According to a 1959 report on Saturn development, the vehicle A-1 configuration, which has a modified Titan stage 1 and a Centaur upper stage as upper stages, was considered due to have early flight availability and low costs. How, it fails to meet the mission requirements for lunar and 24 hour missions.
A 1959 report on Saturn development stated that the A-1 configuration, which combined a modified Titan stage 1 with a Centaur upper stage, was initially deemed suitable due to its expected early flight capabilities and lower costs. Nevertheless, it ultimately fell short of meeting the mission demands for lunar and prolonged missions.