SpaceX Super Heavy

Super Heavy

Super Heavy Booster 12 approaching the tower during Starship 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	5
Failed	1 (Flight 1)
Other	Failed after staging: 2 (Flight 2, Flight 3)
First flight	April 20, 2023
Block 1 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	69.9 MN (15,700,000 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

Super Heavy is the reusable first stage of the SpaceX Starship super heavy-lift launch vehicle, 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.^[4][5][6] Production began in 2021, with the first flight being conducted on April 20, 2023, during the first launch attempt of the Starship rocket.^[7][8]

The booster is powered by thirty-three Raptor engines that use liquid oxygen and methane as propellants. After propelling the second stage towards orbit, it can return to its launch site, where it lands vertically by being caught by its launch tower, allowing for full reusability.

Super Heavy is 71 m (233 ft) tall, 9 m (30 ft) wide,^[9] and is composed of four general sections: the engines, the fuel tank, the oxygen tank, and the interstage.^[10] Elon Musk stated in 2021 that the final design will have a dry mass between 160 t (350,000 lb) and 200 t (440,000 lb), with the tanks weighing 80 t (180,000 lb) and the interstage 20 t (44,000 lb).^[10]

The propellant tanks on Super Heavy are separated by a common bulkhead, similar to the ones used on the S-II and S-IVB stages on the Saturn V rocket^[11][12] After Starship's second flight test, the common dome's design was changed to a more elliptical dome,^[13] which has changed the propellant capacity of both tanks by an unknown, but likely negligible, amount.^[13] Both tanks are heavily reinforced, with roughly 74 stringers attached to the interior walls of the tanks.^[14] The booster's tanks hold 3,400 t (7,500,000 lb) of propellant,^[15] consisting of 2,700 t (6,000,000 lb) of liquid oxygen and 700 t (1,500,000 lb) of liquid methane.^[a]

The methane tank has a camera installed in the forward dome, enabling images of the interior of the tank.^[16] Fuel is fed to the engines via a single downcomer, which terminates in a large distribution manifold above the engines.^[17] The design of this manifold was changed when Super Heavy was upgraded from twenty-nine engines to thirty-three, with the more modern design featuring a dedicated methane sump instead of a direct distribution manifold.^[18]

The oxygen tank terminates with 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 directly to the thrust puck, which is part of the aft dome.^[18] A large steel structure is mounted at the bottom of the dome, reinforcing the thrust puck enough to enable its support of the inner thirteen engines, while also providing pathways for methane and oxygen to flow into the engines.^[18] Large slosh baffles were added in this region as well, beginning on Booster 10.^[13] A header tank is used to supply liquid oxygen during the landing burn for the inner thirteen engines.^[19] On Booster 15, the header tank has at least nine additional tanks attached, increasing total propellant supply during the landing burn.^[20][21] These tanks may have been present on Boosters 12, 13, and 14, though this is unconfirmed.^[22] Booster 5 was the only twenty-nine engine booster to receive a header tank, which was mounted to the side of the oxygen tank.^[18] It is unknown whether or not the top of this tank was ever completed, as a forward dome was never spotted.^[18]

The methane downcomer is partially contained within the header tank, as the methane sump is located directly below it.^[19] On Booster 7 and all subsequent vehicles, four chines are located on the sides of the oxygen tank, protecting the COPVs and CO₂ tanks for fire suppression, as well as providing lift during descent.^[23]

Super Heavy is powered by thirty-three Raptor engines, which are housed within a dedicated shielding compartment.^[24] This compartment is not present before engine installation, thus, boosters are roughly three meters shorter before engine installation.^[25] The outer twenty engines, arranged in a single ring, are in a fixed position.^[24] In order to save weight, these engines are started using ground support equipment on the launch mount and cannot be reignited for subsequent burns.^[26] The inner thirteen engines are attached to an adapter, which rests directly against the thrust puck/aft dome assembly.^[24] These engines are equipped with gimbal actuators, and reignite for the boostback and landing burns.^[27] 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.^[28] This change was made to the upper stage after the second flight test. During the ascent burn 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 the fire suppression system.^[28] This system uses CO₂ tanks to purge the individual engine compartments during flight, as well as a nitrogen purge while on the launch pad.^[29] The aft bay has eighteen vents visible on the outside of the booster, which are believed to be connected to the outer twenty engines,^[29] while the center engines vent directly below the launch pad.^[29]

