Astronomy and Space

Delta IV Heavy

The Delta IV Heavy (Delta 9250H) was an expendable heavy-lift launch vehicle, the largest member of the Delta IV family. Following the retirement of the Space Shuttle in 2011, it was the most capable operational launch vehicle until the Falcon Heavy's debut in 2018. At the time of its retirement in 2024, it ranked third among active rockets in payload capacity. Developed by Boeing and later manufactured by United Launch Alliance (ULA), it first flew in 2004. The Delta IV Heavy was retired after its 16th and final launch on 9 April 2024 and was succeeded by ULA's Vulcan Centaur rocket, which can offer similar heavy-lift capabilities at a lower cost with a single-core and six solid rocket boosters. The vehicle consisted of three Common Booster Cores (CBCs), each powered by an RS-68 engine. Two served as strap-on boosters attached to a central core. During ascent, all three engines ignited at liftoff, with the central engine throttling down partway through flight to conserve propellant before throttling up again after booster separation. A distinctive feature of Delta IV Heavy launches was the hydrogen-fueled ignition sequence, which often produced a large fireball that scorched the booster’s exterior surface.

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• ▸51 Andromedae
• ▸Kangju
• ▸36 Persei

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