China's space development achieved another milestone with the successful operation of the propulsion subsystem of the Tiandu-2 satellite. Launched on March 20, the satellite is dedicated to testing communication and navigation technology for lunar exploration. Since April 3, the propulsion subsystem has been operating normally, marking the first successful application of the liquid ammonia cold gas micro-propulsion system in deep space exploration. Additionally, this signifies the maiden in-orbit application of China's 3D-printed storage tank technology, the Global Times learned from the subsystem developers on Tuesday.