SpaceX reusable launch system development program
|SpaceX Reusable Launch System Development Program|
|Type of project||Privately funded|
|Established||Publicly announced 2011|
The SpaceX reusable launch system development program is a privately funded program to develop a set of new technologies for an orbital launch system that may be reused many times in a manner similar to the reusability of aircraft. The company SpaceX is developing the technologies over a number of years to facilitate full and rapid reusability of space launch vehicles. The project's long-term objectives include returning a launch vehicle first stage to the launch site in minutes and to return a second stage to the launch pad following orbital realignment with the launch site and atmospheric reentry in up to 24 hours. Both stages will be designed to allow reuse a few hours after return.
The program was publicly announced in 2011 and the design for returning the rocket to its launchpad using only its own propulsion systems was completed in February 2012. SpaceX's active test program began in late 2012 with testing low-altitude, low-speed aspects of the landing technology. High-velocity, high-altitude aspects of the booster atmospheric return technology began testing in late 2013.
The reusable launch system technology is under development for the first stages of the Falcon family of rockets. It is particularly well-suited to the Falcon Heavy where the two outer cores separate from the rocket earlier in the flight, and are therefore moving more slowly at stage separation. If the technology is used on a reusable Falcon 9 rocket, the first-stage separation would occur at a velocity of approximately 2.0 km/s (6,500 km/h; 4,100 mph; Mach 6) rather than the 3.4 km/s (11,000 km/h; 7,000 mph; Mach 10) for an expendable Falcon 9, to provide the residual fuel necessary for the deceleration and turnaround maneuver and the controlled descent and landing. The reusable technology will also be extended to both the first and upper stages of the future launch vehicle for the Mars Colonial Transporter.
The first successful controlled landing of an orbital rocket stage on the ocean surface was achieved in April 2014. Two of the controlled-descent tests have also attempted to land the returning first stage on a floating landing platform—one each in January and April 2015. But although the booster was guided to the floating platform in both cases, neither test was successful in achieving a vertical landing on the platform.
- 1 History
- 2 Technologies
- 3 Economic issues
- 4 Technical feasibility
- 5 Test program
- 5.1 Prototype vehicle flight testing
- 5.2 Falcon 9 booster post-mission, controlled-descent tests
- 5.2.1 Reusability test plan for post-mission testing
- 5.2.2 Test flights
- 220.127.116.11 Ocean water test descents
- 18.104.22.168 Floating-platform test landings
- 6 See also
- 7 References
- 8 External links
The broad outline of the reusable launch system was first publicly described on September 29, 2011. SpaceX said it would attempt to develop powered descent and recovery of both Falcon 9 stages—a fully vertical takeoff, vertical landing (VTVL) rocket. The company produced a computer-animated video depicting a notional view of the first stage returning tail-first for a powered descent and the second stage with a heat shield, reentering head first before rotating for a powered descent. In September 2012, SpaceX began flight tests on a prototype reusable first stage with the suborbital Grasshopper rocket. Those tests continued into 2014, including testing of a second and larger prototype vehicle, F9R Dev1.
News of the Grasshopper test rocket become public earlier in September 2011, when the US Federal Aviation Administration released a draft Environmental Impact Assessment for the SpaceX Test Site in Texas, and the space media had reported it by September 26. In May 2012, SpaceX obtained a set of atmospheric test data for the recovery of the Falcon 9 first stage based on 176 test runs in the NASA Marshall Space Flight Center wind tunnel test facility. The work was contracted for by SpaceX under a reimburseable Space Act Agreement with NASA.
In November 2012, CEO Elon Musk announced SpaceX's plans to build a second, much larger, reusable rocket system, this one to be powered by LOX/methane rather than LOX/RP-1 used on Falcon 9 and Falcon Heavy. The new system will be "an evolution of SpaceX's Falcon 9 booster", and SpaceX reiterated their commitment to develop a breakthrough in vertical landing technology. By the end of 2012, the demonstration test vehicle, Grasshopper, had made three VTVL test flights—including a 29-second hover flight to 40 meters (130 ft) on December 17, 2012. In early March 2013, SpaceX successfully tested Grasshopper for a fourth time when it flew to an altitude of over 80 meters (260 ft).
In March 2013, SpaceX announced that it would instrument and equip subsequent Falcon 9 first-stages as controlled descent test vehicles, with plans for over-water propulsively-decelerated simulated landings beginning in 2013, with the intent to return the vehicle to the launch site for a powered landing—possibly as early as mid-2014. The April 2013 draft Environmental Impact Statement for the proposed SpaceX private launch site in south Texas includes specific accommodations for return of the Falcon 9 first-stage boosters to the launch site. Elon Musk first publicly referred to the reusable Falcon 9 as the Falcon 9-R in April 2013.
