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 (
Landings of Falcon 9 first-stage boosters
Overview
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:
- LZ-1ground pad upon first attempt in December 2015;
- Of Course I Still Love Youin April 2016 after four previous attempts ended in destruction of the booster upon impact;
- flights GTOmissions at sea on a drone ship in May 2016;
- 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). As of 15 December 2017[update], 14 routine landings have been performed (100% success) and three missions were launched in expendable configuration, not attempting to land.
The first-stage descent tests were part of the larger
Traditionally, the first stages of orbital carrier rockets have been discarded in the ocean once the ascent was complete. Achieving routine recovery and reuse of the launch vehicles could dramatically reduce the cost of access to space.[1][2][3][4]
History
From the beginning, Elon Musk wanted the first stage of SpaceX launch vehicles to be recoverable, and all Falcon 1 launches and the first two Falcon 9 launches had parachutes. However the boosters burned up on reentry, before the parachutes even deployed.[5] This meant a different approach had to be taken. Experimental prototypes were built and flown during 2012 to 2014 to test the idea of propulsive landings and gain experience.
SpaceX first announced in March 2013 that it would instrument and equip subsequent Falcon 9 first stages as controlled-descent test vehicles, able to propulsively decelerate towards a soft touchdown over the water surface. The company expected to begin these flight tests in 2013, with an attempt to return the vehicle to the launch site for a powered landing no earlier than mid-2014.[6]
In the event, SpaceX did perform their first controlled-descent test flight in 2013 but continued the over-water testing well into 2015. Following analysis of telemetry data from the first controlled descent in September 2013, SpaceX announced that a large amount of new technology passed their real-life test objectives, and that coupled with the technology advancements made on the
This second EDL test took place during the
Post-mission test plan
The post-mission Falcon 9 test plan for the earliest flight tests called for the first stage to perform a retro-propulsion burn in the upper atmosphere to slow it down and put it on a descent ballistic trajectory to its target landing location, followed by a second burn in the lower atmosphere before the first stage reached the water.[11] SpaceX announced in March 2013 that it intended to conduct such tests on Falcon 9 v1.1 launch vehicles and would "continue doing such tests until they can do a return to the launch site and a powered landing". The company said it expected several failures before it could land the vehicle successfully.[9][12]
In detailed information disclosed in the Falcon 9 flight 6
SpaceX did not perform controlled-descent tests on all Falcon 9 v1.1 flights, as payloads going to GTO did not leave enough fuel margin.[14] In September 2013, SpaceX announced that the CRS-3 mission of April 2014 (fourth flight of Falcon 9 v1.1)[15] would be the second test of the descent test profile.[1]
Whereas the early tests restarted the engines only twice, by the fourth flight test, in September 2014, SpaceX was reigniting the engines three times to accomplish its EDL test objectives (although only three of the nine engines were used): a boost-back burn, a reentry burn, and a landing burn. The boost-back burn limits
Test flights
Ocean touchdown attempts
Flight 6
The first
This first experimental descent was considered successful, achieving substantial test milestones and collecting a great deal of engineering data, despite losing the stage into the ocean.[19] 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 now believed it had "all the pieces of the puzzle".[7][19][20]
Flight 9
The second test of controlled-descent hardware and software on the first stage
During the second test, the first stage was traveling at a velocity of Mach 10 (10,200 km/h; 6,340 mph)[23] at an altitude of 80 kilometers (260,000 ft)[24] 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.[3] The "first stage executed a good re-entry burn and was able to stabilize itself on the way down. ... [The] landing in [the] Atlantic [ocean] was good! ... Flight computers continued transmitting [telemetry data] for eight seconds after reaching the water" and stopped only after the first stage went horizontal.[25]
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
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 carried out perfectly.[9] The company was careful to label the entire flight test as "an experiment".[27] 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.[28][29]
Flight 10
The third test flight of a returned first stage was July 14, 2014, on
Following the first stage loft of the second stage and payload on its orbital trajectory, SpaceX conducted a successful
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.[32] and the first stage flew a profile approaching a zero-velocity at zero-altitude simulated landing on the sea surface.[17] SpaceX made no attempt to recover the first stage, since earlier tests had confirmed that the 14-story tall first stage would not survive the tip-over event into the sea. The booster did run out of liquid oxygen.[33]
One month later, detailed
Flight 15
SpaceX had planned to make the sixth controlled-descent test flight and second[34] landing attempt on their drone ship no earlier than February 11, 2015. Landing a returning rocket at sea would have been a "potentially historic rocket launch and landing", as such a feat "was unheard of" five years earlier.[34][35][36]
According to regulatory paperwork filed in 2014, SpaceX plans had called for the sixth test flight to occur on a
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.[38]
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.[39]
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.[40][41] 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.[42]
Landing attempts
As of 28 January 2023[update], 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
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.[43] It would take four more attempts to achieve the first barge landing at sea on flight 23.[44] Meanwhile, ground landing succeeded on the first attempt with flight 20 on December 21, 2015.[45]
In October 2014, SpaceX clarified that the "solid surface" would be a
Flight 14
This fifth controlled-descent test flight was anticipated by the specialized press as a historic core return attempt.
