Lunar photography: Techniques and results

L U N A R P H O T O G R A P H Y : T E C H N I Q U E S A N D R E S U L T S *

RAYMOND L. HEACOCK Jet Propulsion Laboratory, Pasadena, Calif., U.S,A.

(Received 9 January, 1968)

1. Introduction

Since the first photograph of the moon in 1840 by Dr. J. W. Draper using the daguerre- otype process, photography has served as a primary tool in recording and mapping the features of the moon. However, earth-based photography has never been able to record the detail which can be seen by the human observer through the telescope. The equipment and techniques have progressed to the point where the earth's atmos- pheric disturbances provide the major limitation in achieving improved resolution. Very rare seeing conditions have permitted photographic resolutions exceeding 400-500 m per optical pair. In addition, the moon rotates once about its spin axis per orbit about the earth and, except for librations, always presents the same face to earth observation. As a result, the far side of the moon had remained cloaked in the mystery of the unknown.

The advent of the space programs of the U.S.A. and the U.S.S.R. provided a unique opportunity for man to expand his knowledge of his closest neighbor in space. The exploration of the moon has progressed with the developing space technology of the U.S.A. and Russia.

A primary tool in the space exploration of the moon has been photography. Due to the limitations imposed upon the various missions, the photographic techniques used have involved several specialized approaches. This article discusses these various approaches, the missions on which they were used, and the results which were achieved. Unfortunately, the detailed information available to the author on the Soviet systems has severely limited the coverage of their efforts.

2. Historical Background

The exploration of space is generally recognized as beginning with the Soviet Union's successful launch of Sputnik-I on October 4, 1957. The United States joined in that exploration with Explorer-I on January 31, 1958. The exploration of the moon was begun by the United States with its Pioneer series space probes. Pioneer-III was intended to fly by the moon in a test of an optical shutter-trigger device to be used with a camera system on Pioneer-IV. Pioneer-III was launched on December 6, 1958;

* Thispaper presents the results of one phase of research carried out at theJet Propulsion Laboratory, California Institute of Technology, under Contract No. NAS 7-100, sponsored by the National Aero- nautics and Space Administration.

Space Science Reviews 8 (1968) 214-257; �9 D. Reidel Publishing Company, Dordrecht-Holland

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and while it discovered the earth's radiation belts, it did not achieve an escape trajectory and its intended lunar flyby. Because of Pioneer.III 's problems and discovery, the same radiation-detection payload was flown on Pioneer-IV on March 3, 1959. Pioneer-IV passed within 60000 km of the moon on its way into an orbit about the sun. Since Pioneer-IV was the last in its series, the camera system which had been developed for it was never used.

The Soviet lunar exploration program began with Luna-I on January 2, 1959. Luna-I went into solar orbit after flying by the moon at a miss distance of about 7500 km. Luna-II was successfully launched on September 12, 1959, and impacted the moon after only a 33.5-hour flight. Luna-III was launched on October 4, 1959, and was the first to successfully photograph the moon from its near vicinity in space. Luna-III proved to be only the beginning of a long series of successful lunar photographic missions. Table I provides a tabulation of these successful missions. These missions, their photographic approach and, their photographic results are described in the following sections.

3. Luna-III Mission

Russia's Luna-III was launched on the second anniversary of the launch of Sputnik-I. Its primary mission was to photograph the far side of the moon from a highly eccentric earth orbit around the moon. The Automatic Interplanetary Station (AIS) passed within 8000 km of the moon's South pole on its way to the desired location for performing its photographic sequence. The photographic sequence began at 6.30 a.m. on October 7, 1959, Moscow Standard Time, at a distance of approximately 62 800 km from the surface of the moon. The photographic sequence was completed 40 rain later, at 7.10 a.m. MST.

Luna-III used a film camera, and it was necessary to process the film before the photographic data could be transmitted back to the earth. The great distance over which the first transmission of the pictures took place, for the transmitter power available and the sensitivity of the earth-based receiving equipment, resulted in ex- tremely noisey photographs being received. It was intended that this known system limitation would be overcome by a second transmission of the data when the AIS was visible to the Northern hemisphere receiving stations upon its return to the near vicinity of the earth. Luna-III achieved an initial apogee of 470000 km and perigee of 30980 km. The reason that this second transmission did not occur has not been disclosed. In addition, the total number of photographs taken was not disclosed. How- ever, Luna-III must be considered a success in that it revealed many new features of the moon which had never before been seen by man.

A. L U N A - I I I AUTOMATIC INTERPLANETARY STATION

Luna-III was the first Soviet Automatic Interplanetary Station and weighed 278 kg. Its configuration is shown in Figure 1. The AIS apparently had no trajectory correction propulsion system of its own so that it had to be injected accurately by the launch-

f LUNAR PHOTOGRAPHY: TECHNIQUES AND RESULTS 217

Fig. 1. Luna-III was launched on its photographic mission on October 4, 1959, and weighed 278 kg. The following elements are identified in the figure: (1) Camera aperture; (2) Motor of orientation system; (3) Sun sensor; (4) Section of solar battery; (5) Temperature-control shutters; (6) Thermal

screens; (7) Antennas; (8) Scientific instruments.

vehicle system in order to perform its mission. Luna-I I I was basically a spin-stabilized vehicle, but it did contain sensors for spin-axis pointing control. It had roll-rate control about the spin axis, and the system was despun for the photographic sequence. Luna-I I I was temperature-controlled with mechanical shutters that opened when the internal temperature rose above 25 ~ The system was powered by batteries which were continuously charged by solar cells. Two transmitter frequencies of 183.6 megacycles and 39.986 megacycles were used. Power levels of 5 Watts and 20 Watts were

used with the 183.6 megacycles. The power level for the 39.986 megacycle transmitter was not disclosed. Fourmeta l rod antennas were used at the 183.6 megacycle frequency and two at the 39.986 megacycle frequency.

A total of six scientific instruments are indicated as having been flown involving a total of 156 kg of the 278 kg. The nature of the experiments other than the camera system was not disclosed.

B. LUNA-III CAMERA SYSTEM

Luna-I I I utilized a film-camera system to perform its photographic mission. The camera was fitted with two separate optics of 200 m m at f/5.6 and 500 mm at f/9.5. The two optical axes alignments were parallel and pointed out the end opposite the sun and along the vehicle roll axis. Special 35-ram film was used in the camera, but it is not clear whether a single or dual film transport and processing system was used. Once exposed, the film was automatically processed with 'simultaneous' development,


fixing, washing, and drying. Special considerations were given to accomplishing the processing under the weightless conditions in space.

In order to transmit the photographic images to the earth, the processed film was scanned by slowly transporting it through a flying spot-film scanner. A constant intensity-light ray was scanned across the film at a rate compatible with the communication bandwidths, then reset and repeated until the scanning was completed. The intensity of the spot of light passing through the film negative was picked up on a photomultiplier tube and then amplified for application to the frequency modulator in the transmitter. In the ground receiving station, the frequency-modulated signals were directly recorded on magnetic tape and also demodulated and recorded on film with a kinescope film recorder. The magnetic tape-recorded data proved to be quite valuable because of the versatility it provided for replaying the data in order to perform various filtering processes in attempting to minimize the noise effects upon the data.

