Enlarge / Boeing’s Starliner spacecraft atop its Atlas V rocket on the launch pad earlier this month. (credit: NASA/Joel Kowsky)

Senior managers from NASA and Boeing told reporters on Friday that they plan to launch the first crew test flight of the Starliner spacecraft as soon as June 1, following several weeks of detailed analysis of a helium leak and a “design vulnerability” with the ship’s propulsion system.

Extensive data reviews over the last two-and-a-half weeks settled on a likely cause of the leak, which officials described as small and stable. During these reviews, engineers also built confidence that even if the leak worsened, it would not add any unacceptable risk for the Starliner test flight to the International Space Station, officials said.

But engineers also found that an unlikely mix of technical failures in Starliner’s propulsion system—representing 0.77 percent of all possible failure modes, according to Boeing’s program manager—could prevent the spacecraft from conducting a deorbit burn at the end of the mission.