Although he was having ideas since 1948, Korolev's planning for the piloted mission began in 1958 with design studies for the future Vostok spacecraft. It was to hold a single passenger in a space suit, and be fully automated. The space suit, unlike the United States' pure oxygen system, was 80 percent nitrogen and only 20 percent oxygen. The capsule had an escape mechanism for problems prior to launch, and a soft-landing and ejection system during the recovery. The spacecraft was spherical, just like the Sputnik design, and Korolev explained his reasoning for this by saying "the spherical shape would be more stable dynamically". Beginning with work on the Vostok, Konstantin Feoktistov was recruited directly by Korolev to be the principal designer for crewed spaceflight vehicles.