Selenology Today - Moon Societystrabo.moonsociety.org/publications/selenology/sel... · 2018. 3. 1. · Gaetano Filangieri, in 1784 , wrote: "Saying that everything has already been

Editors:

M.T. Bregante

C. Kapral

J. Phillips

C. Wöhler

C. Wood

Cover designPG. Salimbeni

Selenology Today is devoted tothe publication of contributions in

the field of lunar studies.

Manuscripts reporting the resultsof new research concerning the

astronomy, geology, physics,chemistry and other scientificaspects of Earth’s Moon are

welcome.

Selenology Today publishespapers devoted exclusively to the

Moon.

Reviews, historical papersand manuscripts describing

observing or spacecraftinstrumentation are considered.

The Selenology Today

Editorial Office

[email protected]

Selenology Today # 10 June 2008

Editor-in-Chief:

R. Lena

SELENOLOGY TODAY #10SELENOLOGY TODAY #10SELENOLOGY TODAY #10June 2008June 2008June 2008

Selenology Today #10 June 2008

Tribute for our friend Charlie KapralTribute for our friend Charlie Kapral………………………..……....1………………………..……....1

A lunar dome near Palmieri crater and the properties of intru-A lunar dome near Palmieri crater and the properties of intru-sive lunar domessive lunar domes By R. Lena, C.By R. Lena, C. Wöhler, J. Phillips, M. T. BreganteWöhler, J. Phillips, M. T. Breganteand R. Benavidesand R. Benavides ………............................................................................4………............................................................................4

A profile of the Rupes AltaiA profile of the Rupes Altai By S. BointBy S. Boint ……….................................15……….................................15

Calibration of small telescope lunar spectral images using KeckCalibration of small telescope lunar spectral images using Keck120 color reflectance data120 color reflectance data By R. EvansBy R. Evans ………...............................26………...............................26

The O'Neill bridge: discovery, analysis and subsequent track inThe O'Neill bridge: discovery, analysis and subsequent track inliterature to the presentliterature to the present By F. GrahamBy F. Graham ……………..........................34……………..........................34

A study about Rupes Recta, Rima Birt, and two bisected domesA study about Rupes Recta, Rima Birt, and two bisected domesnear Birtnear Birt By R. Lena, C.By R. Lena, C. Wöhler and M. T. BreganteWöhler and M. T. Bregante ...........................41...........................41

The Steinheim basinThe Steinheim basin By A. Wöhler, and S. WöhlerBy A. Wöhler, and S. Wöhler .........................67.........................67

Virtual Moon AtlasVirtual Moon Atlas By C. LegrandBy C. Legrand ………...........................................72………...........................................72

Cover : Images taken by George Tarsoudis

Selenology Today websiteshttp://digilander.libero.it/glrgroup/

page 1

SELENOLOGY TODAY # 10

Charles Kapral

November 3, 1944 – May 27, 2008

The Geologic Lunar Researches group has lost a dear friend and comrade. It is withgreat sadness that we announce the death of Charlie Kapral, May 27, 2008.

Charlie was born on November 3, 1944 and began his interest in amateur astronomy in1958. Charlie was very interested in Meteor and Lunar observations.

He began his observations with a 1” Edmund Scientific refractor, then a Unitron 2.4” re-fractor, later using a Meade 10” SCT and 5” refractor. He worked with Winifred Cam-eron as a member of the ALPO Lunar Transient Phenomenon team.

His interest in the study of lunar domes began with the ALPO lunar dome survey pro-gram under Jim Phillips continuing with the present GLR program. Charlie and RobertGarfinkle, F.R.A.S., published a revised lunar dome catalogue.

Charlie was a member of the GLR Board, carefully plotting locations of new and olddomes, from new information provided by members of the GLR, onto the GLR lunardome map, the most detailed and accurate catalogue and map of lunar domes available.

Charlie also rewrote John Westfall’s Lunar Photoelectric Photometry Handbook whichwas published in our journal, “Selenology Today”.

Charlie was one of a kind, a true gentleman, always considerate and courteous in alltransactions.

He was known to always have a smile on his face with a joke or a happy story for every-one. It does not surprise us that he made plans to help others even after his death, donat-ing his corneas to two individuals and his body to science.

He is survived by his loving wife of 37 years and soul-mate Marie. A memorial servicein Charlie’s honor will be held in his home Sunday, June 8, 2008.

Donations should be sent to the SPCA, 524 E. Main, Fox Hill, Wilkes-Barre PA, 18702,telephone number 570-825-4111.

He will be sorely missed by All.

page 2


.

page 3

Charlie is our friend and we, as members of the GLR group, will do our best toremember his work and his interest in science, and for doing “good scientificresearch”.

Gaetano Filangieri, in 1784 , wrote:

"Saying that everything has already been done is the language of those who eitherlack ability or courage."


page 4

LUNAR DOMES SELENOLOGY TODAY # 10

A lunar dome near Palmiericrater and the properties ofintrusive lunar domes

By Raffaello Lena, Christian Wöhler,Jim Phillips, Maria Teresa Breganteand Rafael Benavides

Geologic Lunar Research (GLR) group

1. Introduction

Lunar domes may form as effusive shield-like volcanoes or may remain subsurfaceas laccoliths (intrusive origin). Asdescribed by Lena and Wöhler (2008) thelow slope of some domes suggests similarmechanisms of origin. Additional workabout intrusive lunar domes is stillrequired to establish similarities withpossibly equivalent features on the Earth.The current programs of imaging,measuring, cataloguing and mapping

intrusive domes will provide theinformation needed to statisticallycharacterize these structures and to havemore detailed insight into the global andregional geologic processes responsiblefor the formation of the observed varioustypes of lunar mare domes.

In this article we examine a low domesituated near Palmieri, comparing itsmorphometric properties with furtherdomes of possibly intrusive nature,recently described in our precedingstudies (cf. Lena and Wöhler, 2008;Wöhler et al., 2006 and referencestherein). Palmieri is a lunar crater that liesto the southwest of Mare Humorum, in thesouthwestern quadrant of the Moon's nearside. The principal feature of the MareHumorum region is the Humorum basin, acircular mare basin approximately 300 kmin diameter. The basin formed early in thehistory of the moon and was later floodedby mare material. Impact cratering withattendant erosion, episodic volcanism, andfaulting have also occurred in the region(Wilhelms, 1987). The inferred history ofHumorum basin is similar to that of theImbrium basin, but the more subduedtopography and the larger density ofcraters on the rim of Humorum basinsuggests that it is older than the Imbriumbasin (Titley, 1967 and referencestherein). Different lithological units,included in USGS lunar geologic map I-495, are apparent in Mare Humorum: theHumorum basalts have been mapped as 4distinct units, Ipm1 through Ipm4. Thedome we describe, of likely intrusivenature, is located in an Ipm1 unit.

2. Telescopic CCD images

A shallow dome has been detected near

Abstract

We describe a dome located at longi-tude 47.88 ° W and 26.63° S, near thecrater Palmieri, including data aboutslope and height. The dome (Palmieri1) has a height of 60 ± 10 m and anaverage flank slope of 0.5° ± 0.1°.The dome is compared with furtherstructures of possible intrusive naturedescribed in our preceding studies.This has made it possible to extractadditional information for its classifi-cation and interpretation in geologicterms. A new classification scheme ofintrusive domes in three subgroups isreported.

page 5


Figure 1

page 6


the crater Palmieri, located at 47.88 ° Wand 26.63° S. According to our precedingstudies we name the dome as Palmieri 1(Pa1). For each of the observations, thelocal solar altitude and the Sun'sselenographic colongitude werecalculated using the LTVT softwarepackage by Mosher and Bondo (2006)which requires a calibration of theimages by identifying the preciseselenographic coordinates of somelandmarks on the image. This calibrationwas performed based on the UCLN 1994list of control points. The dome wasdetected in images taken by J. Phillips onApril 10, 2006, between 01:56 and 02:11UT using a 200 mm TMB apochromaticrefractor and an Atik B&W camera (Fig.1). In Fig. 1, the shading on the dome’santisolar flank is not black, indicatingthat the slope is of low inclination. Thedome diameter amounts to 13.5± 0.60km. Furthermore, a crater on the summitwith an estimated size of 3.9 ± 0.60 km,is apparent, which is presumably ofimpact origin. Fig. 2 shows anotherimage of the dome and the Humorumregion taken by R. Benavides on January19, 2008, at 20:12 UT using a 280 mmSchmidt Cassegrain and a Luna-QHY 5camera. Fig. 3 displays Lunar Orbiterframe IV-133-H2, where the impactcrater on the dome summit and its brightejecta are recognizable. As apparent inthe Lunar Orbiter image shown in Fig. 3,a linear rille possibly representing atensional fracture is located on thenorthwestern part of the dome surface. Itis marked by a red arrow.A similar, more pronounced structure canbe found somewhat further to thenorthwest.

In order to compare the dome Pa1 with

two effusive domes located nearby in theDoppelmayer region (cf. Lena et al,2007), we show two new images of theeffusive domes near Doppelmayer alongwith the corresponding Lunar Orbiter andClementine imagery (Figs. 4 and 5). Fig.4 was taken by R. Lena on December 20,2007, at 22:15 UT using a 180 mmMaksutov Cassegrain and a LumeneraLU075M camera. The elongated summitvent of the larger dome southwest ofDoppelmayer (Fig. 5) was also imagedby Lena on November 20, 2007, at 21:41UT with the same instrumentation.

3. Morphologic and morphometricproperties

Further morphometric data were obtainedby generating a cross-section of the domefrom the image shown in Fig. 1, relying ona photoclinometric analysis (Horn, 1989;Wöhler et al, 2006; Lena et al, 2006 andreferences therein). The effective height ofthe dome was obtained by determiningelevation differences between the summitof the dome and its surroundings. Thisleads to a dome height of 60 ± 10 m,yielding an average flank slope of 0.5° ±0.1°.

Usually the dome volume V is computedby integrating the reconstructed 3Dprofile over an area corresponding to acircular region of diameter D around thedome summit. A rough quantitativemeasure for the shape of the dome isgiven by the form factor

f = V/[πh(D/2)²], where we have f = 1/3for domes of conical shape, f=1/2 forparabolic shape, f=1 for cylindricalshape, and intermediate values forhemispherical shape. Since we were notable to reconstruct the complete dome

page 7


Figure 2

page 8


surface due to the very bright small freshimpact crater near its summit, theintegration approach could not beemployed. Instead we assumed a typicalform factor of f = 1/2, which yields anestimated volume of V = 4.3 km³ basedon the dome diameter D and height hgiven in Table 1. We furthermoredetermined a UVVIS five-band spectrumof the dome based on Clementineimagery at the wavelengths of 415, 750,900, 950, and 1000 nm. The reflectancevalues were derived relying on thecalibrated and normalised ClementineUVVIS reflectance data as provided byEliason et al. (1999). The extractedClementine UVVIS data were examinedin terms of 750 nm reflectance (albedo)and the R415/R750 and R950/R750 colourratios. Albedo at 750 nm is an indicatorof variations in soil composition,maturity, particle size, and viewinggeometry. The R415/R750 colour ratioessentially is a measure for the TiO2

content of mature basaltic soils, wherehigh R415/R750 ratios correspond to highTiO2 content and vice versa (Charette etal., 1974). However, for many lunarregions the relation between R415/R750

ratio and TiO2 content displays asignificant scatter (Gillis and Lucey,2005). The R950/R750 colour ratio isrelated to the strength of the maficabsorption band, representing a measurefor the FeO content of the soil, and isalso sensitive to the optical maturity ofmare and highland materials (Lucey et al.1998).

The Clementine UVVIS spectral data ofthe dome Pa1 reveal a 750 nmreflectance of R750 = 0.1382, a moderatevalue for the UV/VIS colour ratio ofR415/R750 = 0.6054, indicating a moderate

TiO2 content, and a strong maficabsorption with R950/R750 = 1.0224, likelydue to the fresh material excavated by theimpact that formed the small crater onthe top of the dome.

Table 1 reports the flank slope, diameter,height, and edifice volume of Pa1 alongwith data of further intrusive domesdescribed in our preceding studies (Wöhleret al, 2006; Lena and Wöhler, 2008).

4. Volcanism in the Doppelmayer region

The dome we have detected near Palmieriis located in a basaltic plain (Titley, 1967)but its morphometric properties suggest anintrusive origin since it is very similar toother intrusive domes reported in Table 1.These intrusive structures are localizednear Rupes Cauchy, in western MareSerenitatis, and in Sinus Iridum,respectively. They are characterized bylow flank slopes in the range 0.4°-0.7°.

