Apollo 15 and the Lunar Roving Vehicle: An Interview with Earl Swift

The debut of the lunar roving vehicle, or LRV, on the Apollo 15 mission in 1971 made a strong impression on author Earl Swift as a child. Fifty years later, he sought out the full story of the LRV’s origins, development, and traverses  in his new book “Across the Airless Wilds.” We recently connected with him to hear about his research and insights, and he told us why the LRV “changed everything about the Apollo program.”

Why did you decide to spotlight one piece of hardware, instead of the entire Apollo program? What were you able to achieve that you would not have otherwise with a broader topic?

Well, the program as a whole is pretty well-trod turf, so I decided to narrow my focus to the last three Apollo missions, which marked a dramatic leap in the capabilities and achievements of the crews sent to the Moon. Much of their success rested with an additional piece of gear they carried aboard their lunar modules (LM)—a tiny, featherweight, electric go-cart that folded like a business letter and boosted both their range and their available time to conduct science.  

I was surprised to find that no American book had ever been devoted to the lunar rover, and that the two British books on the subject were heavy on technical detail and short on story. So I dived deep on the rover, using its development to place those three missions in the context of the entire space program.

In your book, you call the lunar rover “transformative hardware.” Can you explain what you mean?

The Apollo program put men on the Moon six times. On the first three landings, the astronauts got around on foot—which, despite the fun they seemed to be having as we watched them bunny-hop over the surface on TV, was hard work. The suits weighed more than they did. The weight of their backpacks threw off their balance. From inside their helmets, they couldn’t see their own feet. And their suits were pumped full of air like all-season radials, so that bending a limb or closing their fists around a tool required real muscle. Layer on the weirdness of moving in one-sixth gravity, and those bunny-hops took effort—and that effort elevated their metabolic rates, which meant that they consumed the air and cooling water in their packs at a fast clip.

All of that limited the astronauts’ range from base and the time they could spend outside the LM. The rover eliminated much of their effort: the crews of Apollos 15, 16, and 17 drove to the predetermined spots where they were to gather geological samples or conduct other science, and although the LRV could be a handful to drive, it was a heck of a lot easier than walking. After conducting their assignments at each stop, they enjoyed a cool-down on their way to the next.

The results were startling. The farthest that Apollo 11’s Neil Armstrong and Buzz Aldrin ventured from their LM was 65 yards. All of their wanderings would fit inside a football field. Apollo 12’s and 14’s moonwalkers covered more ground, but never far from base.

Then came Apollo 15. On the first of their three drives in the rover, Dave Scott and Jim Irwin covered more territory than all three previous missions, combined. All told, they drove more than seventeen miles. They twice climbed hundreds of feet up the side of a mountain, drove along the edge of a mammoth canyon, and ranged more than three miles from their lander. They could pile the LRV with samples and carry a full range of tools with ease. Their slower consumption of life support enabled them to stay half again as long outside the LM. And they knew where they were, and where they were going, the entire time they were on the move. All because of the rover. It changed everything.

Can you describe the development of the LRV and NASA’s radical approach of “less is more” engineering?

The rover came along after almost a decade of lunar mobility studies, which were conducted mostly by General Motors [GM], Boeing, Bendix Corporation, and Grumman under contract to the Marshall Space Flight Center. These studies centered on rover concepts that were a lot bigger than the machine we got. The first, a mobile laboratory or “Molab,” was a hulking, multi-ton behemoth with a pressurized cabin, so hefty that it would have required its own Saturn V to reach the Moon. Later, the studies switched gears to a more realistic “lunar jeep,” or open rover, though it remained big enough that it, too, required its own rocket. 

Those concepts were shelved when NASA’s shrinking budget mandated that Apollo wouldn’t see any multi-rocket missions. At that point, it was researchers at GM who stepped up and proposed a much smaller rover—and one that could be folded still smaller to fit into a cargo bay on the lunar module’s descent stage.

