Background: Korolev was born in Zhytomyr, Russian Empire. His father, Pavel Yakovlevich Korolev, was born in Mogilev to a clerk of the Imperial Russian Army and a peasant mother. His mother, Maria Nikolaevna Koroleva (Moskalenko/Bulanina), was a daughter of a wealthy merchant in the city of Nezhin with Cossack heritage. On his maternal side, in addition to Cossacks, he also had Greek and Polish ancestry.
Context: After graduation, Korolev worked with some of the best Soviet designers at the 4th Experimental Section aircraft design bureau OPO-4 headed by Paul Aime Richard who emigrated to the USSR from France in the 1920s. He did not stand out in this group, but while so employed he also worked independently to design a glider capable of performing aerobatics. In 1930 he became interested in the possibilities of liquid-fueled rocket engines to propel airplanes while working as a lead engineer on the Tupolev TB-3 heavy bomber. Korolev earned his pilot's license in 1930 and explored the operational limits of the aircraft he piloted, wondering what was beyond his plane's altitude limit and how he could get there. Many believe this was the start of his interest in space.  Korolev married Xenia Vincentini on 6 August 1931. He had first proposed marriage to her in 1924, but she then declined so she might continue her higher education. In 1931, Korolev and space travel enthusiast Friedrich Zander participated in the creation of the Group for the Study of Reactive Motion (GIRD), one of the earliest state-sponsored centers for rocket development in the USSR. In May 1932 Korolev was appointed chief of the group; and military interest encouraged funding of group projects. GIRD developed three different propulsion systems, each more successful than the last. Their first launch of a liquid-fueled rocket was GIRD-X in 1933. (Although this is often cited as the GIRD-09, the hybrid GIRD-09 used solid gasoline and liquid oxygen.) This was just seventeen years after Colonel Ivan Platonovich Grave's first launch in 1916 (patent in 1924).  Growing military interest in this new technology caused GIRD to be merged with the Gas Dynamics Laboratory (GDL) at Leningrad in 1933 to create the Jet Propulsion Research Institute (RNII), headed up by the military engineer Ivan Kleimenov and containing a number of enthusiastic proponents of space travel, including Valentin Glushko. Korolev became the Deputy Chief of the institute, where he supervised development of cruise missiles and a manned rocket-powered glider. "Rocket Flight in Stratosphere" was published by Korolev in 1934.  On 10 April 1935, Korolev's wife gave birth to their daughter, Natalya; and they moved out of Sergei's parents' home and into their own apartment in 1936. Both Korolev and his wife had careers, and Sergei always spent long hours at his design office. By now he was chief engineer at RNII. The RNII team continued their development work on rocketry, with particular focus on the area of stability and control. They developed automated gyroscope stabilization systems that allowed stable flight along a programmed trajectory. Korolev was a charismatic leader who served primarily as an engineering project manager. He was a demanding, hard-working man, with a disciplinary style of management. Korolev personally monitored all key stages of the programs and paid meticulous attention to detail.
Question: What did he do with that interest?. Whats the answer?
Korolev earned his pilot's license in 1930 and explored the operational limits of the aircraft he piloted,