Saturn Through Rings
Pioneer 11 was the first spacecraft to pass near Saturn's gorgeous ring system. NASA engineers heatedly debated exactly what route the probe should take at the ringed giant. No one knew what exactly the rings were made of and it was possible that the spacecraft could get damaged by debris.
The team decided to just go for it and risk the destruction of the mission for the chance to do great science, and decided to send Pioneer straight through Saturn's mysterious inner rings. But then NASA headquarters overrode the Pioneer team's decision. They wanted to have Pioneer travel on a farther route that would test the path for the later Voyager missions (Pioneer's team members booed when they found out).
Image: NASA