Toyota Designs the Ultimate Off-Roader … for a Mission on the Moon – Technologue

Have you been paying attention to the international moon race going on right now? I’d somehow missed the fact that countries ranging from India and Israel to China and Japan all have moon missions underway or imminent.

Yep, Google Israel’s privately funded Beresheet mission, India’s Chandrayaan-2 (complete with lunar rover), and China’s Chang’e-4. That one’s Yutu-2 rover is currently prospecting on the back side of the moon in search of a helium-3 isotope that could potentially power fusion reactors and/or rockets required to reach Mars and beyond.

The mission that caught my attention was Japan’s, because the Japanese Aerospace Exploration Agency (or JAXA, that nation’s NASA) has enlisted Toyota’s help to build a manned rover big enough to make roadkill of those Indian and Chinese Moon-bas (note: this is not its stated mission).

Unlike the dune buggies GM helped engineer for NASA’s Apollo 15, 16, and 17 missions in 1971–72, Toyota’s rover will be a maxivan pressurized to allow two astronauts to work without space suits in between outdoor excursions. The six-wheel-drive EV utilizes in-wheel electric motors powered by a flexible roll-up photovoltaic solar array, a battery, and a fuel cell. That last item is both a Toyota strong suit and a lynchpin of the new rover’s mission. The farthest any NASA rover traveled on its silver-zinc potassium hydroxide battery was 22.3 miles, never venturing more than 3.1 miles (walking distance) from the lander. Toyota’s rover will spend six years traveling 6,200 miles in total (that’s roughly the equatorial circumference of the moon) supporting four manned missions.

Powering the fuel cell will be two replaceable cartridge-tanks carrying 20 kg of hydrogen and 160 kg of oxygen—enough to power roughly 620 miles of presumably round-trip travel to and from a landing craft. I’d expect scheduling and routing to maximize time spent in the moon’s 14-Earth-day sunshine, when solar power contributes mightily to the rover’s life-support and propulsion needs. Toyota hasn’t disclosed power, acceleration, or top speed figures yet, but the record to beat is Eugene Cernan’s: 11.2 mph.

The rover will reposition itself autonomously to meet successive missions (which will bring fresh fuel tanks), probably traveling by “day” and resting in the darkness. Water produced by the fuel cells will be used for drinking—at least initially, there is no plan to electrolyze it and repressurize the oxygen and hydrogen gas, but maybe with a Chinese fusion reactor …

While NASA’s buggies each weighed a scant 463 pounds (on Earth—one-sixth that on the moon) and folded in half to hang in a small cargo hold, Toyota’s will weigh just under 14,000 (Earth-gravity) pounds with a GVWR of 10 tons. Sized to fit in the cargo bay of a modern transport rocket, the concept measures just under 20 feet long on a 15-foot wheelbase, 17 feet wide (measured at the wheels), and over 12 feet tall with about 20 inches of ground clearance. Roughly one-seventh of that exterior envelope is living space—470 cubic feet.

Construction will be “body on frame,” for optimum isolation/protection of the passenger cell and to protect for future reuse/repurposing of the skateboard chassis in support of a lunar outpost. Aluminum and titanium will be used extensively; carbon fiber may be employed if it proves sufficiently resistant to radiation.

Six wheels were chosen over tracks for reliability and serviceability, and the 600/65R28 airless metal “tires” (being designed with Bridgestone’s input) are sized to safely distribute the porky vehicle’s load on the lunar gravel. All propulsion and suspension components are designed to operate “by wire” and wherever possible, free of rubber and fluids that would be difficult to seal and manage in the near absolute vacuum and drastic temperature extremes of the lunar environment.

Toyota and JAXA kicked this project off in May 2018 with a goal of getting a full-scale prototype running in 2022. The target launch date is 2029 with manned missions arriving yearly between 2030 and 2034. It better have good cameras—by then, there could be as many as 10 little unmanned rovers from other countries running around underfoot.