Exploration Systems Architecture Study

The Exploration Systems Architecture Study (ESAS) is the official title of a large-scale, system level study released by the National Aeronautics and Space Administration (NASA) in November 2005 in response to American president George W. Bush's announcement on January 14, 2004 of his goal of returning astronauts to the Moon and eventually Mars — known as the Vision for Space Exploration (and unofficially as "Moon, Mars and Beyond" in some aerospace circles, though the specifics of a manned "beyond" program remain vague).

Recent (2005–2009) NASA Administrator Michael Griffin ordered a number of changes in the originally planned Crew Exploration Vehicle (CEV) acquisition strategy designed by his predecessor Sean O'Keefe. Griffin's plans favored a design he had developed as part of a study for the Planetary Society, rather than the prior plans for a Crew Exploration Vehicle developed in parallel by two competing teams. These changes were proposed in an internal study called the Exploration Systems Architecture Study, whose results were officially presented during a press conference held at NASA Headquarters in Washington, D.C. on September 19, 2005.

The ESAS includes a number of recommendations for accelerating the development of the CEV and implementing Project Constellation, including strategies for flying manned CEV flights as early as 2012 (now pushed back to at least 2015) and methods for servicing the International Space Station (ISS) without the use of the Space Shuttle, using cargo versions of the CEV.

Originally slated for release as early as July 25, 2005, after the "Return to Flight" mission of Discovery, the release of the ESAS was delayed until September 19, reportedly due to poor reviews of the presentation of the plan and some resistance from the Office of Management and Budget.

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