SpaceX fueled its next Falcon 9 rocket at launch pad 39A and ignited the booster’s nine Merlin engines at sunset Thursday, passing a major step in the launch campaign leading up to liftoff of the Intelsat 35e communications satellite Sunday.

Boeing’s work on the International Space Station, the CST-100 Starliner commercial crew capsule and NASA’s heavy-lift Space Launch System are under the umbrella of John Elbon, who leads the company’s space exploration division in Houston.

Rocketing through gloomy skies with a payload clouded in a veil of secrecy, a United Launch Alliance Atlas 5 rocket fired away from Cape Canaveral on Tuesday to deploy a satellite thousands of miles above Earth.