Video: X-37B payload mated to Atlas 5

Teams at Stennis Space Center in Mississippi removed the core of NASA’s first Space Launch System heavy-lift rocket from a test stand earlier this week for loading onto a barge to carry it to Kennedy Space Center in Florida, where the rocket stage is due to arrive by the end of the month to start final preparations for a test flight around the Moon.

SpaceX called off a Falcon 9 countdown Wednesday due to the threat of lightning from thunderstorms along Florida’s Space Coast, pushing back the departure of a cargo mission for the International Space Station until Thursday.

A rocket engine with a long pedigree marked a big milestone on Monday. It’s 60 years since the hydrogen-fueled RL10 engine debuted onboard a Centaur upper stage launched from Cape Canaveral on Nov. 27, 1963.