SpaceX Starship

• 1. Introduction

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  SpaceX's Starship left its launch pad at Starbase in Texas at 13:33 UTC on the 20th of April 2023. It was the first flight of the complete two-stage vehicle. Three engines were disabled during the launch sequence, and more failed as the climb continued. The booster then lost thrust vectoring control of its Raptor engines, and the rocket began to spin. The vehicle topped out at 39 km. Roughly three minutes after liftoff, the autonomous flight termination system activated, yet the rocket tumbled for another 40 seconds before it broke apart.

  The launch also threw sand and soil into the air, and the debris reached communities within a 10.7 km radius. A brushfire on nearby state parkland burned 3.5 acres. For a machine that SpaceX hopes will become the first fully reusable orbital rocket, it was a harsh debut.

  Why would anyone build a rocket this large and then try to bring both halves back to the launch tower? What are the engines and the steel body doing to make that possible? How does a program survive a long string of prototypes that collapse, crash and burn? And who pays for it, who objects to it, and what is it supposed to carry?

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• 2. Steel and Methane

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  Fully stacked and fueled, Starship weighs about 5300 t, stands 121.3 m tall and measures 9 m across. It is built in two stages. The Super Heavy booster forms the bottom, and the upper stage is the spacecraft that also carries the name Starship. Both burn liquid methane with liquid oxygen, and domes inside the spacecraft keep the two propellant tanks apart. SpaceX states that its baseline reusable design would put 100 to 150 MT into low Earth orbit, or 27 MT into geostationary transfer orbit.

  The bodies of both stages are stainless steel. Workers stack and weld steel cylinders, each 6 ft tall and 3.97 mm thick.

  The engine at the center of the design is the Raptor. It burns oxygen and methane in a full-flow staged combustion cycle, which is both efficient and complicated. SpaceX picked methane over kerosene for two reasons. It gives higher performance, and it avoids coking, the build-up of deposits inside an engine. Methane can also be manufactured from carbon dioxide and water through the Sabatier reaction, a route that matters for Mars. Raptors are meant to be reused many times with little maintenance.

  Raptor runs at an oxygen-to-methane ratio of about 3.6 to 1. Complete combustion would call for 4 to 1, but burning that hot would melt the engine. The propellants leave the pre-burners as hot gases rather than liquid droplets, so they mix quickly by diffusion. They are hot and pressurized enough to ignite on contact, so the main chamber needs no igniters.

  A Raptor 2 engine produces 2.3 MN of thrust. Its specific impulse is 327 at sea level and 350 in a vacuum. The version on the ship, called Raptor Vacuum, adds a nozzle extension of brazed steel tubes that is cooled by the propellant. That raises its expansion ratio to about 90 and its vacuum specific impulse to 380. The main chamber pressure of 350 bar is higher than in any earlier operational rocket engine.

  Oxygen-side turbopumps face corrosive, oxygen-rich flames, so they are made from an Inconel-like superalloy called SX500. Some components are 3D printed. SpaceX aims for a production cost of US$250,000 per engine once mass production begins.

  The engine can swing 15 degrees, compared with 12.5 for the RS-25 and 5 for the Merlin. The ship relies on that gimbaling during its final landing flip, a maneuver that comes up later.

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• 3. From BFR to Starhopper

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  In November 2005, before the Falcon 1 had flown, Elon Musk first mentioned a rocket able to lift 100 MT to low Earth orbit. It was called the BFR. In 2012 he publicly announced plans for a vehicle that would outclass the Falcon 9. SpaceX named it the Mars Colonial Transporter, since it was meant to carry people to Mars and back.

  In 2016 the name became the Interplanetary Transport System, because the rocket was now expected to travel beyond Mars. That design called for a carbon fiber structure, a fueled mass above 10000 MT and a payload of 300 MT to low Earth orbit. By 2017 the project was the BFR again.

  In December 2018 the structural material changed from carbon composites to stainless steel. Musk listed several reasons. Steel was cheap and easy to manufacture, it grew stronger at cryogenic temperatures, and it could withstand high heat.

  In 2019 SpaceX began calling the whole vehicle Starship, with the booster named Super Heavy. The company announced reusable heat-shield tiles similar to those of the Space Shuttle. The ship had settled on six Raptor engines, three tuned for sea level and three for vacuum. That year the number of aft flaps dropped from three to two to save weight. A Starship Users Guide in March 2020 put the payload to low Earth orbit above 100 MT and the payload to geostationary transfer orbit at 21 MT.

