For the public, the big feature of the Apollo 15 mission was its little lunar rover. Americans immersed in an automobile age contemplated with no small joy the beginnings of a stop-and-go traffic jam on the moon. And the rover was worthy of its homeland; it boasted bucket seats and power steering. The 207-kilogram vehicle would run for 65 kilometers on its two 36-volt batteries. As a safety precaution, NASA restricted travel to a 9.5-kilometer radius from the lunar module, the limit of the astronauts' ability to walk home. The rover's payload allowed about 363 kilograms for the two astronauts and their portable life support systems, 54 kilograms for scientific and photographic equipment, the same for communications equipment, and 27 kilograms to bring home lunar samples. All weights, of course, would be reduced by five-sixths when the little car operated in lunar gravity. To meet space limitations inside the lunar module, the rover folded into a wedge-shaped package less than half its operating size.9
The Boeing Company and its prime subcontractor, the Delco Electronics Subdivision of General Motors, designed and built the first lunar rover in 18 months - one of the major rush jobs of the Apollo program. While the forced schedule contributed to the $12.9 million cost, the high price was principally a result of the rover's unique engineering requirements. The harshness of the lunar environment - its extremes in temperature, lack of atmosphere, one-sixth gravity, and rough yet silt-soft surface - posed design problems in vehicle propulsion, stability, control, and wheel-soil interaction. Special wheels made of woven spring steel wire with titanium chevrons for traction were developed to meet the launch weight restrictions and still provide the support and mobility required on the moon. Each wheel had its own electric drive motor. The vehicle had independent steering motors for front and rear wheels so the driver could use front, rear, or both.
The two crewmen sat side by side on the vehicle. Control was provided by a T-bar "joy-stick" mounted on a console in the center. The joystick provided acceleration, brake, and steering control through complex electrical circuitry. It could be operated by either crewman. The console also provided electrical system control, monitor, and alarm capabilities.
Since a magnetic compass could not be used to indicate direction on the moon and because of other problems - such as having to go around craters - a special navigation system was built around a directional gyroscope, odometers, and a small computer. The system used the distance and direction traveled to determine range and bearing from the lunar module. With this information the astronauts could easily determine the shortest course back at any time. The navigational system also provided data for the location and placement of scientific equipment on the lunar surface.10
The launch team started preparing for the rover in late 1970 when the requirements document arrived from Marshall Space Flight Center. Arthur Scholz, Boeing's rover project manager at KSC, drew up the test and checkout plan describing the sequence of operations. The first events on the flow chart involved reception and inspection, activation, and calibration of the rover's ground support equipment.
Meanwhile, Boeing engineers began preparing test procedures for the rover. They relied first on preliminary design data from the Seattle plant and then on the formal requirements document from Marshall. In January 1971 R. Dale Carothers, KSC's manager for rover operations, and a group of Boeing and government engineers journeyed to Seattle where they took part in the last two months of factory tests.
The action switched to KSC in mid-March when the rover arrived at the Cape's skid strip* aboard a C-130 Hercules aircraft. The first rover spent two days in the operations and checkout building undergoing inspections, first in its folded and then in its unfolded condition. During the next three days technicians installed simulators for the two 36-volt batteries and checked out the vehicle's power. The second week was taken up with electrical systems tests including front and rear wheel steering, the four drive motors, and the alarm system. During the tests the rover had to rest on a pedestal while the wheels turned in midair. The pedestal also supported the chassis when an engineer or astronaut entered the rover. The vehicle could support its own weight on earth, but no more. On one or two occasions, with the rover mounted on the pedestal, the test team witnessed a strange sight - the front wheels moving forward and the rear wheels in reverse. Boeing engineers said the drive motors were out of synchronization and that the phenomenon could not occur on the moon, where the wheels would be touching the lunar surface.
The lunar rover. (2) Apollo 15 astronauts training with the rover. David R. Scott(left) prepares to deploy the vehicle's antenna, while James Irwin considers a pile of equipment from a mockup of the lunar module.
approved the proposed modifications and the work was under way in two weeks. The changes did not affect the stowage schedule.
