As missions have become increasingly more challenging over the years, the most adaptable and capable element of space shuttle operations has proven time and again to be human beings. Human space flight provides unique aspects of observation. interaction and intervention that can reduce risk and improve mission success. No other launch vehicle - in development or in operation today - can match the space shuttle's human space flight capabilities. Preserving U.S. leadership in human space flight requires a strategy to meet those challenges. The ongoing development of next generation vehicles, along with upgrades to the space shuttle, is the most effective means for assuring our access to space