In September 2013, SpaceX successfully relit three engines of a spent booster on an orbital launch, and the booster re-entered the atmosphere at hypersonic speed without burning up. With the data collected from the first flight test of a booster-controlled descent from high altitude, coupled with the technological advancements made on the Grasshopper low-altitude landing demonstrator, SpaceX announced it believed it was ready to test a full land-recovery of a booster stage. Based on the positive results from the first high-altitude flight test, SpaceX advanced the expected date of a test from mid-2014 to early 2015, with the intention of doing so on the next Space Station cargo resupply flight pending regulatory approvals. That flight took place on April 18, 2014.
Musk stated in May 2013 that the goal of the program is to achieve full and rapid reusability of the first stage by 2015, and to develop full launch vehicle reusability following that as "part of a future design architecture".
In February 2014, SpaceX made explicit that the newly defined super-heavy launch vehicle for the Mars Colonial Transporter would also make use of the reusable technology. This is consistent with Musk's strategic statement in 2012 that "The revolutionary breakthrough will come with rockets that are fully and rapidly reusable. We will never conquer Mars unless we do that. It'll be too expensive. The American colonies would never have been pioneered if the ships that crossed the ocean hadn't been reusable."
Also in May 2014, SpaceX publicly announced an extensive test program for a related reusable technology: a propulsively-landed space capsule called DragonFly. The tests will be run in Texas at the McGregor Rocket Test Facility in 2014–2015.
In June 2014, COO Gwynne Shotwell clarified that all funding for development and testing of the reusable launch system technology development program is private funding from SpaceX, with no contribution by the US government. SpaceX has not publicly disclosed the cost of the development program.
For the first time, SpaceX stated in July 2014 that they 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."
Several new technologies needed to be developed and tested to facilitate successful launch and recovery of both stages of the SpaceX reusable rocket launching system. Following the completion of the third high-altitude controlled-descent test, and the completion of the third low-altitude flight of the second-generation prototype test vehicle (plus eight flights of the first-generation Grasshopper prototype flight test vehicle), SpaceX indicated that they are now able to consistently "reenter from space at hypersonic velocity, restart main engines twice, deploy landing legs and touch down at near zero velocity."
The technologies that were developed for this program, some of which are still being refined, include:
- restartable ignition system for the first-stage booster Restarts are required at both supersonic velocities in the upper atmosphere—in order to decelerate the high velocity away from the launch pad and put the booster on a descent trajectory back toward the launch pad—and at high transonic velocities in the lower atmosphere—in order to slow the terminal descent and to perform a soft landing.
- new attitude control technology—for the booster stage and second stage—to bring the descending rocket body through the atmosphere in a manner conducive both to non-destructive return and sufficient aerodynamic control such that the terminal phase of the landing is possible. This includes sufficient roll control authority to keep the rocket from spinning excessively as occurred on the first high-altitude flight test in September 2013, where the roll rate exceeded the capabilities of the booster attitude control system (ACS) and the fuel in the tanks "centrifuged" to the side of the tank shutting down the single engine involved in the low-altitude deceleration maneuver. The technology needs to handle the transition from the vacuum of space at hypersonic conditions, decelerating to supersonic velocities and passing through transonic buffet, before relighting one of the main-stage engines at terminal velocity.
- hypersonic grid fins were added to the booster test vehicle design beginning on the fifth ocean controlled-descent test flight. Arranged in an "X" configuration, the grid fins control the descending rocket's lift vector once the vehicle has returned to the atmosphere to enable a much more precise landing location.
- throttleable rocket engine technology is required to reduce engine thrust because the full thrust of even a single Merlin 1D engine exceeds the weight of the nearly empty booster core.
- terminal guidance and landing capability, including a vehicle control system and a control system software algorithm to be able to land a rocket with the thrust-to-weight ratio of the vehicle greater than one, with closed-loop thrust vector and throttle control
- navigation sensor suite for precision landing
- a large floating landing platform in order to test pinpoint landings prior to receiving permission from the US government to bring returning rocket stages into US airspace over land. In the event, SpaceX built the Autonomous spaceport drone ship in 2014, and conducted an initial flight test and landing attempt in January 2015.
- large-surface-area thermal protection system to absorb the heat load of deceleration of the second stage from orbital velocity to terminal velocity
- lightweight, deployable landing gear for the booster stage. In May 2013, the design was shown to be a nested, telescoping piston on an A-frame. The total span of the four carbon fiber/aluminum extensible landing legs is approximately 18 meters (60 ft), and they weigh less than 2,100 kilograms (4,600 lb); the deployment system uses high-pressure Helium as the working fluid.
