The giant rocket NASA is building to carry astronauts to Mars and other destinations in deep space may cost $500 million per launch when it's flying regularly. A gallon of liquid hydrogen weighs 0.2679 kg, so they paid $3.66 per kg for liquid hydrogen. SpaceX CEO Elon Musk revealed that his company's Starship rocket will only require $900,000 of fuel per launch and cost $2 million per mission overall. The SpaceX Merlin is a family of rocket engines developed by SpaceX for use on its Falcon 1, Falcon 9 and Falcon Heavy launch vehicles. SpaceX Keeps Aborting Liftoffs Because Rocket Fuel Is Tricky | WIRED SpaceX is betting superchilled liquid oxygen will give its rockets an edge—except when it comes to reliable launch schedules. Get the Mach newsletter. Merlin engines use RP-1 and liquid oxygen as rocket propellants in a gas-generator power cycle. Oct. 15, 2018, 3:46 PM UTC. Jim Watson / AFP - Getty Images. By Jason Davis. NASA has finally approved SpaceX’s plans to load propellant onto its rockets with people on board — a move that has been considered risky by some aerospace experts. SUBSCRIBE. The Merlin engine was originally designed for sea recovery and reuse. Rapidly growing SpaceX and its Falcon 9 rocket fleet may have cut the cost of space launch to Low Earth Orbit to $50 million. Well, hold onto your pocketbooks, folks -- because it's going to cost you. Stats for the space shuttle according to a 2001 NASA fact sheet: NASA bought hydrogen at 98 cents per gallon. The SpaceX Falcon Heavy rocket costs an estimated $90 million per launch.