Boeing's Starliner spacecraft launching first crew tonight after years of delays: "An absolutely critical milestone"

An Atlas 5 rocket carrying astronauts for the first time in six decades was primed for blastoff Monday night to boost Boeing's long-delayed Starliner crew ferry ship into orbit for its first piloted test flight to the International Space Station.

Running years behind schedule and more than a billion dollars over budget, the Starliner is Boeing's answer to SpaceX's Crew Dragon, an already operational spacecraft that has carried 50 astronauts, cosmonauts and civilians into orbit in 13 flights, 12 of them to the space station.

NASA funded development of both spacecraft to ensure the agency would be able to launch crews to the outpost even if one company's ferry ship was grounded for any reason.