In order to make the Falcon 9 reusable and return to the launch site, extra propellant and landing gear must be carried on the first stage, requiring around a 30 percent reduction of the maximum payload to orbit in comparison with the expendable Falcon 9. Reflight of a previously used stage on a subsequent flight is dependent on the condition of the landed stage, and is a technique that has seen little use outside of the Space Shuttle's reusable solid rocket boosters. In September 2013, SpaceX said that if all aspects of the test program are successful and if a customer is interested, the first reflight of a Falcon 9 booster stage could happen as early as late 2014.
If SpaceX is successful in developing the reusable technology, it is expected to significantly reduce the cost of access to space, and change the increasingly competitive market in space launch services. Michael Belfiore wrote in Foreign Policy that at a published cost of US$56.5 million per launch to low Earth orbit, "Falcon 9 rockets are already the cheapest in the industry. Reusable Falcon 9s could drop the price by an order of magnitude, sparking more space-based enterprise, which in turn would drop the cost of access to space still further through economies of scale." Even for military launches, which have a number of contractual requirements for additional launch services to be provided, SpaceX's price is under US$100 million.
Space industry analyst Ajay Kothari has noted that SpaceX reusable technology could do for space transport "what jet engines did for air transportation sixty years ago when people never imagined that more than 500 million passengers would travel by airplanes every year and that the cost could be reduced to the level it is—all because of passenger volume and reliable reusability." SpaceX has said that if they are successful in developing the reusable technology, launch prices of around US$5 to 7 million for a reusable Falcon 9 are possible.
As of March 2014[update] launch service providers who compete with SpaceX are not planning to develop similar technology or offer competing reusable launcher options. Neither ILS, which markets launches of the Russian Proton rocket; Arianespace; nor SeaLaunch are planning on developing and marketing reusable launch vehicle services. SpaceX is the only competitor that currently sees a sufficiently elastic market on the demand side that justifies the costly development of reusable rocket technology and the expenditure of private capital to develop options for that theoretical market opportunity.
SpaceX pricing and payload specifications published for the non-reusable Falcon 9 v1.1 rocket actually include about 30 percent more performance than the published price list indicates; the additional performance is reserved for SpaceX to do reusability booster demonstration flight tests while still achieving the specified payloads for customers.
In order to achieve the full economic benefit of the reusable technology, it is necessary that the reuse be both rapid and complete—without the long and costly refurbishment period or partially reusable design that plagued earlier attempts at reusable launch vehicles. SpaceX has been explicit that the "huge potential to open up space flight" is dependent on achieving both complete and rapid reusability. CEO Musk has publicly stated that success with the technology development effort could reduce "the cost of spaceflight by a factor of 100."
Separate from the market competition brought about by SpaceX lower launch prices and the potential future of even more radically lower launch prices if the technology can be completed successfully, Aviation Week has said that "SpaceX reusable launch work is an R&D model"—"The audacity of the concept and speed of the program’s progress make it an exemplar. ... [the] breakneck pace of development has been almost Apollo-like in its execution... [even while] success is far from guaranteed."
The return and rapid reuse of an orbital launch system has never been accomplished. Developing a reusable rocket is extremely challenging due to the small percentage of a rocket's mass that can make it to orbit. Typically, a rocket's payload is only about 3% of the mass of the rocket which is also roughly the amount of mass in fuel that is required for the vehicle's re-entry.
Elon Musk said that he believes return, vertical landing and recovery is possible because the SpaceX manufacturing methodologies result in a rocket efficiency exceeding the typical 3% margin. A SpaceX rocket operating in the reusable configuration will have approximately 30% less payload lift capacity than the same rocket in an expendable configuration.
SpaceX is currently testing reusable technologies both for its first-stage booster launch vehicle designs—with three test vehicles—and for its new reusable Dragon V2 space capsule—with a low-altitude test vehicle called DragonFly.
SpaceX has publicly disclosed a multi-element, incremental test program for booster stages that includes four aspects:
- low-altitude (less than 760 m/2,500 ft), low-velocity testing of its single-engine Grasshopper technology-demonstrator at its Texas test site
- low-altitude (less than 3,000 m/9,800 ft), low-velocity testing of a much larger, second-generation, three-engine test vehicle called F9R Dev1. The second generation vehicle includes extensible landing legs and will be tested at the Texas test site
- high-altitude, mid-velocity testing of another of the second-generation test vehicles (F9R Dev2) at a SpaceX leased facility at Spaceport America in New Mexico. The number of engines on F9R Dev2 has not yet been made public.
