Live coverage: Atlas 5 countdown and launch journal

At NASA’s Kennedy Space Center, workers have finished the pre-launch assembly and fueling of OSIRIS-REx for the asteroid sample return spacecraft for liftoff Sept. 8.

Beginning the National Reconnaissance Office’s campaign of four launches in 2016 using boosters big and small to deploy a varied collection of new intelligence satellites, a Delta 4 rocket stands ready for liftoff before sun-up Wednesday from California.

The nuclear power generator for NASA’s Perseverance rover has been installed on the spacecraft atop an Atlas 5 rocket at Cape Canaveral, and mission managers gave a green light Wednesday to continue preparations for the rover’s July 30 launch toward Mars.