Raptor uses a full-flow staged combustion cycle, which has both oxygen and methane-rich turbopumps.^[30][31] Before 2014, only two full-flow staged-combustion rocket engine designs had advanced enough to undergo testing: the Soviet RD-270 project in the 1960s and the Aerojet Rocketdyne Integrated Powerhead Demonstrator in the mid-2000s.^[32] To improve performance, the engines burn super cooled propellant.^[33]

The current version of the booster produces a total of 69.9 MN (15,700,000 lb_f)^[34] just over twice that of the Saturn V first stage,^[35] with this total being expected to increase to 80.8 MN (18,200,000 lb_f) for Block 2 boosters and later up to 98.1 MN (22,100,000 lb_f) with the Block 3 vehicle.^[34] These later versions may have up to thirty-five engines.^[36] The combined plume of the engines produces large shock diamonds in the exhaust during the ascent burn.^[37]

During unpowered flight in the upper atmosphere, control authority is provided by cold gas thrusters fed with residual ullage gas.^[38][39] Four perpendicular vents are located within the interstage, placed at a forty-five degree angle from the hardpoints.^[38] Additionally, four "cowbell" vents are located just below the common dome, which point down towards the engines, though at a slight angle.^[38]

The interstage is also equipped with four electrically actuated grid fins made of stainless steel, each with a mass of 3 t (6,600 lb).^[40] These grid fins are paired together, with the fins in each pair being sixty degrees apart from each other, differing from the Falcon 9 booster, which has titanium grid fins mounted ninety degrees from each other.^[41][42] This is done to improve control in the pitch axis.^[42] Additionally, these fins remain extended during ascent in order to save weight.^[10] The interstage also has protruding hardpoints, located between grid fins, allowing the booster to be lifted or caught by the launch tower.^[43] The ability to lift a booster from these hardpoints was proven on August 23, 2022, when Booster 7 was lifted onto OLM A.^[44] The first catch of a booster occurred on October 13, 2024, using Booster 12.^[45]

After the first Starship test flight, all boosters have an additional 1.8 m^[46] tall vented interstage to enable hot staging.^[47] During hot staging, Super Heavy shuts down all but the 3 center engines,^[48][49] while the second stage fires its engines before separating, thus the second stage "pushes off" from the first stage giving added thrust.^[48] The vented interstage contains a dome to shield the top of Super Heavy from the second stage's engines.^[47][49] Elon Musk in 2023 claimed that this change might result in a 10% increase in the payload to low Earth orbit.^[49] Beginning with Booster 11, the interstage is jettisoned after completion of the boostback burn, in order to reduce mass during descent.^[50] As of June 2024, SpaceX does not intend to jettison the interstage when flying Block 2 and Block 3 boosters, as the interstage will be directly integrated into the vehicle.^[50]

As of November 2024, all Super Heavy components are manufactured at Starbase, Texas.^[51]

The manufacturing process starts with rolls of stainless 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,^[46] and approximately 1600 kg (3,600 lb) in mass.^[b] Thirty-three such rings are used in the Super Heavy Booster,^[52] while four rings are 1.4 m (4 ft 7 in) tall.^[52] These shorter rings are used exclusively in the aft section.^[52] 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.^[52]

The forward dome is constructed out of two segments: the "dome knuckle" and the "dome frustum".^[52][18] The aft dome has a third component: the "thrust puck", which supports the inner thirteen engines,^[18] while the common dome is formed out of a single type of piece, and is more elliptical than the forward and aft domes.^[52]

These rings are stacked and robotically welded along their edges to form stacks of three to four rings in the Starfactory.^[52] Stringers are then added to the ring stacks, improving the structural strength of the booster.^[52] For the forward section, cutouts are made for the grid fins and hardpoints.^[52] Following this, the domes are installed within the forward, aft, and common ring stacks.^[52] The forward ring stack consists of three rings, and the common ring stack consists of four.^[52] The aft section is constructed solely from the four 1.4 m (4 ft 7 in) rings.^[52] Tank vents and external piping is added at this stage, followed by the COPVs and header tank.^[52]

