Super Heavy (booster Rocket)
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Super Heavy is the reusable first stage of the
SpaceX Starship Starship is a two-stage fully reusable launch vehicle, reusable super heavy-lift launch vehicle under development by American aerospace company SpaceX. On 20 April 2023, with the Starship flight test 1, first Integrated Flight Test, Starship b ...
super heavy-lift
launch vehicle A launch vehicle is typically a rocket-powered vehicle designed to carry a payload (a crewed spacecraft or satellites) from Earth's surface or lower atmosphere to outer space. The most common form is the ballistic missile-shaped multistage ...
, which it composes in combination with the Starship second stage. As a part of SpaceX's Mars colonization program, the booster evolved into its current design over a decade. Production began in 2021, with the first flight being conducted on April 20, 2023, during the first launch attempt of the Starship rocket. The booster is powered by 33
Raptor Raptor(s) or RAPTOR may refer to: Animals The word "raptor" refers to several groups of avian and non-avian dinosaurs which primarily capture and subdue/kill prey with their talons. * Raptor (bird) or bird of prey, a bird that primarily hunt ...
engines that use
liquid oxygen Liquid oxygen, sometimes abbreviated as LOX or LOXygen, is a clear cyan liquid form of dioxygen . It was used as the oxidizer in the first liquid-fueled rocket invented in 1926 by Robert H. Goddard, an application which is ongoing. Physical ...
and
methane Methane ( , ) is a chemical compound with the chemical formula (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The abundance of methane on Earth makes ...
as propellants. It returns to its launch site after propelling the second stage toward orbit, landing vertically by being caught by the launch tower.


Design

Super Heavy is tall, wide, and is composed of four general sections: the engines, the oxygen tank, the fuel tank, and the interstage. SpaceX
CEO A chief executive officer (CEO), also known as a chief executive or managing director, is the top-ranking corporate officer charged with the management of an organization, usually a company or a nonprofit organization. CEOs find roles in variou ...
Elon Musk Elon Reeve Musk ( ; born June 28, 1971) is a businessman. He is known for his leadership of Tesla, SpaceX, X (formerly Twitter), and the Department of Government Efficiency (DOGE). Musk has been considered the wealthiest person in th ...
stated in 2021 that the final design will have a dry mass between and , with the tanks weighing and the interstage .


Tanks

The two cryogenic propellant tanks on Super Heavy are separated by a common bulkhead, a similar structural design to the
S-II The S-II (pronounced "S-two") was the second stage of the Saturn V rocket. It was built by North American Aviation. Using liquid hydrogen (LH2) and liquid oxygen (LOX) it had five J-2 engines in a quincunx pattern. The second stage accelerated ...
and
S-IVB The S-IVB (pronounced "S-four-B") was the third stage on the Saturn V and second stage on the Saturn IB launch vehicles. Built by the Douglas Aircraft Company, it had one J-2 rocket engine. For lunar missions it was fired twice: first for Earth ...
stages on the
Saturn V The Saturn V is a retired American super heavy-lift launch vehicle developed by NASA under the Apollo program for human exploration of the Moon. The rocket was human-rated, had multistage rocket, three stages, and was powered by liquid-propel ...
rocket. After Starship's second flight test, the common dome's design was changed to be more elliptical, altering the propellant capacity of both tanks by a small amount. Each tank possesses roughly 74 stringers for structural reinforcement, attached to their interior walls. The booster's two tanks hold a combined of propellant: of liquid oxygen and of liquid methane. Fuel is fed to the engines via a single liquid funnel, and channeled into distribution
manifolds In mathematics, a manifold is a topological space that locally resembles Euclidean space near each point. More precisely, an n-dimensional manifold, or ''n-manifold'' for short, is a topological space with the property that each point has a n ...
of the engines. Block 1 and 2 boosters both have a single booster quick disconnect, along with multiple quick disconnects for the outer engines, while Block 3 boosters have two quick disconnects. One disconnect feeds liquid oxygen into the vehicle, the other liquid methane. The oxygen tank ends at the thrust structure of the vehicle. While the outer twenty engines are mounted to the walls of the aft bay, the inner thirteen are mounted onto the thrust puck, a part of the aft dome. Large steel structures are attached to the bottom of the dome, reinforcing the puck sufficiently to fully support the inner thirteen engines, and at the same time providing pathways for methane and oxygen into the engines. In addition, large filters were added in this region beginning on Booster 10. Liquid oxygen is supplied by a header tank during landing burn for the inner thirteen engines. On Booster 15, the header tank had at least nine additional tanks attached, increasing capacity for the landing burn. The added tanks may have been present on Boosters 12, 13, and 14, though this was unconfirmed as of February 2025. Booster 5 was the only 29-engine booster to receive a header tank, mounted to the side of the oxygen tank instead of being integrated with the thrust puck. The methane funnel is partially contained within the header tank, as the methane sump is directly below it. On Booster 7 and all subsequent vehicles, four aerodynamic chines are located on the outside of the oxygen tank, providing aerodynamic lift during descent, as well as housing batteries,
composite overwrapped pressure vessel A composite overwrapped pressure vessel (COPV) is a vessel consisting of a thin, non-structural liner wrapped with a structural fiber composite, designed to hold a fluid under pressure. The liner provides a barrier between the fluid and the compo ...
s (COPVs), and tanks for
fire suppression Fire suppression may refer to: * Firefighting * Fire suppression systems * Wildfire suppression Wildfire suppression is a range of firefighting tactics used to suppress wildfires. Firefighting efforts depend on many factors such as the availabl ...
. On vehicles with hydraulic power units (HPUs), COPVs dedicated to engine ignition, batteries, and communication antennae are located within the HPU cover instead of the chines.


