.jpg) Super Heavy Booster 12 approaching the tower duringStarship flight test 5 on October 13, 2024 | |
| Manufacturer | SpaceX |
|---|---|
| Country of origin | United States |
| Used on | SpaceX Starship |
| Launch history | |
| Status | In development |
| Total launches | 11 |
| Failed | 1 (Flight 1) |
| Other | Failed after staging: 3 (Flight 2,Flight 3,Flight 9) |
| First flight | April 20, 2023 |
| Block 1/2 Super Heavy | |
| Height | 71 m (233 ft),[1] 69 m (226 ft) without Vented Interstage |
| Diameter | 9 m (30 ft) |
| Empty mass | 275,000 kg (606,000 lb) |
| Gross mass | 3,675,000 kg (8,102,000 lb) |
| Propellant mass | 3,400,000 kg (7,500,000 lb)[2] |
| Powered by | 33 ×Raptor 2 engines |
| Maximum thrust | 73.5 MN (16,500,000 lbf)[3] |
| Specific impulse | SL: 327 s (3.21 km/s),Vac: 347 s (3.40 km/s) |
| Burn time | 166 seconds |
| Propellant | CH4 /LOX |
| Block 3 Super Heavy | |
| Height | 72.3 m (237 ft)[4] |
| Diameter | 9 m (30 ft) |
| Propellant mass | 3,650,000 kg (8,050,000 lb)[4] |
| Powered by | 33 ×Raptor 3 engines[4] |
| Maximum thrust | 80.8 MN (18,200,000 lbf)[4] |
| Specific impulse | SL: 330 s (3.2 km/s),Vac: 350 s (3.4 km/s) |
| Propellant | CH4 /LOX |
Super Heavy is thereusable first stage of theSpaceX Starshipsuper heavy-liftlaunch vehicle, which it composes in combination with theStarship second stage. As a part ofSpaceX's Mars colonization program, the booster evolved into its current design over a decade.[5][6][7] Production began in 2021, with the first flight being conducted on April 20, 2023, during thefirst launch attempt of the Starship rocket.[8][1]
The booster is powered by 33Raptor engines that useliquid oxygen andmethane as propellants. It returns to its launch site after propelling the second stage toward orbit,landing vertically by being caught by the launch tower.[9]
Super Heavy is 71 m (233 ft) tall, 9 m (30 ft) wide,[1] and is composed of four general sections: the engines, the oxygen tank, the fuel tank, and the interstage.[10]
The two cryogenic propellant tanks on Super Heavy are separated by a common bulkhead, a similar structural design to theS-II andS-IVB stages on theSaturn V rocket.[11] AfterStarship's second flight test, the common dome's design was changed to be more elliptical,[12] altering the propellant capacity of both tanks by a small amount.[12] Each tank possesses roughly 74 stringers for structural reinforcement, attached to their interior walls.[13] The booster's two tanks hold a combined 3,400 t (7,500,000 lb) of propellant:[2] 2,700 t (6,000,000 lb) of liquid oxygen and 700 t (1,500,000 lb) of liquid methane.[a] Fuel is fed to the engines via a single liquid funnel, and channeled into distributionmanifolds of the engines.[11] This system was upgraded on Block 3 boosters, featuring a substantially larger transfer tube connecting the engines and the methane tank.[14] 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.[4] One disconnect feeds liquid oxygen into the vehicle, the other feeds liquid methane.[4]
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.[11] 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.[11] In addition, large filters were added in this region beginning on Booster 10.[15][16] Liquid oxygen is supplied by a header tank during landing burn for the inner thirteen engines.[17] On Booster 15, the header tank had at least nine additional tanks attached, increasing capacity for the landing burn.[16] The added tanks may have been present on Boosters 12, 13, and 14, though this was unconfirmed as of February 2025.[18] 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.[17]
The methane funnel is partially contained within the header tank, as the methane sump is directly below it.[17] On Booster 7 and all subsequent vehicles, four aerodynamicchines are located on the outside of the oxygen tank, providing aerodynamic lift during descent,[19] as well as housing batteries,composite overwrapped pressure vessels (COPVs) for spin start,[20] and CO2 tanks forfire suppression.[11][21] On vehicles with hydraulic power units (HPUs), COPVs dedicated to engine ignition, batteries, and communication antennae were located within the HPU cover instead of the chines.[21]
Super Heavy is powered by 33Raptor engines, which on Block 1 and 2 vehicles are housed within a dedicated shielding compartment.[21] This compartment is not present before engine installation, thus boosters are roughly three meters shorter prior to engine installation.[22] The outer 20 engines, arranged in a ring, are fixed in place.[23] To save weight, the 20 engines are started usingground support equipment on the launch mount and cannot be reignited for subsequent burns.[24] The inner thirteen engines are equipped withgimbal actuators and reignite for the boostback and landing burns.[25] AfterStarship'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.[15] This change was made to the upper stage after thesecond 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.[19] 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 thefire suppression system.[15] The aft bay has eighteen vents visible on the outside of the booster, which are believed to be connected to the outer 20 engines,[21] while the center engines vent directly below the launch pad.[21]