  The first hardware came before the rebranding. Construction of a prototype called Starhopper began in 2018, and in 2019 it performed several static fires and two successful low-altitude flights. SpaceX had also started full-size upper-stage prototypes, MK1 and MK2, at Boca Chica in Texas and Cocoa in Florida. Neither flew. MK1 was destroyed in November 2019 during a pressure stress test, and the Florida site for MK2 was taken apart through 2020.

  Next came prototypes named with the prefix SN, short for serial number. SN1 and SN3 collapsed during pressure tests, and SN4 exploded after its fifth engine firing. SN5 had one Raptor engine, fuel tanks and a mass simulator, with no flaps or nose cone. On the 5th of August 2020 it flew 150 m high and landed on a nearby pad. SN6 repeated the hop on the 3rd of September 2020.

  SN8, the first full-size upper-stage prototype, flew on the 9th of December 2020 without a heat shield. It shut down its three engines one by one and reached 12.5 km. On the way down, low methane header tank pressure hampered the engines. The vehicle hit the landing pad hard and exploded. SN7 had used 304L stainless steel, which is less brittle and welds more easily, and later vehicles used a proprietary alloy called 30X that costs slightly over €3.6 per kilogram.

  The Federal Aviation Administration investigated the SN8 flight for two months. It said SpaceX had violated its launch license and had ignored warnings that the flight profile risked an explosion. FAA space division chief Wayne Monteith called the violation "inconsistent with a strong safety culture".

  On the 2nd of February 2021, SN9 flew to 10 km and crashed on landing because one engine did not ignite properly. SN10 followed on the 3rd of March. It landed hard, crushed its legs and exploded less than ten minutes later. SN11 flew into thick fog on the 30th of March and exploded during its descent, possibly because of excess propellant in a Raptor's methane turbopump.

  In March 2021 SpaceX disclosed a public construction plan for two sub-orbital launch pads, two orbital pads, two landing pads, two test stands and a large propellant tank farm. It soon proposed turning Boca Chica Village into a company town called Starbase. Locals worried about SpaceX's power and the threat of eviction through eminent domain. The town was incorporated as Starbase, Texas, in 2025.

  SN12 through SN14 were scrapped before completion, and SN15 flew instead because of its better avionics, structure and engines. On the 5th of May 2021 it repeated the maneuvers and landed safely. A fire broke out in its engine area afterward but was put out. A later SpaceX report said it had lost tank pressure and an engine while landing.

  Then came a regulatory hurdle. In June 2022 the Federal Aviation Administration found more than 75 issues in the preliminary environmental assessment that SpaceX had to address before integrated flight tests could begin.

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• 4. Learning in Public

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  In July 2022, Booster 7 tested the liquid oxygen turbopumps on all 33 of its Raptor engines. An explosion at its base destroyed a pressure pipe and caused minor damage to the launchpad. By the 9th of February 2023 the same booster had fired 31 engines at 50% throttle, and in January the whole stack had gone through a full wet dress rehearsal.

  After the first flight, SpaceX reinforced the foundation of the launch tower. It also built a water-powered flame deflector under the launch mount. Ship 25 and Booster 9 were rolled out in May for a round of tests.

  On the 18th of November 2023, Booster 9 and Ship 25 lifted off. All 33 engines worked until staging, when the ship pushed itself away from the booster in a technique called hot staging. The booster flipped and began its boostback burn. Then multiple engines failed in succession and it exploded about three and a half minutes into the flight, at roughly 90 km over the Gulf of Mexico. A blocked liquid oxygen filter had caused one engine to fail in a destructive way.

  The second stage kept going until about 149 km, after more than eight minutes of flight. Telemetry was lost before engine cutoff. SpaceX said a safe command based on flight data triggered the flight termination system, so the ship never reached its planned orbit or attempted reentry.

  The changes that followed included electric thrust vector control for the ship and measures to delay venting of liquid oxygen until after engine cutoff. Flight 3 launched at about 8:25 a.m. CDT on the 14th of March 2024, the 22nd anniversary of the founding of SpaceX. The booster completed its boostback burn but exploded 462 m above the Gulf of Mexico during its planned landing.

  The ship reached space and orbital velocity. There it moved propellant from its header tanks into its main tanks, a cryogenic transfer that Starship's lunar lander will need in order to leave low Earth orbit. NASA and SpaceX declared the test a success. The ship attempted reentry, and all telemetry from Ship 28 stopped at around 65 km.