Following completion of each of the ring stacks, the stacking of these sections begins, beginning with assembly of the methane tank.^[52] This process occurs in Mega Bay 1. Once the methane tank is completed, the oxygen tank is assembled, already integrated to the common dome.^[52] Before assembly of the oxygen tank is finished, the methane downcomer is added, along with final stringers to the weld lines.^[52] When both tanks are complete, the methane tank is stacked onto the oxygen tank, completing the primary tankage assembly.^[52] Chines are added after this stage.^[53]

The vehicle is then rolled to the Massey's test site, and cryogenically tested two to three times.^[54] These tests fill both tanks with liquid nitrogen, which is nonflammable, though liquid oxygen may be loaded as well.^[52] After returning to the production site, the engines are installed, alongside their shielding, which forms the aft bay.^[24] This is followed by static fire testing at the launch site.^[52] Once this test is completed, the vented interstage is added to the vehicle.^[14]

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.^[55] Later in 2012,^[7] the company first mentioned the Mars Colonial Transporter rocket concept in public. It was to be able to carry 100 people or 100 t (220,000 lb) of cargo to Mars and would be powered by methane-fueled Raptor engines.^[11] Musk referred to this new launch vehicle under the unspecified acronym "MCT",^[55] revealed to stand for "Mars Colonial Transporter" in 2013,^[13] which would serve the company's Mars system architecture.^[56] SpaceX COO Gwynne Shotwell gave a potential payload range between 150–200 tons to low Earth orbit for the planned rocket.^[55] According to SpaceX engine development head Tom Mueller, SpaceX could use nine Raptor engines on a single MCT booster or spacecraft.^[57][13] 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.^[56]

On September 27, 2016, at 67th International Astronautical Congress, 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 spacecraft. The stages' tanks were to be made from carbon 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 spacecraft featured three variants: crew, cargo, and tanker; the tanker variant is used to transfer propellant to spacecraft in orbit.^[58] The concept, especially the technological feats required to make such a system possible and the funds needed, garnered substantial skepticism.^[59] Both stages would use autogenous pressurization of the propellant tanks, eliminating the Falcon 9's problematic high-pressure helium pressurization system.^[60][61][62]

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) of thrust. 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,^[4] several times the 36 MN (8,000,000 lbf) thrust of the Saturn V.^[60] 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.^[4] 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 for directional control, although some directional control would be achieved via differential thrust with the fixed engines. Each engine would be capable of throttling between 20 and 100 percent of rated thrust.^[61]

The design goal was to achieve a separation velocity of about 8,650 km/h (5,370 mph) while retaining about 7% of the initial propellant to achieve a vertical landing at the launch pad.^[61][63]The design called for grid fins to guide the booster during atmospheric reentry.^[61] 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.^[64] The booster was to be designed for 20 g nominal loads, and possibly as high as 30–40 g.^[64]

In contrast to the landing approach used on SpaceX's Falcon 9—either a large, flat concrete pad or downrange floating landing platform, the ITS booster was to be designed to land on the launch mount itself, for immediate refueling and relaunch.^[61]

In September 2017, at the 68th annual meeting of the International Astronautical Congress, Musk announced a new launch vehicle calling it the BFR, again changing the name, though stating that the name was temporary.^[65] 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.^[66] The vehicle was designed to be 106 meters (348 ft) tall, 9 meters (30 ft) in diameter, and made of carbon composites.^[67][5]

In December 2018, the structural material was changed from carbon composites^[61][60] to stainless steel,^[68][69] marking the transition from early design concepts of the Starship.^[68][70][71] 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.^[72][70] In 2019, SpaceX began to refer to the entire vehicle as Starship, with the second stage being called Starship and the booster Super Heavy.^{[73][74][75][76]} In September 2019, Musk held an event about Starship development during which he further detailed the booster.^[77][78][79]

In March 2021, SpaceX assembled the first Super Heavy prototype, BN1, a production pathfinder for future vehicles.^[80] It was scrapped on March 30.^[81] The next booster, BN3, was completed on June 29, 2021.^[82] 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.^[83] It was partially scrapped in August,^[84] with the process concluding in January of 2022.^[85]

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,^[86] and conducted multiple cryogenic tests before being retired in favor of Booster 7 and Ship 24.^[87]

