SpaceX has launched four astronauts to the International Space Station who will oversee the arrival of two new rocketships during their stint. The U.S.-Russian crew should reach the station on Tuesday, following Sunday night's launch from Florida. They'll replace a crew from the U.S., Denmark, Japan and Russia. Boeing's long-delayed Starliner capsule with test pilots and a new private mini shuttle with cargo are due to arrive during the new crew's six-month stay. NASA's Jeanette Epps was originally assigned to fly on Boeing's Starliner. NASA finally switched her to SpaceX.