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).