  Flight 4 launched at 7:50 a.m. CDT on the 6th of June 2024 with two goals. The booster was to land on a virtual tower in the ocean, and the ship was to survive peak heating on reentry. Both worked. The booster made a soft splashdown, and the ship achieved a controlled splashdown despite significant damage to its flight control surfaces.

  On the 13th of October 2024, Booster 12 returned to the launch site on flight 5 and was caught by the tower for the first time. Ship 30 splashed down in the Indian Ocean. Flight 6 flew on the 19th of November 2024, and the booster landed in the water instead of being caught.

  That flight produced the first successful Raptor relight in the vacuum of space, which paved the way for deploying payloads. A stuffed toy banana served as a zero-gravity indicator and became Starship's first payload, though it stayed inside the vehicle. Journalist Eric Berger argued that the relight made it likely Starship would be "cleared to travel into orbit".

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• 5. Blocks and Breakups

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  On the 4th of April 2024, Elon Musk gave an update at Starbase and announced two new versions, Block 2 and Block 3. They were meant to fix the shortcomings of the pre-production prototypes. Block 1 had flown from the first flight test through flights 5 and 6, and was then retired.

  Block 2 first flew on flight 7. Its ships had a thinner forward flap, flaps placed more leeward, redesigned avionics and a 25% larger propellant capacity. The integrated vehicle stood 3.1 m taller than Block 1. Planners had hoped for at least 100 tons to orbit when reused, but the final estimate fell to 35 t, and the version was retired before any orbital flight. The first Block 2 vehicle, Ship 33, flew with upgraded Raptor 2 engines instead of the planned Raptor 3. Six Block 2 vehicles were built.

  Flight 7 flew on the 16th of January 2025. Contact with Ship 33 was lost shortly before its engines were due to shut down, and the ship was seen exploding over the Turks and Caicos Islands. Numerous commercial airline flights were diverted or delayed. The booster, meanwhile, returned and was caught by the tower arms on the pad called OLP-A.

  The 3rd of March 2025 brought a launch attempt that was aborted at T minus 40 seconds after repeated holds. Flight 8 flew on the 6th of March and the booster was caught again. On Ship 34, four of six engines shut down early during the first burn. Attitude control and then telemetry were lost 9 minutes and 30 seconds after liftoff. The breakup was visible from Florida, Jamaica and the Turks and Caicos, and the FAA briefly issued ground stop orders for multiple Florida airports.

  Flight 9 launched on the 27th of May 2025 with Booster 14, the first Super Heavy to fly a second time. The booster was lost before its planned splashdown. Ship 35 reached engine cutoff, but a propellant leak caused loss of attitude control and blocked an engine relight. Its payload bay door also failed to open, so the dummy Starlink satellites stayed aboard, and the ship broke up on reentry.

  On the 18th of June 2025, Ship 36 exploded during a planned six-engine static fire at the Massey test stand near Starbase. Early analysis pointed to a failed composite-overwrapped pressure vessel in the nose section, which ruptured and ignited methane and liquid oxygen. Nobody was injured, and SpaceX paused testing to inspect pressurization hardware and repair the stand.

  Flight 10 was scrubbed on the 24th and the 25th of August 2025 and launched on the 26th. The booster completed its ascent, boostback and landing burns despite losing an engine on the way up. The ship released eight Starlink simulators, relit one engine and splashed down in the Indian Ocean within a few meters of its target.

  Flight 11 launched on the 13th of October 2025 and mostly repeated that profile. Booster 15-2 was the second reused booster. Ship 38 again deployed eight simulators and relit an engine, then flew several banking maneuvers, including a simulated trajectory for future ship catches. At an altitude of 1 km and a descent speed of 338 km/h, it relit three sea-level engines and flipped upright. It splashed down softly, tipped over and exploded. That was the last flight of Block 2.

  Block 3 brings Raptor 3 engines, a new tile design, docking ports for refueling in low Earth orbit and a redesigned quick disconnect. Raptor 3 allows most of the aft shielding to be removed. Block 3 boosters carry an integrated vented interstage and forward dome, and only three grid fins instead of four. Those fins double as catch points, so no separate structure is needed. Removing engine shielding saves over a ton per engine.

  Flight 12 launched on the 22nd of May 2026 with Ship 39 and Booster 19, the first test of Version 3. One Raptor failed early on the booster, and an explosion in engine E6 then knocked out neighboring engines. Only 10 engines were spared, the boostback burn ended prematurely and the booster broke apart over the Gulf of Mexico.

