Photos: America’s 100th EELV blasts off

Eric Boe, one of three astronauts assigned to the first piloted test flight of a Boeing CST-100 Starliner commercial crew ship later this year has been removed from the mission due to unspecified medical issues, NASA announced Tuesday. He will be replaced by veteran astronaut Mike Fincke.

Ready for blastoff just after sunset Wednesday with a classified payload for the U.S. government’s spy satellite agency, a United Launch Alliance Atlas 5 rocket rolled out to its launch pad at Cape Canaveral late Tuesday afternoon after an unplanned trip back inside its integration building for repairs.

The Pentagon has awarded at least $162 million in contracts to Aerojet Rocketdyne and United Launch Alliance for development of the AR1 and BE-4 rocket engines, candidates to power the first stage of a next-generation rocket and replace the Russian-made engine currently flying on the Atlas 5 launcher.