9. Lunar Surface Closeup Stereoscopic Photography · PDF file 2009-12-07 · LUNAR...

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  • 9. Lunar Surface Closeup Stereoscopic Photography

    The lunar samples returned by the Apollo 11 mission have provided preliminary information about the physical and chemical properties of the Moon and, in particular, about Tranquility Base. Because of the mechanical environment to which lunar samples are subjected during their return from the Moon, limited information can be obtained from lunar samples about the structure and texture of the loose, fine-grained material that composes the upper surface of the lunar crust. A stereoscopic camera capable of photo- graphing the small-scale ( between micro and macro) lunar surface features was suggested by Thomas Gold, Cornell University, and built under contract for NASA.

    The photographs taken on the mission with the closeup stereoscopic camera are of outstand- ing quality and show in detail the nature of the lunar surface material. Several photographs con- tain unusual features. From the photographs, information can be derived about the small-scale lunar surface geologic features and about proc- esses occurring on the surface. This chapter presents a description of the closeup stereoscopic camera, lists and shows single photos from pairs available for stereoscopic study, and contains an interpretation of the results reported by Profes- sor Gold in Science, vol. 165, no. 3900, pp. 1345- 1349, Sept. 26, 1969.

    Apollo Lunar Surface Closeup Camera

    The Apollo Lunar Surface Closeup Camera (ALSCC), built by Eastrnan Kodak under con- tract to the NASA Manned Spacecraft Center, was designed to optimize operational simplicity (fig. 9-1). The camera is an automatic, self- powered, twin-lens stereoscopic camera capable of resolving objects as small as SO pm in diameter on color film. Simplicity of operation was achieved by making the camera focus and the flash ex-

    launch with sufficient Ektachrome MS ( SO368 ) film for the complete mission. To obtain a photo- graph, an astronaut merely sets the camera over the material to be photographed and depresses the trigger located on the camera handle. When the exposure is complete, the film is automatically advanced to the next frame, and the electronic flash is recharged.

    posure fixed and by loading the camera prior to FIGURE 9-1. - Apollo lunar surface closeup camera.

    187

  • 188 APOLLO 11 PRELIMINARY SCIENCE REPORT

    The requirement to simplify the ALSCC op- eration necessitated a reasonable depth of field that could be achieved only by limiting the image magnification produced by the system. The camera lenses are diffraction-limited 46.12 mm f/17 Kodak M-39 copy lenses focused for an object distance of 184.5 mm, providing an image magnification of 0.33. The lenses are mounted 29 mm apart, with their optical axes parallel. The area photographed is 72 mm x 82.8 mm and centered between the optical axes; thus, stereo- scopic photographs with a base-to-height ratio of 0.16 are provided (fig. 9-2).

    Location of the Stereoscopic Photographs

    The specific location at the Apollo 11 lunar landing site where individual stereoscopic photo- graphs were taken cannot be determined with a high degree of confidence. Because of the lim- ited size of the area photographed by the cam- era, the subject material cannot be identified within the large-scale lunar surface photography. In the scientific debriefing of the Apollo 11

    I F i lm format: 27.64 by 24 mm Fi lm plane

    - TV u ~ - X n . k 4 - ~

    m x a k J

    - -

    m u 10 5 0 10 20

    Ft -_ LM rocket exhaust disturbance - Crater * Rock

    ;:t;,;!3., Documented-sample area

    LRRR Lunar Ranging Retroreflector PSEP Passive Seismic Experiment Package & Tentative location of stereoscopic photographs

    crew, Astronaut Armstrong indicated the gen- eral areas, relative to the lunar module, where sequential sets of photographs were taken. Based upon Astronaut Armstrong's comments and the time history of events on the surface, the general locations of the photographs were tentatively established (fig. 9-3).

    Description of Photographs

    Analysis of the photographic data is not com- plete and will therefore be published in future documents. For this report, only a preliminary description of four photographs, provided by Gold, is included.

    A stereoscopic view (fig. 9 4 ) shows a close- up of a small lump of lunar surface powder ap- proximately 0.5 in. across, with a splash of glassy material over it. A drop of molten material ap- pears to have fallen on the powder, splashed, and frozen.

    Figure 9-5 shows a clump of lunar surface powder with various small, differently colored pieces. Many small, shiny spherical particles can be seen.

    FIGURE 9-2. - Schematic of the ALSCC. FIGURE 9-3. - Locations of ALSCC photographs.