Fig. 2. These two views of the far side of the moon were taken with the 200-mm focal length lens. The noise bands resulted from the communication system's low signal-to-noise ratio.

LUNAR PHOTOGRAPHY: TECHNIQUES AND RESULTS 219

Fig. 3. By using various processing and enhancement techniques, the Russian scientists and technicians were able to produce this map of the far side of the moon.

C. LUNA-III PHOTOGRAPHIC RESULTS

Luna-III photographic results were unfortunately severely limited by the failure to achieve a second, noise-free transmission of the data. The most spectacular result was the fact of being first to accomplish photography of the moon from space. Figure 2 shows a pair of photographs taken with the 200-mm lens. The noise bands are quite noticeable in these unretouched news-service facsimile transmissions. Using data taken by both lenses and using special processing techniques, the Russian scientists produced 'The Map of the Other Side of the Moon' shown in Figure 3.

4. Ranger Missions

The U.S. Ranger program was initiated in 1959 by the National Aeronautics and Space Administration with the Jet Propulsion Laboratory as the Program Manager.


The initial program was divided into two blocks of flights intended to develop the spacecraft and perform lunar missions. An Atlas-Agena launch-vehicle system was used to launch the Rangers. Only partial success was achieved in the Block-I and -II series. The successful photographic missions were achieved in Block-III where three out of four attempts resulted in superb close-up photographs of the lunar surface. The targets selected for each of the missions were carefully chosen to satisfy certain lighting conditions, trajectory constraints, and lunar terrain requirements. Since the prime objective of these missions was the determination of the topography hazards for future soft-landing missions, it was important to determine the small-scale topography of areas which appeared to be smooth from earth-based observations. The number of available missions would not permit the sampling of a sufficient number of actual soft-landing sites.

Ranger-VI was the first in the Block-III program, and it was launched and guided towards a smooth area on the Western edge of Mare Tranquillitatis at 8.5 ~ North and 21.0 ~ East selenographic coordinates. The Ranger-VI spacecraft performed flaw- lessly and impacted at 9.4 ~ North and 21.5 ~ East. Unfortunately, no photographs were transmitted to the earth. The television subsystem had inadvertently turned on during 'critical-pressure' conditions during launch. The high-voltage power supplies in the television subsystem transmitter were burned out by the resultant

arcing. Due to the failure of Ranger-VI, Ranger-VII was launched with the same objective

of photographing as smooth an area as was available within the lighting and trajectory constraints. The selected target for the July 28, 1964, launch was a smooth area in Northern Mare Nubium at 11 ~ South and 21 ~ West selenographic coordinates. Ranger-VII returned 4308 photographs of the moon to the earth before being destroyed upon its impact. The target area was later renamed Mare Cognitum in honor of the success of Ranger-VII.

The target selected for Ranger-VIII was to be another smooth mare area in order to confirm the observations provided by Ranger-VII. The earliest day in the particular launch window of February 17, 1965, permitted a trajectory far to the East in Mare Tranquillitatis. This target was desirable because Mare Tranquillitatis was considered to be a different type mare than Mare Cognitum and because the target area was in the Apollo landing zone. The specific target was at 3.0 ~ North and 24.0 ~ East selenographic coordinates. Ranger-VIII was a complete success in returning 7137 photographs before its impact.

The similarity of the small-scale topography observed in two widely separated and 'different' mare prompted the selection of a target for Ranger-IX of broader scientific interest. The Crater Alphonsus was selected because of several apparent evidences of internal activity. The specific target at 13.0 ~ South and 2.5 ~ West selenographic coordinates was selected to optimize the view of the central peak and the dark-haloed craters and rilles on the East edge of the crater. Ranger-IX achieved a near-perfect trajectory and returned 5814 photographs. The accuracy achieved for each mission is shown in Figure 4.


Fig. 4. The selected targets for the R ange r Block-I l l miss ions are shown with the accuracies which were achieved. Range r - IX was guided to an impact within 4.8 k m of its selected target.

A. RANGER SPACECRAFT

The Ranger spacecraft was fully attitude stabilized. It used the sun and earth for cruise attitude references but also had a gyro-attitude reference system for midcourse maneuvers and terminal orientation maneuvers. The configuration of the Ranger spacecraft is shown in Figure 5. Its physical dimensions and the approximate weights of the spacecraft and its various subsystems are shown in Table II.

The central axis of the spacecraft was pointed at the sun during the cruise portion of the flight to the moon in order to achieve maximum solar energy input to the solar panels. High-gain communications with the earth-based stations was achieved by controlling the position of the roll axis and the high-gain antenna hinge-angle position to keep the antenna pointed at the earth.

The spacecraft was controlled by an on-board Central Computer and Sequencer and by radio commands. The initial trajectory inaccuracies were corrected by a radio- commanded midcourse maneuver which was carried out by the Central Computer and Sequencer. The required velocity and direction changes were achieved by turning the spacecraft with cold gas attitude control jets to the desired direction relative the gyro-reference system and burning a midcourse-correction rocket engine for the required velocity increment. A similar technique could be used during the terminal


Fig. 5. The Ranger Block-III spacecraft is shown with the solar panels and high-gain antenna in the deployed positions. The main spacecraft weighed 192 kg, and the television subsystem

weighed 173 kg.

TABLE II Ranger Spacecraft

Dimensions m Approximate Weight kg

In launch position, folded Diameter 1.52 Height 2.51

In cruise position, unfolded Span 4.57 Height 3.12

Structure 41 Solar panels 21 Electronics 70 Propulsion 20 Launch back-up battery 23 Miscellaneous equipment 17

Ranger bus total 192 TV subsystem total 173

Gross weight 365

descent phase (except for burning the rocke t engine) in o rder to po in t the cameras in

any desired direct ion.

The cont ro l of the television subsys tem involved in i t ia t ion of a warm-up mode

and then ful l -power opera t ion at the p rope r t ime dur ing the descent phase. The Cent ra l


Computer and Sequencer was programmed to initiate both functions after a fixed time from terminal maneuver execute. The terminal maneuver was commanded with zero angle change when the cruise orientation was to be maintained. The Central Computer and Sequencer was backed up with radio commands to insure proper initiation of the television-subsystems operation. The mixed output of the television- subsystems transmitters was fed through a directional coupler to the high-gain antenna for transmission of the television data to the earth. The television subsystem is described in the following section.

B. R A N G E R TELEVISION SUBSYSTEM

The prime objective of photography of the small-scale topography of the lunar surface dictated that the camera system either use a long focal length telescope from reason- able distances or that the spacecraft get close to the lunar surface. It was decided that an impacting mission offered the best opportunity for the desired resolutions. The special constraints imposed by an impacting mission prompted the use of a television- type photographic system. The selected system had to be capable of performing its photography and transmitting the data before the Ranger was destroyed upon impacting the moon. A television-type system was quite capable of such fast operation and, in fact, presented a problem in achieving high-quality photographs at the reduced video bandwidths which were possible for the Ranger spacecraft system in the transmission of data from the moon to the earth.

