NASA's National Space Transportation System was created to revolutionize America's space launch capabilities and to bolster NASA's space exploration efforts. The STS program that followed Apollo did that and more. For nearly three decades the STS proved to be an extraordinarily versatile cargo, largely because of the Orbiter's reusability, and its cargo return capability. The five space shuttle Orbiters were the only reusable crew space vehicles, and also had the largest crew capacity of any space vehicle including those under development. And with more thrust that the Saturn V, the STS was also the most powerful U.S. booster until the arrival of the Ares V replacement cargo launcher. The space shuttle became the symbol of America's prominence in military and civil space operations, but its enormous costs and its mounting age are bringing it to a forced retirement in 2010.