CAPE CANAVERAL, Fla. (AP) -- NASA may fly its next-generation space vehicle to the international space station through 2020, four years longer than the agency had originally planned to fly to the outpost, an official said.

NASA is now building the capsule-shaped Orion with the assumption that the spacecraft will visit the space station twice a year through 2020 to rotate out crews or service the orbiting lab.

"We're going to assume that the station carries on," said Jeff Hanley, manager of NASA's Constellation Program, which is developing the vehicle and rockets to go to the moon and later to Mars.

Astronauts are scheduled to start flying Orion by 2014, about four years after the space shuttles are grounded permanently in 2010.

NASA and its international partners hope to finish construction on the space station in 2010.

No decision has been made to extend the space station's operation past 2016, but NASA wanted to make sure Orion could fly to the station past that year in case the outpost remains in use, said NASA spokeswoman Kylie Clem.

"We're focused on assembly right now, but at the same time, we're also able to look ahead," Clem said.