Complex sentence: Marvingt ascended in a balloon for the first time in 1901, then on 19 July 1907 she piloted a balloon for the first time, and in September 1909 she made her first solo flight as a balloon pilot.
Split into simpler sentences: Marvingt ascended in a balloon for the first time in 1901. In September 1909 she made her first solo flight as a balloon pilot.