Evolved Expendable Launch Vehicle (EELV)



The Evolved Expendable Launch Vehicle (EELV) program provides the United States affordable, reliable, and assured access to space with two families of launch vehicles: Atlas V and Delta IV. These launch vehicles provide critical spacelift capability to support Department of Defense and other National Security missions (together known as National Security Space (NSS) missions). With multiple launch vehicle configurations and launch sites on both coasts of the U.S., EELV has a proven track record of success, demonstrating unprecedented reliability with 106 successful launches since 2002. Of those 106 launches, 57 have been EELV National Security Space launches in support of the Navy, National Reconnaissance Office and the Space Force.

The EELV program's Delta IV and Atlas V launch vehicles are produced by United Launch Alliance (a joint venture of Boeing and Lockheed Martin formed in 2006). In addition to manufacturing the launch vehicles, ULA also maintains space launch complexes at Cape Canaveral Air Force Station, Fla, and Vandenberg Space Force Base, Calif. Program cost savings are achieved through operability improvements such as the use of common components and infrastructure, a standard payload interface, standardized launch pads and reduced on-pad processing; and acquisition improvements such as launch vehicle block buys.

Program strategy

As the Air Force's spacelift modernization program, EELV was designed to increase reliability and reduce launch costs by at least 25 percent over heritage Atlas, Delta and Titan space launch systems. The EELV program was initiated in 1994 and planned to be a "rolling-downselect" of launch vehicle providers from four to one. In 1998, when it appeared the growth in the commercial satellite industry would be able to sustain two providers of launch services, the Air Force decided to award contracts to both Boeing and Lockheed Martin for their respective launch capabilities. While the anticipated commercial satellite base never materialized, having two different families of launch vehicles, along with multiple launch sites, contributed significantly to the nation's ability to maintain assured access to space.

A new EELV Acquisition Strategy was approved in November 2011 which recognizes only the Atlas V and Delta IV can currently provide reliable launch services to meet NSS requirements but also seeks to take advantage of the growing potential of additional commercial space launch providers. The approach continues procurement of launch services and launch capability from ULA for the next several years but provides for a full and open competitive environment for any alternative sources as soon as they are certified. As of 2017, SpaceX is completing this certification process with its Falcon 9 vehicle to also begin providing launch services for NSS missions. The primary goal remains 100% mission success while incentivizing cost reductions. Steady production rates, long-term commitments and opportunities for competition are among the means to achieve this goal.

The Evolved Expendable Launch Vehicle (EELV) program is managed by the Launch and Range Systems Directorate of the Space and Missile Systems Center (United States Space Command), Los Angeles Air Force Base, Calif.

EELV Launch Vehicles

The Delta IV family is capable of carrying 10,818 kg (23,851 lbs) to geosynchronous transfer orbit, and can lift 21,772 kg (48,000 lbs) to low-Earth orbit. The Delta IV Medium, Medium-Plus and Heavy configurations are evolved from flight proven Delta II and Delta III systems while incorporating the latest technology into a family of vehicles maximizing the use of common hardware.

The Medium & Medium-Plus vehicles use a single Common Booster Core (CBC), while the Heavy variant uses three CBCs. The Pratt & Whitney Rocketdyne -built RS-68, a liquid hydrogen/liquid oxygen engine that produces 663,000 lbs of liftoff thrust, powers the first stage. Launch performance can be augmented by adding either two or four solid rocket motors. The second stage is powered by the RL-10B engine. Either a 4m or 5m fairing encapsulates the payload. Vehicles are defined by the number of solids and the width of the payload fairing.

Delta IV's inaugural flight was marked by the successful launch of a commercial satellite on a Medium-Plus (4,2) in November 2002. The first Heavy vehicle (demo) was launched in December 2004.

The Atlas V family is capable of carrying payloads of 8,900 kg (19,620 lbs) to geosynchronous transfer orbit, and can lift 16,034 kg (35,343 lbs) to low-Earth orbit. The Atlas V provides medium and intermediate lift capability and is evolved from flight-proven Atlas and Titan programs, maximizing flexibility and reliability. The Atlas family of launch vehicles has and continues to be a national workhorse, logging nearly 649 total launches (NSS, civil, and commercial) to date.

The Atlas V family uses a Russian RD-180 to power the first stage Common Core Booster. It uses 457,295 lbs (207,425 kg) of liquid oxygen and 169,008 lbs (76,660 kg) RP-1 rocket fuel propellants. Up to five solid rocket boosters can be added to augment performance. The second stage (known as Centaur) is powered by the RL-10A engine. As with the Delta IV, either a 4m or 5m fairing is used to shroud the payload, and vehicles are defined by the number of solids and the size of the payload fairing.

The Atlas V's inaugural flight was marked by the successful launch of a Hotbird-6 commercial satellite in August 2002.

Current as of October 14, 2021