The Raptor engine uses afull-flow staged combustion cycle with oxygen and methane-rich turbopumps.[26][27] Before 2014, only two full-flow staged-combustion rocket engine designs had advanced enough to undergo testing: the SovietRD-270 project in the 1960s and the Aerojet RocketdyneIntegrated Powerhead Demonstrator in the mid-2000s.[28] 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.[2]
The Block 1 version of the booster (used through November 2024) produces a total of 73.5 MN (16,500,000 lbf)[3] just over twice that of theSaturn V first stage,[29] with this total being expected to increase to 80.8 MN (18,200,000 lbf) for Block 3 boosters and later up to 98.1 MN (22,100,000 lbf) with the Block 4 vehicle.[1] The thirty three engines collectively produce largeshock diamonds in the exhaust jet, visible during ascent and descent.[30]
During unpowered flight in the upper atmosphere,control authority is provided bycold gas thrusters fed with residualullage gas.[17] Four perpendicular vents are located within the interstage.[21] Additional vents are located just below the common dome, pointing down toward the engines at a slight angle.[21]
The Block 3 booster contains an updated aft dome, with metallic heat shield tiles mounted upon it.[31]
The interstage is equipped with four electrically actuatedgrid fins made of stainless steel, each with a mass of roughly 3 t (6,600 lb).[10] The fins remain extended during ascent to save weight,[10][32] though this results in mild warping during stage separation.[33] The interstage also has protrudinghardpoints, located between grid fins, allowing the booster to be lifted or caught by the launch tower.[34] The ability to lift a booster from these hardpoints was proven on August 23, 2022, when Booster 7 was lifted onto OLM A.[35] The first catch of a booster occurred on October 13, 2024, using Booster 12.[7]
After thefirst Starship test flight, all boosters have an additional 1.8 m[36] tall vented interstage to enablehot staging.[37] During hot staging, Super Heavy shuts down all but the three center engines,[38][39] while the second stage fires its engines before separating, thus the second stage "pushes off" from the first stage, giving added thrust.[38] The vented interstage contains a dome to shield the top of Super Heavy from the second stage's exhaust.[37][39] Elon Musk in 2023 claimed that this change might result in a 10% increase in the payload tolow Earth orbit.[39] Beginning with Booster 11, the vented interstage is jettisoned after completion of the boostback burn, to reduce mass during descent.[40] 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.[40]
On Block 3 boosters, the interstage is directly integrated into the methane tank, and the number of grid fins is reduced from four to three, in a 90/90/180 degree arrangement.[4] These grid fins are roughly one and a half times the size of the Block 1 and 2 grid fins,[41] and are positioned lower on the vehicle. According to SpaceX, the repositioning reduces the heat experienced during stage separation. Additionally, the fins are integrated with the catch pins.[42]
The manufacturing process starts with rolls ofstainless steel, which are unrolled, cut, and welded along an edge to create a cylinder of 9 m (30 ft) diameter, 1.83 m (6.00 ft) tall, and 3.97 mm (0.156 in) thick,[36] and approximately 1600 kg (3,600 lb) in mass.[b] Thirty-three such rings are used in the Super Heavy Booster,[11] while four rings are 1.4 m (4 ft 7 in) tall.[11] These shorter rings are used exclusively in the aft section.[11] A 1 m (3 ft 3 in) and a 1.7 m (5 ft 7 in) tall ring are used to construct the liquid oxygen header tank. These rings have a significantly smaller diameter than the main rings.[11]
The forward dome is constructed out of two segments: the "dome knuckle" and the "dome frustum".[11] The aft dome has a third component: the "thrust puck", which supports the inner thirteen engines,[11] while the common dome is composed of a single part, and is more elliptical than the forward and aft domes.[11][12]
These rings are stacked and robotically welded along their edges to form stacks of three to four rings in the Starfactory.[11] Stringers are then added to the ring stacks, improving the structural strength of the booster.[11] Cutouts are made for the grid fins and hardpoints for the forward section.[11] Following this, the domes are installed within the forward, aft, and common ring stacks.[11] The forward ring stack consists of three rings, and the common ring stack consists of four.[11] The aft section is constructed solely from the four 1.4 m (4 ft 7 in) rings.[11] Tank vents and external piping are added at this stage, followed by the COPVs and header tank.[11]