In order to reduce the required video bandwidths to a practical level, it was necessary to utilize slow-scan television techniques. The number of scan lines, the aspect ratio for the scanned area, and the time to readout a frame (including line blanking) sets the video bandwidth. Several factors came into play which had to be properly traded off if a good overall design was to be achieved: (1) As fast a frame time as possible was desired in order to increase the number of photographs and decrease the time (and therefore the distance) between the last photograph and the surface of the moon. (2) The number of scan lines per frame needed to be as high as possible in order to get adequate area coverage at any particular resolution. (3) The video bandwidth selected for the communications power which was available had to be low enough to insure an adequate signal-to-noise ratio in the transmission of the data so that the transmission process did not limit the picture quality. (4) The characteristics of state-of-the-art components had to be considered because of the design and development schedule limitations for the mission and the known rigors of the total environment to be faced in the launch and flight to the moon.

The Jet Propulsion Laboratory contracted with the Radio Corporation of America for the Ranger Television Subsystem. A simplified block diagram of the system is shown in Figure 6. The outputs of two 60-Watt transmitters were combined in a four-port circulator to provide a single combined output of 30 Watts for each channel or 60 Watts total. The rest of the power was dissipated in a dummy load in order to achieve balanced operation and linear mixing. The combined output was fed through a directional coupler with negligible loss to the high-gain antenna for transmission to


Fig. 6. This block diagram of Ranger television subsystem is made up of photographs of actual equipment. The F and P-channel systems were completely separated except for input control and

radio-frequency output to enhance system reliability.

TABLE III

Summary of Camera Characteristics

Characteristics Cameras

FA and FB P1, P2, P~ and P4

Scan Area 11.4 • l l . 4 m m 2.8 • 2.8 mm Real Resolution Lines 800 lines 200 lines Line Rate 450 cps 1500 cps Horizontal Scanning Lines 1152 lines 300 lines Frame Rate 0.39 cps 5 cps Frame Time 2.56 sec 0.2 sec Video Bandwidth 200 kc 200 kc Erase Time 2.24 sec 360 millisec Exposure Time - (Equivalent Shutter

Speed) 5 millisec 2 millisec

Optics FA FB P1 and Pz Pa and P4

25 mm, 76 ram, 76 mm, 25 ram, f/0.95 ]'/2.0 ./72.0 f/0.95

t h e e a r t h - b a s e d r e c e i v i n g s t a t i o n s . T h e v i d e o i n p u t s t o t h e 6 0 - W a t t t r a n s m i t t e r s we re

d e r i v e d f r o m t w o s e p a r a t e sets o f c a m e r a s . T h e o p e r a t i n g p a r a m e t e r s f o r t h e s e

c a m e r a s a re s u m m a r i z e d in T a b l e I I I .

LUNAR PHOTOGRAPHY~ TECHNIQUES AND RESULTS 225

The cameras used identical-type vidicons operating in two different slow-scan

modes which produced the same video bandwidth for the two separate transmitters. The number of cameras and the selected operating parameters resulted f rom a con- sideration of the various factors already cited. The operation of the camera involved an erasure cycle before every optical exposure and picture readout. The erasure is accomplished by illuminating the photoconductor with a high-intensity flash from the erase lamps to swamp any residual image on the target and then over-scanning by an electron beam to establish the initial conditions for the next exposure. The electron beam was defocused and increased in intensity during the erasure so that a uniform charge condition could be established on the photoconductive target. The image presented by the optics was then shuttered onto the target by a mechanical shutter. The target resistance was reduced in accordance with the imposed light intensities such that local discharge would leave a charge pattern equivalent to the optical image.

This charge pattern was then slowly sampled by the readout electron beam. The resulting readout target current was proportional to the amount of discharge which had taken place, and that was proportional to the optical intensity which had been imposed during the shuttering process.

The amount of time required to perform an erasure of a full-scan camera was such that two cameras were used to provide continuous video data to the F-channel transmitter. While one camera was being erased, the other was being readout thus providing continuous coverage with a new photograph every 2.56 sec. However, the time required to adequately erase a partial-scan camera was longer than the readout time for a picture. The erasure lamp illumination was 80 millisec, and the erase scanning required 360 millisec. These requirements plus the shutter exposure (80 millisec for a moving slit equivalent exposure of 2 millisec) and readout (2C0 millisec for 300 scan lines) made a 4-camera configuration necessary for a continuous output to the P-channel transmitter. The total cycle for the four cameras was 840 millisec with a new photograph every 0.2 sec in the cycle and a 40-millisec blanking between cycles. The partial-scan cameras were read out P~,P3, P2, and P4-

Two different size optics were used with the Ranger cameras: a 25 ram f/0.95 lens provided wide area coverage with increased sensitivity, and a 76 mmf/2 .0 provided higher resolution with lower sensitivity. The nominal range of scene brightness over which the Ranger cameras operated were 20- to 650-foot lamberts for the 25-ram lens and 100- to 2700-foot lamberts for the 75-1rim lens.

The central axis of the cameras' pointing directions out of the camera aperture was 38 ~ f rom the roll axis. This is illustrated in Figure 7 along with the nominal fields of new and relative pointing directions of the six cameras.

C. RANGER P H O T O G R A P H I C RESULTS

The three successful Ranger missions returned a total of 17259 photographs of the moon. Three widely separated areas were photographed with resolutions which ranged f rom less than earth-based resolution to less than a meter resolution. The Ranger missions were successful in achieving their objective of categorizing the small-

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scale topography of the lunar surface for the soft-landed Surveyor and Apollo vehicles.

The Ranger photographs revealed that earth-based selected areas of the lunar surface presented no serious topography hazards for these vehicles. The photographs did not resolve the arguments over the origin of the lunar mare or the surface bearing strength. They did, however, show that the small-scale topography was primarily a result of bombardment by meteorites, micrometeorites, and their secondaries.

The Ranger-VII photographs revealed a surprisingly smooth lunar surface with very few positive relief features above the resolution limit which was achieved. The last FA-camera photograph covered an area of approximately 9 km 2 and permitted

Fig. 8. This photograph was taken by the FA camera 2.5 sec before Ranger-VII impacted the moon. P-camera photographs are shown properly mosaiced onto the photograph. The last photograph

in the mosaic is shown in Figure 9.


the detection of 10-m craters. The partial-scan cameras took 12 photographs between the exposure of the last Fa-camera photograph and the impact with the lunar surface. Figure 8 shows the last Fa-camera photograph with 5 of the last 12 partial-scan photographs superimposed upon it. The last partial-scan photograph was taken with the P3-camera and covered an area of 30 by 50 m. This photograph is shown separately in Figure 9, and craters of less than a meter in diameter were detected.

The U.S. Air Force Aeronautical Chart and Information Center used the Ranger photographs to improve their charts of the lunar surface. The charts generated from Ranger-VII data are designated RLC 1 through 5 and replaces chart LAC 76. The RLC-1 chart has a scale of 1 : 1000000 as did LAC 76. Charts RLC 2 through 5 have scales of 1:500000, 1 : 100000, 1:10000 and 1 : 1000, respectively. Similar charts were prepared from Ranger-VIII and Ranger-IX photographs and are designated RLC 6-12 and RLC 13-17.

