Launch of the Curiosity Mars rover

An Ariane 5 countdown in French Guiana was aborted Tuesday with the European-made rocket’s main engine already running, postponing the launch of two commercial communications satellites until engineers can resolve the problem.

Rumbling into the sky from a historic NASA-owned launch pad, SpaceX’s Falcon Heavy rocket — the world’s most powerful present-day launcher — flew for the first time Tuesday, dispatching a road-worn electric Tesla sports car with a spacesuit-clad mannequin nicknamed “Starman” on an interplanetary journey that will reach beyond the orbit of Mars.

A SpaceX Dragon capsule packed with more than 5,000 pounds of hardware, provisions and experiments launched July 25 from Cape Canaveral and arrived at the International Space Station two days later.