Following the completion of each of the ring stacks, the stacking of these sections begins with the assembly of the methane tank.[11] This process occurs in Mega Bay 1. Once the methane tank is completed, the oxygen tank is assembled, already integrated to the common dome.[11] Before assembly of the oxygen tank is finished, the methane downcomer is added, along with final stringers to the weld lines.[11] When both tanks are complete, the methane tank is stacked onto the oxygen tank, completing the primary tankage assembly.[11] Chines are added after this stage.[11]
The vehicle is then rolled to theMassey's test site and cryogenically tested twice.[43] These tests fill both tanks with liquid nitrogen, which is nonflammable, though liquid oxygen may be loaded as well.[11] After returning to the production site, the engines are installed, alongside their shielding, which forms the aft bay.[44][22][21] This is followed by static fire testing at the launch site.[11] Once this test is completed, the vented interstage is added to the vehicle.[45]
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.[46] Later in 2012,[47] the company first mentioned the Mars Colonial Transporter rocket concept in public. It was going to be able to carry 100 t (220,000 lb) of cargo to Mars and would be powered by methane-fueled Raptor engines.[48] Musk referred to this new launch vehicle under the unspecified acronym "MCT",[46] revealed to stand for "Mars Colonial Transporter" in 2013,[49] which would servethe company's Mars system architecture.[28] SpaceX COOGwynne Shotwell gave a potential payload range between 150–200 tons tolow Earth orbit for the planned rocket.[46] According to SpaceX engine development headTom Mueller, SpaceX could use nineRaptor engines on a single MCT booster or spacecraft.[50][28] The preliminary design would be at least 10 meters (33 ft) in diameter, and was expected to have up to three cores totaling at least 27 booster engines.[28]
On September 27, 2016, at the 67thInternational Astronautical Congress, SpaceX CEO Elon Musk announced SpaceX was developing a new rocket using Raptor engines called the Interplanetary Transport System (ITS). It would have two stages, a reusable booster and a spacecraft. The stages' tanks were to be made fromcarbon composite, storing liquid methane and liquid oxygen. Despite the rocket's 300 t (660,000 lb) 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.[51] Both stages would useautogenous pressurization of the propellant tanks, eliminating theFalcon 9's problematic high-pressurehelium pressurization system.[52][53][54]
.jpg)
The ITS booster was to be a 12 m-diameter (39 ft), 77.5 m-high (254 ft), reusable first stage powered by 42 engines, each producing 3,024 kilonewtons (680,000 lbf) ofthrust. Total booster thrust would have been 128 MN (29,000,000 lbf) at liftoff, increasing to 138 MN (31,000,000 lbf) in a vacuum,[5] several times the 36 MN (8,000,000 lbf) thrust of theSaturn V.[52] It weighed 275 tonnes (606,000 lb) when empty and 6,700 tonnes (14,800,000 lb) when completely filled with propellant. It would have used grid fins to help guide the booster through the atmosphere for a precise landing.[5] 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 togimbal for directional control. However, some directional control would be achieved viadifferential thrust with the fixed engines. Each engine couldthrottle to between 20 and 100 percent of rated thrust.[53]
The design goal was to achieve aseparation velocity of about 8,650 km/h (5,370 mph) while retaining about 7% of the initial propellant to achieve avertical landing at the launch pad.[53][55]The design called forgrid fins to guide the booster duringatmospheric reentry.[53] 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.[56] The booster was to be designed for 20 g nominal loads, and possibly as high as 30–40 g.[56]
In contrast to the landing approach used on SpaceX's Falcon 9—either a large, flat concrete pad ordownrangefloating landing platform, the ITS booster was to be designed to land on the launch mount itself, for immediate refueling and relaunch.[53]
In September 2017, at the 68th annual meeting of theInternational Astronautical Congress, Musk announced a new launch vehicle calling it the BFR, again changing the name, though stating that the name was temporary.[57] The acronym was alternatively stated as standing for Big Falcon Rocket or Big Fucking Rocket, a tongue-in-cheek reference to the BFG from theDoom video game series.[58] The vehicle was designed to be 106 meters (348 ft) tall, 9 meters (30 ft) in diameter, and made ofcarbon composites.[59][6]
In December 2018, the structural material was changed from carbon composites[53][52] to stainless steel,[60][61] marking the transition from early design concepts of the Starship.[60][62][63] Musk cited numerous reasons for the design change; low cost and ease of manufacture, increased strength of stainless steel atcryogenic temperatures, as well as its ability to withstand high heat.[64][62] In 2019, SpaceX began to refer to the entire vehicle as Starship, with the second stage being calledStarship and the booster Super Heavy.[65][66][67][68] In September 2019, Musk held an event about Starship development during which he further detailed the booster.[69][70][71]