Things got radical when the Marshall Center laid down a hard-and-fast requirement: the rover couldn’t weigh more than 400 pounds, or about the weight of a single astronaut in his space suit. Every component of the machine was whittled down to its smallest, most efficient, lightest iteration. The result was a car that was tough enough to negotiate rough country, but so gossamer in its constitution that it could be used only in the Moon’s one-sixth gravity environment. If an astronaut had stepped onto the rover on Earth, he’d have snapped its floorboard.

The lunar rover’s development timeline was incredibly short. Can you put it into perspective for us? What made it possible?

From the point they won the contract, Boeing and GM had 17 months to deliver the first rover for Apollo 15. At a minimum, Apollo hardware typically took twice as long to develop.

This breakneck schedule would have been fantasy if not for the fact that GM had worked out many of the rover’s components during its earlier studies. Its Molab concept, which it developed with Boeing, had featured wire-mesh wheels; the LRV relied on smaller versions of the same idea. It had likewise experimented with the electric motors and harmonic drive transmissions that drove the rover. Even so, it took a herculean effort to meet the deadline, and more than twice as much money as expected.

What other ideas were considered to increase the astronauts’ range on the Moon?

Besides the bigger Molab and “lunar jeep” studies of the mid-1960s, a wide range of ideas came and went. Early on, Wernher von Braun thought that the LM itself might be used as a lunar taxi. One contractor proposed a hovercraft. Another pushed a “lunar worm” that would snake its way over the Moon’s broken surface. A Stanford scientist beat the drum for a “lunar leaper,” which amounted to a giant pogo stick. NASA mulled a lunar motorcycle, too.

The scariest idea, to me, was seriously pursued by the Manned Spacecraft Center in Houston: a lunar flying unit, or LFU. This would be a small, rocket-powered device that would zip one or two astronauts over the lunar terrain at high speed—and at what seems enormous risk.

Thankfully, all were sidelined in favor of that most American of designs: a car.

How did the Apollo 15 crew prepare for driving the first vehicle on the Moon?

One of the unique challenges of the LRV project was that the finished product couldn’t be tested in the environment for which it was intended. It could only operate in one-sixth gravity, meaning that its trial run would be on its first actual mission.

So to give the astronauts the driver’s ed they’d need, GM built a beefier Earth model, called the 1G trainer, which the crews drove over terrestrial courses that simulated the landing sites. The U.S. Geological Survey (USGS) built a second trainer, the Grover, that saw duty, too.

The earthly courses included the Nevada test site, the California desert, the Rio Grande Gorge in New Mexico, and back lots in Houston and at Cape Kennedy. USGS also blew craters into a volcanic cinder field outside Flagstaff, Arizona, to create a fairly accurate analog for what the astronauts would encounter while motoring on the Moon.

Can you explain how Apollo 15 marked a transition point for the Apollo program?

I’d call it a fulfillment, rather than a transition. The entire human space program of the 1960s served as preparation for the last three Apollo missions. The Mercury program’s six flights established that astronauts could survive the rigors of launch, space travel, and re-entry. The Gemini program established that crews could survive long stays in space and troubleshot the procedures and machinery that would be necessary for the more ambitious missions to come.

Each of the early Apollo ventures laid the groundwork for its successor: Apollo 7 was the shakedown for the command module. Apollo 8 put men on top of a Saturn V for the first time and sent them around the Moon. Apollo 9 field-tested the lunar module. Apollo 10 was a dress rehearsal for the first landing, and included everything but a final descent to the Moon’s surface. Apollo 11 set men down on a flat lunar desert and got them home safely. Apollo 12 executed the first pinpoint landing, which informed Apollo 14’s touchdown on a far more demanding highland site.

