Video: Orion launch replays

NASA is taking steps to rein in costs, emphasizing bonds with private sector companies, and signaling it might be open to a future where the agency’s flagship Orion deep space capsule and Space Launch System are no longer necessary to explore deep space, at least in their current forms.

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.