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| Delta IV M+(4,2) | |
|---|---|
| Name | Delta IV M+(4,2) |
| Country | United States |
| Manufacturer | United Launch Alliance |
| Family | Delta IV |
| Status | Retired |
| First launch | 2006-11-20 |
| Last launch | 2019-08-22 |
| Payload capacity leo | 28,790 kg |
| Payload capacity gto | 14,220 kg |
Delta IV M+(4,2) The Delta IV M+(4,2) was an expendable medium-class expendable launch vehicle developed and operated by United Launch Alliance for the United States Air Force and civilian agencies. Derived from the larger Delta IV Heavy, the M+(4,2) combined a single Common Booster Core with a four-meter diameter payload fairing and two GEM-60 solid rocket motors to deliver satellites to a variety of orbits. It played a role in national security launches, scientific missions, and commercial payload deployments before the Delta IV family’s retirement.
Delta IV M+(4,2) was part of the Delta IV family conceived under the Evolved Expendable Launch Vehicle program, alongside competitors such as Atlas V, Ariane 5, and later Falcon 9. The vehicle served agencies including the National Reconnaissance Office, National Aeronautics and Space Administration, United States Space Force, and commercial customers like Intelsat. Developed by Boeing, later managed by United Launch Alliance after a joint venture with Lockheed Martin, the M+(4,2) balanced payload performance and cost for medium-lift requirements. It was launched from Cape Canaveral and Vandenberg facilities, supporting missions linked to programs such as GPS modernization, AEHF, and classified reconnaissance platforms.
The first stage used the single Common Booster Core powered by an RS-68 hydrolox engine derived from work at Pratt & Whitney Rocketdyne, while the second stage employed an RL10B-2 engine with an extendable nozzle developed from Aerojet technology. The four-meter composite payload fairing was manufactured with materials techniques utilized by Northrop Grumman and Hexcel. Two Graphite Epoxy Motors (GEM-60) developed by Alliant Techsystems provided additional liftoff thrust, invoking heritage from Solid rocket motor programs and lessons from Space Shuttle Solid Rocket Booster development. Guidance was provided by avionics systems originating from Honeywell and Ball Aerospace, integrating inertial navigation units with telemetry links to NOAA tracking networks and NASA Deep Space Network ground assets for trajectory validation. Structural engineering drew upon design practices from Rockwell International and McDonnell Douglas heritage projects, with thermal protection concepts informed by studies at Langley Research Center.
Delta IV M+(4,2) carried a mix of national security and civil payloads, including payloads for the National Reconnaissance Office, experimental satellites for Air Force Research Laboratory, and science missions for NASA centers such as Goddard Space Flight Center. Notable payloads included classified reconnaissance spacecraft similar in mission class to those launched for KH-11 programs, communications payloads akin to Wideband Global SATCOM and AEHF family requirements, and commercial telecommunications satellites comparable to Intelsat and Eutelsat platforms. The vehicle supported deployment profiles to Geostationary Transfer Orbit, Low Earth Orbit, and polar trajectories used for missions launched from Vandenberg Air Force Base. Mission integrations involved contractors like Boeing Defense, Space & Security, Lockheed Martin Space Systems, Orbital Sciences, and spacecraft manufacturers such as Ball Aerospace and SSL.
The Delta IV M+(4,2) made its inaugural flight in 2006 from Cape Canaveral Space Force Station’s Space Launch Complex 37 before more missions staged from Space Launch Complex 6 at Vandenberg Space Force Base. Throughout its operational life it flew a series of missions for United States Air Force and National Reconnaissance Office customers, integrating launch operations with range control by 45th Space Wing and 30th Space Wing. Launch campaigns interfaced with support organizations including SpaceX rival teams, regulatory oversight from the Federal Aviation Administration, and payload licensing from National Oceanic and Atmospheric Administration when relevant. Each flight involved prelaunch processing at facilities shared with other systems developed by Sikorsky contractors and logistical coordination with Airbus Defence and Space and Thales Alenia Space when international payload elements were present. The program’s final operational flight occurred in 2019 as missions shifted toward newer platforms such as Falcon 9 and future vehicles being developed by Blue Origin and Northrop Grumman.
Launch operations for Delta IV M+(4,2) were conducted from complexes at Cape Canaveral Space Force Station and Vandenberg Space Force Base, utilizing mobile support systems and ground infrastructure originally designed for Titan IV and upgraded for Delta IV processing. Horizontal integration, vertical erection, and payload encapsulation were coordinated in integration facilities run by United Launch Alliance with support from contractors such as General Dynamics and L3Harris Technologies. Range safety and telemetry were managed by units associated with Air Force Space Command and later United States Space Force, and environmental testing was performed at thermal vacuum chambers at Kennedy Space Center and Ames Research Center. Logistics involved interagency coordination with Department of Defense, export controls under International Traffic in Arms Regulations, and mission assurance oversight by National Security Council entities for classified payloads.
Retirement of the Delta IV M+(4,2) reflected a shift in U.S. launch strategy toward cost-reduced, partially reusable systems like Falcon 9 and upcoming national launchers from Blue Origin and ULA’s own Vulcan Centaur. The vehicle’s heritage informed design lessons applied to future architectures, influencing cryogenic engine development at Pratt & Whitney Rocketdyne successors and solid booster strategies at Northrop Grumman. Elements of its program legacy persist in workforce skills at Cape Canaveral, systems engineering approaches at Boeing and Lockheed Martin, and archival lessons held by institutions such as Smithsonian National Air and Space Museum and National Air and Space Intelligence Center. The M+(4,2) remains a reference point in comparative studies involving ArianeGroup, Roscosmos launchers, and international procurement assessments by agencies including European Space Agency and Japan Aerospace Exploration Agency.
Category:Delta IV family