Project Blue Book? Was it really necessary?

UFO crash cover-ups? So, aliens, having traveled light-years past black holes, stars, and other hazardous space environments, immediately after entry into Earth's atmosphere began dropping out of the sky over the deserts of North America. Right.
Something else was happening around the same time: the development of space probes designed to collect telemetry data on other bodies within our solar system (i.e. Mars, Moon, etc.) during entry and before crash. If you look at the archives of those probes, some of them will look surprisingly a lot like UFOs people have described seeing. So what's more likely: the government covering up 'super advanced' alien ships that can't stop crashing on Earth, or the government quickly recovering drop probes they've tested before photos and parts of those experimental devices reach the Soviet Union currently engaged in virtually the same mission.
As for actual flying UFOs, they were more likely experimental spy planes. In New Mexico I saw a map designed for pilots that had a caption: "Beware of unusually shaped aircraft while flying close to government airspace."