The Small variant was dropped by 1999. In 2002, the Delta IV was first launched, with the RS-68 becoming the first large liquid-propellant rocket engine designed in the U.S. since the Space Shuttle main engine (SSME) in the 1970s. The primary goal for the RS-68 was to reduce cost versus the SSME. Some sacrifice in chamber pressure and specific impulse was made, hurting efficiency; however, development time, part count, total cost, and assembly labor were reduced to a fraction of the SSME, despite the RS-68's significantly larger size. The L3 Technologies Redundant Inertial Flight Control Assembly (RIFCA) 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. The RIFCA featured six ring laser gyroscopes and accelerometers each, to provide a higher degree of reliability. Boeing initially intended to market Delta IV commercial launch services. However, the Delta IV entered the space launch market when global capacity was already much higher than demand. Furthermore, as an unproven design it had difficulty finding a market in commercial launches, and Delta IV launch costs are higher than comparable vehicles of the same era. In 2003, Boeing pulled the Delta IV from the commercial market, citing low demand and high costs. In 2005, Boeing stated that it sought to return the Delta IV to commercial service. As of 2009, the USAF funded Delta IV EELV engineering, integration, and infrastructure work through contracts with Boeing Launch Services (BLS). On August 8, 2008, the USAF Space and Missile Systems Center increased the "cost plus award fee" contract with BLS for $1.656 billion to extend the period of performance through the . In addition a $557.1 million option was added to cover FY10. However, the Delta IV series was at that time launched by the United Launch Alliance (ULA), a joint venture between Boeing and Lockheed Martin. In February 2010, naturalized citizen Dongfan Chung, an engineer working with Boeing, was the first person convicted under the Economic Espionage Act of 1996. Chung passed on classified information on designs including the Delta IV rocket and was sentenced to 15 years. In March 2015, ULA announced plans to phase out the Delta IV Medium by 2018. The Delta IV will be replaced by the Atlas V in the near term and Vulcan in the far term. The Delta IV Medium was actually retired on 22 August 2019.