8.0 LUNAR SURFACE OPERATIONAL EQUIPMENT
8.1 EXTRAVEHICULAR MOBILITY UNIT
Throughout the extravehicular activity, the new configuration of the
pressure garment assembly provided good mobility and visibility, allowing
the crew to perform their functions in an effective manner.
Checkout of the Commander's portable life support system prior to the
first extravehicular activity was normal. Portable life support system
startup for the Lunar Module Pilot was normal until the feedwater was turned
on. The feedwater pressure increased faster and higher than expected. A
warning tone and, a short time later, a vent flow flag was activated. The
trouble was traced to a gas bubble trapped in the feedwater bladder during
charging by the flight crew
fig. 8-1, Con't.).
The gas bubble caused high feedwater
pressure. Until the feedwater pressure had decayed to the suit pressure
level, the condensate stowage volume was blocked by the feedwater bladder.
This resulted in the water separator becoming saturated and allowing
droplets of water to be carried over to the fan. This can reduce the fan
speed, thereby activating the vent flow flag. Data confirmed the presence of
current spikes which are a characteristic of water droplets hitting the fan.
Subsequent to recharging the portable life support systems after the
first extravehicular activity, the problem associated with the Lunar Module
Pilot's water separator was found to have resulted from filling the portable
life support system at a 30-degree tilt, and the unit was recharged
thereafter while in the proper upright position.
Throughout the first extravehicular activity, the extravehicular
mobility units maintained crew comfort as required. The feedwater was
depleted in the primary tank of both the Commander and Lunar Module Pilot,
and the auxiliary tank activation and sublimator repressurization were
normal. During this period, the sublimator gas-outlet temperature on the
Commander's extravehicular mobility unit ran slightly higher than expected.
A comparative analysis of the extravehicular mobility unit parameters
indicates that the condition was most likely caused by the cooling water
flow running at a low-normal rate.
The first extravehicular activity was terminated about one-half hour
earlier than planned because of a higher-than-expected oxygen usage by the
The communications check at the beginning of the second extravehicular
activity was initially unsuccessful for the Lunar Module Pilot because his
antenna was broken (sec. 14.5.6). The crewmen taped the antenna to the
oxygen purge system in the stowed configuration and the communications check
was successfully completed. In this configuration the limiting range is
about 305 meters (1000 feet) between crewmen. The feedwater was depleted in
the primary tank of both the Commander and the Lunar Module Pilot during the
second extravehicular activity, and the auxiliary tank activation, the
sublimator repressurization, and the sublimator gas-outlet temperature were
During portable life support system activation for the third
extravehicular period, the sublimator gas-outlet temperature and feedwater
pressure of the Lunar Module Pilot's extravehicular mobility unit were both
reading lower than expected. At lunar module depressurization, these
parameters began an upward trend which led to normal readings by the time
the Lunar Module Pilot reached the lunar surface.
Oxygen, feedwater, and power consumption of the extravehicular mobility
units during the three extravehicular periods are shown in
For the Commander's first and second extravehicular activities, and the Lunar Module
Pilot's first extravehicular activity, the oxygen redline limits were approached,
indicating that the crew workload was approaching the portable life support system
The only problems associated with the lunar module crew station
equipment during the mission was that the Lunar Module Pilot could not get
water from the insuit drinking device during the first and second
extravehicular activities (see sec. 14.5-5), and the Commander's insuit
drinking device mouthpiece became displaced during the second extravehicular
activity. However, neither insuit drinking device problem constrained the
extravehicular activities. The insuit drinking device was not used for the
third extravehicular activity because of the short extravehicular activity
8.2 LUNAR ROVING VEHICLE
The lunar roving vehicle
performed well during the mission.
During the three lunar surface extravehicular activities, the vehicle
traveled 27.9 kilometers (15.1 miles) during 3 hours and 8 minutes of
driving at an average speed of 9.2 kilometers (4.97 miles) per hour. A
total of approximately 52 ampere-hours was consumed. Navigation errors were
within expected tolerances with small distance errors and no apparent gyro
drift. The combined wander and wheel slip factor was within predicted
The front-wheel steering was inoperative during the first
extravehicular activity, but operated normally for the second and third
extravehicular activities. Simultaneous front- and rear-wheel steering
was found to be more sensitive than desired, and difficulties were
experienced with the seat belts; but overall, the crew was very pleased
with the vehicle's performance, particularly, the speed and hill-
Both walking hinge latches were found unlatched during the
predeployment inspection and were easily reset. Televised deployment
operations showed that, when the deployment tapes were pulled, the vehicle
bounced on the lunar surface in a manner similar to that seen during
preflight 1/6-weight vehicle deployment tests. The orientation of the lunar
module (6.9 degrees pitch up and 8.6 degrees roll to the left, resulting in
a tilt of 11 degrees) required an additional hard pull on the deployment
cable by the Lunar Module Pilot after all four wheels had contacted the
surface. Two of the chassis hinge lock pins required additional pressure
to seat them properly. (This possibility had been anticipated and corrective
action was incorporated in the checklist.) The deployment saddle and
the Velcro seat tie-down were difficult to release. The initial failure
of the saddle to release was partially attributed to the vehicle's having
been moved sideways on the surface before saddle release was attempted.
Section 14.6.1 discusses this problem further.
During preparations for the first traverse, the front wheels did not
respond to steering commands. The Commander changed busses and observed the
ammeter closely to find out if power was being applied to the front wheels
in response to steering commands. No response was seen. He then tried,
without success, to manually force the front wheels to turn. The front wheel
steering remained inoperative, thus the rear wheels were used for steering
during the first traverse (see sec. 14.6-3). Little difficulty was
experienced in driving, except that attempts to avoid nearby objects
resulted in the rear wheels sliding into small craters and objects that the
driver was trying to avoid. In at least one slide, the vehicle rotated
through 180 degrees.
