Photos: Delta 4 rocket fires off the pad before sunset

The nine Merlin main engines at the base of a recycled Falcon 9 rocket booster ignited Thursday night for several seconds during a pre-flight test-firing on a Cape Canaveral launch pad, clearing a major hurdle ahead of a scheduled May 31 liftoff with a high-power communications satellite for SES.

A senior SpaceX official said this week that “heat damage” led to the failure of a Falcon 9 booster during a landing attempt Feb. 15, but the company will press on with more launches and will likely surpass the 10-flight threshold on one of its reusable rockets soon. The next Falcon 9 launch, using a booster flying on its eighth mission, is scheduled for liftoff from Florida with 60 more Starlink internet satellites Sunday night.

Look back on last week’s launch of a Russian Proton rocket from Kazakhstan with the EchoStar 21 communications satellite, a commercial craft designed to beam broadband connectivity to customers across Europe.