Propulsion

Super Heavy is powered by 33
Raptor Raptor(s) or RAPTOR may refer to: Animals The word "raptor" refers to several groups of avian and non-avian dinosaurs which primarily capture and subdue/kill prey with their talons. * Raptor (bird) or bird of prey, a bird that primarily hunt ...
engines housed within a dedicated shielding compartment. This compartment is not present before engine installation. Hence, boosters are roughly three meters shorter prior to engine installation. The outer 20 engines, arranged in a ring, are fixed in place. To save weight, the 20 engines are started using
ground support equipment Ground support equipment (GSE) is the support equipment found at an airport, usually on the apron, the servicing area by the terminal. This equipment is used to service the aircraft between flights. As the name suggests, ground support equipment ...
on the launch mount and cannot be reignited for subsequent burns. The inner thirteen engines are equipped with gimbal actuators and reignite for the boostback and landing burns. After Starship's first flight test, this gimbaling system was switched from a hydraulic system to an electric one, enabling the removal of the hydraulic power units. This change was made to the upper stage after the second flight test. During the ascent and boostback burns, the engines draw propellant from the main tanks, with the liquid oxygen being drawn from a dedicated header tank during the landing burn. Like the thrust vector control system, the engine shielding, which isolates individual engines in the event of a failure, was upgraded after Starship's first flight test, alongside the
fire suppression system Fire suppression systems are used to extinguish, control, or in some cases, entirely prevent fires from spreading or occurring. Fire suppression systems have an incredibly large variety of applications, and as such, there are many different types ...
. The aft bay has eighteen vents visible on the outside of the booster, which are believed to be connected to the outer 20 engines, while the center engines vent directly below the launch pad. The Raptor engine uses a full-flow staged combustion cycle with oxygen and methane-rich turbopumps. Before 2014, only two full-flow staged-combustion rocket engine designs had advanced enough to undergo testing: the Soviet
RD-270 RD-270 (, GRAU index: 8D420) was a single-chamber liquid-fuel rocket engine designed by Energomash (USSR) in 1960–1970. It was to be used on the first stages of the proposed heavy-lift UR-700 and UR-900 rocket families, as well as on the N1 ...
project in the 1960s and the Aerojet Rocketdyne
Integrated Powerhead Demonstrator The integrated powerhead demonstrator (IPD) was a U.S. Air Force project in the 1990s and early 2000s run by NASA and the Air Force Research Laboratory (AFRL) to develop a new rocket engine front-end ("powerhead", sometimes also termed a powerpac ...
in the mid-2000s. To improve performance, the engines burn subcooled propellant; i.e. the propellants are cooled below their respective boiling points to further increase their density and the engine mass flow rates. The Block 1 version of the booster (used through November 2024) produces a total of just over twice that of the Saturn V first stage, with this total being expected to increase to for Block 2 boosters and later up to with the Block 3 vehicle. These later versions may have up to 35 engines. The thirty three engines collectively produce large
shock diamond Shock diamonds (also known as Mach diamonds or thrust diamonds, and less commonly Mach disks) are a formation of standing wave patterns that appear in the supersonic exhaust plume of an aerospace propulsion system, such as a supersonic jet engi ...
s in the exhaust jet, visible during ascent and descent. During unpowered flight in the upper atmosphere, control authority is provided by
cold gas thruster A cold gas thruster (or a cold gas propulsion system) is a type of rocket engine which uses the expansion of a (typically inert) pressurized gas to generate thrust. As opposed to traditional rocket engines, a cold gas thruster does not house any co ...
s fed with residual ullage gas. Four perpendicular vents are located within the interstage. Additional vents are located just below the common dome, pointing down toward the engines at a slight angle. The Block 3 booster contains an updated aft dome, with metallic heat shield tiles mounted upon it.


