Ocean touchdown attempts Flight 6 The first
propulsive reentry, descent, and ocean-surface touchdown test occurred on September 29, 2013, on
Falcon 9 flight 6, the maiden launch of the
Falcon 9 rocket, version v1.1. After the three-minute boost phase and separation of the second stage with the
CASSIOPE and
nanosat payloads, the rocket's first stage was
reoriented backwards and three of the nine
Merlin 1D engines were reignited at high altitude to initiate a deceleration and controlled descent trajectory to the surface of the ocean. The first phase of the test "worked well and the first stage re-entered safely". However, the stage began to roll because of aerodynamic forces during the atmospheric descent and the roll rate exceeded the capabilities of the first stage
attitude control system (ACS) to
null it. The fuel in the tanks "centrifuged" to the outside of the tank and the single engine involved in the low-altitude deceleration maneuver shut down. SpaceX was able to retrieve some first-stage debris from the ocean. SpaceX tested a large amount of new technology on this flight, and, combining those results with the advances made on the Grasshopper demonstrator, the company believed it had "all the pieces of the puzzle".
Flight 9 The second test of controlled-descent hardware and software on the first stage
occurred on April 8, 2014, The first stage included landing legs for the first time which were extended to simulate a landing upon touchdown, and the test used more powerful gaseous Nitrogen
control thrusters to control the aerodynamic-induced rotation that had occurred on the first test flight. The first stage successfully approached the water surface with no spin and at zero vertical velocity, as designed. During the second test, the first stage was traveling at a velocity of at the time of the high-altitude turn-around maneuver, followed by ignition of three of the nine main engines for the initial deceleration and placement onto its descent trajectory. The major modifications for the second first stage controlled-descent test flight included changes to both the reentry burn and the landing burn as well as adding increased
attitude control system (ACS) capabilities. SpaceX had projected a low probability of stage recovery following the flight test due to complexity of the test sequence and the large number of steps that would need to be performed. In a press conference at the
National Press Club on April 25, Elon Musk said that the first stage achieved a soft touchdown on the ocean but due to rough seas, the stage was destroyed.
Flight 10 The third test flight of a returned first stage was July 14, 2014, on
Falcon 9 flight 10. Whereas the previous test reached a target landing area some hundreds of kilometers off the Florida coast, this flight aimed for a boost-back trajectory that would attempt the ocean touchdown much nearer the coast, and closer to the original launch location at Cape Canaveral. Following the third controlled-descent test flight, SpaceX expressed confidence in their ability to successfully land in the future on a "
floating launch pad or back at the launch site and refly the rocket with no required refurbishment." Results of the post-landing analysis showed that the hull integrity was lost as the -tall first stage fell horizontally, as planned, onto the ocean surface following the landing.
Flight 13 The fourth test flight of a returned first stage, with a planned ocean touchdown, occurred on
Falcon 9 flight 13 which was launched on September 21, 2014. One month later, detailed
thermal imaging infrared sensor data and video were released of the controlled-descent test. The data was collected by NASA in a joint arrangement with SpaceX as part of research on
retropropulsive deceleration technologies in order to develop new approaches to
Mars atmospheric entry. A key problem with propulsive techniques is handling the
fluid flow problems and
attitude control of the descent vehicle during the supersonic retropropulsion phase of the entry and deceleration. All phases of the night-time flight test on the first stage were successfully imaged except for the final landing burn, as that occurred below the clouds where the
IR data was not visible. The research team is particularly interested in the altitude range of the SpaceX "reentry burn" on the Falcon 9 Earth-entry tests as this is the "powered flight through the Mars-relevant retropulsion regime" that models Mars entry and descent conditions.
Flight 15 SpaceX had planned to make the sixth controlled-descent test flight and second This issue was resolved within days of the ship's return to Jacksonville, and by January 15, SpaceX was unambiguous about its plans to attempt a landing of the first stage following the boost phase of the
Deep Space Climate Observatory mission. However, in a statement by SpaceX, the drone ship was in conditions "with waves reaching up to three stories in height crashing over the decks". Additionally, one of the four thrusters that keep the barge in a constant position had malfunctioned, making station-keeping difficult. For these reasons, the post-launch flight test did not involve the barge, but instead attempted a soft touchdown over water. The test was successful, and the first stage of the Falcon 9 landed "nicely vertical" with an accuracy of 10 meters from the target location in the ocean. Therefore, this test represented the fifth ocean touchdown, and the sixth overall Falcon 9 first stage controlled-descent test.
Flight 46 and 48 Flight 46 and 48 were both boosters on their second flight that were not recovered due to the older Block 3 design only being capable of two flights. Instead of having an uncontrolled descent, SpaceX softly landed both boosters in the water to test high energy landing techniques without the risk of damaging a drone ship. On flight 48, the booster survived landing and stayed intact after tipping over. Unplanned recovery was discussed but the booster broke up before it could be attempted.
