Coming to the Moon in the 2030s: Japanese Astronauts and a “Toyota Lunar Cruiser”?

In April 2024, the Japanese government signed an agreement with the United States to officially join the National Aeronautics and Space Administration’s Artemis moon exploration project. NASA agreed to reserve two seats for Japanese astronauts, thereby making them the first non-Americans to travel to the Moon’s surface. In return, Japan will bring together public and private sector scientists and engineers to deliver a pressurized lunar rover for crewed missions.

The Japan Aerospace Exploration Agency (JAXA) and automaker Toyota are already jointly developing a pressurized lunar rover that they expect will enhance the success of Artemis. The unique feature of this vehicle is not just its ability to move over the Moon’s surface, but to function as a mobile habitat. If all goes to plan, the rover will be transporting Japanese and American occupants over the Moon’s surface by 2031.

Expanding Opportunities for Space Exploration

Previously, the American Apollo program used Lunar Roving Vehicles to increase the distance astronauts could travel outside of the lunar module. This “Moon Buggy” was, however, completely unenclosed, meaning astronauts still needed to wear space suits. The Artemis project currently plans to use a similar Lunar Terrain Vehicle, but this vehicle will still need the occupants to wear an “extravehicular activity suit,” limiting the duration of activity outside the landing vessel to a maximum of about eight hours.

Enter JAXA’s and Toyota’s rover. This will be equipped with a pressurized cabin space that will allow astronauts to “live in shirtsleeves,” without their space suits. By combining both habitation and transportation, the rover and its occupants will be able to travel to remote locations far away from the original landing point on the Moon, enabling a variety of missions over a period of up to 28 days.

The current goal is to for two astronauts to repeat several cycles of eight hours of driving and extravehicular activity during their stay in the Moon’s South Pole region, an area is believed to contain geological features and water that can shed light on the history of the Moon.

Since there are long periods of night without sunlight on the Moon, being able to live in pressurized cabins during their bitter cold will enable astronauts to analyze geological samples and disseminate information about lunar activities while waiting for the next opportunity to explore.

Above is a conceptual drawing of a manned pressurized lunar rover as imagined in 2019. Like the 2023 drawing featured in the banner photo, it is a six-wheel drive vehicle and features a pressurized cabin. The revised conceptual drawing, however, features a different arrangement of communication antennae, a LiDAR obstacle detection sensor, protective bumpers on all surfaces to protect the aircraft from micrometeorites, and changed window shapes. It also adds a gray painted heat exhaust radiator on the side. (Courtesy of JAXA/Toyota)

The Artemis program plans to conduct manned missions about once a year. Each mission will be made up of three sessions of five earth days. Astronauts will conduct about 8 hours of exploration activities per day, with 16 hours of down time for solar power regeneration. Between each session there will be a 36-hour window for rest. Each two-person mission is expected to require around one ton of supplies for the approximately two weeks spent in the rover.

A crewed pressurized rover with solar panels deployed for energy generation. (Courtesy of JAXA/Toyota)

Previous missions such as Apollo 15 through 17 (1971–72) also focused on extended scientific investigation of the Moon. However, they only collectively travelled 90.4 kilometers on three LRV runs. The Artemis program, however, plans for its rovers to cover 10,000 kilometers over 10 years of missions—more than 100 times the distance covered by the Apollo program. Tsutsui Fumiya, the director of JAXA’s Pressurized Rover Engineering Center, explains how having a habitable space where humans can spend time without space suits is about more than comfort: “By enabling continuous operations without having to return to the lander base, the crewed pressurized lunar rover will dramatically expand the scope of exploration.”

Tsutsui Fumiya, Director of JAXA’s Pressurized Rover Engineering Center. (© Akiyama Ayano)

As astronauts’ operational range expands, there is a greater likelihood that they will notice something that turns into a valuable discovery. Tsutsui described a scenario where, “while traveling in a rover, if you think, a certain piece of terrain is a bit unusual, you may want to return to this spot. You could note it down as the next thing to explore.” This will allow Artemis astronauts to design and adapt missions in a more flexible manner on the spot, while in the past they may not have been able to revisit areas of interest.

