众所周知,太空中的高真空、强辐射、温度骤变、失重等特点与地面迥异。载人航天器飞行时的噪音、振动、过载绝非人人都能承受。因此,往返太空与地球的人必须具备强健的身体、良好的心理素质和反应能力、较高的文化程度,受过系统的特殊训练并掌握航天技能。目前的宇航员可大致分 As we all know, high vacuum in space, strong radiation, sudden temperature changes, weightlessness and other characteristics are very different from the ground. Manned spacecraft flight noise, vibration, overload must not be affordable for everyone. Therefore, those who travel to and from space and earth must have a strong body, good mental qualities and responsiveness, a high level of education, systematic special training and space skills. The current astronauts can be broadly divided