- high-altitude (91 km/300,000 ft), very-high-velocity (approximately 2.0 km/s; 6,500 km/h; 4,100 mph; Mach 6) ballistic reentry, controlled-deceleration and controlled-descent tests of post-mission (spent) Falcon 9 booster stages following a subset of Falcon 9 launches that began in 2013
Eight low-altitude booster flight tests were made by Grasshopper in 2012 and 2013. The first booster return controlled-descent test from high-altitude was made in September 2013, with a second test in April, a third test flight in July and a fourth test in September 2014. All four test flights to date were intended to be over-water, simulated landings. Five low-altitude booster flight tests of F9R Dev1 were flown during April–August 2014, before the vehicle self-destructed for safety reasons on the fifth flight. The F9R Dev2 test vehicle is expected to start flight testing prior to the end of 2014.
Prototype vehicle flight testing
Grasshopper is a set of experimental technology-demonstrator, suborbital reusable launch vehicles (RLV). Two versions of the prototype reusable test vehicles have been built, the 106-foot tall Grasshopper (formerly designated as Grasshopper v1.0) and the 160-foot tall Falcon 9 Reusable Development Vehicle, or F9R Dev—formerly known as Grasshopper v1.1. Grasshopper was built in 2011-2012 for low-altitude, low-velocity hover testing in Texas that began in September 2012 and concluded in October 2013 after eight test flights. The second prototype vehicle design, F9R Dev, is built on the much larger Falcon 9 v1.1 booster stage form factor, and will include at least two test vehicles—designated F9R Dev1 and F9R Dev2—to be used for higher-altitude and higher-velocity flight testing.
The flight test program is currently underway. The low-altitude, low-speed flights of the first test vehicle—Grasshopper—were conducted at the SpaceX Rocket Test Facility in McGregor, Texas. F9R Dev will be tested at both the Texas facility and also at Spaceport America in New Mexico, with the initial and low-altitude flight tests of the vehicle occurring in Texas, and the high-altitude—approximately 91,000 meters (300,000 ft)—flights in New Mexico.
In 2011 when SpaceX initially announced its test program, it projected it would begin flight tests in 2012. In the event, Grasshopper began flight testing in September 2012 with a brief, three-second hop at the company's Texas test site, followed by a second hop in November 2012 with an eight-second flight that took the testbed approximately 5.4 meters (18 ft) off the ground, and a third flight in December 2012 of 29 seconds duration, with extended hover under rocket engine power—in which it ascended to 40 meters (130 ft). Five additional test flights were made in 2013 before Grasshopper v1.0 was retired in October 2013. F9R-Dev flight testing began in April 2014.
Grasshopper, the company's first VTVL test vehicle, consisted of a Falcon 9 v1.0 first-stage tank, a single Merlin-1D engine, and four permanently attached steel landing legs. It stood 106 feet (32 m) tall. SpaceX built a 0.5 acres (0.20 ha) concrete launch facility at its Rocket Development and Test Facility in McGregor, Texas to support the Grasshopper flight test program. Grasshopper was also known as Grasshopper version 1.0, or Grasshopper v1.0, prior to 2014 during the time the followon Grasshopper-class test vehicles were being built.
In addition to three test flights in 2012, five additional tests were successfully flown by the end of October 2013—including the fourth test overall in March 2013—in which Grasshopper doubled its highest leap to rise to 80.1 meters (263 ft) with a 34-second flight. In the seventh test, in August 2013, the vehicle flew to 250 meters (820 ft) during a 60-second flight and executed a 100 meters (330 ft) lateral maneuver before returning to the pad. Grasshopper made its eighth and final test flight on October 7, 2013, flying to 744 meters (2,441 ft) (0.46 miles) before making its eighth successful landing. The Grasshopper test vehicle is now retired.
Falcon 9 Reusable Development Vehicle (F9R Dev)
Beginning in October 2012, SpaceX discussed development of a second-generation Grasshopper test vehicle, which would have lighter landing legs that fold up on the side of the rocket, a different engine bay, and would be nearly 50% longer than the first Grasshopper vehicle. In March 2013, SpaceX announced that the larger Grasshopper-class suborbital flight vehicle would be constructed out of the Falcon 9 v1.1 first-stage tank that was used for qualification testing at the SpaceX Rocket Development and Test Facility in early 2013. It has been rebuilt as the F9R Dev1 with extensible landing legs.
The second VTVL flight test vehicle—F9R Dev1, built on the much longer Falcon 9 v1.1 first-stage tank, and with retractable landing legs—made its first test flight on April 17, 2014. F9R Dev1 was used for low-altitude test flights in the McGregor, Texas area with projected maximum altitude below 3,000 meters (10,000 ft). This vehicle self-destructed as a safety measure during a test flight on August 22, 2014.
As of April 2-14[update], a third flight test vehicle—F9R Dev2—was being built and was planned to be flown at the high-altitude test range available at Spaceport America in New Mexico where it was expected to be flown at altitudes up to 91,000 meters (300,000 ft)-plus.
