Live coverage: Orion lands in Pacific

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 launch of NASA’s Parker Solar Probe, on the verge of kicking off a seven-year mission culminating in passages through the sun’s atmosphere, has been delayed to Aug. 6 to resolve a technical snag encountered during encapsulation of the spacecraft inside the nose shroud of its United Launch Alliance Delta 4-Heavy rocket.

A former space shuttle orbital maneuvering system engine has been delivered to Germany for attachment to the European-built service module destined to steer NASA’s next Orion spacecraft on a course around the moon on an uncrewed test flight in late 2018.