In contrast, the region around MareHumorum and the crater Doppelmayer,which is situated only about 120 km eastof Palmieri, shows many traces ofancient volcanic activity. Very darkmaterial partially covering theDoppelmayer floor, also known as theDoppelmayer Formation, has beeninterpreted as fragmental volcanic ejectaor flows, or both, from vents or fissuresalong the edge of Humorum basin(Titley, 1967). The dark material of theDoppelmayer Formation (Eid unit inUSGS map I-495) is prominent in theClementine 750 nm albedo image andcoincides with units of high FeO contentwithin Mare Humorum found by Busseyet al. (1997). Moreover, these two Eid

page 9


Figure 3

Table 1: Morphometric properties of some intrusive domes

DomeLong. Lat. slope

[°]

D

[km]

h

[m]V [km3]

Pa1 -47.88° -26.63° 0.50 13.5 60 4.3 (estimated)

Ga1 -14.84° -0.75° 0.57 30 140 50

L6 -29.16° 47.08° 0.70 10 95 1.5

V1 10.20° 30.70° 0.55 30 130 42

V2 10.26° 31.89° 0.82 11 80 1.9

C9 34.66° 7.06° 0.13 13.3 15 0.5

C10 35.19° 10.00° 0.30 19.2 50 10

C11 36.75° 11.06° 0.70 12.2 75 6.4

C12 37.20° 12.37° 0.45 6.3 25 0.5

M13 -31.53° 11.68° 0.41 27.8 100 15

M14 -32.13° 12.76° 0.27 14.8 35 1.7

page 10


units located just to the west and north ofDoppelmayer have been spectrallycharacterised as lunar pyroclasticdeposits (LPDs) by Gaddis et al. (2003).In a preceding study we have examinedtwo effusive lunar domes nearDoppelmayer, displaying markedlydifferent spectral, morphometric, andrheologic properties (Lena et al., 2007).These two lunar domes nearDoppelmayer, located at 30.08° S 41.92°W (D = 16.8 ± 0.2 km) and 30.66°S and43.42°W (D=12.6 ± 0.2 km), respectively(Fig. 4), do not appear to be connectedwith any of the two LPDs in southernMare Humorum described by Gaddis etal. (2003). However, according to Lenaet al. (2007) dome 1 is a large,comparably steep (flank slope 3°) andvoluminous edifice (V= 34 km3). Dome 2is slightly smaller than dome 1,significantly lower with a flank slope of1.15°, and less voluminous by an order ofmagnitude (V=2.8 km3). These twodomes are interpreted to be effusivevolcanic structures, due to the presenceof a shallow elongated vent on thesummit of dome 1 (Fig. 5) and thepresence of rilles traversing dome 2 (welldefined in Clementine and Lunar Orbiterimagery), the manifestation of a dike thatinitially remained subsurface but gainedaccess to the surface at localized points(Lena et al, 2007).

5. Morphometric classes of intrusivedomes

Some intrusive domes have largediameters of about 30 km (Ga1, V1,M13), most have moderate diameters inthe range 10–20 km (L6, V2, C9, C10,C11, M14), and the dome C12 is rathersmall with a diameter of only 6.3 km.

The edifice volume amounts to largevalues of 40–50 km³ for Ga1 and V1,moderate values of 6–15 km³ for C10,C11, and M13, and is fairly low (< 2km³) for L6, V2, C9, C12, and M14. Fig.6 shows the domes we have analysed andthe corresponding diameter versus slopeincluding also the dome near Palmieri(Pa1).

Several domes of possible intrusive natureare characterised by straight rillestraversing their surface (Ga1, M13 andV1) and/or by the presence of pre-existingengulfed small peaks. Based on the datareported in Table 1 and Fig. 6, the closeresemblance of the domes Ga1 and V1may indicate a similar mode ofemplacement. The diagram reported inFig. 6 shows three distinct groups, In1through In3. The domes of group In1appear to represent end-members of lunarintrusive domes with large diameters andhigh edifice volumes. The rilles andtensional fractures observed on the surfaceof these two domes suggest that they areassociated with dikes that remainedsubsurface but ascended to shallow depthsbelow the surface. Moreover there is aclear distinction between two types ofsmaller intrusive domes, one with lower(In3), the other one with clearly steeperflank slopes (In2). Due to its moderatediameter, Palmieri 1 falls into the groupIn2. The large intrusive domes such asValentine and Gambart 1 (cf. Lena andWöhler, 2008) provide the known upperlimit to the dome diameter. Ourinterpretation based on the available datais that during formation of the largeintrusive domes of group In1, somefracturing and faulting of the crustoccurred, weakening the strength of thecrust and thus facilitating the uplift of the

page 11


Figure 4

page 12


Figure 5

page 13


Figure 6 A new classification scheme ofintrusive domes in three subgroups isreported.

page 14


large volume of crustal material nowvisible as a large intrusive dome. Incontrast, during formation of the smallerintrusive domes, no fracturing or faultingoccurred, and the crust was only bentupwards.

References

[1] Bussey, B. J., Spudis, P. D., Hawke, B.R., Lucey, P. G., Peterson, C., Taylor, G.J., 1997. Humorum basin geology fromClementine data. Lunar Planet. Sci.XXVIII, abstract #1294.

[2] Charette, M. P., McCord, T. B.,Pieters, C. M., Adams, J. B., 1974.Application of remote spectral reflectancemeasurements to lunar geologyclassification and determination oftitanium content of lunar soils. J. Geophys.Res. 79, 1605-1613.

[3] Eliason, E., Isbell, C., Lee, E., Becker,T., Gaddis, L., McEwen, A., Robinson,M., 1999. Mission to the Moon: theClementine UVVIS global mosaic. PDSVolumes USA NASA PDS CL 4001 4078.http://pdsmaps.wr.usgs.gov

[4] Gaddis, L. R., Staid, M. I., Tyburczy, J.A., Hawke B. R., Petro, N. E., 2003.Compositional analyses of lunarpyroclastic deposits. Icarus 161(2), 262-280.

[5] Gillis, J. J., Lucey, P. G., 2005.Evidence that UVVIS ratio is not a simplelinear function of TiO2 content for lunarmare basalts. Lunar Planet. Sci. XXXVI,abstract #2252.

[6] Horn, B. K. P., 1989. Height andGradient from Shading. MIT technicalreport 1105A. http://people.csail.mit.edu/people/bkph/AIM/AIM-1105A-TEX.pdf

[7] Lena, R., Wöhler, C., Bregante, M.T,Fattinnanzi, C. 2006. A combinedmorphometric and spectrophotometricstudy of the complex lunar volcanic regionin the south of Petavius. Journal of theRoyal Astronomical Society of Canada,vol. 100, no. 1, 14-25.

[8] Lena, R., Wöhler, C. Intrusive LunarDomes: Morphometry and Mode ofEmplacement. Lunar and PlanetaryScience Conference XXXIX, abstract#1122, League City, Texas, 2008.

[9] Lena, R., Wöhler, C., Phillips, J.,Wirths, M., Bregante, M.T. 2007. Lunardomes in the Doppelmayer region:Spectrophotometry, morphometry,rheology, and eruption conditions.Planetary and Space Science, vol. 55,1201-1217.

[10] Lucey, P. G., Blewett, D. T., Hawke,B. R. 1998. Mapping the FeO and TiO2

content of the lunar surface withmultispectral imagery. J. Geophys. Res.103(E2), 3679-3699.

[11] Mosher, J., Bondo, H., 2006. LunarTerminator Visualization Tool (LTVT).http://inet.uni2.dk/ d120588/henrik/jimltvt.html

[12] Titley, S. R., 1967. USGS Map I-495.

[13] Wilhelms, D., 1987. The geologichistory of the Moon. USGS Prof. Paper1348.

[14] Wöhler, C., Lena, R., Lazzarotti, P.,Phillips, J., Wirths, M., Pujic, Z. 2006. Acombined spectrophotometric andmorphometric study of the lunar maredome fields near Cauchy, Arago,Hortensius, and Milichius. Icarus, vol.183, 2, 237-264.

page 15

TOPOGRAPHY SELENOLOGY TODAY # 10

A Profile Of The Rupes AltaiBy Steve Boint

American Lunar Society (ALS)

IntroductionThe Rupes Altai trace a 500 km long arc.Formed as the Nectaris Basin’s rimcollapsed shortly after excavation (Wood,2006), they rise between 3000 km and4000 km above the lunar surface to theireast. Smooth deposits at the base areprobably lava which oozed through cracksin the basin rim. The interior is probablymostly fallback from Nectaris’ formationalthough some lines of secondary craterspoint back toward Imbrium (Wood,2006). More recently Wood, reviving aninterpretation of the Rupes Altaioriginally proposed in 1971 (Hartmannand Wood, 1971), suggested that the scarppossibly rose to its current height longafter Nectaris formed. Evidence for this isfound in Altai’s fresh look compared tothe ancient derivation of Nectaris (Wood,2008).

The vertical displacement of the RupesAltai is not known in detail. For its 500km stretch, Viscardy (1985) andCherrington (1969) each provide merelya single measurement. Viscardy lists theheight as 1 km, Cherrington as 1.6 km.Elger (1895) lists an average height of6000 feet—2000 m. A point east ofFermat Crater is called the tallest pointand listed as 13000 feet tall—4.0 x 103

m. Following contour lines on the LACmap (LAC 96), the point east of FermatCrater is calculated as 1800 m – 2100 min height. A little north of this, thescarp’s height comes to 2400 m – 2700m. Directly east of Pons M, LAC 96’scontour lines measure the height asbetween 3000 m and 3300 m. Wood liststhe Rupes Altai as between 3 and 4 kmtall. Strangely, in the same article herefers to the rim topography shown byLAC 96 as having the scarp rise 500 m –1000 m above the surrounding area. Iinterpret this as “500 – 1000” referringto the vertical displacement along thewestern side of the scarp while “3 – 4km” refers to that along the eastern, butthe relationship is not spelled out clearly(Wood, 2006). The relevant contourlines on LAC 96 are very difficult toread due to the scarp’s steep incline. Itcontains no individual measurements ofthe scarp based upon shadow length.In order to more precisely determine thevertical displacement of the cliffs ofAltai, LTVT (Mosher and Bondo, 2006)was used to measure an amateur photoof moderate quality and an extremelyhigh-resolution photograph ofoutstanding quality. The results werethen graphed in Microsoft Excel and arepresented as a profile of the Rupes Altaias if seen by a viewer positioned east ofthe scarp and looking westward.

AbstractUsing two amateur photos, one an ex-cellent, high resolution photograph andthe other of moderate quality, theRupes Altai were measured usingLTVT. A profile was generated. Thescarp’s vertical displacement variesdramatically, but does show a gradualincrease toward Piccolomini Crater,reaching a maximum in the eighty kilo-meter stretch south of 22.35 E longi-tude, 23.47 S latitude. Maximumheights in this area were around 4150m.

page 16


Figure 1

Figure 2

page 17


Figure 3

Figure 4

page 18


MethodThe high resolution photo was taken byPaolo R. Lazzarotti on 10/01/2007 at3:50 UT from Massa, Italy. The telescopewas a Gladius CF-315 Lazzarotti Opt.Scope with an Edmund Optics R filter.The camera was an LVI-1392 PROexperimental camera using a 31 msecexposure. 160/2000 frames were stackedand upscaling was 150%. The finalimage scale was 0.18 arcsec/pixel. Thatis the original sampling image scale, the"final" image scale as perceived by theobserver is 0.12 because of the 150%upscaling.The photo of moderate quality was takenby Steve Boint on 08/03/2007 at 07:15UT from 96.7313 W longitude, 43.5293N latitude, and a height above sea levelof 435 m. The telescope was aNewtonian, Dob mount, 10” primary,f/4.5 using a 2x Barlow lens. The camerawas a Toucam Pro II. Frames werestacked using Registax (@ 50 per photo)and a mosaic was produced using AdobePhotoshop. From measurements madeusing LTVT, a profile of the Altai Scarpwas produced. Presentation of the resultsin the form of a profile was chosenbecause: 1) Calculations of verticaldisplacement using the method ofshadow measurement have traditionallybeen plagued by, minimally, ten percenterror (often more), but the error shouldbe systematic and therefore therelationship of the measurements to eachother should be valid. In other words, aprofile could be adjusted up or down by aspecific factor while maintaining itsrelevance. Once a single part of theRupes Altai is measured with highaccuracy (perhaps by a laser altimeter)then this height can be used to determinean adjustment factor for the whole

profile. 2) There is slop room in thehorizontal positioning of themeasurement. Again, the profile can be“stretched” and still hold its relativeshape and value, and 3) It provides asuccinct visual method of presentingcopious measurements. Heightsmeasured in this study are relativeheights. This means they are notdetermined with reference to someagreed upon “sea level” or the center ofthe moon. Instead, the difference inheight between the point of the featurecasting the shadow and the tip of theshadow is calculated. Ideally, as a checkfor calibrating relative heightmeasurements, a nearby individualfeature’s relative vertical displacementwould have been accurately measuredwith both the point casting the shadowand the tip of the measured shadowindicated. The LAC maps often havethese types of measurements available,but in this case those measurements onLAC 96 whose placement and length ofshadow were specified were alsomeasured on a waxing moon while ourphotos were of a waning moon (exceptfor one which will be mentioned later).This limited the usefulness of the LACmeasurements for our calibrationpurposes. LTO maps provide the mostdetailed and valuable information forcalibration, but none exist of this area.This left only a few, vague benchmarksby which to gauge our measurements.Previously, I had measured the verticaldisplacement at long. 25.625 eastlongitude, 26.808 south latitude as3050m (Boint, 2001). This measurementhad been done using the same telescopeas in this study, but a Meade 216XTCCD camera, and measurements hadbeen performed using the Lunar

page 19


Observer’s Toolkit. Using LTVT and thecurrent mosaic, the height was found tobe 3940 m on the lower resolution photo.The higher resolution photo yielded avalue of 3770 m. I measured Polybius Fat -950 m on the moderate resolutionphoto and -830 m on the high resolutionphoto. LAC 96 has a relative depthmeasurement of -840 m. With similarshadows between the day of theirmeasurement (as indicated by the linedrawn on the map) and the day on whichour photos were taken and with PolybiusF very close to the Rupes Altai, this is animportant check.It suggests the measurements from themoderate resolution photo are enlargedand should be corrected throughmultiplication by 0.88. Double-checkingthis value for the moderate photo againstthe Altai Scarp itself: LAC 96 has thepoint directly east of Pons F as between2100 m – 2400 m, while I measured it at2200 m in height. With no consistenttrend in the data, it was decided not tomodify the initial measurements by anyadjustment factor. The higher resolutionphoto tested out with a strong correlationon Polybius F.