Ranger-VIII did not achieve as high a terminal resolution because of a mis- alignment between the cameras' pointing directions and the spacecraft-velocity vector. This caused excessive image motion in the last full partial-scan photograph. Some image motion can be detected in the last useful frame shown in Figure 10. Craters of 1.5-m diameter may be detected in the 90 by 120 m area. The terminal orientation

Fig. 9. This last Ranger -VII pho tog raph covered an area of 30 by 50 m and permit ted the detection of craters with less than 1 m diameter. Ranger -VII re turned 4308 pho tographs

before its impact on July 31, 1964.

LUNAR PHOTO.GRAPHY" TECHNIQUES AND RESULTS 229

Fig. 10. Ranger-VIII returned 7137 photographs of the moon. This last useful photograph covered an area of 90 by 120 m and, due to image motion effects, permitted the detection of 1.5-m diameter

craters. The surface is seen to be quite similar to that revealed by Ranger-VII.

maneuver was not performed in order to permit the wider-area coverage and because the overlapping coverage which would result without a maneuver had the potential of producing quantitative stereo.

Computer processing techniques had been developed at the Jet Propulsion Labor- atory in order to improve upon the Ranger photographs. Figure 11 shows the effect of using camera calibration data to correct for high-frequency response roll-off (loss of fine-scale contrast) on the same photo as shown in Figure 10. Figure 12 illustrates the application of the rectification program which corrects the image by using the trajectory data and the camera viewing geometry. The unique lunar photometric characteristic also permits the computer to generate contour maps with the application of a derived photometric function and the assumption of a constant albedo over the area.

Ranger-IX photographed far more interesting terrain; and with the slightly better camera system flown on Ranger-IX, superb-quality photographs were obtained. A

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terminal orientation maneuver was performed such that the impact point was observed by all but the F~-camera. The photograph shown in Figure 13 was taken by the FA-camera from an altitude of 415 km and shows an area of approximately 195 km by 175 km. This photograph has an equivalent resolution of approximately 500 m per optical pair. The photograph shown in Figure 14 was taken by the FB-camera from an altitude of 185 kin. It shows the Eastern edge of the Crater Alphonsus with the dark-haloed craters and rille system quite prominent. The filling of the rilles in the immediate vicinity of the dark-haloed craters is accepted as evidence of internal activity which has deposited material around the craters' opening. Another interesting feature of the photograph is the smoothness of the highland terrain. This probably results from the stripping action of the smaller meteorites and micrometeorites upon the harder positive relief material.

The floor of Alphonsus is shown at three different scales in Figure 15 taken by camera P3. These are the last three photographs taken by the P3 camera; and as seen by the noise band to the right of photo 3, the spacecraft impacted a fraction of a second before the full frame was read out. Frames 1, 2 and 3 are separated in time by 0.84 sec. The impact point is the stationary point in the field of view and is shown by a small white circle. The crater to the lower left of the impact point is approximately


Fig. 13. Ranger-IX achieved the best photographic results of the Ranger missions because of improved camera performance and the interest of the selected target. This interesting view of the large Crater Alphonsus was taken fi'om an altitude of 415 kin. The resolution achieved in this

photograph was approximately 500 m per optical pair.

8 m in diameter. A resolution of 0.5 m was achieved with a few positive relief features

being revealed. The Ranger-IX F~-camera photographs were shown 'live' in nationwide television

as they were received from the moon. The pictures were read into a scan converter

system which permitted readout with a standard number of lines and frame

rate. The Ranger photographs have been put together into sequences to make movies which give the viewer the feeling of riding the spacecraft to its impact on the moon. The photographs have been published in atlas form for worldwide

study.

5. Zond-HI

The Zond-III mission involved the test of an interplanetary spacecraft with a camera system and a variety of other scientific instruments. The camera was used to photograph that part of the far side of the moon which was not photographed by Luna-III. Zond-III was launched on July 20, 1965, by an undisclosed launch-vehicle system.

LUNAR PHOTOGRAPHY : TECHNIQUES AND RESULTS 233

Fig. 14. This view of the Eastern edge of Alphonsus clearly shows the effects of internal lunar activity. Material from the dark-haloed craters have filled the rilles in their immediate vicinity. The

unsuspected smooth appearance of the highland terrain can also be seen.

The spacecraft was first put into a parking orbit and then injected on a deep-space

trajectory involving a lunar flyby. The photographs of the far side of the moon were

taken at distances ranging from approximately 9200 km to 11600 kin.

The Zond-III spacecraft detail was not disclosed. The system was attitude stabi-

lized, and the cameras were pointed at the moon for the photographic sequence. Ap-

proximately 25 photographs were taken. The transmission of the photographs to the

earth was delayed for 9 days in order to establish high-gain antenna communications with the earth. The photographs were superior to those of Luna-III but still contained some communication noise and a limited grey-scale rendition.

The Zond-III camera system utilized a 100 ram, f/8 lens and 25-mm film with

shutter speeds of 0.01 and 0.03 sec. The line-scan readout of the photographs produced

television-like photographs with 1100 scan lines. The scanning rates were varied to

match the bandwidth constraints for the particular communication range. Figure 16 shows one of the Zond-III photographs. The Orientale basin is the

prominent feature to the lower right of center. The Zond-III photographs confirmed that the far side of the moon is covered with craters and appears quite similar to

highland terrain areas on the front side of the moon. The Zond-III photographs

Fig. 15. These three photographs were taken by the Ranger-IX Pa camera. The spacecraft impacted the moon before the readout of the last photograph was completed. The crater made by the Ranger spacecraft is estimated to be about the same size as the 8-m crater to the lower left of the impact point.

Fig. 16. This Zond-III photograph shows a portion of the far side of the moon which was not photographed by Luna-III. The Orientale basin is shown to the lower right of centre.


were repeatedly transmitted to the earth in a test of the Zond-I I I reliability and

communications systems.

6. Luna-lX

The Luna-IX mission called for rough landing a capsule on the surface of the moon in order to determine the character and appearance of the lunar surface. Luna-IX was launched on January 31, 1966, and successfully landed on February 3, 1966. Luna-IX was the fifth in the Luna series to at tempt a landing on the moon. The Luna-IX system consisted of a separable midcourse-correction system which was jettisoned before attempting the descent phase. During the descent phase, a variable thrust rocket engine was fired at approximately 76 km altitude above the moon. It was fired for about 48 sec to achieve the required reduction in speed. When the spacecraft had reached the correct speed and altitude, the capsule payload was

ejected to free fall to the lunar surface. The Luna-IX capsule measured approximately 0.6 m in diameter and weighed

slightly under 10.9 kg. Figure 17 shows the capsule configuration. Four petal-like protective covers also served to orient the capsule on the lunar surface. Upon landing, the capsule deployed the petals and then erected four rod antennas and three sets

Fig. 17. This drawing of the Luna-IX moon probe shows the protective petal-like covers which were opened to orient the capsule for its facsimile scanning of the lunar surface.


of dihedral mirrors. Radio signals were received from the capsule 4 min, 10 sec after

landing. Picture transmission began 7 hours after landing.

