The rocket will make its first unmanned flight in 2017, and the flight with astronauts aboard won't happen until 2021, according to NASA's plan.

　　The new rocket was 320 feet in length (the space shuttle was 184 feet on the launch pad), 5.5 million pounds in weight, and with the capacity of holding four astronauts at the top speed of 25,000 miles per hour, Washington Post reported Tuesday.

　　Compared with space shuttle and other predecessors, the new rocket will aim for much farther destinations into the space with its most powerful engine ever built, according to the plan.

　　"We're investing in technologies to live and work in space, and it sets the stage for visiting asteroids and Mars," the NASA administrator Charles Bolden briefed the media at a news conference in Washington.

　　NASA expected to devote 3 billion U.S. dollars a year to the effort, or a total of about 18 billion U.S. dollars over the next six years, said William Gerstenmaier, the agency’s associate administrator for human exploration.

　　The current financial condition of U.S. may slow down the pace of progress, which will be much slower than NASA's Apollo heyday in the 1960s.