Stats: Atlas 5 and Delta 4 histories and backlogs (updated April 20)

When SpaceX’s Falcon 9 rocket takes off with 64 small satellites — a payload cache representing 34 customers in 17 nations — it will be just the first act in a nearly five-hour sequence to deftly deploy each of the spacecraft, which range in size from a Rubik’s cube to a refrigerator.

Two months after a first test-firing ended prematurely, NASA plans to ignite the core stage of the first Space Launch System heavy-lift rocket again Thursday for an eight-minute burn to confirm it is ready for shipment to the Kennedy Space Center for launch preparations.

NASA’s Perseverance rover, set for liftoff Thursday on a journey to Mars, posed some unusual challenges for launch crews working with the robot’s plutonium-fueled power generator, but United Launch Alliance’s Atlas 5 rocket is uniquely suited for the job, the company’s CEO says.