Watch a live view of the Atlas 5 launch pad with countdown audio (members only)

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.

With the payload matching game showing no prospects, the final Delta 2 rocket could be headed to the Smithsonian or another museum instead of space.

Freed from a legal restriction officials said limited its ability to compete for future U.S. military satellite launches, United Launch Alliance has ordered 20 new RD-180 engines from Russia that will keep the Atlas 5 rocket flying into the early 2020s.