Interstage

The interstage is equipped with four electrically actuated
grid fin Grid fins (or lattice fins) are a type of flight control surfaces, flight control surface used on rockets and bombs, sometimes in place of more conventional control surfaces, such as planar fins. They were developed in the 1950s by a team led by ...
s made of stainless steel, each with a mass of roughly . The fins remain extended during ascent to save weight, though this results in mild warping during stage separation. The interstage also has protruding
hardpoint A hardpoint is an attachment location on a structural frame designed to transfer force and carry an external or internal structural load, load. The term is usually used to refer to the mounting points (more formally known as a weapon station o ...
s, located between grid fins, allowing the booster to be lifted or caught by the launch tower. The ability to lift a booster from these hardpoints was proven on August 23, 2022, when Booster 7 was lifted onto OLM A. The first catch of a booster occurred on October 13, 2024, using Booster 12.After the first Starship test flight, all boosters have an additional 1.8 m tall vented interstage to enable hot staging. During hot staging, Super Heavy shuts down all but the 3 center engines, while the second stage fires its engines before separating, thus the second stage "pushes off" from the first stage giving added thrust. The vented interstage contains a dome to shield the top of Super Heavy from the second stage's engines. Elon Musk in 2023 claimed that this change might result in a 10% increase in the payload to
low Earth orbit A low Earth orbit (LEO) is an geocentric orbit, orbit around Earth with a orbital period, period of 128 minutes or less (making at least 11.25 orbits per day) and an orbital eccentricity, eccentricity less than 0.25. Most of the artificial object ...
. Beginning with Booster 11, the vented interstage is jettisoned after completion of the boostback burn, to reduce mass during descent. As of June 2024, SpaceX does not intend to jettison the interstage when flying Block 2 and Block 3 boosters, as the vented section will be directly integrated into the vehicle. On Block 3 boosters, the interstage is directly integrated into the methane tank. Additionally, the number of grid fins is reduced from four to 3, in a 90/90/180 degree arrangment.


