Vulcan Centaur in the context of "Centaur (rocket stage)"

The Delta rocket family was a versatile range of American rocket-powered expendable launch systems that provided space launch capability in the United States from 1960 to 2024. Japan also launched license-built derivatives (N-I, N-II, and H-I) from 1975 to 1992. More than 300 Delta rockets were launched with a 95% success rate. The series was phased out in favor of the Vulcan Centaur, with the Delta IV Heavy rocket's last launch occurring on April 9, 2024.

United Launch Alliance, LLC (ULA) is an American launch service provider formed in December 2006 as a joint venture between Lockheed Martin Space and Boeing Defense, Space & Security. The company designs, assembles, sells and launches rockets. The company uses rocket engines, solid rocket boosters, and other components supplied by other companies.

When founded, the company inherited the Atlas V rocket from Lockheed Martin and the Delta rocket family from Boeing. As of 2024, the Delta family has been retired and the Atlas V is in the process of being retired. ULA began development of the Vulcan Centaur in 2014 as replacement for both the Atlas and Delta rocket families. The Vulcan Centaur completed its maiden flight in January 2024.

Blue Origin Enterprises, L.P. is a private American space technology company headquartered in Kent, Washington. The company operates the suborbital New Shepard rocket and the heavy-lift New Glenn rocket. In addition to producing engines for its own rockets, Blue Origin supplies engines for other vehicles, including United Launch Alliance's Vulcan Centaur. It is also working on the Blue Moon human lunar lander for NASA's Artemis program, the Blue Ring spacecraft platform, and the Orbital Reef space station in partnership with other organizations.

Founded in 2000 by Jeff Bezos, Blue Origin initially operated with a very low profile, funded by Bezos's private investments. In 2015, the company achieved a significant milestone with the first uncrewed launch and landing of the New Shepard and announced plans for New Glenn. In 2021, New Shepard completed its first crewed mission with Bezos himself on board, crossing the Kármán line, the conventional definition of the edge of space, 100 kilometers (62 mi) above sea level. Another key achievement came in January 2023 when the company delivered its first BE-4 rocket engine to United Launch Alliance. Despite these milestones, Blue Origin has faced criticism for its perceived slow progress, particularly when compared to SpaceX. Addressing these challenges, the company underwent a leadership change in September 2023, appointing Dave Limp as CEO to succeed Bob Smith.

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.