December 15, 1999
Vol. 8, No. 4, pp.49-54.
PRELIMINARY SEARCH FOR RUIN-LIKE FORMATIONS ON THE MOON
The Moon is an indicator of possible alien visits to the Earth during past ~4 billion years. New computer algorithms are proposed and tested for the archaeological reconnaissance of our satellite. About 20,000 Clementine lunar orbital lunar images have been processed, and a few ruin-like formations were found. According to a fractal analysis, some of these finds are different from the lunar surface on which they reside, and formally resemble terrestrial archaeological objects. At the least, the catalogued formations should be interesting as geological anomalies.
As it is argued [1,2] the Moon could be used as an indicator of extraterrestrial intelligence visits to the Solar System. Therefore, it is necessary to ascertain the indicator's condition REGARDLESS OF THE RESULT. Unfortunately, such studies are outside of the professional activity of selenologists (because of their orientation only to natural formations and processes) as well as archaeologists (because archaeology adheres to a pre-Copernican geocentric position). That is why the first archaeological reconnaissance of the Moon is realized only as a private project, SAAM: Search for Alien Artefacts on the Moon.
It is more reasonable to use for SAAM the archaeological method (e.g. preliminary assumption of artifact existence) than the planetological "presumption of naturality". According to Dr. B.V.Andrianov (the Russian authority in aerial archaeology): "The main demasking sign of objects, whose origin on the terrain is due to human activity, is their geometric regular configuration (at rare exclusions)" . Terrestrial buildings, as a rule, have rectangular outlines. Hence, it is reasonable to search on the lunar images for unusual patterns of rectangular shape. The status of such finds can not be higher than that artifact candidates. The true nature of the finds cannot be ascertained by the remote sensing only. According to archaeological practice, direct exploration (e.g. excavations) is an obligatory element of the search. Hence, the finds of the SAAM Project cannot be discoveries; but SAAM is a precursor for inevitable archaeological reconnaissance of the Moon.
2.1 PRELIMINARY FRACTAL TEST
As a rule, natural landscapes consist of self-similar details on various dimension scales. For example, lunar craters are similar at diameter of 0.1m to 104 m. By contrast, artificial constructions have some typical dimensions caused by size of their constructors. Hence, the artifacts might be recognized as details of unusually frequent size. The search for such dimension anomalies is an essence of the fractal method proposed by M.J.Carlotto and M.C.Stein . Unfortunately that test is too slow for the express analysis of ~80,000 HIRES images because of so many calculations. That is why the simpler and faster algorithm is proposed here.
nmax sk2 = (gk /nmax) S [ log M(ri) - n log ri - C]2, i=1
where: k is the number of test square; gk is the apparatus factor or average (s*/sk)2 from a lot of HIRES images (s* is sk in the center of image at gk=1); nmax is the number of used scales up to M(ri)=0. Then the average dispersion <s> is estimated from these regional squared residuals.
2.2 RECTANGULAR TEST
The rectangular test reveals the rectangular patterns of lineaments on the image of lunar surface. For each pixel of the image, the probe point at the distance of 6 pixels and position angle j is selected. Let N be the total number of such pairs, and n is the number of pixel pairs, where bright accounts are equal. The function W(j)=n/N characterizes the anisotropy of the image. For the correction of the camera aberration, W(j) was divided by its average quantity, which is calculated for many images at same j. The computer finds maxima of the smoothed W(j) and the corresponding jm angles. Obviously jm describes the orientations of lineament groups. If there is (90oñ10o)-differences between jm , the image is classified as interesting.
2.3 SAAM IMAGE
For the false alarm selection, the SAAM-transformation of the image was used for revealing indiscernible details of the lunar surface. This algorithm is very simple: The image is smoothed by the sliding window in a kind of circle with radius R, then the result of this procedure is subtracted from the initial image. Thus the pixels, which are brighter than the smoothed level, are considered as "white", and others are considered "black". This clipping permits us to see details of extremely low contrast as well as the high contrast features. Moreover, the large details (>R) of the image appear damped, and they do not interfere with small-sized objects.
2.4 GEOLOGICAL TEST
J. Fiebag  supposed that the parallelism of the formation with lineaments of its surroundings is the criterion for naturality of the object. Although the human activity correlates with geological lineaments (e.g. rivers), the conservative Fiebag test was applied to the lunar finds.
3. RESULTS OF THE SEARCH
The polar zones of ñ75o to ñ90o latitudes are most suitable for the SAAM because of oblique lighting. For the preliminary archaeological search of those zones, 20 CDs were selected randomly from the Clementine EDR Image Archive . About 20,000 files or ~25% of the polar HIRES data were analyzed. Only 32 images were selected as interesting after geological test.
