Bob Behnken, Eric Boe, Doug Hurley and Sunita Williams are veteran test pilots who have flown on the shuttle and the International Space Station.
NASA said the four astronauts will train with both companies and have not yet been assigned to flights. Two-person crews will fly the first test flights by each capsule, after they have completed an orbital test flight without people on board. Company proposals anticipate an all-NASA crew flying SpaceX's Dragon test flight, with Boeing's CST-100 carrying a split NASA-Boeing crew. Boeing has not yet identified its astronaut.