Here’s what it’s like to drive on the moon
“Driving the moon is like driving on the ice,” warns Jeff Vogt (GM Advanced Program Lead for Vehicle Dynamics). “Imagine the worst ice storm you have ever seen .”
I was interviewing Vogt to prepare for my turn in GM’s lunar rover simulation. This experience promised to fulfill a childhood dream that I had seen with my eyes when I was a child.
The Apollo 17 crew of astronauts Gene Cernan and Jack Schmitt roved the surface in search of geologically significant rocks, a mission made more productive by their trusty 4×4. But the notion of wheeling an off-roader across the pockmarked surface of the moon has been dormant since Cernan and Schmitt blasted off from the moon in the ascent stage of their lunar lander in December, 1972.
Now General Motors, which built the original Lunar Roving Vehicles in the 1980s, is partnering with Lockheed Martin to create a new Lunar Mobility Vehicle.
The simulator from GM is a critical tool in this program. It allows engineers to test designs for vehicles that can’t be physically tested on Earth. This is due to the moon’s weaker gravity which is one-sixth of Earth’s. The LMV has all of the 1,500 kilograms of mass it has on Earth, but only one-sixth the weight, which is why traction is so poor on the dusty surface.
I slide behind the simulator’s steering wheel. Avoid abrupt movements. There should be no abrupt stops, starts, or turns. Vogt says that it is important to take it easy when driving out of craters. “We quickly learned that if you accelerate too fast to climb an incline, with lower gravitation, you launch into space .”
It turns out that the LMV responds well to gentle driving, just like on ice. The main problem is that the simulator has a 2D screen, which acts as reality. Despite its 270-degree wrap-around display of the one square kilometer of the lunar south pole that is loaded into GM’s computer, there is very little sensation of inclination, like you would feel in reality if you were going up or down a crater.
Operating the sim, you are wrapped within a 26-foot-diameter high-definition display situated in a darkened room. The car’s cockpit section is mounted on a pedestal. It tilts to one side and pitches fore-and-aft. However, most of that motion is not noticeable while driving the moon program. Presumably the ride gets a bit rougher when it is simulating the latest Corvette tearing around a track!
If the LMV seems slow when you press the accelerator pedal, it’s likely that you’re climbing. If the LMV doesn’t seem slow down when you release the accelerator, it’s likely that you’re going downhill.
Large features can be accurately represented by the low-resolution photography of the Moon’s South Pole. Based on an understanding of the moon’s prevalence, smaller craters and rocks were statistically generated. The LMV has enough ground clearance to easily cross the small-looking rocks. I don’t have a reference frame so I don’t know how large they are. However, I do know that the rover should be able to drive over most of them.
The LMV’s top speed is 25 kph, but I never venture above 12 kph. Although a crash would be harmlessly imaginary, the time it takes to reset the simulator would put an end to my moon-driving fantasies. The Apollo LRV topped out at 13 kph, but astronauts tended to drive at about 5 kph to avoid breaking the rover and to minimize the dust kicked up by its wheels.
It is important to model LMV’s capabilities, because unlike the Apollo LRV the LMV will be driving autonomously between jobs with live crews. Remote piloting is impossible because of the 3-second round trip time radio signals take from Earth, especially considering the speeds that the LMV can reach.
GM will apply the expertise from its Cruise autonomous vehicle division, to the LMV, so it can work even when the astronauts aren’t there. Lockheed Martin’s design calls for a dedicated lander that will deliver the LMV to Moon’s surface. This is in contrast to having it stow away on the astronauts’ flight as the LRV did.
Autonomy allows the LMV to start working immediately after it lands. It can explore the terrain and conduct experiments without waiting for the Artemis lunar missions astronauts to arrive. The LMV will use the same Ultium electric drivetrain components as GM’s terrestrial EVs. It will have the same electric motors, and although the Ultium battery cells used so far in the GMC Hummer EV we tested previously and the new Cadillac Lyriq are the pouch-style prismatic cells, GM’s Ultium road map also includes the cylindrical cells the LMV will use. These AA-like cylindrical cells are better suited to the extreme 500-degree temperature swings between the Moon’s two weeks of daylight and two weeks of nighttime, according to the company.
GM has drawn on the experience of the Hummer EV’s control program for its three electric motors to inform the programming for the LMV’s four motors. The motors will be able maximize the available traction and will also allow the rover to do clever tricks such as the tight turns that the Hummer can make by routing power to the outside wheels.
Design details to be aware of about the LMV include the seating arrangement, which places the astronauts ahead of front wheels instead of putting them in the middle of the vehicle like they did in the LRV. This reduces their exposure the abrasive dust that is kicked up by front wheels. It sticks to everything due to its electrostatic charge.
Models shown to me by GM designers have astronauts sitting out in the open. However, they explain that the newer versions feature body panels that enclose seats and the cargo bed of the LMV to further reduce dust.
Knowing GM has taken such measures to keep my future spacesuit pristine makes a volunteer for the mission to drive an LMV on the Moon much easier. Is there anyone else who has done it?
I’m a journalist who specializes in investigative reporting and writing. I have written for the New York Times and other publications.