Arrowed rectangular 800x800m pattern on the hill is an example of lunar ruin-like formations (long.=301.11 deg.; lat.=85.59 deg.; Clementine image: LHD6749R.318).
An example of picturesque ruin-like formations on a hill is shown in Fig. 1. The traditional explanations in terms of crossing of impact fault systems seem inadequate for such compact and closed formations. The Moon did not have conditions (a thin crust above melted mantle) for Venus-like tessera terrains. So the origin of these anomalies is problematical. As a rule, lunar base projects would be expected to show the rectangular patterns of subsurface constructions [7-9]. Formally, such complexes could be classified as (a) and (b) patterns. The (c)-type bands in Fig. 2 are a puzzle. Theirs depth from shadows (~10 m) is about the average thickness of the regolith layer on the Moon. Theirs flat bottoms and geometry remind one of modern projects for lunar regolith mining (e.g. ). Some depressions of (b)-type could be interpreted in mining terms too.
Of course, this visual impression should be tested by some objective procedure. The modified fractal Carlotto-Stein method was used for this purpose. First, the range of HIRES image brightness was increased linearly up to 256 gradations. Then convert the image into an intensity surface in a 3-D rectangular frame of coordinates (x and y are the pixel coordinates; z is its brightness). The Carlotto-Stein method  can be thought of as enclosing the image intensity surface in volume elements. These volume elements are cubes with a side of 2r; where r is the scale in terms of pixel coordinates or its brightness. Let Vr be the average minimal volume of such elements enclosing an image intensity surface at some point. Then the surface area is Ar = Vr/2r. As a function of scale, Ar characterizes the size distribution of image details. The fractal linear relation between log Ar and log r is a good approximation for natural landscapes. However, the self-similar fractals do not approximate artificial objects as a rule. That is why M.J. Carlotto and M.C. Stein used the average of the squared residuals e of the linear regression log Ar=blog r + g as a measure of artificiality.
log Ar = a (log r)2 +blog r + g,
where the factor a is independent of the image size. The shadows lead to a >0, but artificial objects have a <0.
This effect is shown in Fig. 3. There factors a and b are calculated for the random set of HIRES images (crosses) and aerospace photographs of terrestrial archaeological objects (white squares). The fragments of images of the following archaeological sites were used in our analysis: Giza tombs in Egypt (KVR-1000 satellite) and El-Lejjun Roman legionary fortress, Jordan, (CORONA satellite) ; the Cerro Vidal trinchera , the Cerro Juanaquena trinchera and Pueblo She' in Galisteo Basin (New Mexico, aerial photographs ). The parameter a values for lunar ruin-like formations (black squares) is distributed between the geological background (crosses) and archaeological objects (opened squares). Some formations have a as low as the known archaeological sites.
The weak effect of low sunlight could be seen in Fig. 4. At any zenith angle of the Sun (Zsol), the ruin-like formations have systematically lower a than the random set of HIRES images does. The average linear regression relating a of the random set and Zsol is shown as a dashed line. The standard deviation of the crosses from this regression is sa =0.0113. A minimal deviation of 3sa (solid line) is adopted as a formal criterion for the final selection. The selected objects on the Moon listed in Table I all have reasonable levels of archaeological interest.
It is shown that computerized archaeological reconnaissance of the Moon is practicable. The proposed methods can be used for more extensive lunar survey and for planetary SETI in general.
The author is very grateful to Dr. Y.G. Shkuratov for access to the Clementine's CDs. I also thank Dr. F.G. Graham, Dr. J. Fiebag, Dr. T. Van Flandern, Dr. L.N. Litvinenko and Dr. J. Strange for discussions and support.
1. A.V. Arkhipov and F.G. Graham, "Lunar SETI: A Justification", in The Search for Extraterrestrial Intelligence (SETI) in the Optical Spectrum II, ed. S.A. Kingsley & G.A. Lemarchand, SPIE Proceedings, Vol. 2704, SPIE, Washington, 150-154, 1996.
Longitude Latitude Type Dimensions Image Description
28.04 -76.45 a 5.3 x 5.6 LHD0132B.290 separate group of
28.31 79.11 c 1.2 x 1.5 LHD5502Q.290 curious pattern of linear
31.06 78.84 c 0.3 x 1.3 LHD5256Q.293 rectangular zigzag band
151.21 -76.24 b 0.8 x 0.8 LHD0470B.112 rectangular claster of
246.08 81.88 a 2.2 x 2.2 LHD7638R.343 rectangular walls of
301.11 85.59 a-b 0.8 x 0.8 LHD6749R.318 complicated
(This web page produced for Alexey Arkhipov by Francis Ridge of The Lunascan Project)