ResultsFigures 2 – 5, 7-10 have the 0,0 point attheir northernmost extent. LTVT’smeasurement of longitude and latitude isgiven for the 0,0 point. Figures 1(moderate resolution) and 6 (highresolution) show the positions of theother figures. In Figure 3, the dotted linesdenote cliffs which, although backsetfrom the primary cliff face, rise highenough to be seen from a distance as partof the cliff. The dotted lines in Figure 5denote probable heights as the scarpconnects with Piccolomini Crater. The

terrain at the tip of the shadow wasdifficult to decipher. The zeroed-outsection on Figure 8 indicates dataunavailable due to rough terraininterrupting the shadow’s path.Figures 11 – 14 compare the profilesgenerated with the two different photos.Paolo R. Lazzarotti’s photograph wasmany times higher in resolution than wasmine. The ease this lent to positioningand measurement lead me to trustmeasurements from this photo more thanthose from my own—especially when itcomes to a single height. Values from hisphoto are probably much closer to theactual value. However, what stands outon these charts is the similarity betweenthe overall profiles generated.Most differences in this regard can beattributed to: difficulties in horizontalpositioning mostly in my photo(Horizontal positions on Lazzarotti’sphoto vary from the true position by nomore than 570 m according to mymeasurements.), differences in terrain onwhich the shadow tips fell (A rise in theterrain will shorten a measurement and adrop will lengthen one.), and the limits ofearth-based measurements of shadowlength (Traditionally, a ten percent errorrate is the best that can be expected[Davis, 1997].).If measurements from my photo areadjusted so that they perfectly line uphorizontally with those from Lazzarotti’s,the differences fall predominantly nearthe ten percent range. This lends a highlevel of credence to the profilesgenerated. The agreement in overallprofile shape generated for the part ofRupes Altai adjacent to PiccolominiCrater is remarkable given the difficultiesin deciphering the image on the lowerresolution photo. The profiles could

page 20


Figure 5

Figure 6

page 21


Figure 7

Figure 8

Figure 9

Figure 10

page 22


Figure 11

Figure 12

page 23


Figure 13

Figure 14

page 24


easily have varied as greatly as theheight measurements. Again, thissupports the validity of the profiles.

Acknowledgements: I want to thank P.Lazzarotti for taking a remarkable photoof Rupes Altai and sharing it for thiswork.

References

[1] Boint, S. 2001. Lunar ElevationsDetermined Using a CCD-based ShadowMethod. Thesis. Augustana College,Sioux Falls, SD.URL:h t t p : / / t h e - m o o n . w i k i s p a c e s . c o m /Rupes+Altai. (last date accessed: 22 April2008).

[2] Cherrington, E.H. 1969. (2nd Ed.1984). Exploring the Moon ThroughBinoculars and Small Telescopes. Dover.ISBN: 0486244911. URL:h t t p : / / t h e - m o o n . w i k i s p a c e s . c o m /Kurt+Fisher+crater+depths. (last dataaccessed: 22 May 2008).

[3] Davis III, W.F. 1997. Determinationof Lunar Elevations by the ShadowMethod: Analysis and Improvements.URL:http://zone-vs.com/vertical-studies.pdf.(last date accessed: 12 January 2008).

[4] Elger,T. 1895. The Moon: A FullDescription and Map of its PrincipalPhysical Features URL:h t t p : / / t h e - m o o n . w i k i s p a c e s . c o m /Rupes+Altai. (last date accessed: 22 May2008).

[5] Fisher, K.A. 2007. “The ThirdDimension: Crater Depths From The

Apollo Era To The Present”. SelenologyToday , 5:17-61. URL: ht tp: / /digilander.libero.it/glrgroup/journal.htm.(last date accessed: 3 January 2008).

[6] Hartmann, B. Wood, C. 1971. “Moon:Origin and Evolution of Multi-ringBasins.” Moon 3. 3-78.

[7] Mosher and Bondo, 2006. Jim’sLunar Terminator Visualization Tool.URL:http://inet.uni2.dk/~d120588/henrik/jim_ltvt.html. (last date accessed: 3January 2008).

[8] The-Moon Wiki.URL: http://the-moon.wikispaces.com/Introduction. (last date accessed: 22 April2008).

[9] U.S. Air Force, NASA andAeronautical Chart and InformationCenter, 1965. (1st Ed.) Lunar AeronauticalChart (LAC) 96: Rupes Altai.URL:ht tp: / /www.lpi .usra.edu/resources/mapcatalog/LAC/lac96/150dpi.jpg. (lastdata accessed: 22 May 2008).

[10] Viscardy, G. 1985. Atlas-guidephotographique de la lune: ouvrage dereference a haute resolution. Masson.

page 25


ISBN/ISSN/EAN: 2-+225-81090-7.URL:h t t p : / / t h e - m o o n . w i k i s p a c e s . c o m /Kurt+Fisher+crater+depths. (last dataaccessed: 22 May 2008).

[11] Westfall, J.E. 2000. Atlas of theLunar Terminator. Cambridge UniversityPress.

[12] Wood, C. 2008. Four Rings And aMystery. Lunar Photo Of The Day, Feb.4, 2008.URL:h t t p : / / t h e - m o o n . w i k i s p a c e s . c o m /LPOD+Feb+4%2C+2008. (last dateaccessed: 23 April 2008).

[13] Wood, C. 2006. A Fault OfConsequence. Lunar Photo Of The Day,May 17, 2006.URL:http://www.lpod.org/?m=20060517. (lastdate accessed: 23 April 2008).

[14] Wood, C. 2006. Rings Around APiddle. Lunar Photo Of The Day, October22, 2006.URL:http://www.lpod.org/?m=20061022. (lastdate accessed: 23 April 2008).

[15] Wood, C. 2003. The Modern Moon:A Personal View. Sky Publishing Corp.ISBN: 0-933346-99-9. 111-112.

page 26

GEOLOGIC LUNAR RESEARCH SELENOLOGY TODAY # 10

Ca l ibra t io n of Sma l lTelescope Lunar SpectralImages Using Keck 120 ColorReflectance DataBy Richard EvansGeologic Lunar Research (GLR) Group

IntroductionMultifilter spectral images of lunarfeatures must be calibrated if usefulspectra are to be produced from them.The usual technique is to divide eachwavelength image by one percent of thegreyscale value of the Apollo 16 landingsite acquired with the same equipment andat the same time. The image is thenmultiplied by the reflectance of the Apollo16 soil sample #62231 for the samewavelength. For images in 16 bit TIFFformat, a multiplicative scaling factor of0.000135 is applied to each wavelengthimage.Keck 120 color reflectance data wereacquired in the 1970s and 1980s for a

large number of lunar features andapproximately 400 reflectance vswavelength data files are availabe fordownload. The geographic area imagedin the production of these spectra wasabout 5 to 10 kilometers in diameter.These spectra were acquired as relativereflectance and calibrated to scaleddirectional hemispheric reflectance datausing spectra of the Apollo 16 soil sample#62231 acquired by JB Adams. Ifdesired, data conversion factors fortransformation of this directionalhemispheric data to bidirectionalreflectance are available at the websitelisted above. Data conversion allowsdirect comparison of results withClementine data. These Keck reflectancedata can be used to calibrate images oflunar features taken through multipleinterference filters using a smalltelescope. Calibration methods arediscussed below.

MethodologyOn September 20, 2007 beginning at03:00 UT, lunar spectral images wereacquired of Copernicus using a 9.25 inchF10 Schmidt Cassegrain telescope with aset of interference filters covering thespectral range of 650 nm to 1600 nm.This range required the use of twocameras, a Lumenera 075M (650 nm –1064 nm) and a Goodrich SensorsUnlimited Su320MX (990 nm – 1600nm). Below 1000 nm the filters were in10 nm increments. Between 1000 nmand 1300 nm the filters were in 20 nmincrements and above 1300 nm theywere in 100 nm increments. Thebandpass for the filters was between 10nm and 18 nm. The lunar phase was10.8 degrees and lunar illumination was99.3 percent. Images were co-aligned

AbstractThe purpose of this paper is to demon-strate a technique for calibrating smalltelescope lunar spectral images usingKeck 120 color reflectance data avail-able athttp://pds-geosciences.wustl.edu/missions/lunarspec/ .This calibration data allows for greaterimaging flexibility than using only theApollo 16 landing site as a calibrationstandard. The 120 color Keck data hasalready been calibrated against theApollo 16 soil sample #62231.

page 27


Figure 1

page 28


Figure 2

Figure 3

page 29


using the free software program LTVT(see http://inet.uni2.dk/~d120588/henrik/jim_ltvt.html). The image scale wasapproximately 1.17 km/pixel. Imageswere acquired in 16 bit TIFF format butconverted to BMP format for import intoLTVT. Keck data file HC1201 of thenorth wall of Copernicus was chosen as acalibration standard. Images taken ateach wavelength were divided by onepercent of the greyscale of a 64 pixelboxed area of the north wall ofCopernicus centered at 11.0 degreesnorth latitude and –20.1 degrees westlongitude. Calibration was completed onan EXCEL spreadsheet as describedbelow. The target of interest was thefloor of Copernicus at approximately the5 oclock position corresponding to 9.0north latitude and –19.8 west longitude.The image set was imported into the freeprogram ImageJ as an image sequenceand a 64 pixel boxed area centered atthese coordinates was selected (see http://rsb.info.nih.gov/ij/). The histogramfunction in ImageJ was used to determinethe average reflectance and standarddeviation of the boxed area for eachimage across the wavelength range. Thisdata was imported into an EXCELspreadsheet for further calibration andprocessing. Since the data were in 8 bitformat, the data was converted to 16 bitequivalent format by multiplying by65536/256 and the multiplicative scalingfactor 0.000135 was applied as discussedabove. The result for each wavelengthwas multiplied by the correspondingKeck reflectance value found in Keckdata file HC1012. The reflectance scalewas determined by reference to atheoretical maximally bright greyscalevalue at 1600 nm by applying thecalibration described in this paragraph.

However, for comparison purposes, thecalibrated data was then co-scaled to thereflectance vs wavelength plot for Keckfile H90370 which represented spectracentered at the same coordinates. Thesmall telescope spectra were then splinesmoothed using a Loess algorithm in theprogram TableCurve2D and a continuumline drawn tangent to the spectra at 750nm and 1150 nm. The reflectance curvewas divided by the continuum line tobetter define the mafic absorption troughnear 1000 nm. Trough parametersincluding center, width, depth andintegrated area were calculated andcompared to those obtained using Keckdata from file H90370. Characterizationand interpretation of absorption troughsare discussed by Pieters (1999), Pieters(1993), and Karr (1975).

ResultsSpectra of the floor of Copernicus weretaken of the boxed area shown in Figure 1which lies approximately between 20.2and –20.0 west longitude, and 9.2 and 9.4degrees north latitude. The reflectance andstandard deviation of the boxed area wasobtained from calibrated images co-aligned in a single hypercube. These datawere obtained using the histogramfunction in ImageJ following import of thecube image sequence. The scaledreflectance plot is shown in Figure 2.The spectra obtained were then co-scaledat 800 nm to the Keck reflectance dataH90370 of the floor of Copernicuscentered at –19.8 west longitude and 9.0north latitude. This location is immediatelyadjacent to the boxed area sampled in thisstudy. The plot of these two data sets isshown in Figure 3. The 9.25 inch SchmidtCassegrain data was subjected to 25percent Loess spline smoothing using the

page 30


Figure 4

Figure 5

Figura 5

page 31


program TableCurve2D and a continuumline was applied at 750 nm and 1250 nm.The resulting curves are shown in Figure4. Finally the reflectance spectra wasdivided by the continuum line in order tobetter observe the absorption trough near1000 nm.

The continuum division plot is shown inFigure 5. The parameters for theabsorption trough near 1000 nm can beestimated from Figure 5. They are shownin Table 1. The continuum division plotfor the Keck H90370 Data is sown inFigure 6.

Trough parameters calculated from thiscontinuum division plot are shown inTable 2.