The photographic system which weighed slightly less than 1.5 kg was apparently a facsimile camera using a mechanically scanned aperture. The system scanned the

full 360 ~ horizon with about a 30 ~ angular height. Approximately 6000 vertical-scan

lines were achieved in a full 360 ~ rotation of the scanning head. It required 100 min

to perform a single 360 ~ scan. The dihedral mirrors were used to obtain stereoscopic

photos. Luna-IX operated from batteries and transmitted intermittently for 3 days. Four

full panoramas were transmitted during that time. Figure 18 shows a segment of a

panoramic scan taken on February 4. The tip of one of the cover and protective

petals may be seen slightly left of center. The rock immediately above the tip of the

Fig. 18. This view of the lunar surface was taken by the Luna-IX facsimile system on February 4, 1966. The tip of one of the protective covers may be seen slightly left of centre at the lower edge

of the photograph.

petal is estimated to be no more than 15 cm long. The roughness of the lunar surface as revealed by Luna-IX contrasts markedly with the smoothness observed by Ranger.

However, it is consistent with radar data which shows a rapidly increasing roughness as the scale decreases below a meter to a few centimeters. Another significant bit of information related to the surface bearing strength of the lunar surface material

since the 100 kg capsule barely penetrated the lunar surface.


7. Surveyor

A. S U R V E Y O R M I S S I O N S

The U.S. Surveyor program was planned by the National Aeronautics and Space Administration to obtain essential data for its Apollo-manned landing program and to add to our scientific knowledge of the moon. The Surveyor project was managed by the Jet Propulsion Laboratory, who contracted with the Hughes Aircraft Company for the design and fabrication of the spacecraft.

The Surveyor provided the next logical step beyond the Ranger in the detailed investigation of the lunar surface. Surveyor was designed to soft land and operate

on the surface of the moon. Its primary mission was to validate several critical aspects of the Apollo soft-landing technique and to obtain essential data on the compatibility of the Apollo design with the conditions on the lunar surface. In order

to obtain the desired information, the Surveyor spacecraft was designed to carry a variety of scientific and engineering instruments. Principal among these was a special slow-scan television camera.

Surveyor-I was launched by an Atlas-Centaur on May 30, 1966, on a direct ascent lunar trajectory. A midcourse-correction maneuver was used to correct the impact point by approximately 55 kin. The terminal descent commands were all properly acted upon, and the automatic closed-loop descent sequence terminated at 06 17 37 G M T on June 2, 1966. The touchdown occurred at 2.53 ~ South latitude and 43.32 ~ West longitude selenographic coordinates with a velocity of approxi-

mately 3 m per second. Surveyor-I operated from touchdown until it was shut down for the lunar night on June 14, 1966, and then again f rom July 6, 1966, until the close of the second lunar day on July 14, 1966. Over 11000 photographs were returned by Surveyor-I.

Surveyor-III was launched on April 17, 1967, towards a target at 2.92 ~ South latitude and 23.25 ~ West longitude selenographic coordinates. Surveyor-III successfully landed on April 30, 1967, at 2.94 ~ latitude and 23.34 ~ West longitude. In addition to returning approximately 6300 photographs, the spacecraft carried a soil mechanics surface sampler device which manipulated the lunar surface material. Surveyor-III was operated until May 3, 1967.

Surveyor-V was launched on September 8, 1967, towards a target in Mare Tran- quillitatis at 1.45 o Nor th latitude and 23.25 ~ East longitude. The touchdown velocity

was about 12 km per second, and the spacecraft came to rest at a 20 ~ angle within a 9- to 10-m crater. Surveyor-V provided 19 006 photographs and performed elemental analysis of the lunar surface with an a-scattering instrument. The surface material appeared to be quite similar to earth basalt.

Surveyor-VI was launched on November 6, 1967, towards a target in Sinus Medii. The spacecraft successfully landed only 6 km from its target. To this writing, the spacecraft has provided new a-Scattering data and over 30 000 photographs. In addition, the vernier rockets were used to lift and translate the spacecraft over 3 m. This permitted photography of the initial landing area and the area scoured by the rocket exhausts.


Fig. 19. The Surveyor spacecraft has flown four successful missions to date with one more launch remaining in the program. The Surveyor spacecraft has a landed weight of from 270 to over 300 kg,

depending upon the payload flown.

Surveyor-VII is expected to be launched in early 1968. It is felt that Surveyors-I, III, V and VI have adequately served Apollo interests and that a target of more specific scientific interest will be selected. Typical highland terrain or the floor of a large crater are likely targets. Surveyor-VII is expected to carry a television camera, a-Scattering instrument, and soil mechanics surface-sampler device.

B. SURVEYOR SPACECRAFT

The Surveyor-spacecraft configuration is shown in Figure 19. The basic structure is made up of thin-wall aluminum tubing with mounting surfaces and attachments

LUNAR PHOTOGRAPHY ; TECHNIQUES AND RESULTS 239

for the various spacecraft subsystem elements. The spacecraft is made up of the power, telecommunications, thermal, structures and mechanisms, propulsion, flight control, and payload subsystems. The assembled spacecraft stands approximately 3 m high. The landing leg footpads form an equilateral triangle of approximately 3.4 m on a side. The launch weight for Surveyor-I was 995 kg, and the landed weight was 270 kg. The mission weights vary as a function of the particular payload. Sur- veyor-I carried only the television camera in addition to the regular engineering instrumentation.

The majority of the electronic equipment is contained in two thermally controlled compartments. Temperature control of these compartments is achieved by both passive radiative transfer control and active conduction and heating control.

The power for the spacecraft is provided by a silver-zinc battery and a solar

Fig. 20. The Surveyor television camera makes use of a panoramic head with a tilting mirror. The system is capable of varying by radio command its optical focal length, iris setting, shutter speed, and filters for color photography. Photographs can be read out with either 600-line or 200-line

resolutions, depending upon the communication system to be used.

panel of approximately 1 m 2 a r e a . The solar panel produces a nominal 85 Watts when properly oriented during cruise or on the lunar surface. The rechargeable silver-zinc battery has a fully charged capacity of 180 amp/hr. An auxiliary battery of 50 amp/hr capacity may be flown when payload weight permits.

The attitude of the spacecraft is controlled in the cruise mode by cold-gas jets


operated by signals derived from the attitude-reference sensors. The sun and the star Canopus are used as references and are detected by properly located sensors. An inertial system using rate gyros provides the attitude error signals during midcourse maneuvers and combines with the velocity-measuring and altimeter radar data to control the terminal landing maneuver. The solid propellant main retro-rocket is

ignited by the signal from an altitude marking radar. The three-vernier rocket engines

Fig. 21. This 200-line, low-resolution photograph was the first photograph taken by Surveyor-I. It was exposed at an appropriate level to show the details of the spacecraft structure.

continue to slow and control the attitude of the spacecraft after the burnout of the main retro-rocket engine. The velocity-measuring and altimeter radars operate in conjunction with an on-board analog computer, the autopilot, and the vernier engines to form an automatic closed-loop guidance for the final phase of the descent to touchdown.


