Live coverage: Atlas 5 countdown and launch journal

The full broadcast of the Atlas 5 NROL-55 / Cubsat launch. (Membership required)

NASA’s Perseverance rover, contained inside its aeroshell for a searing plunge into the Martian atmosphere next year, has been cocooned inside the payload shroud of its Atlas 5 launcher and mated with the rocket ahead of liftoff from Cape Canaveral scheduled for July 30.

Russia’s Proton rocket took off on its first launch of the year Sunday with a commercial satellite to expand Inmarsat’s next-generation mobile communications network. Liftoff occurred at 1231 GMT (7:31 a.m. EST), and it took more than 15 hours to place the Inmarsat spacecraft in the correct orbit.