Landing attempts , SpaceX has attempted 178 landings of a first stage on a solid surface, 167 of which have succeeded (93.8%), with 139 out of 144 (96.5%) for the Falcon 9 Block 5 version. In July 2014, SpaceX announced that the fifth and sixth controlled-descent test flights would attempt to land on a solid surface, merging the lessons from the high-altitude
envelope expansion of the first four controlled-descent flights over water with the low-altitude lessons of the
F9R Dev1 testing in Texas. At that time, the "solid surface" was not further described, and was later revealed to be a seafaring barge dubbed an
autonomous spaceport drone ship. Many of the test objectives were achieved on the first attempt, including bringing the stage to the specific location of the floating platform and collecting a large amount of test data with the first use of
grid fin control surfaces for more precise reentry positioning. However the touchdown on the corner of the barge was a
hard landing and most of the rocket body fell into the ocean and sank; SpaceX published a short clip of the crash. For the landing to succeed, the -wide span of the rocket
landing legs must not only land within the -wide barge deck, but would need to also deal with
ocean swell and
GPS errors.
Flight 14 This fifth controlled-descent test flight was anticipated by the specialized press as a historic core return attempt. It incorporated for the first time in an orbital mission the
grid fin aerodynamic control surfaces that had previously been tested only during a low-altitude, low-speed test with the
F9R Dev1 prototype vehicle in early 2014. The addition of grid fins, with continuation of the control authority obtained from gimbaling the engines as on previous test flights, was projected to improve the
landing accuracy to , a thousand-fold improvement over the four previous test flights which landed within of their target coordinates. Prior to the flight, SpaceX projected that the likelihood of success on the first try was 50 percent or less. The first test flight for this new hardware occurred on January 10, 2015, on the
CRS-5 mission for NASA. The controlled-descent flight started approximately three minutes after launch, following the second stage separation event, The SpaceX webcast indicated that the boostback burn and reentry burns for the descending first stage occurred, and that the descending rocket then went "below the horizon," as expected, which eliminated the live telemetry signal, so that the
retropropulsive landing attempt was not shown live. Shortly thereafter, SpaceX released information that the rocket did get to the drone ship as planned, but "landed hard ... Ship itself is fine. Some of the support equipment on the deck will need to be replaced." Musk later elaborated that the rocket's flight-control surfaces had exhausted their supply of hydraulic fluid prior to impact. Musk posted photos of the impact while talking to
John Carmack on Twitter. SpaceX later released a video of the impact on
Vine.
Flight 17 A seventh test flight of the first stage controlled-descent profile occurred on April 14, 2015, on Falcon 9 flight 17, which carried
CRS-6 to the
International Space Station. This was SpaceX's second attempt to land on a floating platform. The first stage was fitted with grid fins and landing legs to facilitate the post-mission test. An early report from Elon Musk suggested that the first stage made a hard landing on the drone ship. Musk later clarified that the
bipropellant valve was stuck, and therefore the control system could not react rapidly enough for a successful landing. On April 15, SpaceX released a video of the terminal phase of the descent, the landing, the tip over, and the resulting
deflagration as the stage broke up on the deck of the ASDS.
Flight 20: first landing on ground pad The first attempt to land the first stage of Falcon 9 on a ground pad near the launch site occurred on
flight 20, the maiden flight of the
Falcon 9 Full Thrust version, on the evening of December 21, 2015. The landing was successful and the first stage was recovered. This was
the first time in history that a rocket first stage returned to Earth after propelling an orbital launch mission and achieved a controlled
vertical landing. SpaceX applied to the
Federal Aviation Administration (FAA) US regulatory authority to perform its eighth booster controlled-descent test culminating with a landing attempt at the
Landing Zone 1 facility (formerly
Launch Complex 13) that SpaceX had recently built at
Cape Canaveral Air Force Station. The FAA cleared SpaceX to attempt this landing after assessing that it would inflict minimal damage on the environment. Additionally, NASA planned to close the
NASA Causeway near the launch and landing site and significantly increase the size of exclusion zones during the launch and landing attempt. Both options to attempt landing on the ground pad or on the drone ship at sea remained open until the day of the launch. The final decision to return the booster to Cape Canaveral was made based on a number of factors, including weather at the potential landing sites. Flight 20 took off at 20:29
EST on December 21, 2015 (01:29
UTC on December 22, 2015). About 9 minutes and 45 seconds later, the first stage landed vertically on the pad. SpaceX did not fly the Falcon 9 flight 20 first stage again. Rather, the rocket was inspected and moved back to the launch pad a few miles north to perform a
static fire test. After the hot fire test, the vehicle was evaluated in detail by SpaceX to assess capabilities for reflight of the launch vehicle design after future landings. On December 31, SpaceX announced that no damage had been found on the stage and that it was ready to fire again. On January 15, 2016, SpaceX conducted the static fire test on the recovered booster and reported a good overall outcome, except for some thrust fluctuations in one of the outer engines (engine 9). Elon Musk reported that this may have been due to debris ingestion. This booster has been on display outside of SpaceX headquarters in Hawthorne, California since August 20, 2016.