Booster 7 and Ship 24 conducted several static fire and spin prime tests before launch,^{[88]: 20 [89]} with the first such test doing significant damage to Booster 7 on July 11, 2022.^[90] After a launch attempt aborted on April 17, 2023,^[91] Booster 7 and Ship 24 lifted off on 20 April at 13:33 UTC in the first orbital flight test.^[7] Three engines were disabled during the launch sequence and several more failed during the flight.^[92] The flight concluded when the booster lost thrust vectoring control of the Raptor engines, resulting in the rocket spinning out of control.^[92] The flight termination system (FTS) was activated, though the vehicle tumbled for another 40 seconds before disintegrating.^[93][94][95]

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.^[96] Ship 25 and Booster 9 were rolled to the suborbital and orbital launch sites in May to undergo multiple tests.^[97][98]

On 18 November 2023, Booster 9 and Ship 25 lifted off the pad.^[99] 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 technique.^[100] Following separation, the Super Heavy booster completed its flip maneuver and initiated the boostback burn before exploding following multiple successive engine failures.^{[100][101][102]} 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.^[103]

IFT-3 launched from the SpaceX Starbase facility along the South Texas coast around 8:25 CDT on March 14, 2024, coincidentally the 22nd anniversary of its founding.^[104][105] Like IFT-2, all 33 engines on the booster ignited and stage separation was successful.^[106] B10 conducted a boostback burn, however, the planned landing in the Gulf of Mexico was not successful, as it exploded at 462 m (1,516 ft) above the surface.^[107]

The fourth integrated flight test of the full Starship configuration launched on 6 June 2024, at 7:50 AM CDT.^[108] The goals for the test flight were for the Super Heavy booster to land on a 'virtual tower' in the ocean.^[109] Super Heavy achieved a soft splashdown,^[110] before being destroyed after tipping over.^[111][112]

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.^[113] SpaceX claimed that B12 and S30 were ready to launch in early August, in advance of regulatory approval.^[114] SpaceX flew S30 and B12 on October 13, 2024, with B12 returning to the launch site for a catch.^[6]

Super Heavy and Starship 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.^[115] This is to protect the engine's turbopumps from thermal shock. At three seconds before launch, the thirty-three engines startup sequence begins.^[115]

After liftoff, the engines burn for approximately 159 seconds^[116] before Super Heavy cuts off all but three of its center gimbaling rocket engines at an altitude of roughly 64 km (40 mi).^[117]: 58 It throttles down the remaining engines, before Starship ignites its engines while still attached to the booster, and separates.^[48] The booster then rotates, before igniting ten additional engines for a "boostback burn"^[100] 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. After six minutes, shortly before landing,^[118] it ignites its inner 13 engines, then shuts off all but the inner 3,^[107] to perform a landing burn which slows it sufficiently to be caught by a pair of hydraulic actuating arms attached to the launch tower.^[119][120]

BN1 was the first Super-Heavy Booster prototype, a pathfinder that was not intended for flight tests.^[80] Sections of the ~66 m (217 ft) tall test article were manufactured throughout autumn 2020. Section stacking began in December 2020.^[122] BN1 was fully stacked inside the High Bay on March 18, 2021,^[123] and was scrapped on March 30, 2021.

Booster 3 completed stacking in the High Bay on June 29, 2021,^[124] and moved to the test stand.^[125] A cryogenic proof test was completed on July 13,^[126][127] followed by a static fire test on July 19. BN3/Booster 3 was partially scrapped on August 15, while the liquid oxygen (LOX) tank remained welded to the Test Stand until January 13, 2022.^[128]

B4 was fully stacked on August 1, with all 29 engines installed on August 2, 2021.^[129] Grid fins were added to support atmospheric reentry testing. SN20 was stacked on top of Booster 4 on August 6, 2021 for a fitting test, making it, for two years, the tallest rocket ever fully integrated.^[86] B4 completed its first cryogenic proof test on December 17, 2021,^[130] followed by a pneumatic proof test, another cryogenic proof test and a full-load cryogenic proof test. B4 and Ship 20 were then retired.^[127] On March 6, 2024, B4s grid fins were removed,^[131] it was moved to the Mega Bay on March 21 where it was scrapped the following day.^[132][133]

Parts for B5 were observed as early as July 19, 2021. Stacking for B5 completed in November, although on December 8, B5 was retired alongside SN15 and SN16. It was later scrapped.