In March 2021, SpaceX assembled the first Super Heavy prototype, BN1, a production pathfinder for future vehicles.[72] It was scrapped on March 30.[73] The next booster, BN3, was completed on June 29, 2021.[74] 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.[75] It was partially scrapped in August,[76] with the process concluding in January 2022.[77]
Booster 4 was the first vehicle intended to fly onStarship's Flight Test 1. It was the first Super Heavy to be stacked with Starship,[78] and conducted multiple cryogenic tests before being retired in favor of Booster 7 and Ship 24.[79]
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Booster 7 and Ship 24 conducted several static fire and spin prime tests before launch,[80]: 20 [81] with the first such test doing significant damage to Booster 7 on July 11, 2022.[82] After a launch attempt aborted on April 17, 2023,[83]Booster 7 andShip 24 lifted off on April 20 at 13:33 UTC in the first orbital flight test.[8] Three engines were disabled during the launch sequence and several more failed during the flight.[84] The flight concluded when the booster lostthrust vectoring control of the Raptor engines, resulting in the rocket spinning out of control.[84] Theflight termination system (FTS) was activated, though the vehicle tumbled for another 40 seconds before disintegrating.[85][86][87]
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-poweredflame deflector was built under the launch mount.[88]Ship 25 andBooster 9 were rolled to the suborbital and orbital launch sites in May to undergo multiple tests.[89][90]
On November 18, 2023, Booster 9 and Ship 25 lifted off the pad.[91] All 33 engines continued to function until staging, where the second stage separated by pushing itself away from the first stage using ahot-staging technique.[92] Following separation, the Super Heavy booster completed its flip maneuver and initiated the boostback burn before exploding following multiple successive engine failures.[92][93][94] 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.[95]
IFT-3 launched from theSpaceX Starbase facility along theSouth Texas coast around 8:25 CDT on March 14, 2024, coincidentally the 22nd anniversary of its founding.[96][97] Like IFT-2, all 33 engines on the booster ignited and stage separation was successful.[98] B10 conducted aboostback burn, however, the plannedlanding in theGulf of Mexico was not successful, as it exploded at 462 m (1,516 ft) above the surface.[99]
The fourth integrated flight test of the full Starship configuration launched on June 6, 2024, at 7:50 am CDT.[100] The goals for the test flight were for the Super Heavy booster to land on a 'virtual tower' in the ocean.[101] Super Heavy achieved a soft splashdown,[102] before being destroyed after tipping over.[103][104]
In April 2024, Musk stated one of the goals was to attempt a booster tower landing based on successful booster performance inflight 4. Vehicle testing commenced in May 2024.[105] SpaceX claimed that B12 and S30 were ready to launch in early August, in advance of regulatory approval.[106] SpaceX flew S30 and B12 on October 13, 2024, with B12 returning to the launch site for a catch.[7] After B13 aborted its catch attempt duringflight 6,[107] B14 was caught during flight 7,[9] and was later reused onflight 9.[108]
Super Heavy andStarship are stacked onto their launch mount and loaded with fuel via the booster quick disconnect and ship quick disconnect arm. At the T – 19:40 mark, engine chill begins on the booster.[109] This is to protect the engine'sturbopumps from thermal shock. At three seconds before launch, the engine startup sequence begins.[109]
After liftoff, the engines burn for approximately 159 seconds[110] before Super Heavy cuts off all but three of its centergimbaling rocket engines at an altitude of roughly 64 km (40 mi).[111]: 58 It throttles down the remaining engines, before Starship ignites its engines while still attached to the booster, and separates.[38] The booster then rotates, before igniting ten additional engines for a "boostback burn"[92] 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,[112] it ignites its inner 13 engines, then shuts off all but the inner 3,[99] slowing it sufficiently to be caught by a pair ofhydraulic actuating arms attached to the launch tower.[113][114]
Ship engines will fire up before all the Booster engines shut down. Now need vents for hot staging. Adding an extension to the booster that is all vent and more shielding to the top of the booster. It's the most risky thing for the next flight.
SpaceX's Starship system represents a fully reusable transportation system designed to service Earth orbit needs as well as missions to the Moon and Mars. This two-stage vehicle – composed of the Super Heavy rocket (booster) and Starship (spacecraft)
Musk tackles the hardest engineering problems first. For Mars, there will be so many logistical things to make it all work, from power on the surface to scratching out a living to adapting to its extreme climate. But Musk believes that the initial, hardest step is building a reusable, orbital Starship to get people and tons of stuff to Mars. So he is focused on that.
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