Putting U.S. astronauts aboard private spacecraft originally was intended to accelerate the pace and slash the cost of manned exploration. But now, National Aeronautics and Space Administration officials are debating whether the plan's main goal should be fostering jobs to stimulate the economy.

Tension between boosting science or the economy erupted during a meeting earlier this year at the agency's Washington, D.C., headquarters. Addressing a group of high-level outside advisers, NASA Deputy Administrator Lori Garver emphasized...