section: Rocket teams assembled
question: What year was Sergei Korolev arrested?
article: Space Race
candidates: The German rocket center in Peenemünde was located in the eastern part of Germany, which became the Soviet zone of occupation. On Stalin's orders, the Soviet Union sent its best rocket engineers to this region to see what they could salvage for future weapons systems. The Soviet rocket engineers were led by Sergei Korolev. He had been involved in space clubs and early Soviet rocket design in the 1930s, but was arrested in 1938 during Joseph Stalin's Great Purge and imprisoned for six years in Siberia. After the war, he became the USSR's chief rocket and spacecraft engineer, essentially the Soviet counterpart to von Braun. His identity was kept a state secret throughout the Cold War, and he was identified publicly only as "the Chief Designer." In the West, his name was only officially revealed when he died in 1966. After almost a year in the area around Peenemünde, Soviet officials moved most of the captured German rocket specialists to Gorodomlya Island on Lake Seliger, about northwest of Moscow. They were not allowed to participate in Soviet missile design, but were used as problem-solving consultants to the Soviet engineers. They helped in the following areas: the creation of a Soviet version of the A-4; work on "organizational schemes"; research in improving the A-4 main engine; development of a 100-ton engine; assistance in the "layout" of plant production rooms; and preparation of rocket assembly using German components. With their help, particularly Helmut Groettrup's group, Korolev reverse-engineered the A-4 and built his own version of the rocket, the R-1, in 1948. Later, he developed his own distinct designs, though many of these designs were influenced by the Groettrup Group's G4-R10 design from 1949. The Germans were eventually repatriated in 1951–53. In America, Von Braun and his team were sent to the United States Army's White Sands Proving Ground, located in New Mexico, in 1945. They set about assembling the captured V2s and began a program of launching them and instructing American engineers in their operation. These tests led to the first rocket to take photos from outer space, and the first two-stage rocket, the WAC Corporal-V2 combination, in 1949. The German rocket team was moved from Fort Bliss to the Army's new Redstone Arsenal, located in Huntsville, Alabama, in 1950. From here, Von Braun and his team would develop the Army's first operational medium-range ballistic missile, the Redstone rocket, that would, in slightly modified versions, launch both America's first satellite, and the first piloted Mercury space missions. It became the basis for both the Jupiter and Saturn family of rockets.