The Delta IV launch system in active use at SLC-37. Many elements of the system are clearly visible, including the vehicle and mobile and fixed service structures. The pad itself is obscured by the exhaust plume.

Evolved Expendable Launch Vehicle (EELV) is an expendable launch system program of the United States Air Force (USAF), intended to assure access to space for Department of Defense and other United States government payloads. The program, which began in the 1990s with the goal of making government space launches more affordable and reliable, resulted in the development of two launch systems, Delta IV and Atlas V. These two launch systems are the primary methods for launching U.S. military satellites.^[1] Currently the EELV family, is being retired in 2030 in favor of the Reusable Booster System.^[2]

Development[link]

The U.S. Air Force assembled its initial blue print for the EELV in 1994, following many years of government funded studies into an improved system and architecture, which was intended to replace most if not all existing “legacy” spacelifters (e.g. Delta II, Atlas II/Centaur, Titan IV, etc.). The architecture called for the spacelifter to be based on standardized fairings, liquid core vehicles, upper stages, and solid rockets. The standard payload interface was also proposed as another way to save money and improve efficiency.

The initial bids came from four major defense contractors: Lockheed Martin, Boeing, McDonnell Douglas, and Alliant Techsystems. Each of the bids had a variety of different concepts. One of the contractors, Boeing, initially proposed utilizing the Space Shuttle Main Engines (SSME).^[3] McDonnell Douglas merged with Boeing in 1997 and used its Delta IV spacelifter for their EELV proposal.

Design[link]

Boeing and Lockheed Martin were both collectively awarded US$ 100 million for the final phase of the bid. Both companies built their designs around modularization, standardization and minimizing the amount of equipment and using proven, reliable and simplified systems. Boeing developed the Common Booster Core (CBC) that would be the center of the Delta IV. For the Atlas V Lockheed Martin did something similar, calling it a Common Core Booster (CCB).^[4]

Industrial espionage[link]

Boeing was found to be in possession of proprietary documents from Lockheed Martin.^[5] To end litigation, both companies agreed to join forces and formed the United Launch Alliance joint venture.^{[citation needed]} Each company has a 50% stake in ULA.^[6]

Launch services contracts[link]

In October 1998 two initial launch services contracts (known as Buy 1) were awarded. Along with the award of two development agreements, the total amount was more than $3 billion.^[4] Boeing was awarded a contract for 19 out of the 28 launches; Lockheed Martin was awarded a contract for the other 9. Boeing received $1.38 billion, and Lockheed Martin received $650 million for the launches.^[7] In 2003 the USAF moved 7 launches from Delta IV to Atlas V.^[8]

Human-rating[link]

In 2009 The Aerospace Corporation reported to NASA results of study intended to determine the feasibility of modifying an EELV to be human-rated for use in NASA human spaceflight missions.^[9] According to Aviation Week the study, "found that a Delta IV heavy [...] could meet NASA's requirements for getting humans to low Earth orbit." In a presentation to the Review of U.S. Human Space Flight Plans Committee, an Aerospace Corporation representative presented a summary of the study. The summary asserts that even without a newly developed upper stage, it would be feasible for a human-rated Delta IV Heavy to launch a crewed Orion spacecraft to the International Space Station.^[10] ULA has since published a paper^[11] detailing the changes needed for man-rating EELVs. On February 2, 2010 NASA awarded^[12] ULA $6.7 million in stimulus funds under the Commercial Crew Development (CCDev) program. A Space Act agreement was set up to develop an Emergency Detection System (EDS) that could be used on both EELVs. An EDS monitors critical launch vehicle and spacecraft systems and issues status, warning and abort commands to the crew during their mission to low Earth orbit.

See also[link]

• Delta IV
• Atlas V
• Falcon 9
• Expendable launch system
• Reusable Booster System the program to follow EELV after 2025

References[link]

External links[link]

• EELV on Global Security
• Lockheed Martin's Atlas V 400-series, Atlas V 500-series pages
• Boeing's Delta IV page
• United Launch Alliance (ULA) page