Overshadowed by Apollo 11’s historic Moon landing in 1969, Apollo missions 15, 16 and 17 have slipped into collective obscurity, but those final three journeys to the lunar surface five decades ago still mark the pinnacle of manned space exploration.
No humans have been as far from the Earth since that trio of Moon landings in 1971 and 1972, which also had the greatest scientific return and range of exploration of all six human Moon landings.
Earl Swift, author of the book Across the Airless Wilds, released in Australia as an e-book last Tuesday, says the triumph of these three Apollo missions was very much due to the remarkable – and remarkably simple – lunar roving vehicle, or LRV.
“What they got into was essentially a 1969 General Motors product – a Holden, basically,” the New York Times bestselling author says. “And they drove it across several miles of undulating plains, up a pretty steeply sloping avalanche fan, over a ridge-like raised fault that crossed the valley, and then down the other side.
“If you’ve driven a 1969 General Motors product, you recognise that those cars had as much in common with horseless carriages of the 1890s as they did with the super-reliable appliances that vehicles have become. And the notion that they would get into that and drive it as far as they did in the circumstances – the most hazardous circumstances any drive has ever been conducted in – just boggles my mind.”
There were three individual LRVs, widely known as Moon buggies, used on missions 15, 16 and 17, and they revolutionised Moon exploration. On Apollo 17, which landed on the Moon in December 1972, astronauts Gene Cernan and Harrison ‘Jack’ Schmitt, drove around 36 kilometres in their LRV, including a daring journey 7.6 kilometres (4.72 miles) from the lunar module.
“They were not only 4.72 miles, but they were a long climb back over that ridge away from the lunar module – far out of sight of their one way [to get] home,” says Swift. “They stopped at the foot of a massif several thousand feet high. A great many boulders had rolled down the face of that massif and left craters along the way that could be seen from reconnaissance orbiters circling the Moon. So they knew that the boulders that lay at the foot of the mountain came from way up on top. This gave the program a chance to sample lunar geology from on top of a mountain without having to climb that mountain.
“Almost three-quarters of the total [rock and soil material taken from the Moon] were collected on the last three [Apollo missions]. So half the missions brought back three-quarters of the material, and from much more interesting places than the first three. The first three missions were on foot, so they were limited as to where they could go, and the last missions were able to sample from a wide variety of terrain.”
The concept of driving a vehicle on the Moon – like so much of space exploration – started out like something from science fiction.
The concept of driving a vehicle on the Moon – like so much of space exploration – started out like something from science fiction. An LRV-type vehicle first appeared in a science-fiction novel in 1901 – two years before the Wright brothers’ first flight – and became something of a mainstay in science-fiction novels through the 1930s and ’40s.
“It wasn’t until 1952 that it became the subject of real non-fiction inquiry,” says Swift. “That was in Colours magazine – they published a series of stories prognosticating as to what a future Moon mission might look like.
“Once NASA was created, in 1958, the author of those stories, a fella named Wernher von Braun, took a personal interest at the Marshall Space Flight Center, where he was director, in seeing that the ideas laid out early really took on more concrete form.
“There were a variety of iterations of a rover throughout the ’60s, none of which were all that practical because they were all massive vehicles with pressurised cabins that would have required their own Saturn V to reach the Moon. So NASA eventually walked away from the program and in late 1967, after a particularly tough round of budget cuts, I think Wernher von Braun and his associates at Marshall threw up their hands and walked away, figuring that it wasn’t going to happen during Apollo.”
But outside the walls of NASA, the dream of a creating a practical vehicle for Moon exploration lingered.
“A group of engineers at General Motors in Santa Barbara – not the automotive division but a defence research lab in California – had invested so many years and so much effort in these earlier concepts that they weren’t willing to just kiss off the idea,” says Swift. “So one of them – a guy named Ferenc Pavlics, a refugee of the 1956 Hungarian uprising – spent four months figuring out how can we take what we know about rover concepts and miniaturise them so that we can get a go-kart, for lack of a better word, that will fold up like a business letter – small enough to be able to shoehorn into the one available cargo bay on the lunar module.”
Quickly, Pavlics designed a vehicle with exactly that capability. They just had to get it under the nose and attention of the powers-that-be at NASA.