SummaryThis study shows the result of using Keck120 color reflectance plots of lunarfeatures to calibrate small telescopereflectance data obtained with multipleinterference filters. Copernicus wasimaged and spectra were co-aligned in asingle hypercube image set and calibratedusing Keck spectra of the north wall of thecrater. Spectra were obtained for theregion of the floor adjacent to the lowercentral peak at approximately the 5o’clock position. Spectra from this areaobtained with a small telescope werecompared to Keck data from animmediately adjacent area of the floor ofCopernicus. The co-scaled reflectanceplots and absorption trough parametersfrom the present study closely agreed toresults from the Keck study.

References

[1] Karr, C editor (1975) Infrared andRaman Spectroscopy of Lunar andTerrestrial Minerals. Academic Press.Chapter 4: Interpretation of visible andnear-infrared diffuse reflectance spectraof pyroxenes and other rock formingminerals by JB Adams p. 91-115

[2] Pieters CM (1999) The moon as aspectral calibration standard enabled bylunar samples The Clementine example.Workshop on new views of the moon2:Understanding the moon through theintegration of diverse datasets. Flagstaff,Az. abstract #8025.

[3] Pieters CM and Englert AJ (1993)Remote Geochemical Analysis: Elementaland Mineralogical Composition. Topics inRemote Sensing 4. Cambridge UniversityPress. Chapter 14: CompositionalDiversity and Stratigraphy of the LunarCrust Derived from ReflectanceSpectroscopy. pp. 309-336.

page 32


Table 1

Trough Center Trough Width Trough Depth Trough Area

Copernicus Floor 975 nm 397 nm 3.6 percent 12.54 nm refl.units

Table 2

Trough Center Trough Width Trough Depth Trough Area

Keck H90370Copernicus Floor

960 nm 438 nm 3.6 percent 12.8 nm refl. units

page 33


Figure 7

page 34

HISTORICAL NOTES SELENOLOGY TODAY # 10

TH E O 'N E IL L B R ID GE:DISCOVERY, ANALYSIS ANDSUBSEQUENT TRACK INL I T E R AT U R E TO T H EPRESENT

By Francis Graham[*]Observations by Gus Johnson

[*] Kent State University East LiverpoolRegional Campus- East Liverpool Ohio43920

Near Mare Crisium's Cape Olivium, is astrange 12-mile-long feature which hasbeen called O'Neill's Bridge. Discoveredby John J. O'Neill, science editor of theNew York Herald Tribune, July 29,1953,and studied by the famed selenographerH.P. Wilkins, it was originally thought tobe an example of a natural bridge on theMoon, similar to the natural bridgesproduced by erosion in the Americanwest. The “bridge” is located at latitude+17° , longitude +50°.It can be best seen when the Moon isabout 3 days past full. The “bridge” isnow known, from Apollo-Lunar orbiterinvestigations, to be entirely illusory.One of the more astounding artist'sdepictions of the bridge is in Brenna [1].It shows a natural bridge severalkilometers long as seen by a hypotheticalobserver on the lunar surface. It is anastounding illustration, but even Brennaacknowledged that the “natural bridge”was likely illusory and due to shadows.The idea of a natural bridge, in 1953, wasa reasonable hypothesis given the paucityof information that was known about theMoon. When O'Neill and Wilkins madetheir drawings in August, 1953, and

announced this hypothesis based on whatthey observed, they were engaging inscientific behavior of the highest caliber.Very quickly, other scientists began toinvestigate these claims with additionalobservations and very quickly came to theconclusion that they were erroneous. InJanuary, 1954, using a 12-inch refractor,Paul Rocques of the Griffith Observatoryphotographed this area and showed thefan-shaped lighting area that waspresumed from a low sun shining under anatural bridge was really caused by“sunlight coming through a pass and overthe sloping shoulders of the promontories,falling on rising land westward” [2].Unfortunately things became sad at theBritish Astronomical Association. Whenother observers failed to detect the Moonbridge that Wilkins and O'Neill hadreported, they had the lack of tact tosuggest that Wilkins was no longer seeingthings as clearly as he was when younger,and other ad hominem type comments.Wilkins, the greatest selenographer of thepre-Apollo era, resigned from the BAAfollowing this denigration. Gus Johnsonobserved this area with a 3.2-inchAstrophysics f/11 refractor in 1986, 1987and recently in 1995. The fan of lightseems to emerge from under a naturalbridge in the constricted ridge area. Onthe August 23, 1986 observation, whichhe sketched, we can see the shadow ofwhat appears to be a natural bridge. OnOctober 12, 1995 the effect is also there.It is easy to see how O'Neill and Wilkinswould have reached their conclusions. Itwas only careful restudy which producedthe alternative hypothesis. The March 18,1987 sketch shows the ridge of ProclusAA that O'Neill and Wilkins mistook forthe top of the “Bridge”. But the O’NeillBridge remained in popular literature,

page 35


Figure 1

page 36


even though it was pretty muchdisproved as early as 1954! Brenna'sbook did carry the statement that thebridge by then was regarded asshadows, and his painting of it canonly be described as an excellentrepresentat ion of the W ilkinshypothesis. But in the speculativepopular press things quickly got wayout of hand. The first remention of itwas in Frank Edward 's Forteanmasterpiece [3] Stranger Than Silence. Ifirst heard about the Moon Bridge in1960 when I was 9; Jack Freeman used toread us stories from this book around thecampfire at Camp Algonquin nearRillton, PA.The scientific investigation of the “Bridge”kept up, and again there was no evidenceof a natural bridge, and the Ashbrookexp lan at ion seem ed tho rough lysatisfactory. Donald Menzel investigatedthis with the 15-inch Harvard Observatoryrefractor, and reached much the sameconclusions as Ashbrook. Again, thingsdegenerated into ad hominem attacks, UFObuffs declaring him "one of the Armystooges" [4]. Interestingly, in the hindsightof years, we now know Menzel reallywas a consultant for Army intelligence andthe CIA [5]. But of course, this adhominem stuff has nothing to do with thequestion of the O'Neill Bridge.O'Neill and Wilkins never suggested theirBridge was artificial: to them, it was apossible natural bridge similar to thenatural bridges of the American west, aperfectly reasonable and prosaichypothesis, given the very initial 1953observations and the lack of informationabout the geologic processes of the Moonat the time. But with subsequent exposurein the popular speculative press the bridgebecame artificial. As early as 1955 Donald

Keyhoe [6] reported an observation fromPalomar Observatory that the bridge wasdetermined spectroscopically to be made ofmetal.I have tried to trace this observationwithout any success. The Moon was a rareobject for the 200-inch Hale telescope atMt. Palomar. And, what is more, thetechniques of reflectance spectroscopywere not developed until the 1960's, andthe Hale telescope was never used then forreflectance spectroscopy. The telescope allduring the 1950's was almost exclusivelyused for studies of absorption lines ingalaxies, to determine red shift, when thespectrograph was engaged.Jim Oberg [7] analyzed abundant Apolloand Lunar Orbiter photographs of theregion. Good photos are Apollo-15 metricphoto 378, Apollo-15 panoramic mappingcamera photos 9232/9237 [a stereo pair],and Apollo 17 pan camera stereo pair2259/2262, and Apollo 17 hand-held AS-17-149-22793. The edge of the subduedcrater Yerkes runs into a long ridgeconnecting it with the smaller Yerkes E. Itcasts a long shadow at low sun angle.Another ridge, Proclus AA's rim, alsoappears as a raised bridge in the region.The lighting effects cited by Ashbrook takeover, and this is how Wilkins and O'Neillmade the error.But once the announcement gets stuck inUFO Folklore, Oberg points out, it isuncritically repeated and embellished inUFO books, magazines, films. In 1972Don Wilson, who issued a pseudoscientificbook arguing the Moon was a hollowspaceship, repeated the story [8] withoutany critical appraisal or without citing thecritical literature. In the late 1970's, GeorgeLeonard's book Someone Else is on theMoon [9] portrayed not only the O'NeillBridge itself but many other little

page 37


Figure 2

Figure 3

page 38


“bridgelets”. Leonard's book inspired aflurry of other totally pseudoscientificwritings. Earlier, George Adamski hadwritten a totally bogus book on hisconversations with Venusians and howthey had taken him to the Moon, whichwas much more habitable thancontemporary scientific theory suggested[10]. Three decades later, this hoaxer stillhas substantial devotees, among them FredSteckling, who gave an incredible accountof lunar machines [11]. In 1981, Las Vegasobserver Jack Swaney depicted the“bridge” as seen with a small telescope andconsiderable imagination [12] as part of aseries of articles on “Moon Machines” inFate magazine. Again, there was no criticalanalysis. Says Swaney: “The famousbridge is rather small as these things go butI am offering it because of its notorietyamong UFO buffs”.I wrote two detailed critiques of theLeonard, Steckling [13] and Swaney [14]literature. To his credit, Ufologist WilliamH. Moore reprinted these and sold them inhis catalog. In spite of the fact that I wasgentle, the "moon machiners" fought back[15].The O'Neill Bridge still lives on. In arecently published book, Childress [16]continues to perpetuate the myth uncritically.“And the question remains” he asks, “Is thisbridge over the Sea of Crisis area artificialor natural? A trip to the spot should resolvethis problem once and for all.” Of course,the Soviet probe Luna 24 landed in the Seaof Crisis in 1976, and the Crisium area waswell-surveyed geologically [17]. There isno question about the bridge anymore: itdoes not exist. Most sensational popularwriters on the subject continue to ignorethe critical observations, and pretend thatthe Russian and American space programsnewer returned reliable data about the

Moon. Only Brenna included criticalcomments.Childress advertises Steckling's book forsale in the rear of his book onextraterrestrial archaeology in spite of thefact that Adamski is as bogus a theory as atheory can possibly be. Childress alsowrote the book, The Anti-GravityHandbook, which almost also reaches thislevel of bogusness.And so here is a question for those whostudy anomalies. John O'Neill wasdevoted to the propagation of scientificthought in the popular press. H.P.Wilkins was a consumate selenographerwho deeply wanted an accuratescientific knowledge about the Moonand spent his life to substantialcontributions to that aim. If they wouldhave known their justified speculationsabout a natural bridge on the Moon in1953 would end up in a flurry ofpseudoscientific books nearly a half-century later, would they have beenmore restrained?I cannot speak for O'Neill and Wilkins[who have both passed away] but I canrender a considered opinion. It is notgood for science to restrain thought lestthe popular speculative press misuseone's ideas. The true philosopher can notworry about such social ancillaries in hisquest for knowledge. We must be bravein advancing hypotheses.It is the teacher and the popularizer whomust serve their responsibilities to givea thorough and critical appraisal to thelevel of education they address.Wilson, Childress, Adamski, Stecklingand Leonard -and their publishers-victimize their audiences by falselyclaiming their books are non-fiction, orpretend to be a scientific appraisal.But, since science includes such

page 39


Figure 4

page 40


critical material, which is missing in thesepopular works, it is as much a fraud assomeone selling abridged dictionarieswhile claiming they are unabridged.

It's pretty clear though, that since theO'Neill Bridge has entered this genre ofself-feeding literature, it is likely to bearound for a long, long time.

Reprint from Selenology 14, 41995

References

[1] Brenna, Virgilio The Moon GoldenPress, NY. 1963. p. 93.

[2] Ashbrook, Joseph. "Is there a Bridgeon the Moon?” Sky and Telescope 13[April 1954] p. 205.

[3] Edwards, Frank Stranger than ScienceAce Books, N.Y.1959

[4] Flying Saucers. May, 1959, p. 73.

[5] Blum, H. Out There: TheGovernment's Secret Quest forExtraterrestrials. Simon and Schuster,1990 p. 250. Blum is a history Ph.D. whowrites about the history of UFOlogy.

[6] Keyhoe, Donald. The Flying SaucerConspiracy Fawcett Books, Greenwich,CT. 1955.

[7] Oberg, Jim. Modern Moan Myths andUFO Folklore, 1977. Manuscript.

[8] Wilson, Don. Our MysteriousSpaceship Moon Dell, N.Y.1975 p.12-13.

[9] Leonard, George. Someone Else isOn the Moon Pocket Books, NY. 1977.p. 17, 170.

[10] Leslie, Desmond and Adamski,George Flying Saucers Have LandedBritish Book Center, N.Y.1953.

[11] Steckling, Fred. We DiscoveredAlien Bases on the Moon GAF, Vista,CA. 1951.

[12] Swaney, Jack. Something's Up There.Fate August, 1981 p.112-113.

[13] Graham, Francis G. There are NoAlien Bases on the Moon. Selenology 1,2 -1983. pp. 5-31.

[14] Graham, Francis G. Moon Machinesare Illusions. Selenology 6,2- 1987. pp. 6-13.

[15] Bach, Felix. Shame on You, FrancisGraham! Selenology 7,1-1988. pp. 2-5.

[16] Childress, David H. ExtraterrestrialArchaeology Adventures Unlimited Press,1995. p. 41.

