Challenger Day 2016

1986.  Probably wasn't the end of the space program as we know it--the final Apollo missions were cancelled and the shuttle program was nothing beyond low orbit with no next-generation shuttle or anything else in the pipeline--but it was a very public failure and a very expensive failure.  If NASA had been at all serious about manned spaceflight in the 1970s and later, the shuttle would not have been a dead end.  The Challenger explosion was a huge cover-up, but the reporting was excellent at first.  The story got out pretty quickly that the crew was probably alive till the impact with the water, and reporters reported the day after the bodies were recovered and placed in barrels to be brought back to NASA.  Eventually the lies took over, and the good reporting was mostly lost to history in the pre-internets world.  Reading the reporting at the time was fucking scary though, and quite disheartening in the sense that if the vehicle had been properly designed, the crew might have been able to swim back to shore.