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Advanced Launch System - ALS

In undertaking the ALS,(1) the Air Force sought to develop a reliable, heavy-lift launch vehicle able to achieve high launch rates at low cost. ALS managers were tasked to achieve a factor of ten reduction over current costs per pound of payload orbited. The design of the ALS was also supposed to allow growth to meet changing mission requirements.(2)

In July 1987, seven contractors were each awarded $5 million, 1-year contracts by the Air Force to define conceptual designs. The Air Force asked them to include consideration of ground operations in the system designs and cost estimates and to prepare technology development plans and industrial preparedness plans. The contractors' initial concepts considered both expendable and partially reusable vehicles (some with flyback boosters or recoverable propulsion/avionics modules), with capabilities varying from 100,000 to 200,000 pounds to LEO. Proposed engines included combinations of uprated existing engines, solid rockets, and a variety of new liquid engines.

ALS was expected to capitalize on advanced materials and manufacturing and launch processing technologies to cut costs. For example, aluminum-lithium alloys could be used in tanks and other primary structures, which could result in 20 percent lower cost and a 10 percent increase in strength over common steel and aluminum alloys, once manufacturing and supply development was achieved. Filament-wound composite motor casings, shrouds and adapters likewise were also examined for cost advantages to the ALS by increasing strength and performance while reducing weight. Automation would cut the present high cost of fabricating composite structures, and robotics might be applied to plasma arc welding and other processes effectively, even in relatively low rate production. ALS managers explored a variety of launch operations concepts, including horizontal processing, new launch complexes and improved manufacturing, systems integration, and checkout procedures.(3)

The ALS was intended to be a low cost per flight "space truck" capable of lifting 100,000 to 200,000 pounds to LEO, sending heavy satellites into orbit or delivering bulk supplies such as water, food, and fuel to a Space Station. The Air Force has stated that such a lift capability was primarily be required to launch elements of a ballistic missile defense system and to alleviate payload design weight constraints.(4) The Air Force estimated that the ALS would be capable of 20 to 30 flights per year after 1998.

Reliability estimates for an ALS were difficult to specify at this early phase; however, the program stressed the achievement of significantly higher reliability than current vehicles. One concept ALS contractors investigated would incorporate an "engineout" capability, in which the loss of one rocket engine would not endanger completion of the mission. Commercial aircraft use a similar safety feature.

The Advanced Launch System (ALS) emerged in the mid-1980's as the rocket that would be used to deploy the space-based elements of the Strategic Defense Initiative program. Because the SDI was initially projected to require many thousands of tons of payload to low Earth orbit, ALS was intended to reduce the cost of space transportation by an order of magnitude, from about $10,000 per kilogram to less than $1,000 per kilogram.(5) Thus the Bush Administration inherited a plan for development of the Advanced Launch System that called for the Defense Acquisition Board to approve advanced development of the system in early 1990, leading to a first flight in 1998 and a full operational capability in 2000.(6) This effort would have led to the development of a modular family of launch vehicles, with a payload capacity to low Earth orbit ranging from 5,000 kilograms to 200,000 kilograms, that would replace existing expendable launch vehicles in the 2000-2005 time frame.(7)

However, by late 1989 it had become increasingly apparent that the requirements for the ALS program had largely disappeared.(8) The initial phase of SDI would be deployed using existing Titan 4 and Atlas 2 rockets, and the launch requirements for subsequent phases of SDI deployment were too vague to require immediate development of ALS.(9) With total development cost of ALS pegged at $15 billion through its first flight in 1998,(10) the need for ALS seemed increasing doubtful.(11) By year's end the ALS program, once the centerpiece of space planning, had been reduced to a $150 million per year propulsion development effort.(12)


1. US Congress, Office of Technology Assessment, Launch Options for the Future: Buyer's Guide, OTA-ISC-383 (Washington, DC: U.S. Government Printing Office, July 1988).

2. As Air Force Secretary Aldridge testified before the Senate Committee on Armed Services Subcommittee on Strategic Forces and Nuclear Deterrence on March 25, 1988: "ALS will develop technologies, system design, and operational concepts for the next generation of responsive launch vehicles. These vehicles would provide the capability to meet requirements from the heaviest to the smallest payloads."

3. See U.S. Congress, Office of Technology Assessment, Reducing Launch Operations Costs -- New Technologies and Practices, OTATM-ISC-28 (Washington, DC: U.S. Government Printing Office, August 1988), for a more comprehensive list of technologies and management strategies for launch systems.

4. See, for example, Star Wars at the Crossroads: The Strategic Defense Initiative After Five Years, Staff Report to Senators Bennett Johnston, Dale Bumpers, and William Proxmire, June 12,1988.

5. "ALS Contractors Concentrate on Expendable, Reusable Designs," Aerospace Daily, 20 June 1989, page 463.

6. Wolfe, M.G. et al, "The Advanced Launch System." 40th International Astronautical Federation Congress, Malaga Spain, 8-14 October 1989, IAF Paper 89-229.

7. Branscome, D.R., "United States Space Transportation Survey," Proceedings of the 2nd European Aerospace Conference on Progress in Space Transportation, (European Space Agency, ESA SP-293, August 1989), pages 39-44.

8. "Air Force Embraces Expendable Launchers," Military Space, 17 July 1989, page 3-4.

9. "Adams, Peter, "Congress May Consider ALS Too Costly, Sources Say," Defense News, 27 March 1989, page 25.

10. Smith, Bruce, "USAF Cuts Vehicle Design Work On Advanced Launch System," Aviation Week & Space Technology, 18 December 1989, page 112.

11. Finnegan, Philip, "Report: ALS Program Lacks Mission, Should be Pared to Propulsion Study," Defense News, 25 September 1989, page 4.

12. Finnegan, Philip, "U.S. Air Force, NASA Restructure Advanced Launch System Program," Defense News, 15 January 1990, page 1, 25.

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Page last modified: 21-07-2011 00:45:20 ZULU