[17] Merill, RB., editor, Mare Crisium:The View from Luna 24. PergammonPress, NY. 1978.

page 41


A Study about Rupes Recta, RimaBirt, and two bisected domes nearBirtBy Raffaello Lena, Christian Wöhler,Maria Teresa BreganteGeologic Lunar Research (GLR) group

1.IntroductionMare Nubium, located in the south-central region of the lunar near sidebetween 0° and 30° S and 0° and 30° W,

Abstract

In this article we describe the results ofa study about the slope and height ofRupes Recta, the origin of a narrowrille extending perpendicular to RupesRecta, and the the morphometric andrheologic results for two bisected domessituated at the northern end of RimaBirt, termed Birt 1 and 2. According toshadow length measurements performedin telescopic CCD images acquired atlow illumination angles, the height ofthe fault amounts to 490 m in its centralpart and decreases towards the northand south. Based on Lunar Orbiter im-ages, we determine a width of the faultof 1280 ± 70 m. This value is lower thanthe values around 2500 m usually re-ported in the literature for Rupes Recta.Accordingly, the slope angle is about21° for the highest and steepest part ofthe fault while it decreases towards thenorth and south, where slopes of about19° and 18°, respectively, are obtained.The diameters of the domes Birt 1 and 2are determined to 16.0 ± 0.5 km and 7.8± 0.5 km. Their heights amount to 170± 20 m and 70 ± 10 m, resulting in flankslopes of 1.22° ± 0.14° and 1.03° ±0.15°. The edifice volumes correspondto 17.3 and 1.3 km³. The dome Birt 1belongs to class C1 in the GLR classifi-cation scheme while Birt 2 belongs toclass C1 with a tendency

towards class C2 due to its smaller di-ameter and lower edifice volume. Basedon rheologic modelling we obtained ef-fusion rates of 623 and 228 m3 s-1,magma viscosities of 5.7 x 105 and 4.5 x104 Pa s, and durations of the effusionprocess of 0.88 and 0.18 years, respec-tively. Furthermore, we derive an ap-proximative method for estimating thepressure gradient dp/dz that occurredduring dome formation based on theobserved length of the linear rille thatbisects the surface of Birt 2. Assumingthat the length of the feeder dike thatformed Birt 2 corresponds to the ob-served length of the linear rille of 18.2km, we obtain a pressure gradient of1043 Pa m-1, a dike width of 4.1 m, anda magma rise speed of 3.1 x 10-3 m s-1.For the dome Birt 1, the same pressuregradient yields a dike which is 50 kmlong and 11.2 m wide through which themagma ascended at a speed of 1.1 x 10-3

m s-1. Under the realistic assumptionthat the elastic stiffness of the lunarcrust amounts to between 20 – 30 and100 GPa, the pressure gradient is lar-ger than 600 – 700 Pa m-1 and mayreach values of up to 1320 Pa m-1.These pressure gradients are difficult toexplain solely by a positive magmabuoyancy due to the density differencebetween the material of the crust andthe ascending magma, such that an ex-cess pressure in the magma reservoirappears to be inevitable to allow theascent of magma to the surface.

page 42


Figure 1

page 43


has undergone a long and complexvolcanic activity. Multiple flows ofdifferent ages and compositions haveresurfaced the basin floor (Holt, 1974).Rose and Spudis (2000) have mapped thestratigraphy of Mare Nubium andreconstructed the volcanic history of thisregion of the Moon. They report fivedifferent units of different age,composition, and thickness of the lavaflows. Rose and Spudis identified that thelava flows in Mare Nubium fall into thelow and medium Titanium category,corresponding to 3-6.5 wt%. Based onthe age and volume estimates, Rose andSpudis (2000) suggest rapid effusiveeruptions of high volume flows lasting afew weeks or months. Rima Birt is a rillewith a length of more than 50 km. Twodomes are situated at the northern end ofRima Birt, supporting a volcanic originof the rille. The 120 km long RupesRecta lies on the eastern shore of MareNubium and is the best-known lunarfault. According to Wilhelms (1987), itwas created by the shock wave of theimpact that formed Mare Imbrium andwas later activated by lava loading withslippage on its western side. When thesunrise terminator is situated close toRupes Recta, a long shadow can be seenwest of the fault. During sunset, the faultappears very bright as its sloped surfacethen faces the sun.In this article we examine the slope andheight of Rupes Recta and compare theresults with preceding data in theliterature (cf. Section 2). We furthermoredescribe and examine a nearby narrowrille running perpendicular to RupesRecta. Moreover, we perform a detailedexamination of the two domes at thenorthern end of Rima Birt, which wehave termed Birt 1 and Birt 2. Based on

telescopic CCD observations carried outunder oblique illumination conditions,we examine their morphometriccharacteristics by making use of acombined photoclinometry and shapefrom shading approach (Horn, 1989;Wöhler and Hafezi, 2005; Lena et al.,2006; Wöhler et al., 2006). The obtainedvalues are used to derive informationabout the physical parameters of domeformation (lava viscosity, effusion rate,duration of the effusion process, magmarise speed, dike dimensions), employingthe rheologic model by Wilson and Head(2003). We provide a geologicalinterpretation of our spectrophotometric,morphometric, and rheologic modellingresults, comparing them to thecorresponding parameters observed fortypical lunar mare domes.

2. Rupes Recta: an overview

Several articles report height values forRupes Recta in the range between 200 to400 m (Ashbrook, 1960; Boint, 2003;Vandenbohede, 2005). Ashbrook (1960)reports a height of 260 m on the northernend and 370 m near the centre of thefault. The two locations measured byAshbrook are given as lunar orthographiccoordinates, which translate into (8.32°W, 20.06° S) and (7.71° W, 21.35° S),respectively. At the same coordinates,Boint (2003) calculates average heightsof 280 m and 450 m, respectively. Basedon shadow length measurements,Vandenbohede (2005) reports a height ofabout 300 m in the centre. The height ofRupes Recta diminishes slightly towardsthe south while towards the north, theheight decreases until the fault fadesaway in the mare plane (Vandenbohede,

page 44


Figure 2

page 45


2005). Further measurements arereported by Viscardy (1985) andCherrington (1969), who obtain heightvalues of 300 m and 360 m, respectively.Different slope angles have been reportedin the literature. North (2000) reports anaverage value of 7°, Legault and Brunier(2004) measure a slope of 10°.Vandenbohede (2005) estimates a slopeangle of about 15° for the upper part ofthe fault, which decreases towards itslower part probably due to slumping.Wood (2003) reports that the fault mayrise as much as 450 m above the basin'swestern floor and that it rises relativelysteeply above the mare plain at an angleof more than 20°. The largest slopevalues are given by Dethier (1988) andAshbrook (1960), who observe themoment in time when the shadow cast bythe fault vanishes. Dethier reports a slopeangle of 40° while Ashbrook measures avalue of 41° ± 3°. Furthermore, a typicalwidth of 2-3 km is usually reported forthe fault (Wikipedia, 2008). Rükl (2004)in his Atlas of The Moon reports a widthof 2.5 km. Hence, assuming a height ofabout 300 m a width of about 2.5 kmyields a slope of 7°. A height of 400 mwould imply a slope of 9°.

2.1 Sunrise illumination: Shadow lengthsand height of the faultThe height values obtained in this studywere computed using the LTVT softwarepackage by Mosher and Bondo (2006)which requires a calibration of the imagesby identifying the precise selenographiccoordinates of some landmarks on theimage. This calibration was performedbased on the UCLN 1994 list of controlpoints. The computed heights wereobtained with the shadow length methodbased on the sun angle at specific locations

of the fault and the angular distance fromthis point to the tip of the shadow. In thefigures reported in this article, north is tothe top and west to the left. Fig. 1 displaysRupes Recta under a low solarillumination. The image was taken onSeptember 30, 2006, at 17:50 UT by R.Lena using a 130 mm TMB refractor. Fig.2 was made on April 6, 2006, at 19:26 UTby C. Wöhler using a 200 mm Newtoniantelescope. The results of our shadowlength measurements are shown in Table1.

2.2 Sunset illumination: width of the faultThe width of the fault, measuredperpendicular to the direction in which it isrunning, was determined by measuring thepixel coordinates (u1, v1) and (u2, v2) ofcorresponding locations on both sides ofthe fault, respectively, as described in ourpreceding articles (Wöhler et al, 2006;Wöhler et al, 2007a). Fig. 3 displaysRupes Recta under sunset illumination.This image was taken on August 06,2007, at 03:27 UT by R. Lena with aMaksutov-Cassegrain f/15 of 180 mmaperture. In this image, the fault appears asa bright line. The width of Rupes Rectawas computed as 1.34 ±0.5 km (cf. Table2).

2.3 Width of the fault measured on LunarOrbiter imageWöhler et al (2007c) show thatexcessively large values measured in thetelescopic images for the width of a faultare caused by the effect of the pointspread function (PSF) due to thetelescope aperture and, moresignificantly, the seeing, leading to aneffective image resolution which iscomparable to or lower than the faultwidth. This effect typically occurs for

page 46


Figure 3

page 47


narrow faults observed when they appearbrighter than their surrounding. Hence,we estimated the width of Rupes Rectausing a Lunar Orbiter image (Fig. 4). Thescale is 68 m per pixel, computed basedon the diameter of the crater Birt of 17km. In this image, the fault is not widerthan 20 pixels, corresponding to 1.28 ±0.07 km. The width obtained from thetelescopic image shown in Fig. 3 is ingood agreement with the Lunar Orbiterimage; hence, our measured width valueis different from the commonly citedaverage value of 2.5 km according toRükl (2004).

2.4 Slope of the faultBased on the data we measured, the slope of the Recta fault was computed usingthe relation

= arctan (h/w), (1)

where h and w denote the averagecomputed height and the width of the fault(see Section 2.3), respectively, determinedfor a specific location. Based onmeasurements of the shadow length andthe width of Rupes Recta, the height andthe slope angle of the fault were calculatedfor several locations. Our results arereported in Table 3. The height of the faultamounts to 490 m near the centre anddecreases towards the nor th .Correspondingly, the slope angle is about21° for the highest and steepest part of thefault and decreases towards the north andthe south, where a slope of about 19° and18°, respectively, was computed (Table3). These measurements are drawn as aprofile in Figure 5.

Images independently acquired understrongly oblique illumination conditions(cf. Section 2.1) provide highlyconsistent results for the height of the

fault. In contrast, the height value givenby Ashbrook (1960) are systematicallylower than our measurements. Similarly,his slope estimates are systematicallyhigher than ours. The high slope valuereported by Ashbrook (1960), measuredbased on the moment in time when theshadow cast by the fault vanishes, ispossibly due to the fact that the shadowdoes not disappear suudenly, but a trueshadow on the fault can be easilyconfused with a dark penumbral tone stillpresent after the shadow has disappearedand sunlight reaches the surface of thefault under an oblique angle. Similarly,from the literature (Rükl, 2004) the faultwidth appears to have beenoverestimated by a factor of about two.As shown by Wöhler et al. (2007c) themeasured width of the fault is affected bythe PSF, such that the slope derived maybe clearly too low. The width of the faultwe estimated using the Lunar Orbiterimage shown in Fig. 4, which is largelyunaffected by a PSF on scales of 1 km,amounts to 1.28 ± 0.07 km. Hence, theslope is fairly high, compared to themeasurements reported in the literature(North, 2000; Legault and Brunier, 2004;Rükl, 2004). Our slope value of 21° inaccordance with the measurementsobtained by Wood (2003).The height and slope of Rupes Recta arecomparable to the corresponding valuesof Rupes Bürg described in the study byWöhler et al (2007c). Rupes Bürg has aheight of 400 m and a slope of 19° in itshighest and steepest part. On thecontrary, Rupes Cauchy in MareTranquillitatis is lower than Rupes Rectaand Rupes Bürg. Wöhler et al. (2006)determine the height of Rupes Cauchy as340 m in the centre, slightly decreasingtowards the south. The slope angle is

page 48


Figure 4

page 49


about 12° for the highest part of the faultand decreases towards its northern andsouthern end.

3. An unnamed linear rille on thenortheastern side of Rupes RectaA narrow unnamed linear rille is situatedon the northeastern side of the RupesRecta. The rille starts with a shallowcrater-like depression that resembles acollapse pit and then narrows as itapproaches the fault. This rille isapparent in the image shown in Fig. 2.There is no evidence that it continuesbeyond Rupes Recta. This rille is notmapped in the lunar charts USGS I-822and LAC 95.Fig. 6 displays the rille under stronglyoblique illumination. The image wastaken on February 14, 2007, at 20:10 UTby R. Lena using a f/15 MaksutovCassegrain of 180 mm diameter. Thepossible collapse pit is located atselenographic coordinates 6.73°W and19.75°S. It is of elongated shape has amajor axis of about 16 km. We estimatedits depth by measuring the length of theshadow cast by its rim, which yields adepth of 80 ± 20 m. Note that the depth-to-diameter ratio is significantly differentfrom the value 1/5 which is typical forsmall fresh impact craters of similardiameter (Pike, 1974; Wood andAndersson, 1978).The narrow linear rille also appears inClementine UVVIS imagery taken athigh solar elevation angles. It is markedby green arrows in the Clementineimages shown in Figs. 7 and 8. Likelythis linear rille was formed by the stressfield built up by a pressurised dike thatdid not reach the surface but ascendedalong a crustal fracture to a shallowdepth below the lunar surface, a

mechanism suggested by Petrycki andWilson (1999) for similar narrow linearrilles like Rima Sirsalis or Rima Parry V.

