Complex sentence: The first Dragon spacecraft launched on its first mission--contracted to NASA as COTS Demo Flight 1--on 8 December 2010, and was successfully recovered following reentry to Earth's atmosphere; the mission furthermore marked the second flight of the Falcon 9 launch vehicle.
Split into simpler sentences: The first Dragon spacecraft launched on its first mission--contracted to NASA as COTS Demo Flight 1--on 8 December 2010, and was successfully recovered following re-entry to Earth's atmosphere. The mission also marked the second flight of the Falcon 9 launch vehicle.