Getting astronauts to Mars is only half the battle; bringing them home is just as daunting. Transporting enough heavy rocket fuel from Earth for a return launch adds massive weight and astronomical costs to a mission. To solve this, scientists are developing ways to manufacture fuel directly on the Red Planet using resources already available on-site. Mars’ thin atmosphere is composed of 96% carbon dioxide. Using a process called electrochemical reduction—where electricity splits carbon dioxide and water molecules—researchers can recombine these elements into methane. Methane is a high-performance liquid propellant used by modern rocket engines, such as the SpaceX Raptor engines built for deep-space travel. While converting carbon dioxide into methane isn’t entirely new, traditional methods generate a chaotic mix of unwanted chemical byproducts. On Earth, separating pure methane requires massive, complex refinery equipment that would be impossible to launch into space. The recent br...