China successfully launched its fourth unmanned spacecraft early yesterday morning in what is likely to be a final rehearsal before it sends an astronaut into space. Xinhua said Shenzhou IV (Divine Vessel) was sent into orbit by a Long March II-F carrier rocket, which blasted off from the Jiuquan satellite centre, in Gansu province, at 12.40am. The spacecraft would orbit the Earth 180 times in a seven-day mission, the agency said. Commander Su Shuangning, the chief designer of the astronaut programme for the nation's manned space effort, said candidates to become the first astronauts had trained on Shenzhou IV - the first spacecraft fully equipped for a manned mission. 'The potential astronauts were all selected from jet-fighter pilots. They have already gone through three phases of training including basic theories, professional skills and flight procedures,' Commander Su said. Gu Yidong, the commander and chief designer of the space application system, said in the latest unmanned mission, tests would be carried out on an escape system for astronauts, control of the vessel's environment and life support systems. Xinhua said the spacecraft was carrying two dummy astronauts as part of the experiments. The designer of the landing operation, Zhao Jun, said: 'This mission simulates all requirements for a manned flight. 'Rescue zones for emergency landing and sea rescue have been set up. Medical workers have also launched rescue drills in their positions.' The lift-off was watched by National People's Congress Chairman Li Peng; two members of the new Politburo Standing Committee, Wu Bangguo and Jia Qinglin; the vice-chairman of the Central Military Commission, Cao Gangchuan; and Li Jinai, the head of the PLA General Armament Department. State media hailed the launch as a significant step for China in joining the US and Russia to have the technology to send a human into space. Overseas scientists and analysts have said the endeavour is more for national glory rather than any scientific breakthrough. A Xinhua commentary said a manned space mission would enable China to 'further display to the world its strong overall national strength' and 'further reinforce the confidence and courage for Chinese people to achieve a national revival'. The first unmanned spacecraft, Shenzhou I, was launched in November 1999 and returned to Earth the next day. Shenzhou II was launched in January last year, but few details were given about its return. Scientists suspect it suffered a re-entry failure. The Shenzhou III module was launched on March 25.