Boeing's Starliner faces one more challenge as it returns to Earth

Boeing and NASA teams participate in a mission dress rehearsal to prepare for the landing of the Boeing CST-100 Starliner spacecraft in White Sands, New Mexico

Boeing and NASA teams participate in a mission dress rehearsal to prepare for the landing of the Boeing CST-100 Starliner spacecraft in White Sands, New Mexico

Boeing's Starliner capsule headed back to Earth Wednesday in the final step of a key test flight to prove itself worthy of providing rides for NASA astronauts to the International Space Station.

NASA is looking to certify Starliner as a second "taxi" service for its astronauts to the space station -- a role that Elon Musk's SpaceX has provided since succeeding in a test mission for its Dragon capsule in 2020.