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

A senior NASA official said Tuesday that the Space Launch System, a huge heavy-lift rocket years behind schedule, could launch astronauts on a moon landing mission in 2024 on just its third flight to meet a goal announced last month by Vice President Mike Pence, while commercial companies will be entrusted with more responsibility to develop a lunar lander and a modest mini-space station, or Gateway, in lunar orbit.

United Launch Alliance could load cryogenic methane and liquid oxygen propellants into a Vulcan rocket test article at Cape Canaveral for the first time in the coming weeks, timing key tests for the next-generation rocket in between flights of Atlas 5 rockets that will share the same launch complex for the next few years.

More than three weeks after a faulty electrical component halted a countdown moments before liftoff, an Ariane 5 rocket lifted off from French Guiana on Friday with two commercial communications satellites. Launch occurred at 2156 GMT (5:56 p.m. EDT).