The third week of rover testing began with a navigational systems check. The rover was mounted on the work stand, the wheels started turning in mid-air, and an engineer moved the steering handle. The test team observed the computer's performance as it assimilated driving data from the odometers and gyroscope. The following day the launch team tested the rover's mechanical brakes. Wheel and fender replacements and the closing out of discrepancy records took the remainder of the week. During Easter week technicians completed most of the modifications. A silicone-oil leak from the shock absorbers caused several days' concern before the test team declared the shock absorbers "acceptable for flight." On 16 April Boeing undertook one of the more difficult tasks - loading the rover aboard the lunar module. Technicians successfully deployed the rover the following day, using a landing platform to reduce the distance it fell, so that the impact was equivalent to what would be experienced under lunar gravity.
A second CF squared test inaugurated the last week of operations. The exercise provided a check on the various modifications that had been made since the first test. The rover group joined Grumman engineers the next two days for the electromagnetic compatibility test. As its name implied, this test was to detect interference, primarily with the lunar communications systems. With radios, computers, radars, even the rover's wheels operating, no problems developed in the lunar communications relay unit. The launch team then moved on to the climax - simulated mission runs with the two astronaut crews.
The simulated missions gave Test Conductor Herman Widick some uneasy moments. Whereas lunar module tests usually attracted little attention, the novelty of the rover drew a large crowd of Apollo officials. The simulation involved a number of organizations: a Hamilton Standard representative for the portable life support system, NASA spacesuit technicians, Grumman engineers for the lunar module and rover storage, RCA and Goddard Space Flight Center communications experts, and Houston observers. While Widick had worked with most of these men, the Boeing engineers were new. Matters were complicated by two communications systems. The test conductor talked with the crew by radio through the portable life support system; communications with the rest of the test team were over the operational intercommunication system. The astronauts, their vision limited by the spacesuits, unwittingly interrupted Widick on several occasions. Spacecraft engineer Ernest Reyes had tried for several days to give the rover a sportier look, but Widick rejected every suggestion. As the test was about to begin, Commander David Scott pulled a fox tail from his spacesuit and attached it to the rover's low gain antenna.
The setting for the simulated mission resembled a science-fiction film of the 1940s. Sunlight gleamed off the lunar module's aluminum foil covering. Antennas stretched along the wall of the operations and checkout building's high bay. In the center of the scene the rover, fully deployed, rested on its pedestal. The astronauts, dressed in the lunar surface version of their Apollo spacesuits, completed the picture. Since the test employed the communications equipment within the portable life support system, the 38-kilogram unit was strapped to each astronaut's back. A reasonable load on the moon, it was too heavy to carry on earth, so a dolly with an overhead cantilevered arm supported the equipment. A technician guided each dolly as it moved behind the astronaut.
The mission simulation began with a communications check. While the astronauts stood in front of the rover, a test engineer switched on the drive motors. The wheels were noisy but produced no electrical interference. Technicians then removed the life support system from each astronaut's back and placed the packs on the rover seats. The crew moved to the back of the vehicle where they engaged the equipment pallet pin and disengaged the rear steering pin. The latter operation, a difficult maneuver, was only for emergencies. If the rear steering mechanism failed on the moon, the astronauts could lock the rear wheels in place and steer with only the front wheels. After these tests, the astronauts seated themselves in the rover. A wedge was placed between the life support system and the seat to give the astronaut the feel of lunar gravity with the pack. Wearing pressurized suits, the astronauts had considerable trouble with the seat belts. Finally ready, the astronauts began their lunar ride - simulating specific distances and directions until they returned to the lunar module. The astronauts also checked the TV signal that would return to earth over the relay unit.
After successful mission simulations with both crews, Boeing technicians folded the rover and reinstalled it. Two days of rover deployment followed. The exercise included possible malfunctions and appropriate responses. (On subsequent missions the launch team rigged various deployment malfunctions in the rover trainer and lunar module simulator.) On 25 April the launch team placed the rover inside the lunar module. The spacecraft joined the Saturn stack two weeks later. 11
The rover was stowed away but not forgotten. On 5 May the training vehicle was demonstrated for the press. Scott and Irwin answered newsmen's questions and then drove the one-gravity rover trainer to the lunar simulation area. A few fortunate reporters tried their hand at the T-bar handle controls. The reporters, with instructors at their side, drove the rover through the astronauts' crater-pocked sandpile. Their enthusiastic response carried over to the next day's newspapers.12
* The Cape's hard-surface 45 x 3,050-meter runway earned its name in the 1950s when Air Force launch teams retrieved winged Snark missiles by landing them on skids.
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