Manufacturing

The manufacturing process starts with rolls of
stainless steel Stainless steel, also known as inox, corrosion-resistant steel (CRES), or rustless steel, is an iron-based alloy that contains chromium, making it resistant to rust and corrosion. Stainless steel's resistance to corrosion comes from its chromi ...
, which are unrolled, cut, and welded along an edge to create a cylinder of diameter, tall, and thick, and approximately kg () in mass. Thirty-three such rings are used in the Super Heavy Booster, while four rings are tall. These shorter rings are used exclusively in the aft section. A and a tall ring are used to construct the liquid oxygen header tank. These rings have a significantly smaller diameter than the main rings. The forward dome is constructed out of two segments: the "dome knuckle" and the "dome frustum". The aft dome has a third component: the "thrust puck", which supports the inner thirteen engines, while the common dome is composed of a single part, and is more elliptical than the forward and aft domes. These rings are stacked and robotically welded along their edges to form stacks of three to four rings in the Starfactory. Stringers are then added to the ring stacks, improving the structural strength of the booster. Cutouts are made for the grid fins and hardpoints for the forward section. Following this, the domes are installed within the forward, aft, and common ring stacks. The forward ring stack consists of three rings, and the common ring stack consists of four. The aft section is constructed solely from the four rings. Tank vents and external piping are added at this stage, followed by the COPVs and header tank. Following the completion of each of the ring stacks, the stacking of these sections begins, beginning with the assembly of the methane tank.. This process occurs in Mega Bay 1. Once the methane tank is completed, the oxygen tank is assembled, already integrated to the common dome. Before assembly of the oxygen tank is finished, the methane downcomer is added, along with final stringers to the weld lines. When both tanks are complete, the methane tank is stacked onto the oxygen tank, completing the primary tankage assembly. Chines are added after this stage. The vehicle is then rolled to the
Massey's test site SpaceX Starbase—previously, SpaceX South Texas Launch Site and SpaceX private launch site—is an industrial complex and rocket launch facility that serves as the main testing and production location for SpaceX Starship, Starship launch vehi ...
and cryogenically tested twice. These tests fill both tanks with liquid nitrogen, which is nonflammable, though liquid oxygen may be loaded as well. After returning to the production site, the engines are installed, alongside their shielding, which forms the aft bay. This is followed by static fire testing at the launch site. Once this test is completed, the vented interstage is added to the vehicle.


History


Early concepts


Mars Colonial Transporter

In October 2012, the company made the first public articulation of plans to develop a fully reusable rocket system with substantially greater capabilities than SpaceX's existing Falcon 9. Later in 2012, the company first mentioned the Mars Colonial Transporter rocket concept in public. It was going to be able to carry of cargo to Mars and would be powered by methane-fueled Raptor engines. Musk referred to this new launch vehicle under the unspecified acronym "MCT", revealed to stand for "Mars Colonial Transporter" in 2013, which would serve the company's Mars system architecture. SpaceX COO
Gwynne Shotwell Gwynne Shotwell ( Rowley, previously Gurevich; born November 23, 1963) is an American businesswoman and engineer. She is the president and chief operating officer of SpaceX, an American space transportation company, where she is responsible fo ...
gave a potential payload range between 150–200 tons to
low Earth orbit A low Earth orbit (LEO) is an geocentric orbit, orbit around Earth with a orbital period, period of 128 minutes or less (making at least 11.25 orbits per day) and an orbital eccentricity, eccentricity less than 0.25. Most of the artificial object ...
for the planned rocket. According to SpaceX engine development head
Tom Mueller Thomas John Mueller is an American aerospace engineer and rocket engine designer. He was employee No.1 of SpaceX and is the founder and now CEO of Impulse Space. Mueller is best known for his engineering work on the Merlin, Draco, Super Draco ...
, SpaceX could use nine
Raptor Raptor(s) or RAPTOR may refer to: Animals The word "raptor" refers to several groups of avian and non-avian dinosaurs which primarily capture and subdue/kill prey with their talons. * Raptor (bird) or bird of prey, a bird that primarily hunt ...
engines on a single MCT booster or spacecraft. The preliminary design would be at least in diameter, and was expected to have up to three cores totaling at least 27 booster engines.