B7 was placed on the orbital launch mount on March 31, 2022, and completed two cryogenic proof tests in April, resulting in the rupturing of the downcomer.^[134] After being repaired, it was returned to OLM, and completed two cryogenic tests. It was then moved to Mega Bay 1 for engine and grid fin installation.^[135] On July 11, after returning to OLM A for engine testing, B7 experienced a detonation underneath the engines during an attempted 33 engine spin prime test.^[136] It returned to OLM A on August 4 with only the 20 outer Raptor engines,^[137] and completed its first single-engine static fire test on August 9, followed by a second two days later.^[138] After receiving its thirteen inner engines,^[139] B7 conducted a series of spin prime and static fire tests throughout August and September,^{[140][141][142][143]} before again returning to the Mega Bay on September 21.^[144] After receiving additional upgrades it was lifted on the launch pad on October 8.^[145] Ship 24 was stacked on top B7 on October 12,^[146] and was removed after completing multiple cryogenic load tests.^{[147][148][149]} B7 then completed a spin prime test of multiple engines on November 12,^[150] a 14 engine static fire test on November 14,^[151] and finally an 11 engine static fire in an autogenous pressurization test on November 29.^[152] In January 2023, Booster 7 and Ship 24 conducted a wet dress rehearsal,^[153] before attempting a 33 engine static fire on February 9.^[154] On April 20, 2023, Booster 7 was launched on Integrated Flight Test 1, being destroyed before stage separation after a fire in the aft section severed connections between its engines and flight computers, resulting in a loss of attitude control and FTS activation.^[155]

B8 was fully stacked on July 8, 2022.^[156] It was moved to the launch site on September 19, 2022, though it was not tested there.^[157] Booster 8 was scrapped in January 2023 in favor of Booster 9. Booster 8's hydraulic power units were used to replace Booster 7s, along with several other parts, including the engine shielding.^[158][159]

B9 finished stacking in late 2022, and featured upgrades, including electric thrust vector control (ETVC) gimbaling system of the raptor engines, replacing the previous hydraulic power units that were used up to Booster 8. It was moved to the OLS cryogenic station on December 15.^[160] Two cryogenic proof tests were conducted on December 21 and December 29, both of which were successful.^[160] After engine installation, Booster 9 was rolled to OLM A on July 20,^[161] conducting a cryogenic proof test on OLM A,^[160] followed by a spin prime test on August 4.^[160] On August 6, Booster 9 fired 29 engines for 2.7 seconds, instead of the planned 33 engines for 5 seconds. It was then moved off of OLM A and rolled back to Mega Bay 1, where its vented interstage was added on August 16.^[160] B9 was moved back to OLM A on August 22 and underwent another spin prime test the next day.^[160] On August 25, Booster 9 underwent a static fire of all 33 engines, with two engines shutting off early, which lasted around 6 seconds.^[160] Ship 25 (S25) was lifted onto B9 for the first time on September 5, and was destacked several times throughout the rest of the month and mid October.^[160] On October 22, B9 underwent two partial cryogenic tests, while S25 was not tested,^[160] followed by a full wet dress rehearsal (WDR) two days later.^[160] On November 18, Booster 9 and Ship 25 lifted off with all 33 engines lit at 7:02 am CST.^[162] Following the successful separation from S25, B9 was destroyed after several engine failures during the boost-back burn.^[162]

B10 was fully stacked in March 2023.^[54] B10 was moved to Massey's test site for cryogenic testing on July 7, undergoing a cryogenic proof test on July 18.^[54] Three additional cryogenic tests were performed in mid September.^[54] B10 was moved back to Mega Bay 1 on September 19 for engine and interstage installation.^[54] On December 18, B10 was moved to the orbital launch site,^[54] followed by a lift onto OLM A the next day.^[54] It aborted a static fire test on December 21, before completing a 33-engine static fire test on December 29, followed by its removal from OLM A on December 30.^[54] On January 2, 2024, B10 was moved back to the Production Site,^[54] and was transported to the Orbital Launch Site for a WDR.^[54] On February 9, B10 was lifted onto OLM A,^[54] and on February 10, Ship 28 (S28) was lifted onto B10,^[54] with the combined vehicle aborting two wet dress rehearsal attempts.^[54] The wet dress rehearshal was completed on March 3.^[54] The vehicles were destacked for FTS arming on March 5,^[54] which occurred on March 8,^[54] followed by S28 being restacked on March 10.^[54] On March 14, B10 was launched with S28 on IFT-3, completing the ascent burn with zero engine failures. Six engines failed during the boostback burn.^[163] During its landing burn, only three engines started up with two failing shortly thereafter.^[164]

