Forty years after it first landed men on the Moon, the National Aeronautics and Space Administration has little chance of repeating that accomplishment by the 50th anniversary of Apollo 11.

Maybe not even by the 60th.

Five years after NASA was given a goal of returning to the Moon by 2020, the agency is arriving at an uncomfortable realization  that the American human spaceflight program might not accomplish anything new anytime soon.

“Unless the president is willing to step up and take a bold step like President Kennedy did, the manned spaceflight program is going to go in the ditch,” said Senator Bill Nelson, Democrat of Florida.

NASA’s current plan is to retire the space shuttles by September of next year after completing construction of the International Space Station, then rely on Russian rockets until a next-generation rocket, the Ares I, is ready in March 2015. The agency would then retire and dispose of the space station in 2016 and use the freed-up money to develop the heavy-lift Ares V rocket, a lunar lander and the technology for building a Moon settlement.