The development of the television system used for Apollo 15 mission is discussed. Data cover identification of factors contributing to the high quality of pictures generated on the lunar surface and exploration of several possible present and future uses of the television equipment developed

Russell, S.

English

NASA Technical Reports Server

DEVELOPMENT AND APPLICATION OF COLOR TELEVI SON 
FOR APOLLO XV AND BEYOND 
By Samuel Russell 
RCA Astro-Electronics Division 
Princeton, New Jersey 
Television played a major role in the spectacu- 
lar success of Apollo XV. From a research view- 
point, the quality of the video enhanced the value of 
the lunar surface observations. The real-time 
transmission of astronaut activity on the lunar trav- 
erses  undoubtedly increased the popular appeal of 
the overall mission, also. What was actually done 
to develop and improve the quality of the television 
systeru used on the Apollo XV lllissiuii? hi this ya- 
per, I would like to describe briefly the television 
system developed for the mission, identify the fac- 
tors  contributing to the high quality of the pictures 
generated on the lunar surface, and explore several 
possible present and future uses of the television 
equipment developed for Apollo XV. 
Four factors contributed to the success of 
Apollo XV television. The first factor was mobility. 
The television camera accompanied the astronauts 
during their explorations of the lunar surface and 
permitted television coverage from a variety of lo- 
cations on the moon. Remote control of the camera 
system from earth also was  an important factor in 
the success of the mission. Now the camera could 
follow the action and zoom-in on details of the lunar 
surface ! A third factor consisted of improvements 
in television camera performance. The "smears" 
and "blurs" seen on television during previous mis- 
sions were  eliminated. Gone also were the "Casper 
the ghost" images of the astronauts. But the new 
television camera alone was  not the  only technical 
improvement in the system. 
The fourth and final factor contributing to the 
high quality of Apollo XV television was a major im- 
provement in the overall television transmission 
system - mainly on earth. The original network of 
ground equipment used for the manned space pro- 
gram at  NASA was not designed to receive and proc- 
e s s  color television signals for network distribu- 
tion. Therefore, a joint NASA and RCA effort was 
organized to review and improve the entire televi- 
sion transmission system - from the lunar surface 
to the home receiver. The objective was to gener- 
ate a television picture from the moon that was just 
as good a s  the pictures received of the local Satur- 
day afternoon ballgame! A great deal of work was 
required to achieve this  objective. 
Considering the above factors in more detail, 
Figure 1 shows the components of the television 
system mounted on the Lunar Roving Vehicle ( LRV) . 
On the left-hand side is the completely self-contained 
color camera unit (CTV) . During the lunar landing, 
the camera was mounted on the Lunar Module ( LM) 
Falcon, in a position that could view the astronauts 
descending the steps. The camera then was mounted 
on a tripod to vicw dcploymcnt of thc LRV from the 
LM. After deployment of the Rover, the camera 
was transferred to the television control unit (TCU) 
mounted on the vehicle. The television control unit 
decoded the radio commands from earth and per- 
formed the functions shown in Figure 1. The control 
unit also positioned the camera left or right and up 
or down in response to remote commands from 
earth. 
The Lunar Communications Relay Unit (LCRU) 
is shown at the bottom of Figure 1. This unit con- 
tained the television transmitter and other communi- 
cation equipment required for relaying voice and 
other signals between the backpacks carried by the 
astronauts and earth. The high-gain antenna beamed 
the television signal to earth. The camera (CTV) , 
control unit (TCU) , relay unit ( LCRU) , and antenna 
together were ,  in reality, a complete television 
station. The television shown in Figure 2 (taken by 
the equipment at Cape Kennedy 1 month prior to the 
mission) is mounted right on the front bumper of 
the Rover! When the astronauts stopped on the lu- 
nar surface, one of them got off, turned a power 
switch ON, aimed the antenna at earth, and the show 
began! 
Figure 3 shows the color camera (CTV) and the 
remote control unit (TCU) . The camera functions 
that can be operated by ground command are shown. 
The camera may be panned to the left o r  right, or 
tilted up and down. Motorized drives in the lens 
assembly allow changes in the lens focal length and 
aperture. Exposure control and power also may be 
controlled from earth. The ground controller at 
MSC-Houston has a set of 18 pushbuttons with 
which he can control all camera operations (Fig. 
4 ) .  If the controller wanted the camera to pan left, 
he first depressed the PAN LEFT button, and the 
camera moved slowly to the left. The camera 