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,[49] when the first stage was approximately 80 km (50 mi) high and moving at a velocity of Mach 10 (10,000 km/h; 6,300 mph).[51]
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
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
An early report from Elon Musk suggested that the first stage made a hard landing on the drone ship.[56] Musk later clarified that the
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.[45][59] 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
Flight 20 took off at 20:29
SpaceX did not fly the Falcon 9 flight 20 first stage again.
On December 31, SpaceX announced that no damage had been found on the stage and that it was ready to fire again.[67][68] 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.[69]
This booster has been on display outside of SpaceX headquarters in Hawthorne, California since August 20, 2016.
Flight 21
Flight 22
On March 4, 2016, Falcon 9 flight 22 launched the 5,271 kg (11,620 lb) heavy SES-9 communications satellite,[75][76] the rocket's largest payload yet targeting a
Therefore, SpaceX did not expect to successfully land its Falcon 9 booster on its sea barge, the
Flight 23: first landing on a drone ship
On April 8, 2016, Falcon 9 flight 23, the third flight of
This stage, serial number
Flight 24: first return from GTO mission
On May 6, 2016, Falcon 9 flight 24 delivered the
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.[82] The landing crushed a "crush core" in one leg, leading to a notable tilt to the stage as it stood on the drone ship.[83]
Flight 26
On June 15, 2016, Falcon 9 flight 26 successfully delivered the Eutelsat 117W B[84] and ABS 2A[85] 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.[86][87]
Flight 27
In the early hours of July 18, 2016, Falcon 9 flight 27, carrying the
Flight 28
On August 14, 2016, the Falcon 9 flight 28 successfully propelled the Japanese
Transition to routine reuse
SpaceX continued to return a number of first stages in both ground and sea landings to clarify the procedures needed to re-use flown boosters. The company had hoped to begin offering pre-flown Falcon 9 rocket stages commercially by the end of 2016,[90][91] but the first re-used booster eventually took off on March 30, 2017, with the SES-10 mission. The booster performed well and was recovered a second time.
In January 2016 Musk evaluated the likelihood of success to approximately 70 percent for landing attempts in 2016, hopefully rising to 90 percent in 2017; he also cautioned that the company expected "a few more RUDs", referring to the term
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Falcon 9 first-stage attempts landing on the Autonomous spaceport drone ship, the landing legs are in the midst of deploying
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Falcon 9 Flight 17's first-stage attempting a controlled landing on the drone ship following the successful launch of CRS-6
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Falcon 9 flight 20's first-stage moments before touchdown on Landing Zone 1
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Falcon 9 flight 20's first-stage after landing
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Falcon 9 flight 21's landing approach before it soft-landed and tipped over due to a leg lock failure
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Falcon 9 flight 23's first-stage was the first successful landing on the drone ship
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Falcon 9 flight 24's first stage on the drone ship
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Falcon 9 flight 25 first-stage approached the drone ship with a tilt
See also
- SpaceX reusable launch system development program
- List of Falcon 9 and Falcon Heavy launches
- List of Falcon 9 first-stage boosters
References
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SpaceX is counting on lower launch costs to increase demand for launch services. But Foust cautions that this strategy comes with risk. 'It's worth noting,' he says, 'that many current customers of launch services, including operators of commercial satellites, aren't particularly price sensitive, so thus aren't counting on reusability to lower costs.' That means those additional launches, and thus revenue, may have to come from markets that don't exist yet. 'A reusable system with much lower launch costs might actually result in lower revenue for that company unless they can significantly increase demand,' says Foust. 'That additional demand would likely have to come from new markets, with commercial human spaceflight perhaps the biggest and best-known example.'
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Q. What is strategy on first stage recover? Musk: Initial recovery test will be a water landing. First stage continue in ballistic arc and execute a velocity reduction burn before it enters atmosphere to lessen impact. Right before splashdown, will light up the engine again. Emphasizes that we don't expect success in the first several attempts. Hopefully next year with more experience and data, we should be able to return the first stage to the launch site and do a propulsion landing on land using legs. Q. Is there a flight identified for return to launch site of the first stage? Musk: No. Will probably be the middle of next year.
