
measured in the overlaps of single Hasselblad frames allowsfor an improved reconstruction of those panoramas, whichwere found to suffer from geometric distortion.
 Acknowledgments. This work has been supported by a grant(FKZ 50 OW 0902) from the German Aerospace Center (DLR), Bonn.J. Oberst and I. Karachevtseva have been supported by a grant from the Min-istry of Education and Science of the Russian Federation (agreement N 11.G34.31.0021 on 30.11.2010). We thank the NASA Lunar ReconnaissanceOrbiter project and the LROC Science Operations Center team. We alsothank three anonymous reviewers for their helpful comments.
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