4. Rima Birt and bisected domesRima Birt is a slightly curved rille of morethan 50 km length. At its northern end therille merges into an elongated ventbisecting a dome, which is termed Birt 1(B1) in this study (cf. Figs. 2, 3, and 10).Interestingly, a second rille cuts thewestern edge of the dome Birt 1, which isconnected with the vent of another dometo the north, termed Birt 2 (B2). Thedomes Birt 1 and Birt 2 are located at(9.66° W, 20.73° S) and (9.98° W, 20.39°S), respectively. A Lunar Orbiter image ofthe two rilles is shown in Fig. 9 (mosaic ofimages IV-113-H1 and IV-113-H2). Theassociation of two rilles with the domes isstrongly indicative of volcanic origin.Moreover, Rima Birt has an offset in itscentral section, as visible in Figs. 7 and 8(marked by a red arrow). These offsets areunlikely to appear in a lava channel or tubeproduced by flowing lava.Our interpretation is that lava melt trackedup a fault in this region, bowed up thesurface, and fractured it, resulting in atleast two rilles. Parts of the intrudedmagma reached the surface, thus formingthe domes at the northern end of RimaBirt. Possibly the two rille segmentsformed as a surface expression of twoseparate dikes. Presumably, the dome-forming effusive volcanism was connectedwith pyroclastic activity as the Birt domesare located in a patch of dark soil likelyrepresenting pyroclastic material (Holt,1974).

4.1 Spectral properties of the bisecteddomes

We determined a UVVIS five-band

page 50


Figure 5

Figure 6

page 51


spectrum of the domes based onClementine imagery at the wavelengths of415, 750, 900, 950, and 1000 nm. Thereflectance values were derived relying onthe calibrated and normalised ClementineUVVIS reflectance data as provided byEliason et al. (1999). The extractedClementine UVVIS data were examined interms of 750 nm reflectance (albedo) andthe R415/R750 and R950/R750 colour ratios.Albedo at 750 nm is an indicator ofvariations in soil composition, maturity,particle size, and viewing geometry. TheR415/R750 colour ratio essentially is ameasure for the TiO2 content of maturebasaltic soils, where high R415/R750 ratioscorrespond to high TiO2 content and viceversa (Charette et al., 1974). However, formany lunar regions the relation betweenR415/R750 ratio and TiO2 content displays asignificant scatter (Gillis and Lucey,2005). The R950/R750 colour ratio is relatedto the strength of the mafic absorptionband, representing a measure for the FeOcontent of the soil, and is also sensitive tothe optical maturity of mare and highlandmaterials (Lucey et al. 1998). The samplearea amounts to 2 x 2 km2

. Both domes arespectrally red with their low R415/R750 ratioof about 0.59, indicating a low TiO2

content of less than 2 wt% according toGillis and Lucey (2005). The ClementineUVVIS spectral data of the dome Birt 1reveal a 750 nm reflectance of R750 =0.0985, a low value for the UV/VIS colourratio of R415/R750 = 0.5935, and a weakmafic absorption with R950/R750 = 1.02164.The spectral data for the northern domeBirt 2 indicate a 750 nm reflectance of R750

= 0.0978, a low UV/VIS colour ratio ofR415/R750 = 0.5961, and a weak maficabsorption with R950/R750 = 1.03977suggesting a high soil maturity.

4.2 Morphometric properties andclassification of the bisected domesThe image shown in Fig. 10 displays thetwo bisected domes Birt 1 and Birt 2located at the northern end of Rima Birt.The image was taken by C. Wöhler onApril 25, 2007, at 19:48 UT using a 200mm Newtonian reflector and a LumeneraLU75M CCD camera.The dome diameters of Birt 1 and Birt 2amount to 16.0 ± 0.5 km and 7.8 ± 0.5 km,respectively. The height values for the twodomes as reported in Table 4 were derivedby a combined photoclinometry and shapefrom shading analysis (Horn, 1989;Wöhler et al, 2006; Lena et al., 2006, andreferences therein). Based on the imageshown in Fig. 10, the height of the domeBirt 1 was determined to 170 ± 20 m,resulting in an average slope of 1.22° ±0.14°. The height of the dome Birt 2 wasdetermined to 70 ± 10 m, yielding a slopeof 1.03° ± 0.15°. The dome volume V wascomputed by integrating the reconstructed3D profile over an area corresponding to acircular region of diameter D around thedome summit. A rough quantitativemeasure for the shape of the dome is givenby the form factor f = V/[πh(D/2)²], wherewe have f = 1/3 for domes of conicalshape, f = 1/2 for parabolic shape, f = 1 forcylindrical shape, and intermediate valuesfor hemispherical shape. For the domesexamined in this study, we thus obtainedifice volumes of 17.3 km³ (f = 0.51) and1.3 km³ (f = 0.39) for Birt 1 and 2,respectively. A digital elevation map(DEM) of the region around Birt 1 and 2 isshown in Fig. 11.Wöhler et al. (2006) introduce anextension of the definitions of classes 1-3of the scheme by Head and Gifford(1980). They base the distinctionbetween these shield-like volcanoes on

page 52


Figure 7

page 53


their associated spectral andmorphometric quantities. Four classestermed A, B, C, and E describingmonogenetic mare domes are establishedessentially according to the diameter,flank slope, volume of the dome edificeand the TiO2 content of its soil. Lena(2007) formulates this scheme as a flowchart, additionally taking into account therheologic properties of the dome-forminglava (cf. also Wilson and Head, 2003). Inthis classification scheme, domes of classC have diameters between 8 and 20 km,with relatively low flank slopes typicallybelow 2°. Domes formed from spectrallyred lavas of low to moderate R415/R750

ratio with large diameters between 13and 20 km and large edifice volumes ofseveral tens of km3 are assigned tosubclass C1, while domes with smallerdiameters between 8 and 13 km andlower edifice volumes are assigned tosubclass C2 (cf. Wöhler et al, 2006;Wöhler et al, 2007a; Lena et al, 2008).Hence, the dome Birt 1 belongs to classC1 while Birt 2 belongs to class C1 with atendency towards class C2 due to itssmaller diameter and lower edificevolume (Table 4 and 5).4.3 Rheologic properties of the domesBirt 1 and 2The rheologic model by Wilson andHead (2003) estimates the yield strengthτ, i. e. the pressure or stress that must beexceeded for the lava to flow, the plasticviscosity η, yielding a measure for thefluidity of the erupted lava, the effusionrate E, i. e. the lava volume erupted persecond, and the duration of the effusionprocess T. The computed values for τ, η, E and T are valid for domes that wereformed from a single flow unit(monogenetic volcanoes). Otherwise, thecomputed rheologic values are upper

limits to the respective true values. Therheologic model by Wilson and Head(2003) yields effusion rates of 623 and228 m3 s-1 for the domes Birt 1 and 2.They were formed from lava of moderateviscosities of 5.7 x 105 and 4.5 x 104 Pa sover a period of time of 0.88 and 0.18years, respectively. For these calculationswe assumed a magma density of ρ = 2900 kg m -3 (Wieczorek et al., 2001).With their high effusion rates, moderateto large erupted lava volumes, and low tomoderate lava viscosities, the domes Birt1 and 2 belong to rheologic group R1

introduced by Wöhler et al. (2007a).Hence, they are similar to many of thedomes in the region around Milichius andTobias Mayer (Wöhler et al., 2006,2007a). Furthermore, Rima Birt, themajor axes of the vents of the domes, theoutflow channel of Birt 1, and the linearrille associated with Birt 2 are oriented inparallel, approximately in the samedirection as Rupes recta and thus radialto the Imbrium basin. Similar alignmentshave been observed in the dome fieldaround Milichius and Tobias Mayer andfor the chain of domes situated innorthern Mare Tranquillitatis. Anotheralignment has been observed for domesin Mare Undarum, radial to Crisiumbasin (Lena et al., 2008). Thesealignments indicate that the domes wereformed by dikes whose ascent wasguided by the crustal fractures and thestress field of the Imbrium impact basinand Crisium impact basin respectively(Wöhler et al., 2007a; Lena et al., 2008).

4.4 Modelling the feeder dike geometryfor the dome Birt 2As shown by Wilson and Head (2003),the inferred rheologic properties can beused to model the magma rise speed U

page 54


Figure 8

page 55


and the geometry of the dike throughwhich the magma ascended, given by thedike width W and the length L. The threeparameters U, W, and L are related to theeffusion rate E by

E = U W L (2)The magma rise speed U is found bybalancing the vertical pressure gradientdp/dz driving the magma upwards (seebelow) against the friction at the dike wall,where the yield strength τ has to beovercome before ascending motion canoccur:

U = [W²/(12 η)] [dp/dz-2τ/W] (3)

Rubin (1993) has shown by modelling apressurised dike propagating in a linearviscoelastic medium that the values of Wand L are not independent of each otherbut that their ratio L/W depends on thelava viscosity η. The ratio p0/G betweenthe magma pressure p0 and the elasticstiffness (Young modulus) G of the hostrock is an important parameter, whichlies in the range between 10-4 and 10-3

and typically amounts to 10-3.5. In theelastic domain, where the viscositycontrast between the host rock and themagma (a broadly accepted value for the“viscosity” of the host rock is 1018 Pa s)is larger than about 12-14 orders ofmagnitude, the ratio L/W is independentof the magma viscosity and increasesapproximately linearly with decreasingvalue of p0/G (Lena et al., 2008). Forhigher magma viscosities the magma andthe host rock are treated as two viscousmedia. In this domain the value of L/Wdecreases strongly with increasingmagma viscosity. Combining the resultsof the viscoelastic model by Rubin(1993) with Eqs. (2) and (3) yields arelation for the dike width W which

cannot be solved analytically but needs tobe computed numerically (Wöhler et al.,2007a).Another important parameter formodelling the geometry of lunar feederdikes is the vertical pressure gradientdp/dz. Most petrologic models of lunarbasaltic magmas suggest an origin bypartial melting at 200-400 km depth(Ringwood and Kesson, 1976). Theclassical model of magma ascent throughthe lunar crust (Head and Wilson, 1992;Wilson and Head, 1996) predicts thatbasaltic melts are less dense than thelunar mantle but denser than theoverlying crust. Hence, without assumingan excess pressureof the magma, basalticdiapirs would rise buoyantly through thelunar mantle but stall near the base of thecrust at the so-called neutral buoyancyhorizon. According to Wilson and Head(1996), the minimum excess pressurerequired to drive magma to the surfacethrough a dike and to erupt it onto thesurface amounts to 21 Mpa for a typical,64 km thick nearside crust,corresponding to a pressure gradient ofdp/dz = 328 Pa m-1. More recently,Wieczorek et al. (2001) introduced adifferent model of basaltic magma ascentwhich assumes a dual-layered structureof the lunar crust. They show thatbasaltic magma should be less dense thanthe material of the lower crust. In placeswhere the upper anorthositic crust wasremoved by an impact event, basalticmagma could have been driven to thesurface by its positive buoyancy alone.These findings are supported byestimates of the thickness of the lowerand the upper crust based on the analysisof gravity anomalies (Wieczorek et al.,2006), indicating that mare basalts arepresent where the upper crust is found to

page 56


Figure 9

page 57


be absent. In this model, the drivingpressure gradient is given bydp/dz = g Δρ, where g = 1.63 m s-1

denotes the acceleration due to gravityand Δρ the density difference betweenthe ascending magma and the crustalmaterial. For basaltic magmas of lowTiO2 content (as found in the MareNubium region), Wieczorek et al. (2001)derive a density difference of Δρ = 200kg m-3 at liquidus temperature, implyinga vertical pressure gradient of dp/dz =320 Pa m-1. This value is nearly identicalwith the minimum excess pressuregradient of 328 Pa m-1 resulting from theclassical model (Head and Wilson, 1992;Wilson and Head, 1996). In previousworks by Wöhler et al. (2007a) and Lenaet al. (2008) which apply the dike modelby Rubin (1993) to lunar effusive domes,none of the two described models ofmagma ascent could be confirmed basedon observations since the regardedeffusive domes are not associated withlinear rilles indicating the longitudinalextension of the dome-forming dikes.Instead, to compute the dike width W andlength L, a default value of dp/dz = 328Pa m-1 is used.In contrast, we use in this study thevisible expression of the dike of thedome Birt 2, i. e. the linear rille of 18.2km length that bisects the dome surface,in order to estimate the pressure gradientdp/dz that occurred during domeformation. Stratigraphic relations indicatethat the dome Birt 2 and its associatedlinear rille were formed after Birt 1 andthat the domes were not formedsimultaneously, since the surface of Birt1 is cut by the linear rille. Based on thedike model mentioned above with p0/G =10-3.5, a pressure gradient of dp/dz = 1043Pa m-1 is required for a dike length of L =