B11 was fully stacked in June 2023.^[165] On October 12, B11 was moved to Massey's test site, where it was cryo-tested on October 14 and October 18.^[166] On November 19, B11 was moved back to Mega Bay 1 for engine and interstage installation.^[166] B11 was moved to OLM A for static-fire testing on April 4,^[166] where it conducted a 33-engine static-fire on April 5.^[167] On April 7, it was removed from OLM A,^[166] and rolled back to Mega Bay 1 for pre-flight modifications.^[166] On May 10, B11 was rolled out of Mega Bay 1,^[166] and rolled to the Orbital Launch Site.^[168] It was lifted onto the OLM on May 11.^[169] On May 15, Ship 29 (S29) was lifted onto B11, with the combined vehicle completing a partial cryogenic test on May 16,^[170] and a full wet dress rehearsal on May 20,^[171] A second wet dress rehearsal was completed on May 28.^[172] On May 29, S29 was destacked for final tile work and Flight Termination System (FTS) Installation,^[166] with FTS installation occurring on May 30.^[166] S29 was stacked onto B11 for the final time on June 5.^[166] On June 6, B11 and S29 launched on IFT-4, with a single engine failure occurring shortly after liftoff.^[173] The boostback burn saw no engine failures, though a second engine failed during the landing burn.^[173] B11 was destroyed after tipping over, with several components being recovered in late September.^[174][175] On October 9, Vice President of Build and Flight Reliability of SpaceX, Bill Gerstenmaier, claimed that B11 landed within "half a centimeter" of the target.^[176]

B12 began assembly in June 2023.^[165] On December 28, 2023, B12 was moved to Massey's for cryogenic testing, where it conducted two cryogenic tests on January 10 and January 12.^[177] B12 was moved production site in mid-January for engine installation.^[178] B12 was moved to OLM A on July 9 for static fire testing,^[179] where it conducted a pressurization test on July 11,^[177] followed by a 33 engine spin prime on July 12 and a 33 engine static fire on July 15.^[180][181] B12 was rolled back to the production site on July 16, 2024.^[182] SpaceX claimed that B12 and S30 were ready to fly on August 8.^[183] On September 20, B12 was rolled to the launch site, with S30 being lifted onto B12 the next day.^[184] A partial wet dress rehearsal was conducted on September 23.^[185] A second partial wet dress rehearsal occurred on October 7,^[186] followed by S30 being destacked for FTS installation.^[187] FTS was installed on both vehicles on October 9,^[188] and S30 was stacked onto B12 for Flight 5 on October 11.^[177] B12 and S30 launched on October 13, with B12 successfully conducting the ascent, boostback, and landing burns with no engine failures, before being caught by the gantry chopsticks,^[6] and lowered onto OLM A.^[189] Musk claimed that B12 suffered damage that could be "easily addressed", including warping of the outer engine nozzles.^[190] B12's FTS was removed on October 14,^[191] followed by being returned to Mega Bay 1 for post-flight inspections.^[192] On October 22, B12s vented interstage was recovered.^[193] B12 was retired to the rocket garden on October 28.^[194]

B13 and subsequent vehicles have upgraded lox vents, a new raceway design, and reinforced chines.^[195] B13's assembly was completed on February 3, 2024.^[196] It was rolled to Massey's test site for cryogenic testing on April 25.^[197] B13 completed its first cryo-test on April 26,^[198] and a second cryogenic test on April 29.^[199] On October 22, B13 was rolled to OLM A,^[22] where a partial cryogenic test was performed two days later.^[200] Following this, B13 conducted a static fire,^[200] and was subsequently rolled to Mega Bay 1.^[201] It returned to the launch site for IFT-6 on November 14,^[202] where Ship 31 (S31) was lifted onto the booster.^[203] FTS was installed on November 15,^[204] followed by a partial wet dress rehearsal on November 17.^[205]

