Falcon 9 first-stage landing tests

The Falcon 9 first-stage landing tests were a series of controlled-descent flight tests conducted by SpaceX between 2013 and 2016. Since 2017, the first stage of Falcon 9 missions has been routinely landed if the rocket performance allowed it, and if SpaceX chose to recover the stage. The program's objective was to reliably execute controlled re-entry, descent and landing (EDL) of the Falcon 9 first stage into Earth's atmosphere after the stage completes the boost phase of an orbital spaceflight. The first tests aimed to touch down vertically in the ocean at zero velocity. Later tests attempted to land the rocket precisely on an autonomous spaceport drone ship (a barge commissioned by SpaceX to provide a stable landing surface at sea) or at Landing Zone 1 (LZ-1), a concrete pad at Cape Canaveral. The first ground landing at LZ-1 succeeded in December 2015, and the first landing at sea on a drone ship in April 2016. The second landed booster, B1021, was the first to fly again in March 2017, and was recovered a second time. The first landing test occurred in September 2013 on the sixth flight of a Falcon 9 and maiden launch of the v1.1 rocket version. From 2013 to 2016, sixteen test flights were conducted, six of which achieved a soft landing and recovery of the booster: flight 20 (Orbcomm OG2 M2) safely touching down on the LZ-1 ground pad upon first attempt in December 2015; flight 23 (CRS-8) finally achieving a stable landing at sea in the Atlantic on the drone ship Of Course I Still Love You in April 2016 after four previous attempts ended in destruction of the booster upon impact; flights 24 (JCSAT-14) and 25 (Thaicom 8) returning at higher speed from GTO missions at sea on a drone ship in May 2016; flight 27 (CRS-9) returning to LZ-1 in July 2016; flight 28 (JCSAT-16) landing on a drone ship in August 2016; Since the January 2017 return to flight, SpaceX has stopped referring to landing attempts as "experimental", indicating that they have become a routine procedure (see Iridium-1 and CRS-10 press kits of 2017, compared with CRS-9 and JCSAT-16 of 2016).