Over the next three years the National Aeronautics and Space Administration (NASA) is undergoing a critical transition by retiring the Space Shuttle program while completing construction of the International Space Station (ISS) by 2010. During this timeframe, NASA is undertaking its most complex and costly acquisition program, termed Constellation, to provide a Space Shuttle replacement capability by 2011 followed by subsequent lunar missions by 2018 in preparation for Mars missions. This paper demonstrates why NASA should restructure its proposed manned spaceflight program to ensure the success of NASA's future manned spaceflight program following the retirement of the Space Shuttle program in 2010. The arguments outlined in this paper for proposed restructure of NASA's future manned spaceflight program center on several key elements: national interest, prohibitive cost, manned spaceflight risk and contributions to science and exploration. The recommendations focus on ensuring long-term viability and success of future US manned space programs.