The Surveyor spacecraft carries two transmitters, two receivers, two omni-directional antennas, and a planar array high-gain antenna for operation and control of

the spacecraft on the lunar surface in performing its engineering and scientific in- vestigations and transmitting the data to the earth. The television-camera system used in the Surveyor missions is described in the following section.

c . SURVEYOR TELEVISION-CAMERA SYSTEM

The Surveyor slow-scan television camera is shown in Figure 20. The camera uses a 360 ~ pan head with a tilting mirror for near and far field viewing. Since the azimuth position of the head and the elevation angle of the mirror are controlled by radio command from the earth, the camera has the ability to view any desired area. In addition, the camera has a commandable color filter wheel for color photography through a sequence of photos through selected filters. The optical system is a variable focal-length lens capable of local lengths ranging f rom 25 m m to 100 mm. An iris is adjustable in steps with an area change of 0.5 per step from f / 4 to f /22.

By utilizing various modes of operation, the camera can accommodate scene luminance levels f rom approximately 0.008- to 2600-foot lamberts. The normal mode

Fig. 22. The Surveyor camera was used in the high-resolution 600-line mode to take the hundreds of photographs which were mosaiced to show the details of the surrounding lunar terrain.


of operation involves reading out one 600-line television picture every 2.6 sec. One second is required to read out the image. Two hundred millisec are required to transmit engineering data such as the lens and mirror positions and camera tempera-

tures. The remaining 1.4 sec are required to erase the residual image. A second mode involves reading out a 200-1ine television image every 60.8 sec. The image is read out in 20 sec with a 1.2 kcps video bandwidth (as compared with 220 kcps) for trans-

mission via the omni-antennas. A third mode of operation involves operation with the shutter open to permit light integration for increased sensitivity. The electron- scanning beam is turned off during the integration period. Such an operation permits photographs with stellar and earthshine illumination.

As with the Ranger television camera, the Surveyor television system was thor-

Fig. 23. The character of the lunar surface material is shown by its interaction with a Surveyor-I spacecraft footpad. The surface material appears to be a very fine-grained, slightly cohesive soil.


oughly calibrated. The calibration involves the total system including the telecom-

munications system. The calibration data is used to correct images for geometric

nonlinearities and distortions, frequency or aperture response, photometric non-

uniformities, and coherent noise. The calibration data were recorded on magnetic

tape for use with digital computers in optimizing the information in the returned

photographs. The primary parameters that were calibrated were the dynamic range or light-transfer characteristic, the modulation transfer or sine-wave response, the

geometric distortion, and the signal-to-noise ratio. The calibration stimuli involves

a series of test slides used to provide a controlled image to the camera system with an accurately calibrated and controlled collimator and light source.

Fig. 24. This photograph reveals the interaction of a shock-absorbing block under the spacecraft frame with the lunar surface. The cohesive character of the lunar surface material is further

demonstrated by the block of material which has slumped into the hole made by the shock-absorbing block.


D. SURVEYOR PHOTOGRAPHIC RESULTS

Thirty-five minutes after it landed on the surface of the moon, Surveyor-I t ransmit ted

its first photograph, shown in Figure 21. The first photograph contained only 200

scan lines and was exposed at a level to reveal spacecraft-structure detail. This

Fig. 25. Surveyor-V landed inside a small crater with a rest position tilt of approximately 20 ~ These two photgraphs show that the a-Scattering Instrument slid down the slope as a result of the

firing of the vernier engines.


photograph was only the beginning of a series of thousands of photographs to be

accumulated f rom Surveyor spacecrafts on the moon. Figure 22 illustrates the use of several hundred photographs taken in a controlled sequence to reveal the terrain in the vicinity of the Surveyor-I spacecraft. This survey was taken on June 13, 1967, about 24 hours before the local sunset. The individual photo chips have been mosaiced inside a hemisphere to correct the perspective for a human observer.

The character of the lunar surface material was revealed by Surveyor-I in the photographs shown in Figures 23 and 24. These photos show the interaction of a spacecraft footpad and shock-absorbing block with the lunar surface. The material appeared to be finely divided and quite similar to slightly cohesive soil or damp, fine-grain sand. The nature of the lunar surface material was further revealed by observing the surface sampler effects upon the surface material during its use on the Surveyor-III mission. Time-lapse movies put together f rom separate Surveyor-III photographs show the initial trenching by the surface sampler, and cracks are seen to radiate away from the surface sampler.

Surveyor-V flew the a-Scattering instrument, and the television system was used to photograph the surface where the instrument would be deployed and its position

Fig. 26. The floor of the crater in which Surveyor-V landed is shown in this nine-photograph mosaic. The furrow dug by the spacecraft footpad may be seen to the right of the footpad.


after deployment. Figure 25 shows that the instrument slipped down the slope after

the firing of the vernier engines. The floor of the crater Surveyor-V landed in is shown in a nine-photograph

mosaic in Figure 26. The furrow dug by the number two footpad as it slid down the

slope extends to the right. A part of the structure seen in the lower frames is the

television-camera housing. Surveyor-VI landed in Sinus Medii which was known from Lunar Orbiter photos

to be rough. The spacecraft was given a fifty-fifty chance of a successful landing

Fig. 27. Surveyor-VI landed in Sinus Medii and was given a fifty-fifty chance of success because of the roughness of the terrain. This photograph shows the very large number of craters in the vicinity

of the spacecraft.


Fig. 28. This Surveyor-VI mosaic shows a large crater which is rimmed with blocks of material. Some of these blocks are estimated to be a meter across.

based upon the roughness assessment. The spacecraft landed on flat terrain; bu t as

can be seen from Figures 27 and 28, the terrain is very rough with a large n u m b e r

of craters. The large crater shown r immed with blocks of material in the mosaiced

Figure 28 has blocks approaching a meter across.

Surveyor-VI was lifted and translated by the vernier-rocket engines over 3 m up

and 3 m across. The fact that lunar material is picked up and blown by such an

operat ion is shown in Figure 29, where the photo cal ibrat ion chart moun ted on the

omni -an tenna boom is shown before and after the maneuver . The t ranslat ion of the

Fig. 29. The fact that the lunar surface material can be picked up and blown around is demonstrated in these two photographs. Surveyor-VI was lifted and translated over 3 m by the vernier-rocket engines

with the resultant deposits on the television test target located on the omni-directional antenna.


spacecraft by 3 m will permit excellent stereo photographs. Complete panoramic views from both locations have been performed for this purpose.

The Surveyor missions have satisfied their objectives in support of the Apollo program and have demonstrated that successful soft landings on the moon can be safely accomplished. The Surveyor missions have categorized the terrain from a surface point of view and have shown the nature of the surface material. The Surveyor findings support the Ranger-established contention that the small-scale topography is a result of bombardment by meteorites, micrometeorites, and their secondaries. It is evident that this process has generally reduced the 'basalt-like' material to the form of a soil. Blocks seem to exist on the surface only where 'large' meteors have ejected them from beneath the surface layer.

Surveyor-VII has yet to be flown, but its planned selection of a target of more specific scientific interests should provide new, valuable data in our growing awareness of what the moon is really like.