During checkout of the vehicle for the second traverse, the crew cycled
the forward steering power switch and circuit breaker, and found that the
front wheel steering operated normally. In starting the second traverse, the
Commander first tried dual steering. Then, after the dual steering was found
to be very sensitive, he tried front-wheel-only steering. However, this mode
was discontinued because the rear wheels tended to wander. (It had been
decided not to lock the rear wheels mechanically because of the prior problem
with the front wheels.) Therefore, the dual steering mode was used for the
remainder of the second traverse and the entire third traverse.
8.2.3 Electrical Power
The lunar roving vehicle used less power than predicted. The predicted
power consumption was based on worst-case surface roughness and soil
composition, but the actual surface conditions were less severe. The cause of
an initial ampere-hour reading of 105 ampere-hours instead of 121 ampere-hours
is not known. Subsequent readings, correlated with ammeter readings, produce
an estimated total power consumption of 52 ampere-hours of the 242 ampere-
hours available. The consumed electrical power corresponds to a rate of 1.87
ampere-hours per kilometer. The preflight prediction of the usage rate was
3.67 ampere-hours per kilometer. Except for the ampere-hour indicator readings
and the inoperative battery 2 volt/ammeter (sec. 14.6.2), the electrical power
system operation was normal during the traverses.
After ascent, the video signal was lost from the lunar surface
television camera. Postflight analysis and tests show that this loss
(section 8-3) was probably caused by opening of the auxiliary power circuit
breaker under combined electrical and thermal loads. This anomaly is
discussed further in section 14-5.2.
The vehicle navigation system operation was normal. The odometer
showed a total distance traveled of 27.9 kilometers (15.1 miles). The
navigation system provided sufficient information to locate the lunar
module at any time during all traverses. Evaluation indicates that the gyro
drift rate was essentially zero and the distance error at the maximum range
of 5.0 kilometers (2-7 miles) was approximately 0.3 kilometer (0.16 mile).
No traverse realignments were required. Closure errors for the three
traverses were 0, 100, and 200 meters, well within predictions.
The thermal control system, in general, performed satisfactorily, drive
motors remained cool and battery temperatures were maintained within
At the beginning of the second extravehicular activity, the battery 1
cover had closed automatically, as expected. Battery 2 apparently had not
cooled down enough and the cover was still open. It was closed manually
powering up the vehicle. When the vehicle was activated, battery-1
temperature was 68 degrees F and battery-2 temperature was 78 degrees F.
The difference was probably caused by the difference in dust accumulation on the thermal
mirrors. These temperatures are consistent with predicted cool-down rates
with the covers open and warm-up rates with the covers closed. During the
second traverse, the battery-1 and battery-2 temperatures increased to 92 F
and 98 F, respectively. The battery covers were opened at the conclusion
of the second extravehicular activity period.
At the beginning of the third extravehicular activity, both covers
were open. Little battery cool-down had occurred, probably because of
further dust accumulation on both battery mirrors, although the battery
covers had been closed for the traverses. The covers must not have been
closed tight enough against the Velcro edges to keep dust off the mirror
surfaces. Only a small amount of dust on the surface will preclude the
desired cool-down. At the conclusion of the traverse, battery-1 and battery-
2 temperatures had increased to 108 F and 113 F, respectively, which is
an acceptable level.
8.2.6 Crew Station
The crew station was satisfactory except that the seat belts were
difficult to fasten (sec. 14.6.4). Prelaunch belt adjustment did not properly
account for the reduced gravity in combination with the pressurized suits,
and the belts were too short for lunar surface operations. Additionally, the
Commander's seat belt hook caught repeatedly on the ground support equipment
electrical connector on the console post.
8.3 EXTRAVEHICULAR COMMUNICATIONS EQUIPMENT
The lunar communications relay unit operated normally during all
lunar surface extravehicular activities. The voice and data quality were
Communications from the lunar roving vehicle while it was in motion
or temporarily stopped were satisfactory except that the lack of manual
realignment of the low-gain antenna to earth resulted in noisy down-link
voice at one time when the lunar roving vehicle was parked on a steep
slope during the second extravehicular activity.
Fixed-site television operation on the lunar roving vehicle was
satisfactory except for difficulty in using the antenna optical sight. With
the lunar roving vehicle pointed in the down-sun direction, the sun was
directly in the crewmen's eyes when using the optical sight. The design
concept was to orient the rotatable sight to a position where sun glare would
be avoided. When the lunar roving vehicle was parked north or south, the sun
was 90 degrees to the side and no glare resulted. In those instances when
glare prevented the use of the optical sight, the lunar communication relay
unit automatic gain control meter was used.
Lunar dust on the television camera lens caused a halo effect and sun
reflected glints. Improvement in picture quality was restored periodically
after the crew brushed the lens.
The ground-commanded television assembly operated successfully during the
three extravehicular activity periods and provided coverage of the lunar lift-
off. Good quality video signals were received while the camera was operating
with the lunar module and the lunar communications relay unit. The elevation
clutch began to slip during the second extravehicular period and the condition
became worse during the third extravehicular period (section 14.5-1). The
crew, on several occasions, manually assisted the elevation mechanism to
regain an operative camera pitch angle.
The television camera was activated about 40 hours after the ascent
from the lunar surface. After about 13 minutes of satisfactory operation,
signals from the lunar communications relay unit were lost and all attempts
to reactivate this system have failed. Refer to section 14.5.2 for a
discussion of this anomaly.