18.2 km that equals the length of thelinear rille associated with Birt 2.The corresponding dike width amounts toW = 4.1 m and the magma rise speed toU = 3.1 x 10-3 m s-1. For the “defaultvalue” of dp/dz = 328 Pa m-1, the dikemodel would yield U = 3.7 x 10-4 m s-1,W = 11.7 m, and L = 52.5 km – the valueof U is thus approximately proportionalto (dp/dz)² while W and L are inverselyproportional to dp/dz (cf. also Wöhler etal., 2007a). For the larger dome Birt 1,assuming the same pressure gradient ofdp/dz = 1043 Pa m-1 implies U = 1.1 x10-3 m s-1, W = 11.2 m, and L = 50 km(cf. also Table 5). For p0/G = 10-3, apressure gradient of dp/dz = 279 Pa m -1

yields a dike length of L = 18.2 km,while for p0/G = 10-4, this is the case fordp/dz = 2185 Pa m-1. We now model therelation between the logarithmslg(dp/dz)L (where the index L indicatesthat the value of dp/dz yields the dikelength L = 18.2 km) and lg(p0/G) by asecond-degree polynomial Q2, such that

lg(dp/dz)L = Q2(lg(p0/G)) (4)

At the dike entrance, the magma pressurep amounts to p = p0 + pc, where pc is theleast compresive stress of the host rock(Rubin, 1993). At the surface, the valueof p must still be larger than pc sinceotherwise the fracture would not remainopen, and lava effusion would cease.According to Jackson et al. (1997), thevertical extension of the dikeapproximately corresponds to its lengthL. Hence, we may assume for thepressure difference Δp between the dikeentrance and the surface the approximaterelationΔp = pentrance – psurface = L (dp/dz)L ≈p0.

page 58


Figure 10

Figure 11

page 59


This expression is equivalent to

G = [L/(p0/G)] · (dp/dz)L = [L/(p0/G)] ·10^Q2(lg(p0/G)). (6)

Eq. (6) yields the elastic stiffness G ofthe host rock as a function of p0/G for agiven fixed dike length L. For basalt, thevalue of G may range from 16 to 100GPa with an average of 63 GPa (Pollardand Fletcher, 2005); for the terrestrialcrust, values around 10 GPa are adoptedin the literature (Carlino et al., 2006), butthe terrestrial rocks listed by Pollard andFletcher (2005) have typical elasticstiffnesses higher than 20 – 30 GPa; forthe lunar crust, Head et al. (1980) assumeG = 1012 dyn cm-2 = 100 GPa. We foundbased on Eq. (6) that G obtains values inthe range 10 – 100 GPa for p0/G between2.4 x 10-4 and 7.5 x 10-4. This intervalcontains the value 10-3.5 ≈ 3.2 x 10-4

regarded by Wöhler et al. (2007a) as themost likely value for p0/G. Thecorresponding pressure gradient (dp/dz)L

ranges from 441 Pa m-1 for G = 10 GPato 1320 Pa m-1 for G = 100 GPa, whilethe magma pressure p minus the leastcompressive stress pc, denoted byp0 = p – pc, obtains values between 7.5and 24 MPa (cf. Table 6). Forcomparison, a typical value for thecompressive stress in the lunar crust is 15MPa (Wilson and Head, 2008), hence pc

and p0 are of comparable magnitude. Weobserved that the values of (dp/dz)L andp0 are approximately proportional to G1/2.The inferred high value of the pressuregradient is difficult to explain accordingto Wieczorek et al. (2001) by the densitydifference between the material of thecrust and the ascending magma, since therequired density difference Δρ would

then be between 271 and 815 kg m-3. Forall types of basaltic magma regarded byWieczorek et al. (2001), these values ofΔρ cannot be obtained at liquidustemperature except when a very lowelastic stiffness G of the host rock of G ≈10 GPa and superheated magma isassumed. For the magma compositionslisted by Wieczorek et al. (2001), thedensity difference between magma andlower crust (the latter being more than200 kg m-3 denser than the upper crust) atthe liquidus point hardly exceeds 250 kgm-3. For magmas of low Titaniumcontent like those encountered in theRupes Recta region, the densitydifference is typically 180 – 200 kg m-3

or lower. Furthermore, the magmaviscosities around 105 Pa s inferred forthe domes Birt 1 and 2 are not consistentwith superheated basaltic magma, whichshould have a viscosity lower than 1 Pa s,where the latter value corresponds to theviscosity found by Murase and McBirney(1970) for the magma that formed themare plains. On the contrary, duringdome formation the magma temperaturelikely was even below the liquidus pointand crystallisation began to occur(Wöhler et al., 2007a). Hence, if valuesof the crustal elastic stiffness G largerthan 20 – 30 GPa are assumed, andespecially when G = 100 GPa accordingto Head et al. (1980) is adopted, theassumption of an excess pressure in themagma reservoir as proposed by Wilsonand Head (1996) appears to be inevitable.

5. Summary and conclusionIn this study we have presentedmeasurements of the height and slope ofRupes Recta, considerations about theorigin of a narrow linear rille runningperpendicular to Rupes Recta, and

page 60


computations of the morphometric andrheologic properties of the two bisecteddomes Birt 1 and 2 situated at the northernend of Rima Birt.According to shadow length measurementsperformed in telescopic CCD imagesacquired at low illumination angles, theheight of the fault amounts to 490 m in itscentral part and decreases towards thenorth and south. Based on Lunar Orbiterimages, we have determined a width of thefault of 1280 ± 70 m. This value is lowerthan the width of about 2500 m usuallyreported in the literature. Accordingly, theslope angle amounts to 21° for the highestand steepest part of the fault and decreasestowards the north and south, where wemeasured slopes of about 19° and 18°,respectively. We have thus confirmed thesteep slope angle reported by Wood(2003). We found that the diameters of thedomes Birt 1 and 2 correspond to 16.0 ±0.5 km and 7.8 ± 0.5 km, respectively. Thedome heights were determined to 170 ± 20m and 70 ± 10 m, resulting in flank slopesof 1.22° ± 0.14° and 1.03° ± 0.15°. Theedifice volumes correspond to 17.3 and 1.3km³, respectively. The dome Birt 1belongs to class C1 in the GLRclassification scheme (Wöhler et al., 2006;Lena, 2007) while Birt 2 belongs to classC1 with a tendency towards class C2 due toits smaller diameter and lower edificevolume. According to the rheologic modelby Wilson and Head (2003) we obtainedeffusion rates of 623 and 228 m3 s-1 for thedomes Birt 1 and 2, magma viscosities of5.7 x 105 and 4.5 x 104 Pa s, and durationsof the effusion process of 0.88 and 0.18years, respectively.

We have derived an approximative methodfor estimating the pressure gradient dp/dzthat occurred during dome formation basedon the observed length of the linear rillethat bisects the dome surface. Presumably,this rille is the surface manifestation of thefeeder dike through which the dome-forming magma ascended. Thus, assumingthat the dike length corresponds to theobserved length of the linear rille of 18.2km, we obtained for Birt 2 a pressuregradient of 1043 Pa m-1 , a dike width of4.1 m, and a magma rise speed of 3.1 x10-3 m s-1. For the dome Birt 1, the samepressure gradient yields a dike which is 50km long and 11.2 m wide through whichthe magma ascended at a speed of 1.1 x10-3 m s-1. Under the realistic assumptionthat the elastic stiffness of the lunar crustamounts to between 20 – 30 and 100 GPa,the pressure gradient is larger than 600 –700 Pa m-1 and may reach values of up to1320 Pa m-1. We have shown that thesepressure gradients are difficult to explainsolely by a positive magma buoyancy dueto the density difference between thematerial of the crust and the ascendingmagma, and that an excess pressure in themagma reservoir appears to be inevitableto allow the ascent of magma to thesurface.

page 61


Table 1: Shadow length measurements obtained using the images shown in Figs. 1 and 2. The measurements were com-puted with the LTVT software package. (*) In Fig. 2, the shadow tip is undefined at the northern end of the fault.

Table 2: Width of Rupes Recta obtained using the image shown in Fig. 3. The results are in agreement with theLunar Orbiter image. We thus adopt the width of 1.28 ± 0.07 km measured in the Lunar Orbiter image.

Longitude [°] Latitude [°] Solar altitude [°] Width [km]

-8.17 -20.42 6.09 1.34 ± 0.30

-7.97 -20.82 5.92 1.34 ± 0.30

-7.81 -21.37 5.75 1.34 ± 0.30

-7.68 -21.66 5.60 1.34 ± 0.30

-7.60 -21.97 5.57 1.34 ± 0.30

-7.39 -22.55 5.24 1.34 ± 0.30

-7.21 -23.03 5.06 1.34 ± 0.30

Figure 1 Figure 2

Longitude [°] Latitude [°] Solar altitude [°] Height [m] Solar altitude [°] Height [m]

-8.32 -20.12 2.50 294±30 1.64 -- -- (*)

-8.17 -20.42 2.63 429±30 1.73 436±20

-7.97 -20.82 2.81 464±30 1.91 475±20

-7.81 -21.31 2.95 483±30 2.09 495±20

-7.68 -21.66 3.08 480±30 2.19 488±20

-7.60 -21.97 3.15 454±30 2.26 467±20

-7.39 -22.55 3.33 425±30 2.43 429±20

-7.21 -23.03 3.47 402±30 2.52 415±20

page 62


Table 3: Height and slope values obtained for different locations along Rupes Recta.

Longitude[°]

Latitude[°]

Width measured in Lunar Or-biter image [km]

Height[m]

Slope[°]

-8.17 -20.42 1.28±0.07 436 ± 30 18.81

-7.97 -20.82 1.28±0.07 469 ± 30 20.12

-7.81 -21.37 1.28±0.07 489 ± 30 20.91

-7.68 -21.66 1.28±0.07 484 ± 30 20.71

-7.60 -21.97 1.28±0.07 460 ± 30 19.77

-7.39 -22.55 1.28±0.07 427 ± 30 18.45

-7.21 -23.03 1.28±0.07 408 ± 30 17.68

Table 4: Morphometric and rheologic properties of the two domes examined in this study.

Dome h [m] Slope [°] D [km] V [km3] η [Pa s] E [m3 s-1] T [years] class

Birt 1 (B1) 170 1.22 16.0 17.3 5.7 x 105 623 0.88 C1

Birt 2 (B2) 70 1.03 7.8 1.3 4.5 x 104 228 0.18 C1-C2

page 63


Table 5: Feeder dike geometries of the domes Birt 1 and 2, assuming p0/G = 10-3.5 ≈3.2 x 10 -4 and dp/dz =1043 Pa m-1, thus assuming a dike length equal to the observed length of the linear rille associated withBirt 2.

Dome U [m s-1] W [m] L [km]

Birt 1 (B1) 1.1 x 10-3 11.2 50

Birt 2 (B2) 3.1 x 10-3 4.1 18.2

Table 6: Quantities characterising the magma pressure as a function of the crustal elastic stiffness, assuming adike length for Birt 2 equal to the observed length of the associated linear rille.Birt 2.

Model parameter G = 10 GPa G = 20 GPa G = 30 GPa G = 100 GPa

dp/dz [Pa m-1] 441 601 742 1320

p0/G 7.5 x 10-4 5.5 x 10-4 4.5 x 10-4 2.4 x 10-4

p0 [MPa] 7.5 10.9 13.5 24.0

page 64


References

[1] Ashbrook, J., 1960. Publications of the Astronomical Society of the Pacific.

[2] Boint, S., 2003. Measuring Rupes Recta, Selenology, vol. 22, no. 1, pp.14-15.

[3] Carlino, S., Cubellis, E., Luongo, G., Obrizzo, F., 2006. On the mechanics of calderaresurgence of Ischia Island (southern Italy). In: Troise, C., De Natale, G., Kilburn, C. R. J. (eds.),Mechanisms of Activity and Unrest at Large Calderas, Geological Society, London, SpecialPublications, vol. 269, pp. 181-193.

[4] Charette, M. P., McCord, T. B., Pieters, C. M., Adams, J. B., 1974. Application of remotespectral reflectance measurements to lunar geology classification and determination of titaniumcontent of lunar soils, J. Geophys. Res., vol. 79, pp. 1605-1613.

[5] Cherrington, E. H., 1969. Exploring the Moon Through Binoculars and Small Telescopes.Dover, (2nd ed. 1984). http://the-moon.wikispaces.com/Kurt+Fisher+crater+depths.

[6] Dethier, T., 1988. Maanmonografieen. Vereniging voor Sterrenkunde.

[7] Eliason, E., Isbell, C., Lee, E., Becker, T., Gaddis, L., McEwen, A., Robinson, M., 1999.Mission to the Moon: the Clementine UVVIS global mosaic, PDS Volumes USA NASA PDSCL 4001 4078, http://pdsmaps.wr.usgs.gov

[8] Gillis, J. J., Lucey, P. G., 2005. Evidence that UVVIS ratio is not a simple linear function ofTiO2 content for lunar mare basalts. Lunar Planet. Sci. XXXVI, abstract #2252.

[9] Head J. W., Gifford A., 1980. Lunar mare domes: classification and modes of origin, TheMoon and Planets 22, 235-257.

