A Beijing space research institute tested a new rocket engine that is twice as powerful as its American competitor in the race to put the next astronaut on the moon, according to China’s space authorities . The ground test was carried out on Monday with “complete success”, the China Aerospace Science and Technology Corporation (CASC) said on Tuesday. The engine will be used to launch China’s Long March 9 rockets , still under development, and propel astronauts in future missions to the moon, CASC said. The upper-stage rocket engine can generate a 25 ton-force – more than twice the thrust produced by the RL10, the US-made engine that is expected to take American astronauts back to the moon . Upper-stage rocket engines are used at high altitudes to generate additional boost to propel a spacecraft to its destination. CASC said it was “the world’s largest closed expander cycle engine test run”, marking a “breakthrough” in the development of a key technology for heavy-duty launch vehicles. Closed expander cycle rocket engines are the most efficient power source for human space travel . The engines can turn a small amount of liquid hydrogen fuel into high-pressure gas using waste heat. The gas drives turbines to raise the pressure of hydrogen and oxygen in the fuel pumps. The gas then enters the top of the combustion chamber to be used as fuel. The cycle, known as closed expansion, is more efficient than the combustion process in conventional rocket engines because it does not require the rocket to carry extra gas to power the pumps. Chinese team eyes lunar base in volcanic caves for long stays The US has played a leading role in the development of the technology. RL10 engines have propelled rockets since the 1960s. Russia and Europe have also developed rocket engines with similar or greater thrust. But increasing the thrust of a closed expander cycle engine is difficult, according to Chu Baoxin, lead scientist of the engine project at the Beijing Aerospace Propulsion Institute. A complex mission such as a lunar landing requires the engines to turn on and off many times. Each time the engine must produce a sufficient amount of excess heat and pass it to the liquid hydrogen, turn it into gas and drive the fuel pump to normal working speed as soon as possible, according to Chu’s team. When the engine is at full throttle, the pressure of the vaporised hydrogen can become extremely high and difficult to handle. The bigger the engine, the more serious these problems become. The Chinese rocket scientists said they had found methods for boosting the thrust. They invented a new heat exchanger consisting of many rib-like components that can absorb heat from the surface of the combustion chamber and pass it to liquid hydrogen with unprecedented efficiency, according to a recent paper by the team in the peer-reviewed Journal of Rocket Propulsion. The components were made with the latest 3D-printing technology to produce an extremely smooth surface that can speed up heat exchange much faster than traditional components. The researchers also used new titanium alloys to make gas-powered fuel pumps that can maintain high efficiency while working in extreme conditions, according to the paper. The Chinese space experiment to help astronauts grow food in low gravity Putting Chinese astronauts on the moon would require four of the new engines working together, according to Chu. China and the United States are in a new race to the moon. The Nasa-led Artemis programme, which includes about 20 member countries, aims to land American astronauts on the moon by 2025. To carry out the programme, Nasa has built the most powerful rocket ever, the Space Launch System, but it is now sitting on a launch pad awaiting its much-delayed first flight. China has teamed up with Russia to build an international research station on the moon and aims to send an astronaut to the lunar surface before 2030. China’s heavy-duty rocket for the lunar landing mission is still under development.