English: A graph showing by month, the cumulative number of USAF ICBM and NASA launch vehicle flight tests, marking successes and failures as of 1965, along with future scheduled launches planned by NASA. Launches of boosters with less than intercontinental range (ie, Redstone IRBMs) are not shown.

The human spaceflight program was a highly visible means of demonstrating ICBM booster reliability, translating directly to national defense implications, during a period when the new developing technology had an extremely high failure rate. At the time of the first Mercury-Atlas orbital astronaut flight by John Glenn, more than 100 Atlas's had been launched with a track record of nearly half failures (48). Exactly half of the first 22 Titan missile launches failed (11). NASA acquired their boosters straight from the same manufacturing source that the Air Force procured their nuclear weapon boosters from, with the NASA rockets even being delivered with Air Force serial numbers.

By the time of the NASA Gemini-Titan astronaut launches, reliability had been firmly established with an unbroken string of successful launches that carried through Apollo-Saturn dominance and the Moon landings (projected on this 1965 chart).