The actual Icarus spacecraft would have consisted of an Apollo Service Module (SM) with a five-foot cylindrical extension known as the Payload Module (PM) at the top. Instead of a Command Module, the top of the stack would be a simple aluminum cone containing a few necessary systems. Although the Apollo Command Module and its associated guidance and control systems would have been useful, its weight was prohibitive and unnecessary. Weight had to be kept to a minimum in order to enable the rocket to carry the biggest possible bomb.
The Payload Module would have carried a 100-megaton bomb shaped as a cylinder roughly three feet in diameter and mounted horizontally along the diameter of the spacecraft. The bomb would weigh 18,150 kilograms. One side of the PM would sport a phased array radar antenna for tracking and rendezvous with the Icarus asteroid.
The plan would have used an essentially unmodified Saturn V rocket. At the time, the first Saturn V test was not scheduled until November 1967 and the planners did not know if it would work. The only real difference with the Icarus Saturn V was the modified adapter shroud at the top of the S-IVB third stage. On a standard Apollo mission to the moon these panels normally would have enclosed the Lunar Module, with the Service Module and Command Module mounted on top. But by modifying them and using them to enclose the entire Service Module and its attached Payload Module, the designers were able to improve the aerodynamics of the rocket, and more importantly, eliminate aerodynamic loads and heating on the radar antenna. In profile, the stack would have looked much like the Skylab launch vehicle lofted by the Saturn V in 1973, although slightly shorter.