Interplanetary Transport System

On September 27, 2016, at the 67th
International Astronautical Congress The International Astronautical Congress (IAC) is an annual meeting of the actors in the discipline of space science. It is hosted by one of the national society members of the International Astronautical Federation (IAF), with the support of ...
, SpaceX CEO Elon Musk announced SpaceX was developing a new rocket using Raptor engines called the Interplanetary Transport System. It would have two stages, a reusable booster and a spacecraft. The stages' tanks were to be made from
carbon composite Carbon fiber-reinforced polymers (American English), carbon-fibre-reinforced polymers (Commonwealth English), carbon-fiber-reinforced plastics, carbon-fiber reinforced-thermoplastic (CFRP, CRP, CFRTP), also known as carbon fiber, carbon compo ...
, storing liquid methane and liquid oxygen. Despite the rocket's launch capacity to low Earth orbit, it was expected to have a low launch price. The concept, especially the technological feats required to make such a system possible and the funds needed, garnered substantial skepticism. Both stages would use autogenous pressurization of the propellant tanks, eliminating the Falcon 9's problematic high-pressure
helium Helium (from ) is a chemical element; it has chemical symbol, symbol He and atomic number 2. It is a colorless, odorless, non-toxic, inert gas, inert, monatomic gas and the first in the noble gas group in the periodic table. Its boiling point is ...
pressurization system. The ITS booster was to be a , , reusable first stage powered by 42 engines, each producing of
thrust Thrust is a reaction force described quantitatively by Newton's third law. When a system expels or accelerates mass in one direction, the accelerated mass will cause a force of equal magnitude but opposite direction to be applied to that ...
. Total booster thrust would have been at liftoff, increasing to in a vacuum, several times the thrust of the
Saturn V The Saturn V is a retired American super heavy-lift launch vehicle developed by NASA under the Apollo program for human exploration of the Moon. The rocket was human-rated, had multistage rocket, three stages, and was powered by liquid-propel ...
. It weighed when empty and when completely filled with propellant. It would have used grid fins to help guide the booster through the atmosphere for a precise landing. The engine configuration included 21 engines in an outer ring and 14 in an inner ring. The center cluster of seven engines would be able to
gimbal A gimbal is a pivoted support that permits rotation of an object about an axis. A set of three gimbals, one mounted on the other with orthogonal pivot axes, may be used to allow an object mounted on the innermost gimbal to remain independent of ...
for directional control. However, some directional control would be achieved via differential thrust with the fixed engines. Each engine could
throttle A throttle is a mechanism by which fluid flow is managed by construction or obstruction. An engine's power can be increased or decreased by the restriction of inlet gases (by the use of a throttle), but usually decreased. The term ''throttle'' ha ...
to between 20 and 100 percent of rated thrust. The design goal was to achieve a separation velocity of about while retaining about 7% of the initial propellant to achieve a
vertical landing Vertical takeoff, vertical landing (VTVL) is a form of takeoff and landing for rockets. Multiple VTVL craft have flown. A notable VTVL vehicle was the Apollo Lunar Module which delivered the first humans to the Moon. Building on the decades of ...
at the launch pad.The design called for
grid fin Grid fins (or lattice fins) are a type of flight control surfaces, flight control surface used on rockets and bombs, sometimes in place of more conventional control surfaces, such as planar fins. They were developed in the 1950s by a team led by ...
s to guide the booster during
atmospheric reentry Atmospheric entry (sometimes listed as Vimpact or Ventry) is the movement of an object from outer space into and through the gases of an atmosphere of a planet, dwarf planet, or natural satellite. Atmospheric entry may be ''uncontrolled entry ...
. The booster return flights were expected to encounter loads lower than the Falcon 9, principally because the ITS would have both a lower mass ratio and a lower density. The booster was to be designed for 20 ''g'' nominal loads, and possibly as high as 30–40 ''g''. In contrast to the landing approach used on SpaceX's
Falcon 9 Falcon 9 is a Reusable launch system#Partial reusable launch systems, partially reusable, two-stage-to-orbit, medium-lift launch vehicle designed and manufactured in the United States by SpaceX. The first Falcon 9 launch was on June 4, 2010, an ...
—either a large, flat concrete pad or
downrange Downrange, or down range, is the horizontal distance traveled by a spacecraft, or the spacecraft's horizontal distance from the launch site. More often, it is used as an adverb or adjective specifying the direction of that travel being measure ...
floating landing platform, the ITS booster was to be designed to land on the launch mount itself, for immediate refueling and relaunch.