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https://ntrs.nasa.gov/search.jsp?R=19730005128 2020-03-17T07:52:53+00:00Z
motion continued until he depressed the P A N  STOP 
button. 
The flight controllers at Houston faced a unique 
time delay problem. When a pushbutton was 
pressed, 3.5 sec passed before any response was 
seen on the television screen. Only through realistic 
simulation of the time delay before the mission were 
the controllers able to train themselves to follow 
the action. 
In discussing the improvements in the Apollo XV 
camera, the difficulty in obtaining good television 
pictures on the moon must be stressed. Lighting on 
t h e  moon consists of extreme contrasts. The as- 
tronauts appear brilliant because of the highly 
reflective cloth of the spacesuits. 
itself, however, is rather dark. Furthermore, 
shadows on the moon are  extremely dark because no 
sky light exists to  soften the shadows. One way to 
solve the lunar illumination problems was to develop 
a compatible camera tube. A tube under develop- 
ment at RCA,  known as  a Silicon Intensifier Target 
(SIT) tube, was found to have the characteristics 
needed for the Apollo XV camera. The tube is very 
sensitive and can see details in shadow areas. I t  
also can withstand the direct rays of the  sun without 
being damaged. Sensitivity of the SIT tube can be 
controlled electrically over a range of light levels 
of about 1000 to 1. 
The lunar soil 
In conjunction with the SIT tube, all circuitry 
in the camera was of such a nature as  to optimize 
performance under conditions expected on the moon. 
Figure 5, a good example of this optimization, 
shows the camera is imaging two astronauts on a 
scale model of the lunar surface. One of the astro- 
nauts is in direct sunlight (simulated) while the 
other i s  in shadow. The television system just 
does not have the dynamic range to simultaneously 
image properly both the astronaut in sunlight and the 
one in shadow. This problem may be resolved, 
however, by having two separate modes of automatic 
light control (ALC). A peak mode detects the 
brightest object in the scene, and adjusts the SIT 
tube sensitivity to give t h e  highest modulation value 
of the picture signal for this object. In this way, a 
good image of the astronauts is obtained. An aver- 
age mode is used for looking in the shadow, and 
picture highlights a r c  allowed to saturate and 
"bloom." A brightly lit astronaut cannot be seen 
clearly in an average mode because his image has 
saturated. The astronaut in shadow, however, can 
be seen clearly. By using two modes of ALC, im- 
proved exposure control for the pictures seen dur- 
ing Apollo XV was possible. 
When the Apollo XV television signal left the 
transmitter and antenna on the moon, the signal 
traveled to one of three ground stations on earth. 
Let US use, for example, the Australian station and 
trace the path of the television signal from there to 
a home television receiver. From the Australian 
ground station, the signal went via a groundline to a 
COMSAT ground station. From the COMSAT 
ground station, the signal was transmitted to 
INTELSAT, a satellite 22 000 miles above the Pa- 
cific, then back to a COMSAT ground station in Cal- 
ifornia. Bell System then took the signal to MSC- 
Houston where the color television signal was 
changed to the form used for commercial color tel- 
evision transmissions. 
distributed to the television networks from MSC- 
Houston for transmission to the public. Along this 
complicated transmission path from the moon, po- 
tential system problems are  constantly threatening 
television signal quality. The NASA and RCA sys- 
tems team turned up quite a number of problems 
that could have caused picture degradation. In one 
case, the ground station receivers caused a break- 
up in the edge of the picture. In another case, a 
special processing amplifier was introducing noise. 
A filter, designed to separate the voice signal from 
the television signal, was producing ghosts in the 
picture. These and other problems were discovered 
and, for the most part, were fixed for the Apollo 
XV mission. 
Finally, the signal was 
Another difficult t a s k  was isolating the location 
of ground system malfunctions during television 
transmissions. In commercial network operations in 
the U. S., the originating station gives the 
television signal to a common car r ie r  (i.e., the Bell 
System) which then routes the signal to its desti- 
nation. For the Apollo mission, however, many 
carr iers  were involved. There was one link from 
the moon to the earth, another link through a com- 
mon carr ier  in Australia under t h e  jurisdiction of the 
Australian Postal Department, then another through 
COMSAT and International Telecommunication 
Satellite Consortium ( INTELSAT) over the Pacific, 
and finally one through the Bell System to the space 
center. A break in any one link would have spoiled 
the show. To pinpoint where problems were occur- 
ring was a difficult task. For this reason, a special 
NASA Television Flight Control Group was formed 
to supervise the entire television operation during 
