"Final Delta IV Heavy Rocket Retires in Spectacular Classified Satellite Launch"
United Launch Alliance's Delta IV Heavy rocket made its final launch on Tuesday, retiring after 16 flights. Despite its high cost and low flight rate, the rocket demonstrated the potential for commercial heavy lift rockets. Known for its spectacular launches and fireball phenomenon due to its RS-68 rocket engines, the Delta IV Heavy was once the most powerful operational rocket in the world. While it was surpassed by other rockets, it offered a glimpse of a more sustainable exploration architecture through distributed launch. The future of space exploration lies in companies like SpaceX and Blue Origin, which are developing plans for multiple launches and propellant depots to create a sustainable plan for space exploration.