Chinanews, Beijing, March 2 – According to the research (by Dai Changda, Jiang Xiaoguang and Xi Xiaohuan) of the Institute of Opto-Electronics of the Chinese Academy of Sciences, the Great Wall is totally invisible to the naked eye in space, though it can be seen on pictures taken by high-definition space-based sensing devices.The result of the research was published in the latest issue of Science and Technology Review.The three Chinese astronauts also proved that the Great Wall “could not be seen up in space”.