Apollo 15 Mission
Science Experiments - Metric and Panoramic Cameras
The Metric and Panoramic cameras provided systematic photography of the lunar surface.
Apollo 15, 16, and 17 carried a set of cameras in the Scientific Instrument Module of the Service Module. These cameras were used to obtain high-resolution photographs of the lunar surface, for use both in studying the geology of the surface and for producing detailed topographic maps of the surface. These cameras included a Metric Camera, a Panoramic Camera, and a Stellar Mapping Camera. The Metric and Stellar Mapping Cameras were operated as a unit along with the Laser Altimeter. The Panoramic Camera was operated separately, but was often used at the same time as the Metric Camera. The film canisters used by these cameras were retrieved from the Service Module and stowed in the Command Module during a spacewalk by the Command Module pilot on the return trip to Earth.
The Metric Camera obtained pictures of the surface covering 165 kilometers on a side, with a horizontal resolution of 20 meters, based on a nominal spacecraft altitude of 110 kilometers. The Stellar Mapping Camera obtained photographs of star fields at the same time, which were used to establish the spacecraft's precise orientation, thus improving the accuracy of the resulting lunar maps. The Panoramic Camera obtained pictures of narrow strips, 20 kilometers wide in the direction of spacecraft motion and 320 kilometers long across the spacecraft's ground track. These pictures had extremely high resolution, showing features just 1 to 2 meters across. Photographs with both cameras were taken so that there was substantial overlap in the ground coverage of consecutive photos. This allowed the technique of stereo photography to be used to determine the heights of features shown in the photos. Under ideal conditions, the heights of these features could be determined to an accuracy of better than 10 meters. The results of this stereo photography were used in producing topographic maps.
During Apollo 15, the Metric Camera was used on 18 orbits and during the early hours of the return to Earth, obtaining 2240 usable photographs. The Panoramic Camera was used on 11 orbits and during the early hours of the return to Earth, obtaining 1529 usable photographs. This covered virtually all of the Moon visible in sunlight to the Apollo 15 crew.
Examples of Apollo 15 Metric Photography
Photographs taken while looking down from great heights, such as from an airplane or an orbiting spacecraft, often have a two-dimensional quality to them, with little or no indication of how high the features shown in the image actually are. If a region is photographed from two different perspectives, the differences in appearance of the two photos can be used to determine the heights of features in the images. This is known as stereo photography and is similar to the process the human brain uses to merge the images from the left and right eyes into a single image that provides information about the distances to various objects.
The image shown here has been digitally processed to illustrate this stereo effect. The image should be viewed with special red-blue stereo glasses. The red lens goes over the left eye and the blue (or green) lens goes over the right eye.
Lambert Crater, 30 kilometers in diameter, is a typical example of a small, complex crater. In this image, one can see slumping and terracing of the inner rim of the crater, a central peak, and an ejecta blanket surrounding the crater rim. Lambert is about 2.4 kilometers deep and the rim is about 800 meters higher than the surrounding plains. The heights in this image are vertically exaggerated by a factor of 4.2. (Based on Apollo 15 Metric photographs AS15-260 and AS15-265. Stereo processing by Paul Schenk, Lunar and Planetary Institute. Stereo image © copyright Lunar and Planetary Institute, 1997.)
This photograph shows Dawes crater, 18 kilometers in diameter and about 2 kilometers deep, in southeastern Mare Serenitatis. Dawes is typical of moderate-sized lunar craters. Whereas small craters (less than about 15 kilometers in diameter) tend to have simple bowl-shaped forms, in larger craters, slumping of material off the interior of the crater rim helps to flatten the crater floor. Unlike larger craters, such as King or Tsiolkovsky, Dawes does not have terraces on the interior of the crater rim or a central peak. North is at the right side of this photograph. (Part of Apollo 15 Panoramic photograph AS15-9562.)