  • LUNAR CLOSEUP STEREOSCOPIC PHOTOGRAPHY 189

    FIGURE 9-4. - A small lump of lunar soil with a glazed FIGURE 9-6. - Stone embedded in powdery lunar surface top and a smaller glazed piece to the right. The larger material. ( NASA ASll-45-6712 object shows no change of color or texture compared with the surrounding ground, known to be soft, fine- grained soil, except for the glaze mark. (NASA AS11- 45-6704 )

    Another stereoscopic view (fig. 9-6) shows a stone, approximately 2.5 in. long, embedded in the powdery lunar surface material. The small pieces grouped closely around the stone suggest that it suffered some erosion. On the surface, several small pits are seen, mostly less than one- eighth in. in size and with a glazed surface. The pits have a raised rim, characteristic of pits

    made by high-velocity micrometeorite impacts. One stereoscopic view (fig. 9-7) of the sur-

    face of a lunar rock shows an embedded %-in. fragment of a different color. On the surface, several small pits are seen, mostly less than one- eighth in, in size and with a glazed surface. The pits have a raised rim, characteristic of pits made by high-velocity micrometeorite impacts.

    FIGURE 9-5. - Clump of lunar surface powder (NASA FIGURE 9-7. - Stereoscopic view (NASA ASll-45-6709) ASll-45-6706)

  • 190 APOLLO 11 PRELIMINARY SCIENCE REPORT

    The stereoscopic views in figures 9-8 to 9-20 are included in this report to make the avail- ability of the photographs known. Descriptions or interpretation of these photographs were not available for this publication.

    These photographs are available upon request from the NASA Manned Spacecraft Center, Houston, Tex. The following is a listing of the 17 photograph numbers, keyed to the figure number used in this chapter.

    Photograph

    AS 11-45-6704 AS1145-6706 ASll45-6712 AS 1145-6709 AS1145-6697 AS1145-6698 AS 11-45-6699 ASll45-6700 ASll45-6701 AS1 1-45-6702

    FIGURE 9-9. - Stereoscopic view ( NASA AS11-45-6698 )

    FIGURE 9-10. - Stereoscopic view (NASA AS11-45-6699)

    FIGURE 9-8. - Stereoscopic view ( NASA ASll-45-6697 )

  • LUNAR CLOSEUP STEREOSCOPIC PHOTOGRAPHY

    FIGURE 9-11. -This is the bottom of a crater, and the affected area is close to the upper edge of the frame (and re sum ably beyond). Here, glazing is seen in a very regular fashion, with the edges and points that face upwards and out in a direction to the upper right consistently affected. The stereoscopic view is re- quired to observe the directional effect. (NASA AS11-

    FIGURE 9-13. - Stereoscopic view (NASA ASll-45-6702)

    FIGURE 9-12. - Stereoscopic view ( NASA ASll-45-6701)

    FIGURE 9-14.-Stereoscopic view (NASA ASll-45- 6702-1 )

  • 192 APOLLO 11 PRELIMINARY SCIENCE REPORT

    FIGURE 9-15. - Stereoscopic view (NASA ASll-45-6703)

    FIGURE 9-17. - Stereoscopic view (NASA ASll-45-6707)

    FIGURE 9-16. - Stereoscopic view ( NASA ASll-45-6705 ) FIGURE 9-18. -A large area of glazing is seen in the

    lower left region, both on the horizontal and on the sloping surfaces of the ~rotuberance. Some glazing is also seen on the lower right object, with edges and points particularly affected. In the upper part of the picture a small glossy bead is seen poised on a nar- row pedestal. (The detail in the color stereoscopic transparencies far exceeds that which can be repro- duced in the present print. ) ( NASA ASll-45-6708)

  • LUNAR CLOSEUP STEREOSCOPIC PHOTOGRAPHY 193

    known previously or that could not be seen with similar definition by Astronauts Armstrong and Aldrin in their careful inspection of the lunar surface. One of those is outstanding in being wholly unexpected and possibly of consequence not only to lunar geology but also to aspects of the study of the Sun, the Earth, and other bodies of the solar system.

    The observation is that of glossy surfaces, in appearance a glass of color similar to the sur- rounding powdery medium, lying in very par- ticular positions. Small craters that are plentiful on the lunar surface - 6 in. to 2 or 3 feet in diameter - have frequently some clumps of the lunar soil or rough spots of the surface texture concentrated toward their center. They give the . -

    FIGURE 9-19. - Stereoscopic view (NASA ASll-45-6710) appearance of having been swept in at a time later than the formation of the crater. Some of these little lumps appear to have just their top surfaces glazed. The glassy patches that can be

    FIGURE 9-20. - Stereoscopic view (NASA ASll-45-6713)

    Apollo 1 1 Observations of a Remarkable Glazing Phenomenon on the Lunar Surface

    T. Gold

    The Apollo 11 mission carried a closeup stereo camera with which the a