Hitting the Books: How NASA selected the first Lunar Rover to scoot across the moon
The concept of space travel was so new to us that when President Kennedy issued his famous moonshot speech, not even NASA's top scientists were completely sure we could actually land on the lunar surface. Some thought any craft that set down there would simply sink into the moon's regolith like it was a massive, airless pit of quicksand! In his latest book, Across the Airless Wilds: The Lunar Rover and the Triumph of the Final Moon Landings, journalist and former Fulbright fellow, Earl Swift, examines the oft ignored Apollo 15, 16, and 17 missions, our last trips to the Moon's surface (at least until the Artemis project takes place). In the excerpt below, Swift takes the reader on a tour of the JPL's hyper-rigorous, tread-shredding lunar test course and the battle for rover supremacy waged there between GM and Bendix.
From the book ACROSS THE AIRLESS WILDS: The Lunar Rover and the Triumph of the Final Moon Landings by Earl Swift. Copyright © 2021 by Earl Swift. From Custom House, a line of books from William Morrow/HarperCollins Publishers. Reprinted by permission.
All through 1962 and into 1963, both GM and Bendix kept an eye on the Surveyor program. Sure enough, come summer, the Jet Propulsion Laboratory laid out its requirements for a hundred-pound, remote-controlled rover that it wanted to stash aboard the landers. The vehicle would explore the lurrain up to a mile from the Surveyors, while its drivers back on Earth steered it with television eyes. The laboratory alerted companies planning to bid on the phase 1 design study—the normal first stage of any new hardware program—that they’d be expected to supply engineering models of their concepts. Proposals were due in seven weeks.
The short deadline weeded out the dilettantes. In October the two companies left standing—GM and Bendix—started work under contract. GM was ready with its six-wheeled design. Its Surveyor lunar roving vehicle was six feet long on eighteen-inch wheels and weighed ninety pounds—half the size and half again as heavy as its test bed, with a sure-footedness that was no less jaw-dropping. On Pavlics’s “lunarium” of rocks, craters, and slopes outside the Santa Barbara lab, it climbed forty-five-degree inclines, leapt twenty-inch crevasses, and bent its way up and over thirty-inch steps.
Bekker and Pavlics had been working on the idea for more than three years by then. Their main advancement this time: the wheels. Again, they were made of wire, but it was knotted into a wide mesh that resembled chain-link, and shaped into fat doughnuts. Like the team’s earlier wire tires, they deflected when they hit an obstacle and absorbed some of the bumps of cross-country travel. They worked with or without a fabric covering.
“We had a big program to try to come up with the wire material that would survive the vacuum environment on the moon,” John Calandro recalled. “Frank had devised a testing device that created the vacuum environment we needed.”
When fully geared up for a mission, the rover would be an electronic wonder, with subsystems supplied by RCA Astro-Electronics and by AC Electronics, a GM division in Milwaukee: it would have a stereo TV imaging rig, sophisticated navigation and control, and silver-zinc batteries recharged by solar panel. But Santa Barbara’s part of the job, the vehicle itself, was a study in doing more with less. The hardware was constantly “assessed to see if something simpler might be able to do the same job,” designer Norman J. James would remember. “‘The part that’s left off never breaks’ was an often-repeated phrase.”
Bendix took a radically different approach. Its SLRV was a squarish, two-part, articulated robot, with curving, shock-absorbing legs at its corners that ended in small caterpillar track assemblies. The tracks pitched independently to follow uneven ground. Its handlers steered it with commands to slow, speed up, or reverse the tracks on one side or the other, and the pivot linking the two halves did the rest. On the moon, it would be powered by a radioisotope thermal generator—a small nuclear device—hanging off the back, and bristle with scientific instruments and antennas. It weighed one hundred pounds.
Side by side with the GM model, the Bendix machine looked bulky and awkward, and those tiny tracks didn’t seem much of a match for Pavlics’s nearly spherical wire wheels. But Bendix was bullish on its design right up to the day in May 1964 when a panel from the U.S. Geological Survey, Caltech, and NASA took the two models to a volcanic field north of Flagstaff, Arizona, and turned them loose on the rugged Bonito Lava Flow. “We had one little section where they could really get into some pretty rough stuff,” the Geological Survey’s Jack McCauley recalled years later. “The GM vehicle was perfect. It got from point A to point B without any mishaps or turning over.
“The poor Bendix vehicle had tanklike treads that were made of some kind of rubber-type thing,” McCauley said. “The vehicle just started shredding the treads. In fact, when they finished halfway down the course, it had no treads left. So, the GM thing obviously got our blessing.”
General Motors had scored a decisive victory. Unfortunately, it didn’t add up to a rover on the moon. The “Rover Boys,” as that panel of testers came to be known, were mightily impressed with the six-wheeler, but its capabilities didn’t square with the Jet Propulsion Laboratory’s requirements: namely, to “go around and take pictures every ten meters, and also to use a penetrometer to see what the strength of the lunar soil was—and to do it in a preordained manner,” McCauley said. “Basically, just do a grid survey.” Bendix had produced too little rover for the mission; GM had produced too much. The Rover Boys reluctantly reported that neither rover matched the Surveyor program’s stated needs, and that was among the reasons that NASA scrubbed the rover component not long after.
By that time, JPL’s Ranger program had finally given NASA its first close looks at the moon. By design, they were fleeting glimpses: Ranger probes crashed into the lunar surface while taking high-resolution photos right up to the moment of impact. Conceived in 1959, the program had, at times, seemed another exercise in frustration. After Rangers 1 and 2 made two development test voyages in 1961, along came Rangers 3 through 6, all of which were busts. It wasn’t until July 1964, and Ranger 7, that the program literally hit pay dirt. As the spacecraft fell toward the moon, its cameras kicked on, and, for some seventeen minutes, it took and transmitted photographs of the approaching surface—4,316 images in all, some of them at a resolution hundreds of times greater than the best taken from Earth. The photos didn’t put to rest the fears inspired by Thomas Gold’s writings and lectures, but they did establish that the maria were smooth enough for a landing.