NASA says its new giant rocket system passed an internal milestone Wednesday, but the first test launch got pushed back a year to 2018.

NASA is designing its Space Launch System to take astronauts beyond Earth orbit to an asteroid and eventually to Mars. The rockets will be more powerful than the Saturn V rockets that sent Apollo astronauts to the moon.

Agency officials gave the program the go-ahead for further planning with its first and smaller version of the rocket after it passed a key internal review. The smaller of the rockets would be able to carry 77 tons of crew and cargo into orbit. Larger ones could hoist 143 tons.

NASA says building that smaller rocket will cost more than $7 billion between 2014 and launch.

(AP)