16 Facts About Delta IV

Delta IV is a group of five expendable launch systems in the Delta rocket family introduced in the early 2000s.

The Delta IV is primarily a launch vehicle for United States Air Force military payloads, but has been used to launch a number of United States government non-military payloads and a single commercial satellite.

Delta IV originally had two main versions which allowed the family to cover a range of payload sizes and masses: the retired Medium and Heavy.

Delta IV vehicles are built in the ULA facility in Decatur, Alabama.

Latest evolutionary development of the Delta rocket family, Delta IV was introduced to meet the requirements of the United States Air Force's Evolved Expendable Launch Vehicle program.

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In 2002, the Delta IV was first launched, with the RS-68 becoming the first large liquid-propellant rocket engine designed in the United States since the Space Shuttle main engine in the 1970s.

L3 Technologies Redundant Inertial Flight Control Assembly guidance system originally used on the Delta IV was common to that carried on the Delta II, although the software was different because of the differences between the Delta II and Delta IV.

However, the Delta IV entered the space launch market when global capacity was already much higher than demand.

Possibility of a higher performance Delta IV was first proposed in a 2006 RAND Corporation study of national security launch requirements out to 2020.

Possible future upgrades for the Delta IV included adding extra strap-on solid motors, higher-thrust main engines, lighter materials, higher-thrust second stages, more strap-on CBCs, and a cryogenic propellant cross feed from strap on boosters to the common core.

In 2009, The Aerospace Corporation reported on NASA results of a study to determine the feasibility of modifying Delta IV to be crew-rated for use in NASA human spaceflight missions.

Delta IV Medium was available in four configurations: Medium, Medium+, Medium+, and Medium+ .

Delta IV launches occur from either of two rocket launch complexes.

The partial horizontal rocket assembly of the Delta IV is somewhat similar to the Soyuz launch vehicle, which is completely assembled horizontally.

On 4 October 2012, a Delta IV M+ experienced an anomaly in the upper stage's RL10B-2 engine which resulted in lower than expected thrust.

Delta IV Heavy launched the Orion spacecraft on an uncrewed test flight, EFT-1, on 5 December 2014.