Showcasing Japan’s Unique Capabilities

Japan is not the only foreign country participating in NASA’s project. Like Japan, the European Space Agency is also providing unique technology and expertise to Artemis.

Tsutsui believes that Japan succeeding in designing and developing “the world’s first mobile habitat” will showcase the nation’s own unique capabilities and strengths.

This is despite the Japanese space program having only just recently made its first lunar landing. In January 2024, SLIM, the Smart Lander for Investigating Moon, successfully touched down on the Moon’s surface and provided JAXA with its first experience operating small lunar rovers in the lunar environment. In 2018, JAXA’s asteroid probe Hayabusa2 also succeeded in separating small robotic explorers from the main probe as part of its sample return mission. However, as an asteroid’s gravity is about 80,000 times weaker than Earth’s, this is a completely different proposition from operating a larger manned vehicle on a lunar surface.

Driving on the Moon’s surface is also considerably different from driving on the Earth’s surface. The Moon is blanketed with regolith, a type of powdery deposit of dust, sand, and loose rocks and other material. Together with numerous rocky outcrops and steep slopes, it is easy for vehicles to get stuck.

The variation in temperature is also more extreme than is found on Earth, ranging from minus 170 degrees to 120 degrees Celsius. A rover must be able to cope with one-sixth the gravity of the Earth, generate and store energy using large solar panels, and possess a heat removal system that prevents the whole system from overheating. A lunar rover that does all of this while enabling human habitation as it travels over the Moon’s surface in extreme conditions represents an immense technical challenge compared to operating Earth-based vehicles.

Tsutsui nevertheless saw an opportunity to gain international acceptance by involving Japan’s globally recognized automobile industry and its technology in the search for a solution. In 2019, Toyota Corp. raised its hand in support of the project. Japan’s automobile industry would play an instrumental role in designing a mobility solution that would offset JAXA’s inexperience with lunar surface operations and attract NASA’s attention.

The Challenge of Combining Drivability and Liveability

Toyota immediately began developing and testing a six-wheel driving system for the rover, nicknamed the “Lunar Cruiser.” The prototype, which was built in 2022, is an unprecedented vehicle with all six wheels under independent control. Bridgestone, a tire manufacturer, is cooperating in the development of airless “moon tires.” Normal rubber tires cannot be used on the Moon’s surface due to the risk of getting stuck—instead, moon tires use stainless-steel-based metal.

Prototype of the driving system first built in 2022. (Courtesy of JAXA)

A prototype of “moon tires” developed by Bridgestone that do not get stuck in the fine, powdery regolith that blankets the moon’s surface. (© Akiyama Ayano)

GPS-like positioning satellites are also not available on the Moon, making navigation and detecting location difficult. The United States and Europe have been working on creating the Moon’s own positioning infrastructure through a project called the Lunar Navigation Satellite System. Japan will also be involved in this part of the Artemis program.

Toyota’s challenge is to ensure that high driving performance does not come at the expense of comfortable living. Tsutsui explains: “While astronauts do not need a large living space, they need to lie down and sleep. We want the crew to be as comfortable as possible during a month-long mission.” Tsutsui does not imagine an inorganic, austere space. He wants the designers to come up with something that is comfortable for humans and also preserves some semblance of privacy for the two astronauts to ensure the working relationship is not damaged by unnecessary tensions.

Design, demonstration vehicle production, and various tests will begin in earnest in fiscal 2025. The third phase of the Artemis project (Artemis III) aims to put humans back on the Moon’s surface for the first time since 1972. With a focus on exploring the lunar South Pole, Artemis V is scheduled to operate unpressurized LTVs. If Toyota and JAXA are successful in delivering a pressurized rover unlike anything the world (or the Moon) has ever seen, we may well see a Toyota “lunar cruiser” and Japanese astronauts rolling over the surface of the moon as part of Artemis VI or later in the 2030s, proudly displaying the red sun of the Japanese flag.

(Originally published in Japanese. Banner photo: A 2023 conceptual drawing of the pressurized lunar rover being developed by JAXA, Toyota, and other Japanese companies. Courtesy of JAXA/Toyota.)