🚀Many rocket concepts and missions are proposed, but only a few make it beyond the drawing board.
💔It is frustrating when concepts are canceled after extensive development and investment.
🇬🇧The UK's Black Arrow rocket successfully flew four times before being canceled due to budget constraints and cheaper alternatives.
🛰️Russia's Buran spacecraft completed a successful unmanned flight before being canceled with the collapse of the Soviet Union.
🔥NASA's Ares I was a proposed replacement for the Space Shuttle but faced problems with vibrations and safety concerns.