Budget constraints led to cancellation of the study and exclusive use of the Space Shuttle for orbital payloads.

In the mid-1960s NASA's Marshall Space Flight Center (MSFC) initiated several studies to extend the capabilities of the Saturn family.

This would allow closing down Chrysler Space Division production lines for the S-IB first stage, and would allow for more efficient integration of rocket systems.

Such a vehicle could not fly without modification, because the S-II was designed to operate in the near-vacuum of high altitude space.

This required that the S-II be either refit with higher thrust engines, augmented with solid rocket boosters, or both.

Before any version could be put into production, work on all Saturn variants was stopped in favor of launching all future payloads from the Space Shuttle.

The following configurations were studied:[4] The Saturn INT-19 would have used smaller solid boosters, derived from the first stage of the Minuteman missile, to supplement the thrust of the S-II.