So, if all goes to plan, the Eco Rocket could become Japan’s first operational spaceplane. On its website, Space Walker explains that “we envision sustainable commercial space transportation for all, as familiar and accessible as commercial air travel today.”

The company says it has patented the technology behind a world-first lightweight-composite cryogenic propellant tank. It also emphasizes the value of reusability, which has been shown in practice by SpaceX’s incredibly successful Falcon 9 program. Space Walker will go the extra mile for sustainability, though, as the Eco Rocket will use a carbon-neutral liquefied biomethane propellant.