Photos: Delta 4-Heavy with Orion on eve of launch

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.

On its second flight, SpaceX’s mammoth Falcon Heavy rocket hurled an Arabsat communications satellite the size of a school bus nearly one-quarter the way to the moon Thursday, days after NASA’s administrator identified the privately-developed rocket as a backup to the agency’s behind-schedule Space Launch System for sending astronauts back to the lunar surface.

The three U.S. astronauts aboard the International Space Station said Monday they’re ready to sign up for a trip to the moon if NASA can meet the Trump administration’s newly stated goal of returning Americans to the lunar surface within the next five years.