“He and his boss at GM took a 1:6 scale model with a GI Joe action figure at the controls to Wernher von Braun,” says Swift. “It was set up with a little radio-control device so they could run it into von Braun’s office without being seen. He was on the phone at the time that this toy robot came skittering across his rug. He put down the phone and said, ‘What is this?’ The rest is history.
“This is a departure from what most people envision about the Apollo program, in that they see it as the product of NASA. In reality, NASA was a ringleader of a huge private-contractor effort.”
In researching Across the Airless Wilds, Swift spoke to two of the three living astronauts from the final trio of Apollo missions: David Scott, the commander of Apollo 15; and Charlie Duke, the lunar module pilot on Apollo 16. He describes the pair, who were both former fighter pilots, as “no-nonsense individuals who have very little patience for foolishness”. They were task-oriented and highly intelligent and, as a result, took active roles in the development of the rovers.
They’re also, with Jack Schmitt, the only living people who know what it was like to drive an LRV on the Moon.
“They all talk about how bouncy, how squirrely, how much like a being in a small boat in rough water it felt, but it had a very responsive suspension with 10 inches [25 cm] of travel,” says Swift.
Each of the three LRVs weighed between 209 and 213 kilograms, but on the Moon, with one sixth the gravity of Earth, they were as good as weightless, tipping the scales at just 35 kg.
“So when you hit a bump, it tended to kind of hang in the air for a while and come down almost in slo-mo,” says Swift. “Charlie Duke in particular described it as like driving on snow or ice, where you fishtail if you turn too quickly. It had very responsive steering at both ends and a very short wheelbase. With those two things combined, it didn’t track well in a straight line necessarily.”
Lunar conditions were also a literal speed limiter on the vehicles.
“It was initially designed to be able to top out at about 10 miles per hour (16 km/h),” says Swift. “A reasonably fit human on Earth could outrun it pretty easily. But what the astronauts found was that on the lunar surface … they dare not drive at 10 miles an hour most of the time. Apparently it felt like you were moving along at a pretty good clip at six miles per hour (9.6 km/h).
“The power source was two large 36-pound [16-kg] batteries that were not rechargeable. They powered tiny quarter-horsepower electric motors in each wheel hub that were then attached to – perhaps the most unique thing about the rover – a transmission that had three parts. Only two of them moved and yet it was able to step down this fast-spinning electric motor, which spun around at about 10,000 revolutions per minute.
“So when you hit a bump, it tended to kind of hang in the air for a while and come down almost in slo-mo.”
“So the entire vehicle boasted one horsepower total in all four wheels – you can find a weed whacker that will outgun it. But with that transmission, it generated enough torque to be able to get it and its pretty heavy load of cargo wherever it needed to be, and that included going up some pretty impressive slopes, of 18 degrees or more, and climbing mountainsides hundreds of feet high.”
Time and technology have moved on since the LVR made its last road trip on the Moon in December 1972. Currently the robotic Perseverance rover, which is almost unrecognisable against the LVR, is exploring the surface of Mars. But it was those three final Apollo missions that proved the value of rover vehicles in stretching the possibilities and the science of space missions. Pressed to nominate a favourite LVR mission, Swift responds like a parent asked to name a favourite child.
“I think they all performed well beyond the expectations of anyone at NASA,” he says. “That first drive [on the Apollo 15 mission] was really the last developmental mission of the Apollo program. After that it was all, ‘let’s go explore, let’s go do science’.
“So LRV one appeals because it was the guinea pig. LRV two appeals mostly because the guys in it had the most fun of any crew – Charlie Duke and John Young were pretty funny guys. And LRV three appeals because it went the furthest – it took its astronauts right out to the edge of human exploration – but also because it broke, and they fixed it. They did some automotive body repair on LRV three and saved the mission with a group of maps and duct tape.
“The shadow cast by Apollo 11 has dimmed our recollections of the other five landings, and those last three were by far the most audacious and the most ambitious in scope, in science and in the range of exploration. No one seems to really remember that. I came into this [book] interested in the rover as an engineering project and left the story really seeing the rover as the key to a completely different style of lunar program. It transformed Apollo.
“The apogee of our explorations as a species are with Apollos 15, 16 and 17.”
Across the Airless Wilds was released as an e-book in Australia on 6 July. It will be in bookshops in October.