the mission. 
in the control center right behind the controller 
operating the camera. From this vantage point, 
he could communicate with points all over the world 
and locate problems as they occurred. Fortunately, 
no serious problems occurred, and the show went 
off on schedule. 
The manager of this group was located 
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What sort of applications can the Apollo XV tele- 
vision system be used for?  In science, there a re  a 
number of advantages in having high-quality televi- 
sion. One i s  just having a good record of scientific 
exploration. During the Apollo XV, the television sig- 
nals provided invaluable documentation of the lunar 
surface investigations. This w a s  really unexpected 
by scientists and the scientists realized the value in 
these analyses only after extensive replay of the 
videotapes. A film record of the same data would 
not have been practical because the weight of film 
would have reduced the weight allotment for lunar 
samples. Thus, television provided the ideal way 
to secure these data. 
Television also may change the method of doing 
scientific rcscarch in two rathcr interesting ways. 
The use of high-quality television for costly scien- 
tific projects such as  lunar exploration permits 
"real-time" scientific research. When a scientist 
wants to make a normal geological exploration of a 
region, he first researches the area, then plans an 
exploration, and goes into the field to take samples. 
Then he analyzes his field data and defines a geo- 
logical model. Generally, his conclusions lead to 
the need for more additional field work and a new 
model. On earth, this iterative process for scien- 
tific research is acceptable. 
In exploring the  moon, however, the high cost 
involved precludes such luxury. Returning to the 
same place to gather data for an incomplete model 
i s  not feasible. Instead, the whole investigative 
procedure must be compressed within the available 
mission time. Scientific teams must work in real 
time to analyze data and decide how to proceed with 
the exploration as  the exploration is taking place. 
Television, for example, could have been used 
to an advantage during the Apollo XlV mission when 
the astronauts were on their second extravehicular 
activity (EVA) near the edge of Cone Crater. They 
reported seeing some white-rock formations, but 
did not elaborate. The response from Houston 
was for them to take a photograph of a sample of 
the white rock. When the films were developed 
after the mission, the photograph of the white rocks 
showed something completely unexpected. Never 
had formations like this been seen on the lunar 
surface nor have they been seen since. Due to the 
pressure of time, o r  perhaps limited geological 
training, the astronauts missed the significance 
of these formations. Scientists on earth may have 
seen the formations with television. The EVA 
timeline then would have been reorganized to 
sample this region more fully in an attempt to ex- 
plain these formations. 
A second use of the television camera during 
future Apollo missions is a s  a multispectral sensor. 
The SIT pickup tube has a broader spectral response 
than the human eye, and the moon exhibits much 
higher contrast in the infrared spectral region than 
in the visible region. A television camera, there- 
fore, can enable scientists on earth to see scene 
details that even the  astronauts themselves cannot 
see. 
Television also is important as  a tool to educate 
and to give everyone a unique sense of participation 
in the Apollo missions. The many applications of 
space technology to our more earthly needs must be 
realized by the public, especially in the fields of 
communications, weather forecasting, navigation, 
and earth resources surveying. The space program 
is  really beginning to bear fruit, and yet many ex- 
ploratory parts of the space program a re  difficult to 
justify to the American public. For the Apollo mis- 
sions, the justification is science. Much s t ress  has 
been placed on the importance of discovering how the 
moon was formed, what relationships it has with 
earth, and how the moon may hold the secrets to the 
origin of the solar system. 
To the man on the street, the "need to know" is 
often a little difficult to understand. He probably has 
justified to himself why we are exploring space, the 
moon, and the planets - just as a mountain climber 
has reasons to climb a mountain. By allowing him 
to  see and experience space exploration through tele- 
vision, as w e  did on Apollo XV, perhaps we have the 
key for his continuing support of our endeavors in 
space. 
281 
Figure 1. Lunar Communication/Television System 
Figure 2. Television installation on Rover. 
2 82 
Figure 3. Ground Commanded Television Assembly (GCTA) . 
Figure 4. Command functions. 
399 -vu  
Figure 5. Automatic light control. 
I.', 
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Development and application of color television for Apollo 15 and beyond

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