NASA simulated a launch by firing the engines of the core stage of the Space Launch System (SLS) rocket while it was anchored to a tower at its Stennis Space Center in Mississippi.
The four RS-25 engines roared to life for the full eight minutes of the test and filled the surrounding area and sky with clouds of white smoke. After the engines cut off, NASA employees could be heard applauding on the space agency's live-streaming video, and many aerospace firms publicly congratulated NASA on a successful test.
A previous test in January ended after about a minute - well short of the roughly four minutes engineers needed to gather enough data.
The Space Launch System is now expected to go to the Kennedy Space Center in Florida for integration with Lockheed Martin Corp's Orion spacecraft.
NASA aims to send an uncrewed spacecraft to orbit the moon in November and return US astronauts to the moon by 2024, but the SLS program is three years behind schedule and nearly $3 billion over budget.
President Joe Biden has tapped former Democratic senator and astronaut Bill Nelson to run the US space agency, according to two people familiar with the decision.
It was a much-sought-after victory for Boeing after multiple setbacks.
Boeing lost a race for its Starliner crew capsule to be the first to carry astronauts from US soil to the International Space Station in nearly a decade to Elon Musk's SpaceX.
Jeff Bezos' Blue Origin is also racing to send its own crewed mission to space for the first time.