Video: Falcon 9 fires up engines on pad 39A (members only)

Technicians planned to attach two Boeing-built communications satellites to a SpaceX Falcon 9 rocket Monday, a day after launch controllers fueled the rocket and fired its nine Merlin first stage engines in a key preflight test.

The United Launch Alliance Atlas 5 rocket, standing 191 feet tall and and weighing 745,000 pounds, generates 860,000 pounds of thrust from its main engine to launch NASA’s Tracking and Data Relay Satellite-M.

With this mission, SpaceX has now launched 98 Falcon 9 rockets and two Falcon Heavy rockets this year. Liftoff of the OneWeb #20 mission happened at 10:13 p.m. PDT (1:13 a.m. EDT, 0513 UTC).