Photos: Atlas 5 rocket aims for International Space Station

The announcement was made by Robert Lightfoot, the ULA Lockheed Martin Board Chair, in a statement on Monday. The board now begins a search for his permanent replacement.

An Ariane 5 rocket and four Galileo navigation satellites launched from French Guiana at 1125 GMT (7:25 a.m. EDT), beginning a four-hour climb into orbit more than 14,000 miles above Earth.

SpaceX’s Falcon Heavy rocket lifted off from NASA’s Kennedy Space Center in Florida at 2:30 a.m. EDT (0630 GMT) to begin a three-and-a-half hour mission to deliver two dozen satellites into three distinct orbits. The Falcon Heavy’s two side boosters returned to Cape Canaveral for successful landings, but the center core stage crashed during a landing attempt on SpaceX’s drone ship in the Atlantic Ocean.