It is increasingly difficult to separate the space launch issues the U.S. Air Force must resolve from those United Launch Alliance, the Pentagon's chief launch services provider, must decide. At root, the Air Force demands "assured access to space," a phrase whose meaning has evolved since the Pentagon first used it more than 30 years ago to explain why it was reluctant to entrust all its payloads to NASA's space shuttle. "Assured access" got a second run in the 1990s when the Air Force started the Evolved Expendable Launch Vehicle program to spark development of two competing launchers: Boeing's Delta 4 and Lockheed Martin's Atlas 5. When market conditions made it tough to keep both rockets in business, the Air Force invoked "assured access" again as it brokered the 2006 merger that created ULA: one provider, but two rockets with enough differences that a failure on one wouldn't ground the other.
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