  Ship 39 lost one vacuum engine early. It still released 20 Starlink simulators and two modified Starlink V3 satellites, and one of the V3s filmed the ship's belly as it departed. The ship landed on target in the Indian Ocean, tipped and exploded as expected.

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• 6. Catching a Rocket

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  About 159 seconds after liftoff, at roughly 64 km, Super Heavy shuts down all but three of its center engines. That follows ignition of all 33 at the pad, once the quick disconnect arms retract. The ship lights its own engines while still attached and separates, and the booster throttles down. It then rotates and relights ten more engines for a boostback burn that cancels its forward velocity.

  The booster falls back on a controlled path, making minor corrections with its grid fins. About six minutes after launch it lights its inner 13 engines and then drops to the inner 3 for a landing burn. That slows it enough for a pair of electrically actuated arms on the launch tower to grab it.

  The ship, meanwhile, keeps accelerating on its six Raptors. In orbit it could be refueled by a tanker variant. Musk has estimated that 8 launches would refill a ship completely in low Earth orbit. NASA estimates that 16 launches in quick succession would be needed to partly fuel one lunar landing, because cryogenic propellant boils off.

  On a world with an atmosphere, such as Earth or Mars, the ship first slows with its heat shield. It then dives at a 60 degree angle in a belly-flop, steering with four flaps at its front and rear. Just before touchdown the Raptors fire, using fuel from the header tanks, for a landing flip back to vertical. The lunar lander and the fuel depot cannot do this, since they lack a thermal protection system and flaps.

  A ship that lands on a pad is moved by a mobile hydraulic lift to a transporter. A ship that lands on a floating platform goes by barge to a port and then by road. Either way it returns to the launch mount or to a SpaceX facility for refurbishment.

  The tower at Starbase is built from steel truss sections, with a lightning rod on top and the pair of mechanical arms. SpaceX chose to catch the booster in order to remove landing legs. That reduces mass and mechanical complexity and puts the rocket straight back on the pad for faster reuse. A carriage carries the arms, a cable runs over a pulley at the top to a winch and spool at the base, and a linear hydraulic actuator moves the arms sideways. Tracks on top of the arms position the booster or ship.

  Starbase has two launch sites, Pad A and Pad B, also called OLP-1 and OLP-2. Each tank farm holds eight tanks, enough for one orbital launch. The mount on Pad A has a water-powered flame diverter and 20 clamps to hold the booster. Starbase also includes a manufacturing facility. Both facilities run around the clock, and up to 450 full-time employees may be onsite.

  Raptor engines are tested at a facility in McGregor, Texas, with a horizontal stand for both engine types and a vertical stand for sea-level engines. In Florida, a facility at Cocoa purifies silica for the heat-shield tiles. It produces a slurry that is shipped to another facility at Cape Canaveral.

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• 7. Money, Rivals, Regulators

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  SpaceX chief financial officer Bret Johnsen disclosed in court that the company had put more than $3 billion into Starbase and Starship from July 2014 to May 2023. Musk said in April 2023 that SpaceX expected to spend about $2 billion on Starship that year. In a 2024 court response, the company put the program's cost at about $4 million per day, and said each day of delay meant a $100,000 loss. In late October 2025, SpaceX said it was self-funding over 90% of system costs.

  Musk has suggested that an orbital Starship launch might eventually cost SpaceX only $1 million. Pierre Lionnet, research director at Eurospace, argued in 2022 that customer prices would probably be higher because of development costs.

  NASA's money arrived in April 2021, when it awarded SpaceX a $2.89 billion fixed-price contract for the Starship lunar lander for Artemis III. Rival bidder Blue Origin disputed the decision and sued NASA and SpaceX in August 2021. NASA suspended the contract for three months until the Court of Federal Claims dismissed the case. Two years later Blue Origin won a $3.4 billion fixed-price contract for its own lander. In 2022, NASA also gave SpaceX a $1.15 billion fixed-price contract for a second lander, for Artemis IV.

  Florida has produced another dispute. SpaceX has been building a Starship pad at Kennedy Space Center Launch Complex 39A since 2021, on a site leased to it in 2014. In 2024 the FAA began an environmental impact statement for a cadence of up to 44 launches a year there. Blue Origin and United Launch Alliance both objected in June 2024. ULA argued that a fully fueled Starship needs an evacuation zone so large that it would block other operators, and that repeated launch noise could injure people nearby. Musk suggested the objections were disingenuous and aimed at slowing SpaceX through lawfare.

