Astronaut Ron Evans is pictured retrieving film canisters
from the Mapping and Panoramic Cameras in the Service Module.
He is holding a handrail on the Service Module, and his body is extended over
the open instrument bay. The Mapping Camera film canister is near his left elbow.
At the rear of the Service Module, the
Lunar Sounder Experiment's VHF antenna
extends toward the top right corner of the photograph.
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 project were used in producing topographic maps.
During Apollo 17, the Metric Camera was used on 15 orbits and during the early
hours of the return to Earth, obtaining 2140 usable photographs.
The Panoramic Camera was used on nine orbits and during the early hours of the
return to Earth, obtaining 1574 usable photographs.
This covered virtually all of the Moon visible in sunlight to the Apollo 17 crew.
Examples of Apollo 17 Metric Photography
This photo shows about 160 kilometers of southeastern Mare Serenitatis.
The surface in this region is composed of basalt, emplaced between about
3.0 and 3.5 billion years ago.
A number of ridges, termed wrinkle ridges, are seen in this picture.
The weight of several kilometers of mare basalt caused the surface to sag
somewhat, and the resulting motion caused the surface to buckle, producing the
ridges.
These ridges are generally less than 100 meters high.
Similar ridges are seen in other lunar mare basins, including
Mare Humorum,
Mare Imbrium,
Mare Nectaris, and Mare Crisium.
In the lower right portion of the picture, the surface is a darker gray.
This material, near the southern edge of Mare Serenitatis, formed in a different,
somewhat older episode of lava emplacement.
In this older material, there is a set of narrow valleys, termed graben.
When the central part of the mare sags due to emplacement of a basalt load,
material on the edge of the mare may be uplifted and stretched, producing
the graben.
(Apollo 17 Metric photograph AS17-602.)
This oblique photograph was taken looking south across Mare Imbrium, which
is the smooth region at lower right. Mare Serenitatis is the smooth region
at upper left, and Sinus Medii is the smooth region at upper right.
The Apennine Mountains, which form part of the main rim of the Imbrium Basin,
are prominent in the center of the photograph.
In places, the Apennines are more than 4 kilometers higher than Mare Imbrium.
(Apollo 17 Metric photograph AS17-2432.)
The crater Euler in Mare Imbrium has a diameter of 28 kilometers and is
about 2.5 kilometers deep.
It is
typical of craters in this size range on the Moon.
The next two photographs illustrate the structure of Euler as seen in
different illumination conditions.
In this photograph, taken at a very shallow sun angle (very early in the
lunar morning), the long shadows obscure the inside of the crater and
highlight structures surrounding the crater.
Material that was ejected from the crater and deposited in the region
around the crater is visible as a clearly defined, rough ejecta blanket.
When this ejecta lands on the lunar surface, it sometimes creates additional
craters, termed secondary craters, that are much smaller than the original
crater.
Numerous small secondary craters are visible around Euler, extending out to a
distance of about one crater diameter from the rim of Euler.
(Apollo 17 Metric photograph AS17-2293.)
This photograph of Euler was taken about one Earth day after the previous
photograph.
At this time, the sun was higher in the sky and the shadows were less pronounced.
The ejecta blanket and secondary craters are less obvious than in the
previous photograph.
However, more detail can be seen in the crater's interior.
A small peak is present at the center of the crater, and material that
has slumped off the crater rim is present in many places on the crater floor.
These structures are characteristic of most craters of this size on the Moon.
(Apollo 17 Metric photograph AS17-2923.)
This oblique photograph was taken looking south across Mare Imbrium.
The crater Copernicus,
93 kilometers in diameter, is seen in the distance.
Several chains of small craters are visible.
These are oriented toward Copernicus and are secondary craters
produced by material ejected when Copernicus formed.
In the foreground, the crater Pytheas is 20 kilometers in diameter.
The general structure of Pytheas is similar to Euler.
(Apollo 17 Metric photograph AS17-2444.)
The Moon in Three Dimensions
Photographs taken while looking down from great heights, such as
from an airplane or 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 conceptually 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.
It 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.
This image is 86 kilometers across and shows a portion of southwestern Mare Serenitatis.
The Serenitatis impact basin, which is 920 kilometers in diameter, formed
3.89 billion years ago when a large asteroid or comet struck this part of
the Moon.
Large impact basins are typically
surrounded by several mountain rings.
The rough structures in the lower part of the image are the Haemus Mountains,
which are part of one of the rings of the Serenitatis impact basin.
The smoother regions in the upper part of the image are the mare plains,
formed when basaltic lava flooded this region roughly 3.5 billion years ago.
The mountains are 2 to 3 kilometers higher than the mare plains.
The ridges in the upper right of the image and the valley-like graben in the
upper left are similar to features seen elsewhere in
Mare Serenitatis.
Both the ridges and the graben formed when the weight of the basaltic lava
caused the mare plains to buckle.
The largest crater visible in this image is Sulpicius Gallus, which is 12
kilometers in diameter and 2.2 kilometers deep.
As is typical of small lunar craters,
Sulpicius Gallus has a relatively simple structure.
Heights in this image are vertically exaggerated by a factor of 3.9.
(Based on Apollo 17 Metric photographs AS17-1816 and AS17-1818.
Stereo processing by Paul Schenk, Lunar and Planetary Institute.
Stereo image © copyright Lunar and Planetary Institute, 1997.)
Example of Apollo 17 Panoramic Photography
In this spectacular panoramic view of the eastern limb of the Moon,
the entire area of Mare Smythii, more than 400 kilometers from left to right,
is visible.
In the near field, the 150-kilometer-diameter crater Hirayama extends across
the middle one-third of the bottom of the photograph.
(Apollo 17 Panoramic photograph AS17-2871.)
Additional Information on the Metric Camera (NSSDC)
Additional Information on the Panoramic Camera (NSSDC)
Walter S. Kiefer
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