DragonFly is a prototype test article for a propulsively-landed version of the SpaceX Dragon space capsule, a suborbital reusable launch vehicle (RLV), intended for low-altitude flight testing. It will undergo a test program in Texas at the McGregor Rocket Test Facility, in 2014–2015.
The DragonFly test vehicle is powered by eight SuperDraco engines, arranged in a redundant pattern to support fault-tolerance in the propulsion system design. SuperDracos utilize a storable propellant mixture of monomethyl hydrazine (MMH) fuel and nitrogen tetroxide oxidizer (NTO), the same propellants used in the much smaller Draco thrusters used for attitude control and maneuvering on the first-generation Dragon spacecraft. While SuperDraco engines are capable of 73,000 newtons (16,400 lbf) of thrust, during use on DragonFly flight test vehicle each will be throttled to less than 68,170 newtons (15,325 lbf) to maintain vehicle stability.
A test flight program of thirty flights has been proposed, including two propulsive assist (parachutes plus thrusters) and two propulsive landing (no parachutes) on flights dropped from a helicopter at an altitude of approximately 3,000 meters (10,000 ft). The other 26 test flights are projected to take off from a pad: eight to be propulsive assist hops (landing with parachutes plus thrusters) and 18 to be full propulsive hops, similar to the Grasshopper and F9R Dev booster stage test flights.
Falcon 9 booster post-mission, controlled-descent tests
In an arrangement unusual for launch vehicles, some first stages of the SpaceX Falcon 9 v1.1 rockets are being used for propulsive-return controlled-descent flight tests after they complete the boost phase of an orbital flight. These boosters would ordinarily just be discarded in the ocean once boost phase is complete. The over-water tests are occurring in the Pacific and Atlantic oceans south of Vandenberg Air Force Base and east of Cape Canaveral Air Force Station. The first flight test occurred on September 29, 2013, after the second stage with the CASSIOPE and nanosat payloads separated from the booster. These descent and simulated landing tests are continued into 2014 and 2015, with the second flight test having occurred on April 18, 2014, and the fifth and sixth tests occurred in January and February 2015.
Following analysis of the flight test data from the first booster-controlled descent in September 2013, SpaceX announced it had successfully tested a large amount of new technology on the flight, and that coupled with the technology advancements made on the Grasshopper low-altitude landing demonstrator, they were ready to test a full recovery of the booster stage. The first flight test was successful; SpaceX said it was "able to successfully transition from vacuum through hypersonic, through supersonic, through transonic, and light the engines all the way and control the stage all the way through [the atmosphere]". Musk said, "the next attempt to recovery [sic] the Falcon 9 first stage will be on the fourth flight of the upgraded rocket. This would be [the] third commercial Dragon cargo flight to ISS."
This second flight test took place during the April 2014 Dragon flight to the ISS. SpaceX attached landing legs to the first stage, decelerated it over the ocean and attempted a simulated landing over the water, following the ignition of the second stage on the third cargo resupply mission contracted to NASA. The first stage was successfully slowed down enough for a soft landing over the Atlantic Ocean. SpaceX announced in February 2014 that they intend to continue the tests to land the first-stage booster in the ocean until precision control from hypersonic all the way through subsonic regimes has been proven.
Reusability test plan for post-mission testing
The post-mission Falcon 9 test plan for the earliest flight tests called for the first-stage booster to do 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 booster reaches the water. 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 can land the vehicle correctly.
In detailed information disclosed in the Falcon 9 Flight 6 launch license for the CASSIOPE mission, SpaceX said it would fire three of the nine Merlin 1D engines initially to slow the horizontal velocity of the rocket and begin the attempt at a controlled descent. Then, shortly before hitting the ocean, one engine would be relighted in an attempt to reduce the stage's speed so that it could be recovered. As of 10 September 2013[update], SpaceX said the experiment had approximately a ten percent chance of success.
SpaceX is not performing controlled-descent tests on all Falcon 9 v1.1 flights. In September 2013, SpaceX announced that the fourth Falcon 9 v1.1 flight—which occurred in April 2014—would be the second test of the booster controlled descent test profile.
Whereas the early tests restarted the engines only twice, by the fourth flight test, in September 2014, SpaceX was reigniting the main engines three times to accomplish its controlled-descent test objectives (although only three of the nine engines are reignited each time): a boost-back burn, a reentry burn, and a landing burn. The boost-back burn limits downrange translation of the used stage; the reentry burn (from approximately 70 to 40 km (43 to 25 mi) altitude) is used to control the descent and deceleration profile at atmospheric interface; and the landing burn completes the deceleration from terminal velocity to zero velocity at the landing surface.