  SpaceX has also proposed a pad at Cape Canaveral Space Launch Complex 37, which fell vacant in 2024 after the Delta IV retired. The Space Force began an environmental review there for up to 76 launches a year.

  Other countries are watching. China Aerospace Science and Technology Corporation and other Chinese groups are reportedly working on the Long March 9, a super-heavy rocket designed to become fully reusable. In 2021 the China Academy of Launch Vehicle Technology showed a rendered video of a rocket strikingly similar to Starship. SpaceNews noted that the start-up Space Epoch and the engine maker Jiuzhou Yunjian were building a smaller Starship-like rocket. Blue Origin's Project Jarvis, a reusable upper stage for New Glenn, may also owe something to Starship.

  At home, members of Congress voiced concern in 2021 about how the FAA handled the SN8 license violations. In 2023, SpaceX vice president Bill Gerstenmaier told the Senate that the test campaign faced "regulatory headwinds and unnecessary bureaucracy". After the second flight, the Government Accountability Office recommended that the FAA improve its mishap investigation process. Several environmental groups have sued the FAA and SpaceX, claiming that reviews were bypassed because of Musk's political and financial influence.

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• 8. Missions and Doubts

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  As of 2021, Starlink delivered high-speed internet to over 70 countries, and SpaceX plans to launch its second generation on Starship. A Morgan Stanley analyst saw the two programs as intertwined. Cheaper launches would help Starlink, and Starlink's profits would help pay for Starship. Starlink ran at a deficit until the end of 2022, and Musk said it reached only "break-even cashflow" in 2023. In December 2023 the FCC finally denied an $885 million subsidy, citing Starlink's "continuing inability to successfully launch on the Starship rocket".

  NASA first chose Starship as the only lunar Human Landing System for Artemis III and Artemis IV. A docking test is planned for Artemis III in 2027, with a crewed landing in 2028. The lander would launch to low Earth orbit and be refueled by several tankers. It would then fire toward the Moon and enter a near-rectilinear halo orbit, with a closest point of 1500 km over the north pole and a farthest point of 70000 km over the south pole.

  The Orion spacecraft would dock with it, and two of Orion's four crew would transfer across. The lander would descend under power to a site near the lunar south pole. After the surface mission it would lift the crew back to Orion.

  Astronomers see an opportunity too. Starship's 9 m fairing could hold an 8 m telescope mirror in one piece, avoiding the complex unfolding that added cost and delays to the JWST's 6.5 m mirror. The Ariane 5 had imposed a weight limit of about 6,500 kg. A refueled Starship could carry a 5 MT mirror built like Hubble's, and the JWST would then amount to only 10% of what it could deliver to the Sun-Earth L2 point. The Habitable Worlds Observatory is planned with a 6 to 8 m mirror and a launch in the 2040s. Lee Feinberg, its lead architect and the JWST manager, visited SpaceX in 2024. Former NASA JPL architect Casey Handmer thinks the design is far too conservative.

  In January 2022 SpaceX won a $102 million, five-year Rocket Cargo contract from the United States Space Force to find out what a rocket can do when moving freight. It includes an eventual point-to-point demonstration with a cargo-laden Starship. The Department of Defense has also planned a test of delivering up to 100 tons of cargo rapidly, in fiscal year 2025 or 2026. SpaceX itself has proposed Earth-to-Earth passenger flights anywhere in under an hour, though Musk said hundreds of cargo flights would come first.

  Other payloads include the Superbird-9 communication satellite, Starship's first contract for an externally built commercial satellite, and the Starlab space station, which it expects to launch in one piece. Space tourism is possible, for example on the third flight of the Polaris program. Project Lyra found that with refueling in low Earth orbit, a Starship could send a spacecraft to ʻOumuamua in 20 years, using a gravity assist at Jupiter.

  Mars is the mission that drives the design, according to SpaceX, which has not published technical plans for life support, radiation protection, docking or in-orbit refueling for it. The company and Musk aim to send one million people there by 2050 for the long-term survival of humanity. In March 2022, Musk estimated that the first crewed landing could happen in 2029.

  Oxford physicist Kevin Olsen called that timeline unrealistic, saying a colony "needs to become a factory" because a fully closed environment in space is impossible. Serkan Saydam, a mining engineering professor at the University of New South Wales, said humanity lacks the technology for a Martian city of one million people by 2050. So far, one proof-of-concept experiment, MOXIE, has extracted oxygen from Martian carbon dioxide. George Dvorsky wrote in Gizmodo that we are not "remotely close" to making that practical.

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