APOLLO 16 Mission Report Excerpt 81 Lunar Roving Vehicle

The lunar roving vehicle performance was good; however, several system problems occurred. These problems are:

a. Higher-than-expected battery temperatures b. Multiple failures of instrumentation hardware c. Loss of rear fender extension d. Temporary loss of rear steering.

Procedural errors resulted in the temporary loss of rear drive power and a temporary loss of all navigation displays except heading and speed.

The approximate distances driven during the three extravehicular activities were 4.2, 11.1 and 11.4 kilometers for a total of 26.7 kilometers. Speeds up to 14 kilometers per hour were achieved on the level surfaces. Slopes estimated to be as steep as 20 degrees were negotiated without difficulty.

The lunar roving vehicle provided electrical power for voice, telemetry, and television communications throughout the first two extravehicular activities, and also provided power for television operations after the third extravehicular activity. A total of 98.2 ampere-hours was consumed from the 242 ampere-hours available in the two batteries.

Several minor problems, which subsequently disappeared, were experienced during the activation of the lunar rover. The rear steering was inoperative, the

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battery 2 ampere-hours remaining and voltage readings were off-scale low, and both battery temperatures were off-scale low.

After returning to the lunar module near the end of the first traverse, the Commander performed a lunar roving vehicle evaluation while the Lunar Module Pilot took 16-mm documentary motion pictures.

At the conclusion of the first extravehicular activity, the vehicle was parked with the front of the vehicle pointing towards the north. The battery temperatures were 104 degrees F and 105 degrees F with 108 and 105 ampere-hours remaining. The battery covers were brushed and opened, the radiator surfaces were dusted, and the power-down was completed. The battery covers did not close between the first and second extravehicular activities and temperatures at power-up for the second extravehicular activity were 70 degrees F and 82 degrees F.

On the second traverse, the attitude indicator pitch scale fell off, but the needle was still used to estimate pitch attitudes. Incorrect matching of switches caused a loss of rear-wheel power. Correct switch configuration returned the vehicle operation to normal. The crew noted that the forward wheels tended to dig in when attempting to climb slopes without rear-wheel power. The right rear fender extension was knocked off and, thereafter, dust was thrown up from the right rear wheel and covered the crew, the console, and the communications equipment. Mid-way through the second extravehicular traverse, the ampere-hour integrator for battery 1 began indicating about four times the normal battery usage. Because of high-than-desired temperatures on battery 1, a series of procedures were initiated to lower the load. These procedures probably caused the inadvertent removal of drive power from a pair of wheels, thereby losing two odometer inputs and the associated static range, bearing, and distance displays. The problem cleared when the normal switch and circuit breaker configuration was restored.

At power-up for the third traverse, the battery covers were closed manually and the lunar communications relay unit was switched to its own power. The lunar roving vehicle battery temperatures were 102 degrees F and 120 degrees F. About 2 hours after power-up, the caution and warning flag was activated because the battery 2 temperature exceeded 125 degrees F. Rear-wheel drive power and steering were switched to battery 1 bus B. Later, the battery 1 temperature indicator went off-scale low, indicating a meter failure. Both batteries were functional at the end of the third extravehicular activity when the lunar roving vehicle was configured to provide power for television. The closeout reading of the battery 2 temperature was 143 degrees F.

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