Ary Sternfeld (14 May 1905 – 5 July 1980) was co-creator of the modern aerospace science. He was a Polish engineer of Jewish origin, who studied in Poland and France. From 1935 until his death he worked in Moscow.
He was the first person to describe the bi-elliptic transfer technique of changing orbits, in 1934.
In 1934, Sternfeld won the Prix REP-Hirsch (later known as the Prix d´Astronautique) of the French Astronomical Society for his book Initiation à la Cosmonautique. He is thus credited with introducing the word cosmonautics in the language of science and engineering.
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