宇航员 (yǔhángyuán): This term refers to astronauts or cosmonauts who travel into space. They are trained professionals who operate spacecraft and conduct missions.
太空探索 (tàikōng tànsuǒ): This term means space exploration. It involves discovering and studying celestial bodies beyond Earth, such as planets, stars, and galaxies.
重力 (zhònglì): This term translates to gravity. It is the force that attracts objects towards each other and keeps them grounded on Earth. In space stations, there is microgravity or zero gravity.