Complex sentence: Later the site was used to launch the world's first Earth's artificial satellite Sputnik 1, for Yuri Gagarin's flight, Valentina Tereshkova flight and numerous other human spaceflight missions, including all Soviet and Russian manned spaceflights to Mir.
Split into simpler sentences: Later the site was used to launch the world's first Earth's artificial satellite Sputnik 1. Manned spaceflights launched from the site include Yuri Gagarin's flight, Valentina Tereshkova's flight, and numerous other human spaceflight missions, including all Soviet and Russian manned spaceflights to Mir.