Cruising on the Moon: the Lunar Roving Vehicle

Ever since the Apollo program was first conceived, scientists had great visions for manned lunar exploration. From surface stays of a couple of weeks to small rocket-propelled flying vehicles to move across the surface, many ideas had been put on the table in the early ‘60s. Unfortunately, budget cuts were applied as the decade reached its end, and those projects were abandoned. Only one would be evolved into actual flight hardware: the Lunar Roving Vehicle (LRV).

Original idea and earlier development

The idea of a wheeled vehicle to extend the explorable area around a landing site beyond the distance astronauts could cover on foot, had been around since the early Apollo Program.

Originally, plans were for a big pressurized vehicle. It would be launched by a dedicated Saturn V rocket. As budgets shrunk and Saturn V production was cut to just 15 units, this idea was no longer feasible. In the end, Boeing was contracted to build a small unpressurized rover that could be carried by the same Lunar Module that landed the crew on the Moon. General Motors also played a significant role in the project, supplying the wheels and motors.

An early concept for an Apollo pressurized rover that would have landed on the Moon on a dedicated mission. Image credit: NASA/BENDIX — An early concept for an Apollo pressurized rover. *Image credit: NASA/BENDIX*

From paper to metal: technical analysis

Wheels are probably the feature that sets apart the LRV the most from the vehicles we are used to. To avoid sinking in the fine lunar regolith, the wheels were made of a woven mesh of steel wires, attached to a central aluminum hub.

Titanium chevrons were applied to the surface to improve traction. A DC motor powered each wheel, and each pair (front and rear) had its own steering motor. Power was supplied by two silver-zinc potassium hydroxide batteries located in the front of the vehicle. These granted the vehicle a theoretical range of up to 92 km, even if in practice much less was needed.

The LRV for Apollo 15, folded, is loaded on the Lunar Module. The wire mesh wheels can be seen. Image credit: NASA MSFC — The LRV for Apollo 15, folded, is loaded on the Lunar Module. The wire mesh wheels can be seen. *Image credit: NASA MSFC*

The vehicle’s frame was made of tubular aluminum, as were the seats. The astronauts could drive the rover using a T-shaped stick that controlled power and steering. A small control power with several status indicators was also present.

A diagram of the Lunar Roving Vehicle, showig all major components. Image credit: NASA — A diagram of the Lunar Roving Vehicle, showing all major components. *Image credit: NASA*

The Missions

The LRV was carried by all three Apollo J-class missions: Apollo 15, 16, and 17. These were the last three lunar missions, with a three-day surface stay. They had a greater focus on science than previous landings. As such, the added mobility offered by the rover turned out very useful. The vehicle reached the lunar surface folded in one of the triangular bays of the descent stage of the Lunar Module.

Jim Irwin works on the LRV during Apollo 15. Image credit: NASA MSFC — Jim Irwin works on the LRV during Apollo 15. *Image credit: NASA MSFC*

Lunar Roving Vehicle on the Moon's Surface from Apollo 15 Mission. Photo Credits: NASA — Lunar Roving Vehicle on the Moon’s Surface from Apollo 15 Mission. *Image credit: NASA*

The rover never had major reliability issues: on a couple of occasions, a fender broke off, resulting in dust being kicked up. In any case, the astronauts never ventured beyond 10 km from the landing site, to ensure they could walk back should anything happen. The mission that drove the most was Apollo 17, which reached 35.7 km, followed by Apollo 15 at 27.8 km and by Apollo 16 at 27.1 km.

In addition to moving astronauts and cargo, the LRV also carried some instruments of its own. One of these was a laser ranging reflector to accurately measure the distance of the Moon. But, perhaps most famously, it also carried a camera. With accurately timed movements that only worked during Apollo 17, it was able to film the liftoff of the Lunar Module, gifting us with sights no astronaut could have witnessed.