Ocean water test descents
Falcon 9 Flight 6
After the three-minute boost phase of the September 29, 2013 launch—the first flight of the v1.1 version of the Falcon 9—the first stage was reoriented, and three of the nine Merlin 1D engines 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 descent through the atmosphere, and the roll rate exceeded the capabilities of the booster attitude control system (ACS) to null it out. 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. The company did not expect a successful booster recovery on this flight and, as of March 2013[update], had said that they did not expect booster recovery following the first several powered-descent tests. The test was successful—with substantial test milestones achieved and a great deal of engineering test data collected—but the booster was not successfully recovered from the ocean.
SpaceX tested a large amount of new technology on the flight, and that—coupled with the technology advancements made on the Grasshopper technology demonstrator—means the company now believes it has "all the pieces of the puzzle".
Falcon 9 Flight 9
The second test of controlled-descent hardware and software on the first-stage booster occurred on April 18, 2014, and became the first successful controlled ocean soft touchdown of a liquid-rocket-engine orbital booster. The booster included landing legs for the first time which were extended for the simulated "landing", and the test utilized more powerful gaseous Nitrogen control thrusters to control the aerodynamic-induced rotation that had occurred on the first test flight. The booster stage successfully approached the water surface with no spin and at zero vertical velocity, as designed.
During the second test, the booster was traveling at a velocity of Mach 10 (6,300 mph; 10,000 km/h) at an altitude of 80,000 meters (260,000 ft) 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 "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 8 seconds after reaching the water" and stopped only after the booster went horizontal.
The major modifications for the second booster 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 carried out perfectly. The company was careful to label the entire flight test as "an experiment". In an press conference at the National Press Club on April 25, Elon Musk said that the first stage achieved soft landing on the ocean but due to rough seas, the stage was destroyed.
Falcon 9 Flight 10
The third test flight of a returned booster was July 14, 2014 on Falcon 9 Flight 10. Whereas the previous test did its "soft landing" some hundreds of kilometers off the Florida coast, this flight aimed for a boost-back trajectory that would attempt the simulated ocean landing 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."
Following the booster loft of the second stage and payload on its orbital trajectory, SpaceX conducted a successful flight test on the spent first stage. The first stage successfully decelerated from hypersonic velocity in the upper atmosphere, made a successful reentry, landing burn, deployment of its landing legs, and touched down on the ocean surface. The first stage was not recovered for analysis as the hull integrity was breached, either on landing or on the subsequent "tip over and body slam". Results of the post-landing analysis showed that the hull integrity was lost as the 46-metre (150 ft)-tall booster rocket body fell horizontally, as planned, onto the ocean surface following the landing.
Falcon 9 Flight 13
The fourth test flight of a returned booster, with a planned water landing, occurred on Falcon 9 Flight 13 which was launched on September 21, 2014. and the booster flew a profile approaching a zero-velocity at zero-altitude simulated landing on the sea surface. SpaceX made no attempt to recover the first stage, since earlier tests had confirmed that the 14-story tall booster would not survive the tip-over event into the sea.
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 nighttime flight test on the booster 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 70–40-kilometer (43–25 mi) 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.
Falcon 9 Flight 15
SpaceX had planned make the sixth controlled-descent test flight and second landing attempt on the floating recovery ship, no earlier than February 11 (see below for first attempt). This would be a "potentially historic rocket launch and landing" because the first stage will attempt a test landing on a droneship, something that "was unheard of" five years ago.
According to regulatory paperwork filed in 2014, SpaceX plans had called for the sixth test flight to occur on a late January 2015 launch attempt. However, after the completion of the fifth test flight, and with some damage being incurred by the drone ship in the unsuccessful landing, it was not clear if the sixth test would still be able to occur only a few weeks later. That was resolved within days of the ship returning to Jacksonville, and by January 15 SpaceX was unambiguous about its plans to attempt a landing of the booster following the boost phase of the DSCOVR 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 which keep the barge in a constant position had malfunctioned, making station-keeping difficult. Due to these factors, the post-launch flight test did not involve the barge, but instead attempted a soft landing 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 landing, and the sixth overall booster controlled-descent test by a Falcon 9 first stage.
Floating-platform test landings
SpaceX has attempted two landings of a test vehicle on a solid surface as of April 2015[update]. Many of the test objectives were achieved, including landing on a floating platform at a specific point in the Atlantic ocean and a large amount of test data obtained from the first use of grid fin control surfaces used 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.
In July 2014, SpaceX had announced that the fifth and sixth controlled-descent test flights would attempt landings 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 Dev testing in Texas. At that time, the tests were stated to be planned for the 14th and 15th Falcon 9 flights, and the "solid surface" was not further described. In the event, the 14th Falcon 9 flight became the fifth controlled-descent test and first attempted landing on floating platform, but the 15th F9 flight was redirected to target another over-ocean landing due to excessive sea state conditions.