Flight 21 Flight 21, the final launch of a
Falcon 9 v1.1, carried the
Jason 3 payload. At one point this was the first possible opportunity for an attempt to land the first stage on land, but the launches were reordered following the loss of
Falcon 9 flight 19 in June 2015. Jason-3 was successfully launched on January 17, 2016, and while the first stage managed to slow down towards a soft landing, the lockout
collet on one of the landing legs did not latch correctly, which caused the rocket to fall over and explode after touching down. Elon Musk noted that ice buildup on the collet from the high-humidity launch conditions may have led to the failure of the latch.
Flight 22 On March 4, 2016, Falcon 9 flight 22 launched the heavy
SES-9 communications satellite, the rocket's largest payload yet targeting a
highly-energetic geosynchronous transfer orbit (GTO). Consequently, the Falcon 9 first stage followed a
ballistic trajectory after separation and re-entered the atmosphere at high velocity with very little fuel to mitigate potential aerodynamic damage. Therefore, SpaceX did not expect to successfully land its Falcon 9 booster on its sea barge, the
Of Course I Still Love You, positioned in the Atlantic Ocean. Elon Musk confirmed in a tweet that the landing attempt had failed.
Flight 23: first landing on a drone ship On April 8, 2016, Falcon 9 flight 23, the third flight of
the full-thrust version, delivered the
SpaceX CRS-8 cargo on its way to the
International Space Station while the first stage conducted a boostback and re-entry maneuver over the Atlantic Ocean. Nine minutes after liftoff,
the booster landed vertically on the drone ship
Of Course I Still Love You, from the Florida coastline, achieving a long-sought-after milestone for the
SpaceX reusability development program. This stage, serial number
B1021, was refurbished and flown again in March 2017 for the
SES-10 mission, setting another milestone in the development of reusable rockets.
Flight 24: first return from GTO mission On May 6, 2016, Falcon 9 flight 24 delivered the
JCSAT-14 satellite on a
geostationary transfer orbit (GTO) while the first stage conducted a re-entry burn under ballistic conditions without prior boostback. Following the controlled descent through the atmosphere, the booster executed a short landing burn as it approached the drone ship
Of Course I Still Love You, and succeeded in landing vertically. This second landing at sea was more difficult than the previous one because the booster at separation was traveling about compared to on the CRS-8 launch to
low Earth orbit. Pursuing their experiments to test the limits of the
flight envelope, SpaceX opted for a shorter landing burn with three engines instead of the single-engine burns seen in earlier attempts; this approach consumes less fuel by leaving the stage in free fall as long as possible and decelerating more sharply, thereby minimizing the amount of energy expended to counter gravity. Elon Musk indicated this first stage may not be flown again and will instead be used as a life leader for ground tests to confirm future first stage rockets are good.
Flight 25 On May 27, 2016, Falcon 9 flight 25 delivered
THAICOM 8 to a supersynchronous transfer orbit; despite high re-entry speed, the first stage again landed successfully on the SpaceX drone ship. The landing crushed a "crush core" in one leg, leading to a notable tilt to the stage as it stood on the drone ship.
Flight 26 On June 15, 2016,
Falcon 9 flight 26 successfully delivered the
Eutelsat 117W B and
ABS 2A satellites into GTO. The first stage conducted a re-entry burn and successfully deployed its grid fins, before attempting a landing on the barge. The landing failed in its final moments due to low thrust on one of the first stage engines, caused by the exhaustion of its liquid oxygen fuel supply. That caused the engines to shut down early while the first stage was just above the drone's deck, causing a landing failure.
Flight 27 In the early hours of July 18, 2016, Falcon 9 flight 27, carrying the
Dragon spacecraft for the
CRS-9 mission was followed by a successful landing of the first stage at
Landing Zone 1,
Cape Canaveral.
Flight 28 On August 14, 2016, the Falcon 9 flight 28 successfully propelled the Japanese
JCSAT-16 telecommunications satellite to a
geosynchronous transfer orbit. The first stage
re-entered the atmosphere and landed vertically on the
Of Course I Still Love You drone ship that was located in the Atlantic Ocean. == Transition to routine reuse ==