SpaceX goes old-school to fuel new rockets
In a move fitting of a steam punk feature film plot line, the most advanced heavy lift rocket on Earth will one day be fueled by a gas station on Mars powered with 1890’s tech.
The SpaceX Starship is revolutionary in about every way; from its stainless steel body to its ability to land vertically, there is simply no craft quite like it. The one feature though that sets it apart from any other spacecraft – and makes it perfectly suited for Mars are the “Raptor” engines that power it. These revolutionary engines are not only some of the most powerful rocket engines ever created but they are also one of the only built to run on a Methane-Oxygen fuel blend. SpaceX specifically designed the “Raptor” version of its engines to use Methane and Oxygen because both chemicals can be created on Mars using nothing more than the CO2 in the atmosphere and a small supply of hydrogen.
Producing methane out of CO2 is not new science but actually tried and true 1890’s tech. The science was pioneered by the French chemists Paul Sabatier and Jean-Baptiste Senderens in 1897 and is surprisingly simple. CO2 is mixed with Hydrogen in a chemical reactor and under the right conditions it produces Methane and water. The process is well known and has been used for over 100 years to produce Methane commercially. The concept of using Sabatier methanation to create rocket fuel is also not a new one. In 1986, NASA proposed this solution alongside a new (and at that point undeveloped) engine that could burn Methane and Oxygen. Then in the early 1990’s, scientists at Martin Marietta built a fully functional prototype sabatier CO2 reactor for NASA that produced methane at 94% efficiency proving this old science is ready to fuel new rockets.
The remaining chemicals, hydrogen and oxygen, can both be produced on Mars through electrolysis. NASA’s Perseverance Rover is currently making oxygen on Mars out of carbon dioxide (CO2) using MOXIE (Mars Oxygen In-situ Resource Utilization Experiment), which splits the carbon and oxygen apart. The NASA Curiosity Rover and orbiting Mars reconnaissance satellites have both found evidence of surface and subsurface water that could be used to produce hydrogen and oxygen.
The Raptor engine in its current form (Raptor V2) is a marvel of science. The Raptor V2 is a full-flow staged-combustion-cycle rocket engine and each one is able to produce up to 230 tons (~510,000 lbf) of thrust at sea level. The starship has six Raptor V2s and the booster has a total of 33 Raptor V2 engines. Combined, these revolutionary engines are capable of generating over 16 million pounds of thrust at launch. That much raw power translates to 100+ tons lifted into low earth orbit placing Starship in the same lift category as the famed Saturn V rocket and Space Shuttle.
In another steam punk styled twist of fate, the sabatier reactor may actually give the beloved internal combustion engine a new purpose – on Mars. Using adapters available at most hardware stores, a gasoline engine can be easily converted to burning a methane-oxygen blend that will run perfectly well in Mars’ carbon dioxide rich atmosphere. This simple solution would allow readily available small engine powered generators to run on the same fuel the Raptor engines need. Small highly efficient generators can be found at any hardware store and with a few small changes can be used to power a Mars settlement when solar is not available or when higher loads are needed.
The Mars Blueprint for exploring and settling red planet must include an accessible and renewable source of fuel at both ends of the journey. Using a little 1890’s tech will single handedly give future explorers the ability to power critical equipment and enable regular two-way trips between the planets with the heavy payloads that are critical to create a sustained manned presence on Mars. Turning Mars atmosphere into fuel via the Sabatier process is the key to this plan and employs the “living off the land” strategy used by the most successful explorers in Earth’s history.