Exploration Systems Architecture Study

The Exploration Systems Architecture Study (ESAS) was a 90-day study of human spaceflight systems, conducted by the National Aeronautics and Space Administration (NASA) between May and July of 2005. The final report was released in November 2005. The report presented recommendations for implementing the Vision for Space Exploration. The report recommended the approach adopted in the Constellation program, which was cancelled in 2010 and replaced with the Artemis program.