Almost from the time the National Aeronautics and Space Administration (NASA) opened its doors for business 60 years ago on Oct. 1, 1958, it has had to be ready to provide an answer to one question: “Why send people into space, given the costs and risks associated with human spaceflight?”

In its six decades, NASA launched just over 400 different people, many for more than one mission. Of that number, only 24 journeyed beyond Earth orbit to the Moon and back; three made that trip twice. The rest stayed close to their home planet. Although privately-funded space flights, both suborbital and into orbit and beyond, are planned for coming years, to date only NASA and its counterpart government agencies in Russia and China have developed the capabilities to carry out crewed …