section_path: Capabilities/Reusability/Post-mission flight tests and landing attempts
section_name: Post-mission flight tests and landing attempts
paragraph_text: Post-mission flight tests and landing attempts
  
  For Flight 6 in September 2013, after stage separation, the flight plan called for the first stage to conduct a burn to reduce its reentry velocity, and then a second burn just before reaching the water. Although not a complete success, the stage was able to change direction and make a controlled entry into the atmosphere. During the final landing burn, the RCS thrusters could not overcome an aerodynamically induced spin. The centrifugal force deprived the engine of fuel, leading to early engine shutdown and a hard splashdown.
  
  After four more ocean landing tests, the CRS-5 booster attempted a landing on the ASDS floating platform in January 2015. The rocket incorporated (for the first time in an orbital mission) grid fin aerodynamic control surfaces, and successfully guided itself to the ship, before running out of hydraulic fluid and crashing into the platform. A second attempt occurred in April 2015, on CRS-6. After the launch, the bipropellant valve became stuck, preventing the control system from reacting rapidly enough for a successful landing.
  
  The first attempt to land a booster on a ground pad near the launch site occurred on flight 20, in December 2015. The landing was successful and the booster was recovered. This was the first time in history that after launching an orbital mission, a first stage achieved a controlled vertical landing. The first successful booster landing on an ASDS occurred in April 2016 on the drone ship Of Course I Still Love You during CRS-8.
  
  Sixteen test flights were conducted from 2013 to 2016, six of which achieved a soft landing and booster recovery. Since January 2017, with the exceptions of the centre core from the Falcon Heavy test flight, Falcon Heavy USAF STP-2 mission, the Falcon 9 CRS-16 resupply mission and the Starlink -4, 5, and 19 missions, every landing attempt has been successful. Two boosters have been lost or destroyed at sea after landing: the center core used during the Arabsat-6A mission, and B1058 after completing a Starlink flight.