The Tianzhou-9 cargo spacecraft docked with the China Space Station at 8:52 a.m. on Tuesday. The journey from the launching site in south China's Hainan Province took just some three hours, even faster than a regular flight from Beijing to Guangzhou. The designer explains to CGTN's Wan Hongjia how the method, which is now the go-to for all of China's cargo spacecraft, was developed and perfected.