Falcon 9 Flight 14
In October 2014, SpaceX clarified that the "solid surface" would be a floating platform that was then being built for SpaceX in Louisiana, and confirmed that they would attempt to land the first stage of the 14th Falcon 9 flight]] on the platform. For the landing to be successful, the 18 m (60 ft)-wide span of the rocket landing legs must not only land within the 52 m (170 ft)-wide barge deck, but would need to also deal with large ocean swell and GPS errors. In late November, SpaceX revealed that the barge—now designated the Autonomous spaceport drone ship—would be capable of autonomous operation and would not need to be anchored or moored. The fifth flight of the over-ocean controlled descent test series—referred to as an "historic core return attempt" by NASA SpaceFlight—was the first orbital flight to test the grid fin aerodynamic control surfaces that had previously been tested only on a low-altitude, low-speed test flight on 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, are projected to improve the landing accuracy to 10 m (33 ft); the landing accuracy on the previous four controlled-descent test flights was only 10 km (6.2 mi). Prior to the flight, SpaceX projected that the likelihood of successfully landing on the platform on the first try was 50 percent or less.
The first flight attempt for the test hardware occurred on January 10, 2015 on the CRS-5 flight contracted to NASA. The controlled-descent flight started approximately three minutes after launch, following the second stage separation event, when the booster was approximately 80 km (50 mi) high and moving at a velocity of Mach 10 (6,300 mph; 10,000 km/h).
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. Shortly thereafter, SpaceX released information that the rocket did get to the drone spaceport 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.
Falcon 9 Flight 17
A seventh test flight of the booster controlled-descent profile occurred on April 14th 2015 on Falcon 9 Flight 17. This was SpaceX's second attempt to land on a floating platform. The booster was fitted with grid fins and landing legs to facilitate the post-mission test. If successful, this would have been first time in history that a rocket booster was returned to a vertical landing.
An early report from Elon Musk suggested that the booster 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 15 April, SpaceX released a video of the terminal phase of the descent, the landing, the tip over, and a small deflagration as the stage broke up on the deck of the ASDS.
Falcon 9 Flight 19
Falcon 9 Flight 19, scheduled for 19 June 2015, is slated to be the third attempt to land on a solid surface as it is lofting a lower-mass LEO payload. On 15 April 2015, SpaceX President and COO Gwynne Shotwell said that the company hopes to land the rocket on ground rather than at sea. No controlled-descent test will be conducted on Falcon 9 Flight 18 as it is lofting its primary mission payload to a higher-energy geosynchronous orbit.
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Both of the rocket's stages would return to the launch site and touch down vertically, under rocket power, on landing gear after delivering a spacecraft to orbit.
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(@18:15 It is a very tough engineering problem—and it wasn't something that I thought, wasn't sure it could be solved for a while. But then, just relatively recently, in the last 12 months or so, I've come to the conclusion that it can be solved. And SpaceX is going to try to do it. Now, we could fail. I am not saying we are certain of success here, but we are going to try to do it. And we have a design that, on paper, doing the calculations, doing the simulations, it does work. Now we need to make sure that those simulations and reality agree, because generally when they don't, reality wins. So that's to be determined.)
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much bigger [than Falcon 9], but I don’t think we’re quite ready to state the payload. We’ll speak about that next year.
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Q. What is strategy on booster 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 booster? Musk: No. Will probably be the middle of next 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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hopeful that sometime in the next couple of years we'll be able to achieve full and rapid reusability of the first stage—which is about three-quarters of the cost of the rocket—and then with a future design architecture, achieve full reusability.
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This technology element [reusable launch vehicle technology] all this innovation is being done by SpaceX alone, no one is paying us to do it. The government is very interested in the data we are collecting on this test series. ... This is the kind of thing that entrepreneurial investment and new entrants/innovators can do for an industry: fund their own improvements, both in the quality of their programs and the quality of their hardware, and the speed and cadence of their operations.
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SpaceX is using private capital to develop and demonstrate the Falcon 9 rocket's reusability. SpaceX has not disclosed how much the reusable rocket program will cost
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[Rocket stages are not passively stable on rentry from orbit], ... so there is a lot of software involved, a lot of guidance navigation and control involved, and a lot of thermal protection required; so we have to make advances in all those areas. We also have to restart the engines supersonically.
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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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The Falcon 9 first stage carries landing legs which will deploy after stage separation and allow for the rocket’s soft return to Earth. The four legs are made of state-of-the-art carbon fiber with aluminum honeycomb. Placed symmetrically around the base of the rocket, they stow along the side of the vehicle during liftoff and later extend outward and down for landing.
