The Blair Cuspids: A Mystery Revisited

Lan Fleming

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In 1966, NASA released a photograph taken by Lunar Orbiter 2 of a region on the western edge of the Sea of Tranquility that showed several objects casting unusually long shadows. A few scientists at the time speculated that the shadows were too elongated to be cast by common lunar boulders or ridges. Among them was William Blair, reportedly of the Boeing Institute of of Biotechnology. Blair noted that the objects casting these shadows appeared to be arranged in a subtly regular fashion that, together with the seemingly anomalous height of the objects, suggested an artificial origin. These objects came to be known as the Blair Cuspids. While there is some evidence that NASA was at first interested in the unorthodox possibilities raised by Mr. Blair and others, an official explanation was quickly settled upon that attributed the elongated shadows to a very low sun angle. A brief account of the discovery of the Blair Cuspids and how they came to be dismissed as the product of "uncritical" thinking is here.

When the photograph was released, the NASA public affairs office identified it according to a numbering system that has since become obsolete, so there was no way authenticate the image or to access the photographic support data listing the sun angle at the time and place of the photograph. This information on the illumination geometry is of critical importance in evaluating the validity of the official explanation of why the shadows were so long. Thanks to the efforts of Fran Ridge of the Lunascan Project,  Mike Lomax, and the espcially to the kind assistance of the National Space Science Data Center (NSSDC), the correct frame number, LO2-61H3, was located a few months ago. Knowing the frame number, we were able to acquire copies of the 8X10 inch black and white negatives directly from NSSDC. Figure 1 below shows the small section of Frame LO2-61H3 containing the Cuspids and their shadows. The numbers in the photograph reference five of the objects that will be discussed in more detail here.

Figure 1. The Blair Cuspids and the Rectangular Trench. This JPEG shows a section of LO2-61H3 with each pixel 2/3 the size of the smallest resolvable feature at a 3:1 contrast ratio. A larger GIF version (345K) with each pixel 1/2 times the smallest resolvable feature can be downloaded by clicking here

The quality of the negatives is greatly superior to the old washed-out photographs that have appeared in a few books in decades past.

With the correct frame number, we were also able to quickly reference the photographic support data in the Lunar Orbiter 2 catalog to find the angle of sun light illuminating the objects in the photograh. The catalog data showed that the sun was in the East at an angle of 79.1 degrees from the lunar vertical, or 10.9 degrees above the lunar horizon. While this sun angle is in fact low, it is by no means low enough to support the claim that the shadows were cast by common boulders. From the support data, it was also determined that this region is located at lunar coordinates 15.5 degrees East, 5.1 degrees North. In close proximity to the main group of "Cuspids," is an unusually regular rectangular depression. The shadow of Cuspid #5, the longest by far of the Cuspid shadows, falls across this trench and ends almost at the southern edge of the partially-shadowed interior.

Figure 2. The Trench. The contrast has been increased by 40% in this image, making the darker region of the trench nearly black to reveal the unusual rectangular shape of this depression. The corner of the trench at the one-o'clock position is an almost unnaturally well-defined right-angle. When an unusual feature such as this trench is found in close proximity to other unusual features of an entirely different kind, such as the "Cuspids", it is reasonable to suppose that the possibility for an artificial origin of all the features is substantially increased. This is so because a common geological explanation is made more difficult and an appeal to improbable coincidence becomes more necessary to support a natural origin for the disparate features.

But how different are these Cuspids from garden-variety moon rocks? What should be a reasonable - albeit tentative and approximate - reconstruction of the Cuspids' appearance as viewed in profile is shown in Figure 3 below.

Figure 3. Strange Shapes In Profile. These profile images are really negative images of the shadows of the 5 objects indicated by the numbers in Figure 1.  The background has been blacked out by hand to emphasize the overall shape of each object.

In Figure 3, the shadows have been compressed in the direction of their length according to the simple trigonometric relationship between an object's height, H, the length of its shadow, Ls, and the tangent of the sun's elevation angle, A, above the surface on which the shadow falls. This relationship is:

H = Ls tan(A)

Because the first four cuspids appear to be situated on a fairly horizontal surface, the value of angle A was taken from the NASA support data to be the sun's elevation above the horizontal, 10.9 degrees and the images of the shadows were compressed by the value of that angle's tangent, 0.193. A greater compression, corresponding to a sun angle of 8 degrees (tan(8) = 0.14) was used for the profile of Cuspid 5 because its shadow falls over the surface of the rectangular "trench", which is sloping downward away from the sun, thus effectively decreasing the sun's elevation above the surface. The problem of the uncertainty of sun angles and the rationale for the ones selected for these profile images is discussed at length here. The detailed contours of the objects are lost in these profiles due to the irregularities of the lunar surface and due to the blurring caused by the image compression algorithm. However, the general shapes of all the objects except the first can still be clearly be seen to differ radically from the shapes of common lunar boulders and ridges. The profiles suggest that Cuspids 2 through 5 have heights greater than their widths, which would be a very unstable placement for a randomly placed boulder and even more unusual for a cluster of them. The hills and ridges of Luna tend to be very low and rounded. The great lunar mountain Pico Mons in Mare Imbrium, for example, has a height only 16% of its width. Cuspids 2 though 4 are conical or pyramidal, while Cuspid 5 (still the tallest even with a lower sun angle assumed) appears to be a cylinder. Based on the assumption that the sun's elevation is 8 degrees above the slope on which Cuspid 5's shadow is being cast, the object itself would have a height of approximately 15 meters or 50 feet. Because of its large size, Cuspid 5 and its shadow may present a possible solution to the problem of sun angles and surface slopes, which is discussed here.

Cuspids Page 2

Cuspids Page 3

Cuspids Page 4