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 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 Commander.

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 normal.

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 table 8-1. 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 capability.

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 time.


The lunar roving vehicle ( fig. 8-2) 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 limits.

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- climbing capability.

8.2.1 Deployment

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.

8.2.2 Steering

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.

8.2.4 Navigation

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.

8.2.5 Thermal

The thermal control system, in general, performed satisfactorily, drive motors remained cool and battery temperatures were maintained within established limits.

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.


The lunar communications relay unit operated normally during all lunar surface extravehicular activities. The voice and data quality were good.

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.