- "Falcon Heavy Landing Legs". SpaceX.com. April 12, 2013. Retrieved December 4, 2013.
The Falcon Heavy first stage center core and boosters each carry landing legs, which will land each core safely on Earth after takeoff. After the side boosters separate, the center engine in each will burn to control the booster’s trajectory safely away from the rocket. The legs will then deploy as the boosters turn back to Earth, landing each softly on the ground. The center core will continue to fire until stage separation, after which its legs will deploy and land it back on Earth as well. The landing legs are made of state-of-the-art carbon fiber with aluminum honeycomb. The four legs stow along the sides of each core during liftoff and later extend outward and down for landing.
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F9R (pronounced F-niner) shows a little leg. Design is a nested, telescoping piston w A frame... High pressure helium. Needs to be ultra light.
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[Falcon 9 v1.1] vehicle has thirty percent more performance than what we put on the web and that extra performance is reserved for us to do our reusability and recoverability [tests] ... current vehicle is sized for reuse.
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SpaceX's work with the F9R is part of an effort to develop fully and rapidly reusable launch systems, a key priority for the company. Such technology could slash the cost of spaceflight by a factor of 100.
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Expendable rockets, which many smart people have worked on in the past, get maybe 2% of liftoff mass to orbit -- really not a lot. Then, when they’ve tried reusability, it’s resulted in negative payload, a 0 to 2% minus payload [laughs]. The trick is to figure out how to create a rocket that, if it were expendable, is so efficient in all of its systems that it would put 3% to 4% of its mass into orbit. On the other side, you have to be equally clever with the reusability elements such that the reusability penalty is no more than 2%, which would leave you with a net ideally of still 2% of usable load to orbit in a reusable scenario, if that makes sense. You have to pry those two things apart: Push up payload to orbit, push down the mass penalty for reusability -- and have enough left over to still do useful work.
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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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WATCH: Grasshopper flies to its highest height to date - 744 m (2441 ft) into the Texas sky. http://youtu.be/9ZDkItO-0a4 This was the last scheduled test for the Grasshopper rig; next up will be low altitude tests of the Falcon 9 Reusable (F9R) development vehicle in Texas followed by high altitude testing in New Mexico.
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SpaceX has constructed a half-acre concrete launch facility in McGregor, and the Grasshopper rocket is already standing on the pad, outfitted with four insect-like silver landing legs.
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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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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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Musk: 'Rocket booster 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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While the Falcon 9’s second stage continues to orbit with the Dragon spacecraft, its first stage will execute a series of manoeuvres 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.
- "SpaceX CRS-% Mission: Cargo Resupply Services" (PDF). nasa.gov. NASA. December 2014. Retrieved January 17, 2015.
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.
- Musk, Elon. "Post-launch Twitter news releases". SpaceX. Retrieved January 10, 2015.
Rocket made it to drone spaceport ship, but landed hard. Close, but no cigar this time. Bodes well for the future tho. ... Ship itself is fine. Some of the support equipment on the deck will need to be replaced... Didn't get good landing/impact video. Pitch dark and foggy. Will piece it together from telemetry and ... actual pieces.
- Musk, Elon. "Twitter @elonmusk". Elon Musk. Retrieved January 13, 2015.
- Bergin, Chris (April 3, 2015). "SpaceX preparing for a busy season of missions and test milestones". NASASpaceFlight.com. Retrieved April 4, 2015.
- Elon Musk (14 April 2015). https://twitter.com/elonmusk/status/588076749562318849. Missing or empty
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|Wikimedia Commons has media related to Grasshopper (rocket).|
- SpaceX Reusable Launch System, concept video released prior to completion of the system design, 3:58, September 29, 2011.
- Video of Grasshopper low-altitude, low-velocity landing test, 4th test flight, March 8, 2013.
- Video of 7th Grasshopper low-altitude test flight, including a 100-meter lateral maneuver, August 13, 2013.
- Video of 8th and final low-altitude Grasshopper v1.0 test flight, to 744 meters (0.462 miles), October 7, 2013.
- Low-resolution photograph of the Falcon 9 booster controlled-descent test on September 29, 2013, just moments before impacting the Atlantic ocean.
- Video of Falcon 9 Reusable Development vehicle no. 1 (F9R Dev1) 1st test flight, to 250 meters (0.16 miles), hovering and then landing just next to the launch stand, April 17, 2014.
- Video of CRS-3 booster 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 booster 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 booster stage landing test: Falcon 9 First Stage Reentry Footage from Plane , SpaceX-released video of the controlled descent test, released August 14, 2014.
- SpaceX rocket nails launch but narrowly misses landing test, Reuters, Irene Klotz, January 10, 2015.