The space program of the People's Republic of China is directed by the China National Space Administration (CNSA). Its technological roots can be traced back to the late 1950s, when the People's Republic began a rudimentary ballistic missile program in response to perceived American (and, later, Soviet) threats. However, the first Chinese crewed space program only began in earnest several decades later, when an accelerated program of technological development culminated in Yang Liwei's successful 2003 flight aboard Shenzhou 5. This achievement made China the third country to independently send humans into space. Plans currently include a permanent Chinese space station in 2020 and crewed expeditions to the Moon and Mars.