Live views of launch pad 39A (members only)

The launch of a commercial Bulgarian television broadcast satellite from NASA’s Kennedy Space Center in Florida is set for Monday after SpaceX ran through a mock countdown Thursday and test-fired a previously-flown Falcon 9 rocket’s Merlin main engines.

Boeing Satellite Systems, Airbus Defense and Space and Orbital ATK have won orders from Luxembourg-based satellite operator SES for three new communications spacecraft for launch in 2017.

SpaceX launched a Falcon 9 rocket Sunday from Cape Canaveral with 143 small satellites, a record number of spacecraft on a single mission, giving a boost to startup space companies and stressing the U.S. military’s tracking network charged with sorting out the locations of all objects in orbit.