The Vanguard TV-2BU rocket was the U.S.'s first rocket specifically designed to launch satellites. As part of the Vanguard program, the Vanguard TV-2BU test vehicle was prepared for launch by the Martin Company on September 3, 1957. Due to a technical problem, the mission was cancelled. The next launch opportunity was on June 22, 1959. However, the TV-4BU test version of the Vanguard was launched instead and orbited Vanguard 3.