NASA’s Ionospheric Connection Explorer satellite was scheduled to launch Wednesday aboard an air-dropped Northrop Grumman Pegasus XL rocket over the Atlantic Ocean, but managers aborted the mission after encountering a technical concern with the rocket following departure from Cape Canaveral Air Force Station. The launcher’s L-1011 carrier jet returned to Florida.

NASA fired up four hydrogen-fueled main engines on the core stage of the first Space Launch System heavy-lift rocket Thursday in on a test stand in Mississippi, a redo of a crucial hot fire test that was cut short in January by technical issues. The engines burned more than eight minutes in an apparently successful test.

Carrying a $2.7 billion NASA mission to Mars, a United Launch Alliance Atlas 5 rocket took off July 30 from Cape Canaveral and fired into a summer sky powered by four powerful solid rocket boosters and a kerosene-burning main engine.