All were development missions, aimed at testing gear and procedures. Then, with Apollo 15, all the collected know-how gleaned over a decade of space flight was fully put to use, on a mission devoted wholly to science and discovery. Scott and Irwin were better trained as geologists than any of their predecessors and equipped for a much more daring and fruitful style of exploration. 

If you want to get technical, Apollo 15’s first EVA [extravehicular activity] was a development run, in that it marked the first use of the rover. But beginning with the second drive, the mission was all about digging into the moon’s scientific mysteries.

What was it like to drive a lunar rover on the Moon?

Jim Irwin, who rode shotgun in the Apollo 15 rover, likened it to a bucking bronco and to a small boat in choppy seas. Apollo 16’s Charlie Duke told me it was “squirrely,” and fishtailed like a car on an icy road. All of the crews professed thanks for their seat belts.

The rover’s light weight and extremely short wheelbase, combined with the Moon’s broken surface and one-sixth gravity, pretty much guaranteed a wild ride. Duke reported that when the front wheels hit an obstacle, they’d launch into the air and hang there, as if the LRV were moving in slow motion. Two or more wheels were often off the ground. And bear in mind, this was while the machine was moving at only five or six miles per hour.  

You stress the point that three central figures in the development of the LRV—Wernher von Braun, M.G. “Greg” Bekker, and Ferenc “Frank” Pavlics—were foreign-born. What does this reveal about the history of the Apollo program, and perhaps U.S. history more generally?

All of Apollo relied on immigrants. A sizeable share of the roughly 400,000 people who worked on the program were born elsewhere, and an even larger number were first-generation Americans whose parents had immigrated. For a sense of their contributions, you need look no further than Huntsville, where von Braun’s team of German-born engineers dreamed up the rockets that got us to the Moon. America might have achieved that goal without them, but it would have taken years longer than it did.

I think this testifies to the foundational philosophy that has always been among the country’s greatest strengths: that as a “land of opportunity,” we can attract the best and brightest from around the world—and in so doing, we better and brighten ourselves. Immigrants make us who we are.

For this project, you interviewed engineers who worked on the LRV. What did you learn from those conversations that is not found in archival material?

As on any story, you can construct the framework of the rover’s development with documents. But there’s simply no substitute for talking with people who were there, who actually participated in the events the documents describe.

You can suss out the difficulties that Boeing, GM, and NASA experienced in the frantic race to finish the LRVs in time for the late Apollo missions, for example, by reading the letters and memos they produced. But talking to Boeing’s Gene Cowart, GM’s Ferenc Pavlics, and the Marshall Center’s Sonny Morea really brought home to me just how hell-for-leather that effort was. My conversations with them, and many others, infused the story with the personalities and emotions that it would have otherwise lacked.

You argue that the greatest achievements of the Apollo program came after the first Moon landing. In your opinion, what was the greatest achievement of Apollo 15, and what role did the LRV play?

Apollo 11 demonstrated that a moon landing was possible. All the follow-on missions explored how we might take advantage of that. With Apollo 15, the fourth moon landing, we fully realized the potential of what was possible with the technology of the day.

Of all the improvements that came with those final three “J” missions—an improved lunar module, better spacesuits, more capable machinery and stores in the moonwalkers’ backpacks—the most powerful addition was the rover. It can seem a gimmicky piece of gear, when considered through modern eyes—we, the most automotive people on the planet, sent a car into space. Of course we did! And it’s easy to overlook or minimize its contributions, especially as you’re beholding one of the test units at the National Air and Space Museum or the U.S. Space and Rocket Center in Huntsville. It’s not much to look at: tiny, wispy, barely there.

But that stripped-down “spacecraft on wheels” gave the astronauts the range and time to fulfill the promise of the entire Apollo campaign. It changed everything. As Rocco Petrone said after Apollo 15, “it made the mission.”

You can learn more about the lunar roving vehicle in Earl Swift’s new book Across the Airless Wilds: The Lunar Rover and the Triumph of the Final Moon Landings (Custom House, 2021).