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[The] partnership between NASA and SpaceX is giving the U.S. space agency an early look at what it would take to land multi-ton habitats and supply caches on Mars for human explorers, while providing sophisticated infrared (IR) imagery to help the spacecraft company develop a reusable launch vehicle. After multiple attempts, airborne NASA and U.S. Navy IR tracking cameras ... captured a SpaceX Falcon 9 in flight as its first stage [fell] back toward Earth shortly after second-stage ignition and then reignit[ed] to lower the stage toward a propulsive "zero-velocity, zero-altitude" touchdown on the sea surface.
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We managed to re-enter the atmosphere, not break up like we normally do, and get all way down to sea level.
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The first successful "soft landing" of a Falcon 9 rocket happened in April of this year
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The April 17 F9R Dev 1 flight, which lasted under 1 min., was the first vertical landing test of a production-representative recoverable Falcon 9 v1.1 first stage, while the April 18 cargo flight to the ISS was the first opportunity for SpaceX to evaluate the design of foldable landing legs and upgraded thrusters that control the stage during its initial descent.
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At this point, we are highly confident of being able to land successfully on a floating launch pad or back at the launch site and refly the rocket with no required refurbishment
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Musk: 'Rocket first stage reentry, landing burn & leg deploy were good, but lost hull integrity right after splashdown (aka kaboom) ... Detailed review of rocket telemetry needed to tell if due to initial splashdown or subsequent tip over and body slam.'
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{{cite web}}
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To space and back, in less than nine minutes? Hello, future.
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While the Falcon 9's second stage continues to orbit with the Dragon spacecraft, its first stage will execute a series of maneuvers which SpaceX hope will culminate in a successful landing atop a floating platform off the coast of Florida. The demonstration follows successful tests during two previous launches where the first stage has been guided to a controlled water landing, however the stage has not been recoverable on either previous attempt. ... Achieving a precision landing on a floating platform is an important milestone for SpaceX as they attempt to demonstrate their planned flyback recovery of the first stage of the Falcon 9.
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A key upgrade to enable precision targeting of the Falcon 9 all the way to touchdown is the addition of four hypersonic grid fins placed in an X-wing configuration around the vehicle, stowed on ascent and deployed on reentry to control the stage's lift vector. Each fin moves independently for roll, pitch and yaw, and combined with the engine gimbaling, will allow for precision landing – first on the autonomous spaceport drone ship, and eventually on land.
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Approximately 157 seconds into flight, the first-stage engines are shut down, an event known as main-engine cutoff, or MECO. At this point, Falcon 9 is 80 kilometers (50 miles) high, traveling at 10 times the speed of sound.
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Falcon lands on droneship, but the lockout collet doesn't latch on one the four legs, causing it to tip over post landing. Root cause may have been ice buildup due to condensation from heavy fog at liftoff.
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- ^ "SpaceX on Twitter". Twitter. Retrieved June 15, 2016.
- ^ "SpaceX on Twitter". Twitter. Retrieved June 15, 2016.
- ^ "Elon Musk on Twitter". Twitter. Retrieved June 15, 2016.
- ^ "Elon Musk on Twitter". Twitter. Retrieved June 15, 2016.
- ^ SpaceX launches space station docking port for NASA, The Associated Press, July 18, 2016
- ^ Clark, Stephen (August 14, 2016). "Falcon 9 rocket launches Japanese satellite, then nails bullseye landing". Spaceflight Now.
- ^ "Returned Falcon 9 Booster fires up for Static Fire Test". Spaceflight 101. January 15, 2016. Retrieved January 18, 2016.
- ^ Money, Stewart (April 9, 2016). "Musk: SpaceX Plans to Re-Fly Falcon 9 in June". Innerspace.net. Retrieved May 8, 2016.
Having previously suggested that SpaceX would like to re-fly a Falcon 9 first stage by the end of the year, Musk surprised nearly everyone by confidently asserting that the time frame was instead late May or more realistically June. Moreover, the odds were favorable that it would be a paying launch.
- ^ @elonmusk (January 19, 2016). "My best guess for 2016: ~70% landing success rate (so still a few more RUDs to go), then hopefully improving to ~90% in 2017" (Tweet). Retrieved May 8, 2016 – via Twitter.
External links
- Video of CRS-3 first-stage landing test, April 2014: low quality, corrupted data and higher quality, after video frames recovered by open-source recovery effort by NSF team.
- On-board camera video of ORBCOMM Mission-1 first-stage landing test: Falcon 9 First Stage Return : ORBCOMM Mission, SpaceX-released video of the controlled descent test, July 2014.
- Chase-plane camera video of ORBCOMM Mission-1 first-stage landing test: Falcon 9 First Stage Reentry Footage from Plane, SpaceX-released video of the controlled descent test, released August 14, 2014.