8. Lunar Orbiter

A. L U N A R ORBITER MISSIONS

The National Aeronautics and Space Administration's Lunar Orbiter program must be considered the most successful lunar program to date. All five of the missions achieved nearly 100~ of their mission objectives. Outstanding photographs of the desired lunar areas and of the earth were obtained. NASA's Langley Research Center provided the Project management with the Boeing Company as their prime sub- contractor. Eastman-Kodak and the Radio Corporation of America were two of the major subcontractors on the program.

The prime objective of the Lunar Orbiter program was the return of high-resolution and wide-area coverage photographs of candidate Apollo landing sites. These candidate sites are distributed along the lunar equator in order to minimize the launch-opportunity constraints. Another key photographic objective was the return of photographs of high scientific interest. The Lunar Orbiter was highly successful in satisfying both of these objectives.

The Lunar Orbiter spacecraft was launched by the Atlas-Agena launch-vehicle system. In order to achieve the desired lunar orbit, the spacecraft performed a midcourse maneuver, an orbit injection maneuver, and an orbit correction maneuver. The areas to be photographed on a particular mission were selected by controlling the launch date, the orbit inclination, the particular time in orbit as the moon slowly turned (13 ~ per day) under the spacecraft, and the pointing direction of the camera. The launch dates and the numbers of photographs returned were summarized in Table I.

B. L U N A R ORBITER SPACECRAFT

The Lunar Orbiter spacecraft weighed 380 kg and measured approximately 2 m high and 4 m across the solar panels. The spacecraft configuration is shown in Figure 30.


Fig. 30. The first Lunar Orbiter was launched on July 10, 1966, and weighed 387 kg. All five of the Lunar Orbiter missions were successful. The Lunar Orbiter returned more photographic

information than all other lunar photographic missions to date.

The four solar panels provided a nominal 330 Watts of electrical power and in conjunction with a 12 amp/hr, nickel-cadmium battery provided the required spacecraft power.

The attitude control system utilized cold-gas jets controlled by signals f rom inertial and celestial sensors to maintain the required attitude in the various hold conditions. In the celestial hold condition, the sun and the star Canopus are used as the reference points with the gyros operating as rate sensors. In the inertial hold mode, the three gyros operate as attitude-angle sensors and are used whenever a celestial sensor is occulted, during engine firing and during part of the photographic

hold mode. In the photographic hold mode, the pitch and roll axes are put in inertial hold. The yaw axis must be maintained at zero yaw rate to avoid photographic smear. This is accomplished by nulling the output of a velocity and crab-angle sensor. Commanded positions are held to within _+0.2 ~ in the photographic hold mode.

The velocity control system utilizes a 45-kg thrust bipropellant rocket engine. The system is capable of a total velocity change of about 1000 m per second and is adequate for two midcourse maneuvers, lunar orbit injection, and orbit trim. The velocity increment is controlled by using a precision linear accelerometer and integra- tor to accomplish engine shutdown at the appropriate time.

Communication is provided by two separate transmitters. A 10-Watt output travelling wave tube feeds a circular dish antenna of almost a meter diameter. This system is used for the transmission of the photographic information. A half-Watt


output transmitter feeds the omni-antenna for normal telemetry transmissions. The

omni-antenna is used for the reception of radio commands for the control of the

system.

The spacecraft programmer is a digital data-processing system which accepts radio commands to achieve the necessary control of the spacecraft in its various

modes including the photographic sequences. The system made use of a large number

of stored commands for sequences which were used repeatedly. In such cases, the

radio command needed only to designate the desired sequence and initiate it. In

other cases, the required 'magnitude' of the command was temporarily stored for

action.

C. L U N A R ORBITER P H O T O G R A P H I C SYSTEM

The Lunar Orbiter used a unique film-camera system with two sets of optics. The camera system is diagrammed in Figure 31. The high-resolution system used a

610 mmf/5 .6 lens. The moderate resolution, wide area coverage optical system used

an 80 m m f / 5 . 6 lens. The images from these two optical systems could be shuttered

at speeds of 0.01, 0.02 or 0.04 sec. The film used in the Lunar Orbiter was 70-mm

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FILM SCANNER

Take-up Looper

Film Take-up

Fig. 31. The Lunar Orbiter camera made use of a 610 mm f/5.6 lens and an 80 mm f/5.6 lens. The exposed film was processed with the Eastman-Kodak 'Bimat' system. The processed film was

read out by optically scanning the film with a 6.5 micron scanning spot.

SO-243 film. This is an Eastman-Kodak aerial film and is preprinted along one edge with grey scales, resolution bars, and other pertinent information. The format used

on the film resulted in a 55 by 219 mm frame for the 610-mm lens and a 55 by 60 mm frame for the 80-mm lens. At an altitude of 46 km, the 55 by 219 mm frame corresponds to 4.19 km by 16.6 km and the 55 by 60 mm corresponds to 31.6 km by


37.4 km for the high- and moderate-resolution lenses. Each exposure command

resulted in a medium-resolution photograph and a high-resolution photograph. The high-resolution photograph was centered on the medium-resolution photograph with its long dimension transverse to the trajectory path. Various command sequences were used to obtain overlap for extended coverage at both high and medium resolution and for stereo purposes.

The exposed film was developed, fixed, and dried by the processor-dryer. The Eastman-Kodak 'Bimat '-system was used, and it processes the film at the rate of 6.1 cm per minute and requires 3.4 rain from start to finish for a particular image. The process involves temporarily laminating the emulsion side of the Bimat film against the SO-243 film emulsion as it travels around the processing drum. After leaving the processor drum, the film is passed over a heated drum to assure removal of any moisture for collection by a desiccant. When all the film is processed, the Bimat film is cut by a hot wire so that the film can be translated back and forth for arbitrary readout of the processed film.

S L~ne Scan Tube

to TransmHter Amplifier

Fig. 32. The film readout scanning technique is illustrated in this figure. The scanning spot is moved 2.67 mm along the film with 286 scan lines per millimeter across the film. These segments are recorded

in the ground receiving station and then reconstructed into the original format.

The photographic film is converted by the readout system, diagrammed in Figure 32, into an electrical signal for transmission back to the earth. A high-intensity beam of light is used to read out the film. The light intensity transmitted through the film is picked up by a photomultiplier tube for conversion to an electrical signal. The high-intensity light beam is generated by a special line-scan tube. The scanning spot focussed onto the film is 6.5 microns in diameter. The spot is scanned 2.67 mm in the long direction of the spacecraft film. The scan is repeated 286 times per m m across the width of the film. The film is then advanced 2.54 mm, and the transverse scan is repeated. This process is continued until the processed film is read out. The high-density scan provides over 15000 scan lines in the 55 m m width of the film.

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LUNAR PHOTOGRAPHY" TECHNIQUES AND RESULTS 253

D. L U N A R ORBITER P H O T O G R A P H I C RESULTS

The Lunar Orbiter photographic return far exceeds that of any other lunar program to date. This occurs despite the low number of separate photographs because of the high resolution achieved in their readout. A single moderate-resolution photograph (55 x 60 ram) is equivalent to over 680 Surveyor photographs in terms of numbers of scanned elements. A single high-resolution photograph (55 x 219 mm) is equivalent to almost 2500 Surveyor photographs. This unique feature of the Lunar Orbiter film- camera system was used effectively in satisfying the prime mission objective of photographing the Apollo landing areas. Resolutions of a meter or so were obtained with the high-resolution camera. However, the most spectacular results were obtained in photographs of areas of scientific interests.

