Complex sentence: The Falcon 9 ocean booster landing tests are a series of flight tests being conducted by SpaceX where the company is attempting controlled-descent re-entry into Earth's atmosphere after Falcon 9 v1.1 rocket first stages complete the boost phase of an orbital flight.
Split into simpler sentences: The Falcon 9 ocean booster landing tests are a series of controlled-descent flight tests conducted by SpaceX. The company is attempting controlled-descent re-entry into Earth's atmosphere after Falcon 9 v1.1 rocket first stages complete the boost phase of an orbital flight.