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

A critical test firing Saturday of the four main engines powering the first stage of NASA’s gargantuan Space Launch System moon rocket is the final major hurdle before the fully assembled booster’s costly, oft-delayed launch late this year on an unpiloted test flight.

The Biden administration supports continuing NASA’s Artemis program to return astronauts back to the moon, the White House said last week, without stating whether it will back away from the program’s already-in-doubt schedule for a lunar landing by the end of 2024.

NASA has announced two veteran space shuttle engineers have taken charge of space agency’s Space Launch System and Orion deep space exploration projects after their previous managers both took the No. 2 jobs at space centers in Alabama and Texas.