One of the most interesting photographs taken by Lunar Orbiter-I involves the view of the earth, shown in Figure 33. This photograph was taken on August 23, 1966,

as the Lunar Orbiter was about to pass behind the moon. In addition to providing our first view of the earth f rom the moon, it also provides a unique astronaut 's view

Fig. 34. This oblique view of the lunar surface was taken by Lunar Orbiter-II using the 80-ram medium resolution optical system. The large crater Copernicus can be seen in the distance.

Fig. 35. This high-resolution photograph was taken at the same time as the photograph shown in Figure 34. The crater walls and centre peaks of the crater Copernicus are seen to be quite rough

as would be expected of this relatively young lunar feature.

Fig. 36. Lunar Orbiter-III was also used to photograph the area where Surveyor-I landed. These three views illustrate the technique used to locate the Surveyor-I spacecraft. The right-hand photo

shows the Surveyor-I spacecraft as a bright spot casting a 10-rn shadow.

t UNAR PHOTOGRAPHY : TECHNIQUES AND RESULTS 255

of the lunar surface. Another oblique view of the moon is shown in Figure 34. This

photograph was taken on November 23, 1966, by Lunar Orbiter-lI and shows the

large crater Copernicus. A high-resolution photograph was taken at the same time

and is shown in Figure 35. The central peaks rise a kilometer above the crater floor

and are seen to be rough with large blocks of material. Copernicus is much younger

than Alphonsus whose central peak and crater walls were found to be very smooth

by the Ranger-IX photographs.

Fig. 37. This spectacular view of the Orientale basin was taken by Lunar Orbiter-IV on May 25, 1967. The basin is seen to consist of three concentric circular rings. The outer ring, formed by the

Cordillera Mountains, has a diameter of about 960 km.


The Lunar Orbiter-III was used to photograph the Surveyor-I spacecraft sitting on the moon. The three views of the lunar surface shown in Figure 36 are of the Surveyor-I landing area. The left-hand photograph shows the landing area in Oceanus Procellarum, the crater Flamsteed E, and the crater-wall peaks of the large-ghost crater which were photographed by Surveyor-I. The center photograph shows the high-resolution camera view of the Surveyor-I landing area. The right-hand photograph is a 16 to 1 enlargement of a portion of the area inside the black square shown in the center photograph. The Surveyor-I spacecraft is seen as a white object casting a 10-m shadow.

Lunar Orbiter-IV provided the spectacular view of the Orientale basin shown in Figure 37. This photograph was taken on May 25, 1967, from an altitude of over 2700 km. The Orientale basin is seen to consist of three concentric circular rings and appears to have been formed by the impact of a large meteorite with the subsequent filling of the center basin and the concentric fractures with dark mare volcanic material. The outer scarp, the Cordillera Mountains, form a circle of about 960 km in diameter. The rough mantle of the ejecta resulting from theimpact is shown to cover the surface for another 600 or more kin. Oceanus Procellarum is shown in the upper left-hand corner.

Only a few examples of the superb Lunar Orbiter photographs have been shown. Many areas of high scientific interest were photographed. The far side of the moon was included in the Lunar Orbiter missions, and several orders of magnitude im- provement over the Luna-III and Zond-III results were obtained.

9. Conclusion

The lunar photography missions have included flyby, impacter, lander, and orbiter spacecrafts. These missions have provided photographs of the far side of the moon and a ten-fold increase in frontside resolution plus higher resolution of selected frontside areas. The resolutions which have been achieved vary from 1 m for the Lunar Orbiter to �89 m for the impacting Ranger to millimeters for Luna-IX and the Surveyors. The return from these missions have resolved much of the mystery surrounding the moon.

The prime objective of the U.S. photographic missions has been the support of the Apollo-manned lunar landing program. The Ranger program, the Surveyor program, and the Lunar Orbiter program provided a logical progression in the utiliza- tion of a developing space exploration technology. These programs have provided the required information and have confirmed that the Apollo landing vehicle design is compatible with the conditions to be experienced on selected areas of the lunar surface.

The future manned landing missions can be expected to provide additional lunar photography. Since the astronauts can be more selective in their photography, even more outstanding and informative results should be achieved. The addition of movies and even 'live' television coverage will permit earth-based man to share more directly in the manned exploration of the moon.


The u n m a n n e d photographic explorat ion of the m o o n has provided much of the

technology required for similar missions to the planets. The U.S. Mar iner - IV was

the first successful mission to obta in close-up photographs of the planet Mars. I t

can be expected that bo th the U.S.A. and Russia will try for further photographic

successes in the explorat ion of our solar system.

Bibliography

1. BARABASHOV, N.P., MIKHAILOV, A.A., and LIPSKIY, Y.N. : 1961, 'Atlas of the Other Side of the Moon', Acad. Sci. USSR, 11-141.

2. SHOEMAKER, E.M.: 1964, 'The Moon Close Up', Nat. Geopgraphic, Nov., 692-707. 3. KUIPER, G.P. : 1965, 'Lunar Results from Rangers 7 to 9', Sky and Telescope, May, 293-308. 4. HEACOCK, R.L.: 1965, 'Ranger: Its Mission and Its Results', Space Log, Summer, 2-23. 5. LIPSKIY, J.N.: 1965, 'The Far Side of the Moon', Flight International, Sept., 554-556. 6. SCHURMEIER, H.M., HEACOCK, R.L., and WOLFE, A.E.: 1966, 'The Ranger Missions to the

Moon', Sci. Am., Jan., 52 67. 7. COSPARInformation BulletinNo. 31: 1966, 'The First Automatic StationtoLandontheMoon',

Intern. Aerospace Abstr., April, 36-47. 8. SHOEMAKER, E.M., BATSON, R.M., and LARSON, K.B.: 1966, 'An Appreciation of the Luna 9

Pictures', Astronaut. Aeronaut., May, 40-49. 9. GAULT, D.E., QUAIDE, W.L., OBERBECK, V.R., and MOORE, H. J. : 1966, 'Luna 9 Photographs:

Evidence for a Fragmental Surface Layer', Science 153, 986 988. 10. MONTGOMERY, D.R. and WOLF, F.J.: 1966, 'The Surveyor Lunar Landing Television System',

IEEE Spectrum, August, 54-61. 11. RINDFLEISCH, T. : 1966, 'Photometric Method for Lunar Topography', Phot. Sci. Eng., March. 12. JOHNSON, R.W.: 1966, 'The Lunar Surface According to Luna IX and Surveyor I', Astronaut.

Acta 12, 370-383. 13. Report on Surveyor Project: 1967, 'Twelve Articles', J. Geophys. Res. 72, 773-856. 14. KOSOESKY, L.J. and BROOME, G.C.: 1965, 'Lunar Orbiter: A Photographic Satellite', J. Soc.

Motion Picture Television Engrs. 74, 773-776. 15. SCHERER, L.R. : 1967, 'The First Four Lunar Orbiter Photographic Missions', COSPAR, Plenary

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Documents

Lunar photography: Techniques and results