Delta’s history stretches back to the late 1950s when the U.S. government, responding to the Soviet Union’s launch of Sputnik in 1957, contracted for development of the rocket. These early Delta rockets derived their design from Thor, the U.S. Air Force’s intermediate-range ballistic missile. The first successful Delta launch was of NASA’s Echo 1A satellite on Aug. 12, 1960.
The Delta legacy grew with launches of the Tiros and GOES satellites, beginning in 1960, which revolutionized weather forecasting, and the first Telstar and Intelsat launches, which enabled the now-famous TV phrase, “Live, via satellite!” The Explorer research satellites provided data about energy fields and particles that could affect communications satellites, while NASA’s Pioneer probes undertook a long series of space exploration missions.
Through the years, Delta became larger, more advanced and capable of carrying heavier satellites into orbit. Design changes included larger first-stage tanks, addition of strap-on solid rocket boosters, increased propellant capacity, an improved main engine, adoption of advanced electronics and guidance systems, and development of upper stage and satellite payload systems. In a series of incremental steps, Delta payload capacity grew from 45 kilograms (100 pounds) to a 115-mile (185-kilometer) circular low Earth orbit (LEO) up to 21,892 kilograms (48,264 pounds) to a 253-mile (407-kilometer) circular LEO and 12,980 kilograms (28,620 pounds) to geosynchronous transfer orbit (GTO) using Delta IV.
Until the early 1980s, Delta served as NASA’s primary launch vehicle for boosting communications, weather, science and planetary exploration satellites into orbit. In 1981, the U.S. space shuttle changed U.S. space policy, and after 24 years Delta production halted, as NASA planned to use the shuttle for satellite launches.
However, in January 1986, President Reagan announced that shuttles would no longer carry commercial payloads, opening the way for the return of Delta. Following a contract from the Air Force for 20 launch vehicles, the newer, more powerful Delta II version emerged in 1989.
In response to market needs for a larger rocket to launch commercial satellites, Delta III began development in 1995. Its first launch was in 1998 and its final launch in 2000, paving the way to the next configuration of the Delta rocket, the Delta IV.
The Delta IV family of medium-to-heavy launch vehicles became operational in 2002. The first Delta IV launch, of Eutelsat’s W5 commercial satellite, took place on Nov. 20, 2002. The first payload delivered for the U.S. government’s Evolved Expendable Launch Vehicle program was the Defense Satellite Communications System (DSCS) A3 satellite on March 10, 2003.
Delta IV launch vehicles can accommodate single or multiple payloads on the same mission. The rockets can launch payloads to polar orbits, sun-synchronous orbits, geosynchronous orbits and GTOs, and LEO.
Each Delta IV rocket is assembled horizontally, erected vertically on the launch pad, integrated with its satellite payload, fueled and launched. This process reduces on-pad time to less than 10 days and the amount of time a vehicle is at the launch site to less than 30 days after arrival from the factory, reducing cost and increasing schedule flexibility.
In December 2006, Boeing and Lockheed Martin Corporation combined their Delta and Atlas expendable launch vehicle businesses, forming the United Launch Alliance (ULA) joint venture. ULA provides launch services to U.S. government customers. Its first Delta launch, of a National Reconnaissance Office satellite aboard a Delta II, took place on Dec. 14, 2006.
Delta launches for commercial customers are provided by Boeing. Boeing Launch Services procures the launch vehicles and related services for its commercial customers from ULA.