On May 11, 2024, SpaceX released an image showing that B14 had been assembled.^[206] B14 was rolled out of Mega Bay 1 on October 2, ahead of a rollout to Massey's the next day.^[207] On October 4, B14 conducted its first cyrogenic test,^[208] followed by a second on October 5.^[209] It was then moved to Mega Bay 1 on October 7.^[210]

On July 23, 2024, B15's aft section was spotted with additional tanks attached to the liquid oxygen header tank.^[20]

On October 14, 2024, the first section for B16 was spotted being moved around Starfactory.^[211] Stacking began in late October.^[212]

BN2.1 was rolled out on June 3, 2021^[217] for cryogenic tests. It conducted two tests, the first on June 8, 2021,^[218] and the second on June 17, 2021.^[219]

B2.1 (not BN2.1) conducted three cryogenic tests on December 1, 2021, December 2, 2021, and December 3, 2021.^[220][221]

B6.1 was originally intended to be the third flight-worthy Super Heavy, but was repurposed as a test tank.^[222] In May 2023, it was used to test the modified FTS system, after the FTS on B7 and S24 failed to destroy the vehicle.^[223]

Liquid Oxygen Landing Test Tank (LOX LTT) was based on the LOX Landing tank on the Booster. It was cryogenically proof tested at Mcgregor in early 2022.^[17]

B7.1 was first cryogenically proof tested on 28 June 2022,^[224] and tested again on 19 July 2022.^[225] During a suspected pressurize to failure test two days later, it received minor damage.^[226] After repairs, it underwent a fourth cryogenic proof test on July 27, 2022, a fifth on September 1, 2022, and a sixth five days later.^[227] It then rolled back to the production site on September 16, 2022.^[228] B7.1 was then moved to the Massey's test site in September 2022, and then scrapped in December 2023.^[229]

Hot Stage Load Head (HSLH) was a test article designed to verify the structural integrity of the interstage of Super Heavy Boosters 9+.^[230] It was transported to the Massey's test site on July 30, 2023,^[231] before being loaded onto the Can Crusher stress testing device.^[232] In mid-October 2023, it was moved back to the production site,^[233] where it was disassembled.^[234]

B14.1 is a test article consisting of a booster common dome and a forward section.^[235] After structural testing at Masseys, it was moved to the launch site on June 21, 2024,^[236] and lifted onto OLM A.^[237] It was tested on June 26,^[215] followed by additional testing on June 27.^[238] It conducted additional testing on August 15.^[239] On August 17, it was returned to the production site.^[216]

Test Tank 1 (TT1) was a subscale test tank consisting of two forward bulkheads connected by a small barrel section. TT1 was used to test new materials and construction methods. On January 10, 2020, TT1 was stress tested to failure as part of an ambient temperature test, reaching a pressure of 7.1 bar (103 psi).^[240][242]

Test Tank 2 (TT2) was another subscale test tank similar to TT1. On January 27, 2020, TT2 underwent an ambient temperature pressure test where it reached a pressure of 7.5 bar (109 psi) before a leak occurred.^[243] Two days later, it underwent a cryogenic proof test to destruction, bursting at 8.5 bar (123 psi).^{[244][241][245]}

GSE 4.1 was first spotted in August 2021 and was the first ground support equipment (GSE) test tank built, made from parts of GSE 4.^[227] It underwent a cryogenic proof test in August 2021 before it was rolled to the Sanchez site.^[246] It was rolled back to the launch site in November 2021, where it underwent an apparent cryogenic proof test to failure on January 18, 2022, where it burst at an unknown pressure.^[247]

EDOME was a test tank created to test flatter domes, possibly used on future Starship prototypes. It was moved to the launch site in July 2022, and then back to the production site the next month, after undergoing no tests.^[222] It was later moved from the production site to the Massey's test site in late September 2022, where it was damaged during a cryogenic pressure test to failure.^[222] After repairs, it was tested to destruction in late October 2022.^[222]

EDOME 2 was a test tank which is likely designed to continue testing a flatter dome design. As of October 4, 2023, its official designation is unknown. It was tested once, before being scrapped for unknown reasons.^[248]

• List of Falcon 9 first-stage boosters
• Starship HLS, lunar variant of the Starship spacecraft
• SpaceX Starbase, launch site of Super Heavy
• Starlink, large satellite constellation by SpaceX