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.

After a four-day delay due to a ground power supply anomaly and unfavorable weather, an Ariane 5 rocket lifted off at 4:23 p.m. EST (2123 GMT) Tuesday to send into orbit a hush-hush communications satellite for the Egyptian military and a spacecraft to expand the capacity of Inmarsat’s mobile Internet service.

John Grunsfeld, Associate Administrator for the Science Mission Directorate at NASA Headquarters, speaks about the EFT-1 test flight and science opportunities made possible by the Orion capsule and its Space Launch System rocket.