MOUNTING Of LRV AFT PALLET TO LRV
The Aft Pallet Assembly was engineered and built by NASA to be mounted to the rear of the LRV in order to carry tools, lunar samples, lunar drill, core tubes, and small scientific experiment packages. A hinged gate was mounted to the Aft Pallet Assembly to secure tools and permit additional lunar sample bags. (NASA)
readouts in the event of power loss, and it had to be manufactured using existing technology. Functional requirements included navigation to a predetermined location, providing vehicle speed and distance traveled, and providing information to permit return to the LM by the shortest distance possible.
MSFC chose a system made up of a directional gyro, four odometers (one at each wheel traction drive), a signal processor, and devices for indicating vehicle attitude, position and speed. The gyro heading was initialized by using a simple Sun Shadow Device (mentioned in the Crew Station Subsystem) working alongside the vehicle attitude indicators. The Astrionics Lab built a prototype using essentially off-the-shelf parts and tested it at MSFC (including thermal-vacuum tests) and out at Flagstaff, Arizona.
In the tests in Arizona, MSFC technicians used a Jeep with blacked out windows, a television camera mounted on the hood and the prototype navigation system. Technicians in a station wagon followed the Jeep with the necessary equipment to act as "mission control." In this way the navigation system was validated and these tests proved the system could meet the Apollo mission requirements. Computer simulations confirmed the validity and performance of the design. The Directional Gyro Unit (DGU) was a Lear Seigler Model 9010. The Integrated Position Indicator (IPI) was manufactured by Abrams Instrument Corporation and was mounted on the left side of the Crew Display Console. The Signal Processing Unit (SPU) was engineered and built by Boeing. The Navigation Subsystem provided readouts for total distance traveled in kilometers for each EVA, based on the combined average from the four odometers, roll attitude of plus or minus 25 degrees, pitch attitude of plus or minus 25 degrees, heading (0-360 degrees), bearing to the LM (0-360 degrees), range to the LM (0-30 Km), speed in kilometers per hour, and the Sun angle provided by the Sun Shadow Device. The Apollo astronauts would refer to the navigation system almost constantly during their EVAs and relayed the information back to Houston during their traverses.
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