Big Falcon Rocket

In September 2017, at the 68th annual meeting of the
International Astronautical Congress The International Astronautical Congress (IAC) is an annual meeting of the actors in the discipline of space science. It is hosted by one of the national society members of the International Astronautical Federation (IAF), with the support of ...
, Musk announced a new launch vehicle calling it the BFR, again changing the name, though stating that the name was temporary. The acronym was alternatively stated as standing for Big Falcon Rocket or Big Fucking Rocket, a tongue-in-cheek reference to the BFG from the Doom video game series. The vehicle was designed to be tall, in diameter, and made of
carbon composite Carbon fiber-reinforced polymers (American English), carbon-fibre-reinforced polymers (Commonwealth English), carbon-fiber-reinforced plastics, carbon-fiber reinforced-thermoplastic (CFRP, CRP, CFRTP), also known as carbon fiber, carbon compo ...
s.


Starship

In December 2018, the structural material was changed from carbon composites to stainless steel, marking the transition from early design concepts of the Starship. Musk cited numerous reasons for the design change; low cost and ease of manufacture, increased strength of stainless steel at cryogenic temperatures, as well as its ability to withstand high heat. In 2019, SpaceX began to refer to the entire vehicle as Starship, with the second stage being called
Starship A starship, starcraft, or interstellar spacecraft is a theoretical spacecraft designed for interstellar travel, traveling between planetary systems. The term is mostly found in science fiction. Reference to a "star-ship" appears as early as 1 ...
and the booster Super Heavy. In September 2019, Musk held an event about Starship development during which he further detailed the booster.


Ground testing

In March 2021, SpaceX assembled the first Super Heavy prototype, BN1, a production pathfinder for future vehicles. It was scrapped on March 30. The next booster, BN3, was completed on June 29, 2021. It conducted the first cryogenic proof test of a Super Heavy on July 13, followed by the only static fire of a Super Heavy booster at the Suborbital Launch Site on July 19. It was partially scrapped in August, with the process concluding in January 2022. Booster 4 was the first vehicle intended to fly on Starship's Flight Test 1. It was the first Super Heavy to be stacked with Starship, and conducted multiple cryogenic tests before being retired in favor of Booster 7 and Ship 24.


