“Ultimately, NASA felt it was not able to understand why the thrusters malfunctioned and decided that it was too risky to return its astronauts to Earth aboard

“Ultimately, NASA felt it was not able to understand why the thrusters malfunctioned and decided that it was too risky to return its astronauts to Earth aboard Starliner, which will attempt to return uncrewed.” Too risky? Stranded? Rescued (hopefully)?