For all the ambition packed into humanity’s plans for Mars colonies, lunar bases, and permanent off-world settlements, one fundamental question has quietly gone unanswered: can humans actually reproduce in space? Gravity, radiation, and microgravity-induced biological changes present obstacles that are significant and poorly understood by current science. China has now taken the most direct step…

Getting to the moon is expensive. Every kilogram of fuel that a spacecraft carries has to be lifted off Earth, which itself burns more fuel. This is why aerospace engineers and orbital mechanics researchers spend enormous amounts of time hunting for even the smallest efficiencies in how a spacecraft travels. A few meters per second…