Flight testing

Booster 7 and Ship 24 conducted several static fire and spin prime tests before launch, with the first such test doing significant damage to Booster 7 on July 11, 2022. After a launch attempt aborted on April 17, 2023, Booster 7 and Ship 24 lifted off on April 20 at 13:33 UTC in the first orbital flight test. Three engines were disabled during the launch sequence and several more failed during the flight. The flight concluded when the booster lost
thrust vectoring Thrust vectoring, also known as thrust vector control (TVC), is the ability of an aircraft, rocket or other vehicle to manipulate the direction of the thrust from its engine(s) or motor(s) to Aircraft flight control system, control the Spacecra ...
control of the Raptor engines, resulting in the rocket spinning out of control. The
flight termination system In rocketry, range safety or flight safety is ensured by monitoring the flight paths of missiles and launch vehicles, and enforcing strict guidelines for rocket construction and ground-based operations. Various measures are implemented to protect ...
(FTS) was activated, though the vehicle tumbled for another 40 seconds before disintegrating. After the first test flight, SpaceX began work on the launch mount to repair the damage it sustained during the test and to prevent future issues. The foundation of the launch tower was reinforced and a water-powered flame deflector was built under the launch mount. Ship 25 and Booster 9 were rolled to the suborbital and orbital launch sites in May to undergo multiple tests. On November 18, 2023, Booster 9 and Ship 25 lifted off the pad. All 33 engines continued to function until staging, where the second stage separated by pushing itself away from the first stage using a
hot-staging A multistage rocket or step rocket is a launch vehicle that uses two or more rocket ''stages'', each of which contains its own engines and propellant. A ''tandem'' or ''serial'' stage is mounted on top of another stage; a ''parallel'' stage is ...
technique. Following separation, the Super Heavy booster completed its flip maneuver and initiated the boostback burn before exploding following multiple successive engine failures. Three and a half minutes into the flight at an altitude of ~90 km over the Gulf of Mexico, blockage in a liquid oxygen filter caused one of the engines to fail in a way that resulted in the destruction of the booster. IFT-3 launched from the
SpaceX Starbase SpaceX Starbase—previously, SpaceX South Texas Launch Site and SpaceX private launch site—is an industrial complex and rocket launch facility that serves as the main testing and production location for SpaceX Starship, Starship launch vehi ...
facility along the
South Texas South Texas is a geographic and cultural region of the U.S. state of Texas that lies roughly south of—and includes—San Antonio. The southern and western boundary is the Rio Grande, and to the east it is the Gulf of Mexico. The population of th ...
coast around 8:25 CDT on March 14, 2024, coincidentally the 22nd anniversary of its founding. Like IFT-2, all 33 engines on the booster ignited and stage separation was successful. B10 conducted a boostback burn, however, the planned
landing Landing is the last part of a flight, where a flying animal, aircraft, or spacecraft returns to the ground. When the flying object returns to water, the process is called alighting, although it is commonly called "landing", "touchdown" or " spl ...
in the
Gulf of Mexico The Gulf of Mexico () is an oceanic basin and a marginal sea of the Atlantic Ocean, mostly surrounded by the North American continent. It is bounded on the northeast, north, and northwest by the Gulf Coast of the United States; on the southw ...
was not successful, as it exploded at above the surface. The fourth integrated flight test of the full Starship configuration launched on June 6, 2024, at 7:50 am CDT. The goals for the test flight were for the Super Heavy booster to land on a 'virtual tower' in the ocean. Super Heavy achieved a soft splashdown, before being destroyed after tipping over. In April 2024, Musk stated one of the goals was to attempt a booster tower landing based on successful booster performance in flight 4. Vehicle testing commenced in May 2024. SpaceX claimed that B12 and S30 were ready to launch in early August, in advance of regulatory approval. SpaceX flew S30 and B12 on October 13, 2024, with B12 returning to the launch site for a catch. After B13 aborted its catch attempt during flight 6, B14 was caught during flight 7, and was later reused.


Mission profile

Super Heavy and
Starship A starship, starcraft, or interstellar spacecraft is a theoretical spacecraft designed for interstellar travel, traveling between planetary systems. The term is mostly found in science fiction. Reference to a "star-ship" appears as early as 1 ...
are stacked onto their launch mount and loaded with fuel via the booster quick disconnect (BQD) and ship quick disconnect (SQD) arm. At the T – 19:40 mark, engine chill begins on the booster.. This is to protect the engine's
turbopump A turbopump is a fluid pump with two main components: a rotodynamic pump and a driving gas turbine, usually both mounted on the same shaft, or sometimes geared together. They were initially developed in Germany in the early 1940s. The most co ...
s from thermal shock. At three seconds before launch, the 33 engines startup sequence begins. After liftoff, the engines burn for approximately 159 seconds before Super Heavy cuts off all but three of its center
gimbal A gimbal is a pivoted support that permits rotation of an object about an axis. A set of three gimbals, one mounted on the other with orthogonal pivot axes, may be used to allow an object mounted on the innermost gimbal to remain independent of ...
ing rocket engines at an altitude of roughly . It throttles down the remaining engines, before Starship ignites its engines while still attached to the booster, and separates. The booster then rotates, before igniting ten additional engines for a "boostback burn" which stops all forward velocity and reverses the trajectory towards the launch site. After the boostback burn, the booster's engines shut off with Super Heavy on a trajectory for a controlled descent to the launch site using its grid fins for minor course corrections. At six minutes after launch, shortly before landing, it ignites its inner 13 engines, then shuts off all but the inner 3, slowing it sufficiently to be caught by a pair of hydraulic actuating arms attached to the launch tower.


Notes


References

{{SpaceX Proposed reusable launch systems Reusable spaceflight technology Reusable launch systems Rocket stages SpaceX Starship