[10] Head, J. W., Solomon, S. C., Whitford-Stark, J. L., 1980. Oceanus Procellarum Region:Evidence for an Anomalously Thin Lunar Lithosphere. Lunar Planet. Sci. XI, pp. 424-425.

[11] Head, J. W., Wilson, L., 1992. Lunar mare volcanism: Stratigraphy, eruption conditions, andthe evolution of secondary crusts. Geochim. Cosmochim. Acta 56, pp. 2155-2175.

[12] Holt, H.E., 1974. Geologic Map of the Purbach Quadrangle of The Moon, USGS I-822.http://www.lpi.usra.edu/resources/mapcatalog/usgs/I822/72dpi.jpg

[13] Horn, B. K. P., 1989. Height and Gradient from Shading. MIT technical report 1105A.http://people.csail.mit.edu/people/bkph/AIM/AIM-1105A-TEX.pdf

[14] Jackson, P. A., Wilson, L., Head, J. W., 1997. The use of magnetic signatures in identifyingshallow intrusions on the moon. Lunar Planet. Sci. XXVIII, abstract #1429.

page 65


[15] Legault, T., Brunier, S., 2004. Le Grand Atlas de la Lune. Larousse.

[16] Lena, R., Wöhler, C., Bregante, M. T., Lazzarotti, P., Lammel, S. 2008. Lunar domes inMare Undarum: Spectral and morphometric properties, eruption conditions and mode ofemplacement. Planetary and Space Science, vol. 56, pp. 553-569.

[17] Lena, R., 2007. Lunar Domes Classification and Physical Properties. Selenology Today, 5,pp. 62-78.

[18] Lena, R., Wöhler, C., Bregante, M.T, Fattinnanzi, C. 2006. A combined morphometric andspectrophotometric study of the complex lunar volcanic region in the south of Petavius. Journalof the Royal Astronomical Society of Canada, vol. 100, no. 1, 14-25.

[19] Lucey, P. G., Blewett, D. T., Hawke, B. R., 1998. Mapping the FeO and TiO2 content of thelunar surface with multispectral imagery, J. Geophys. Res., vol. 103, no. E2, pp. 3679-3699.

[20] Murase, T., McBirney, A. R., 1970. Viscosity of lunar lavas. Science 167, pp. 1491- 1493.

[21] North, G., 2000. Observing the Moon, the modern astronomer’s guide. CambridgeUniversity.

[22] Petrycki, J. A., Wilson, L., 1999. Volcanic Features and Age Relationships Associated withLunar Graben. PLunar Planet. Sci. XXX, abstract #1335.

[23] Pollard, D. D., Fletcher, R. C., 2005. Fundamentals of structural geology. CambridgeUniversity Press, Cambridge, UK.

[24] Pike, R. J. 1974. Depth/Diameter relations of fresh lunar craters: Revision from SpacecraftData, Geophys. Res. Lett., vol. 1, pp. 291-294.

[25] Ringwood, A. F., Kesson, S. E., 1976. A dynamic model for mare basalt petrogenesis. LunarSci. Conf. 7, pp. 1697-1722.

[26] Rose, D.E. and Spudis, P.D., 2000. Stratigraphy of Mare Nubium. Lunar Planet. Sci. XXXI,abstract #1364.

[27] Rubin, A. S., 1993. Dikes vs. diapirs in viscoelastic rock. Earth and Planet. Sci. Lett. 199,pp. 641-659.

[28] Rükl, A., 2004. Atlas Of The Moon. Sky Publishing Corp.

[29] Vandenbohede, A., 2005. Taking the measures of Rupes Recta, The Lunar Observer, no. 1,pp. 3-9.

[30] Viscardy, G., 1985. Atlas-guide photographique de la lune: ouvrage de référence à hauterésolution. Masson. http://the-moon.wikispaces.com.

[31] Wieczorek, M. A., Zuber, M. T., Phillips, R. J., 2001. The role of magma buoyancy on the

page 66


eruption of lunar basalts. Earth Planet. Sci. Lett. 185, pp. 71-83.

[32] Wieczorek, M. A., and 15 coauthors, 2006. The Constitution and Structure of the LunarInterior. Rev. Mineralogy and Geochemistry 60, pp. 221-364.

[33] Wikipedia. http://en.wikipedia.org/wiki/Rupes_Recta

[34] Wilhelms, D. E., 1987. The geologic history of the Moon. USGS Prof. Paper 1348.

[35] Wilson, L., Head, J. W., 1996. Lunar linear rilles as surface manifestations of dikes:theoretical considerations. Lunar Planet. Sci. XXVII, abstract #1445.

[36] Wilson, L., Head, J. W., 2003. Lunar Gruithuisen and Mairan domes: Rheology and mode ofemplacement. J. Geophys. Res. 108(E2), pp. 5012-5018.

[37] Wilson, L., Head, J. W., 2008. Eruption rates of mare lava flows on the Moon andimplications for mantle melt volumes and dike geometries. Lunar and Planet. Sci. XXXIX,abstract #1104.

[38] Wöhler, C., Lena, R., Phillips, J., 2007a. Formation of lunar mare domes along crustalfractures: Rheologic conditions, dimensions of feeder dikes, and the role of magma evolution.Icarus, vol. 189, no. 2, pp. 279-307.

[39] Wöhler, C., Lena, R., Pau, K. C., 2007b. The lunar dome complex Mons Rümker:Morphometry, rheology, and mode of emplacement. Lunar Planet. Sci. XXXVIII, abstract #1091.

[40] Wöhler, C., Lena, R., Phillips, J., Bregante, M.T., Lazzarotti, P., Sbarufatti, G., 2007c.Vertical studies about Rupes Bürg. Selenology Today, 3, pp. 65-79.

[41] Wöhler, C., Lena, R., Lazzarotti, P., Phillips, J., Wirths, M., Pujic, Z., 2006. A combinedspectrophotometric and morphometric study of the lunar mare dome fields near Cauchy, Arago,Hortensius, and Milichius, Icarus, Vol.183, 2, pp. 237-264.

[42] Wöhler, C., Lena, R., Bregante, M.T., Lazzarotti, P., Phillips, J., 2006. Vertical studiesabout Rupes Cauchy. Selenology, vol. 25, no. 1, pp. 7-12.

[43] Wöhler, C., Hafezi, K., A general framework for three-dimensional surface reconstructionby self-consistent fusion of shading and shadow features, Pattern Recognition, vol. 38,no. 7, pp. 965-983, 2005.

[44] Wood, C. A., 2003. The Modern Moon, a Personal View. Sky Publishing Corp.

[45] Wood, C., Andersson, L., 1978. New morphometric data for fresh lunar craters, LunarPlanet. Sci. IX, pp. 3669-3689.

page 67

TERRESTRIAL IMPACT STRUCTURES SELENOLOGY TODAY # 10

The Steinheim Basin

By Alexander Wöhler and Sebastian Wöhler

Geologic Lunar Research (GLR) group

While the Moon's surface is mainly characterised by impact craters, not many impact structures areimmediately apparent on the surface of the Earth. This article gives a short overview of a small impactcrater in southern Germany showing a very distinct topographic profile along with characteristic rockmodifications (Reiff and Heizmann, 2007).

About 15 million years ago a double asteroid impacted into the region east of the mountains of theSwabian Alb in southern Germany. The large asteroid had a diameter of about 1 km and generated a craterof more than 20 km diameter. The smaller asteroid was 100 m large and formed a crater of 4 km diameterin a distance of about 35 km from the first impact site. Today, in the middle of the larger crater the city ofNördlingen is situated, while the smaller crater is partially occupied by the village of Steinheim. Therefore,the large crater has been termed “Nördlinger Ries” (also known as Ries crater) and the smaller one“Steinheimer Becken” (Steinheim basin).

During the impact, the asteroid evaporated completely. For this reason, no meteoritic material is found anymore in and around the crater. The pressure wave caused by the impact energy caused an explosion whichformed a 4 km large and very deep hole. The hot and partially fluidized terrestrial crust bounced back suchthat the crater became shallower and a central peak formed. At the same time, huge masses of dust andimpact melt were ejected.The rock layers into which the asteroid impacted consist of limestone, i. e. primarily calcium carbonate

(CaCO3), formed during the Jurassic age when the Swabian Alb was the bottom of a tropical sea.Inside the crater, the limestone layers were squeezed radially outwards, shattered, tilted, and lifted, leadingto the formation of the crater wall.

Figs. 1-4 provide an impression of the rock modifications and the topographic profile that can be observedtoday.

References

Reiff, W., Heizmann, E. P. J., 2007. Der geologische Lehrpfad im Steinheimer Meteorkrater. Verlag Dr.Friedrich Pfeil, München, Germany.

page 68


Fig. 1: Outcrop at the outer southeastern crater wall. In this image the shatteredlimestone layers are clearly apparent.

page 69

Fig. 2: Shattered limestone block at the outer southeastern crater wall. The rockdisplays a finer texture than in Fig. 1; it was presumably compressed more strongly.


page 70

Fig. 3: The authors examining in the snowstorm a large block of shatteredlimestone.


page 71

Fig. 4 Left:Panorama of the Steinheim basin (view angle 180°), taken from the top of thesouthern crater wall. The crater wall and the central peak are indicated. Thepanorama was generated with the open source software Hugin (downloadfrom http://hugin.sourceforge.net). Link to full image

Upper right:View over a gap in the southern crater wall, which was crossed by a river mil-lions of years ago.

Lower right:Panoramic view along the southeastern crater wall.


http://digilander.libero.it/glrgroup/steinheim.jpg

http://digilander.libero.it/glrgroup/steinheim.jpg

page 72

LUNAR SOFTWARE SELENOLOGY TODAY # 10

Virtual Moon Atlas

By Christian Legrand

The Virtual Moon Atlas exists now since6 years. During this period, it has beendownloaded more than 500 000 times byamateur astronomers worldwide. It is alsoused by professional observatories (KittPeak, Japan National AstronomicalObservatory.), TV channels (BBC.),research institutions (University Collegeof London, University of India.) andastronomical magazines (Ciel et Espace,Espace Magazine.) and numerous Websites. Finally, it has been recommendedby European Space Agency and isregistered as an educational software byfrench Ministry of Education. For the 6thanniversary of its creation, I'm pleased,with Patrick Chevalley to announce youthe new version "Pro" 4.0, importantevolution of the Virtual Moon Atlas.It presents :

THE NEW MODULE "POCKETLUN" ©It's the translation of VMA "Light"version on Pocket PC! It allows you amore easier field use of VMA andbecomes a real interactive partner with theaudio comments it can handle. Thismodule is an exclusive complement to theCD PRO 4.0 version.

THE NEW PICTURES MANAGERM O D U L E " P H O T L U N " ©We release "PHOTLUN", a picturesmanager that allows you to selectformations pictures, to view, rotate andprocess them about luminosity andcontrast, and to magnify them.And you can record the selected setup tofind them later !

THE NEW « LUNAR ORBITER » HIGHRESOLUTION TEXTUREUSGS has recently released new Moonsurface map built on Lunar Orbiterpictures. We have improved these data toprovide to VMA users a newexclusive texture shows the highest lunarsurface resolution available incomputerized lunar atlases.

THE NEW CLEMENTINE RATIO andALBEDO SCIENTIFIC OVERLAYSThese new high resolution overlays andbased on exclusives data fromClementine probe show very clearly soilscomposition and albedo differences.

THE NEW PYROCLASTIC DEPOSITSS C I E N T I F I C D A T A B A S EBeyond traditional databases compilingpublic IAU officially named formations,it exists peculiar formations with a hugescientific interest that have to be includedin VMA databases. After the "Historicalsites" database, here is now the"Pyroclastic deposits" databasepresenting volcanic ashes deposits onlunar surface compiled by Lisa Gaddisand her team.Sure, these deposits are localized on themap and can be sorted withDATLUN © VMA database manager.

THE NEW PICTURES LIBRARIESThe new "Best of Lazzarotti" library :Paolo Lazzarotti is presently the mostprolific lunar imager releasing hishigh resolution pictures to othersamateurs. In this new library, more than450 pictures formations have beenextracted from Paolo production.

page 73

LUNAR SOFTWARE SELENOLOGY TODAY # 10

THE NEW BEST OF HIGGIN LIBRARY :Wes Higgins is back to lunar imaging with his 18" Dobson since some months. In thisnew dedicated library, more than 250 pictures formations have been extracted fromWes production.

THE NEW "LOPAM DESTRIPPED" LIBRARY :A routine provided by Niels Noordhoek blows away those stripes on original LOPAMpictures. It was possible to produce the new "LOPAM Destripped" pictures library thatshows now the extracted pictures in all their beauty and resolution.

These new pictures libraries grow the collection to near 4000 pictures available toVMA users.

We hope that all these news will improve a lot the VMA functionaries and them moreuseful for lunar observers and for scientists working on our satellite.

Find all detailed information about this new release on our new Web site :

http://ap-i.net/avl/en/start

Documents

Selenology Today - Moon Societystrabo.moonsociety.org/publications/selenology/sel... · 2018. 3. 1. · Gaetano Filangieri, in 1784 , wrote: "Saying that everything has already been