SpaceX Starship development

For other starships, see Starship.

The SpaceX Starship is a fully-reusable launch vehicle and spacecraft that is being privately developed by SpaceX. It is designed to be a long-duration cargo and passenger-carrying spacecraft. The development of the Starship began in 2014.

Background

The launch vehicle was initially mentioned in public discussions by SpaceX CEO Elon Musk in 2012 as part of a description of the company's overall Mars system architecture, then known as Mars Colonial Transporter (MCT). It was proposed as a privately-funded development project to design and build a spaceflight system of reusable rocket engines, launch vehicles and space capsules to eventually transport humans to Mars and return them to Earth.

As early as 2007 however, Musk had stated a personal goal of eventually enabling human exploration and settlement of Mars. Bits of additional information about the mission architecture were released in 2011–2015, including a 2014 statement that initial colonists would arrive at Mars no earlier than the middle of the 2020s, and SpaceX began development of the large Raptor rocket engine for the MCT before 2014.

Musk stated in a 2011 interview that he hoped to send humans to Mars' surface within 10–20 years, and in late 2012 that he envisioned the first colonists arriving no earlier than the middle of the 2020s.

In October 2012, Musk first publicly articulated a high-level plan to build a second reusable rocket system with capabilities substantially beyond the SpaceX launch vehicles on which SpaceX had by then spent several billion US dollars. This new vehicle was to be "an evolution of SpaceX's Falcon 9 booster ... much bigger [than Falcon 9]." But Musk indicated that SpaceX would not be speaking publicly about it until 2013. In June 2013, Musk stated that he intended to hold off any potential IPO of SpaceX shares on the stock market until after the "Mars Colonial Transporter is flying regularly."

In February 2014, the principal payload for the MCT was announced to be a large interplanetary spacecraft, capable of carrying up to 100 tonnes (220,000 lb) of passengers and cargo. Musk stated that MCT will be "100 times the size of an SUV". According to SpaceX engine development head Tom Mueller, concept designs at the time indicated SpaceX could use nine Raptor engines on a single rocket, similar to the use of nine Merlin engines on each Falcon 9 booster core, in order "to put over 100 tons of cargo on Mars." At that time, it appeared that the large rocket core that would be used for the booster to be used with MCT would be at least 10 meters (33 ft) in diameter—nearly three times the diameter and over seven times the cross-sectional area of the Falcon 9 booster cores—and was expected to have up to three rocket cores with a total of at least 27 engines.

By August 2014, media sources speculated that the initial flight test of the Raptor-driven super-heavy launch vehicle could occur as early as 2020, in order to fully test the engines under orbital spaceflight conditions; however, any colonization effort was then reported to continue to be "deep into the future".

Interplanetary Transport System

2016 artist's concept of Interplanetary Spaceship

In January 2015, Musk said that he hoped to release details of the "completely new architecture" for the Mars transport system in late 2015 but those plans changed and, by the end of the year, the plan to publicly release additional specifics had moved to 2016. Musk stated in June 2016 that the first uncrewed MCT Mars flight could happen as early as for 2022, to be followed by the first crewed MCT Mars flight departing as early as 2024. By mid-2016 the company continued to call for the arrival of the first humans on Mars no earlier than 2025. By 2016, the rocket had not yet been given a formal name by SpaceX, although Musk commented on a proposal on Twitter to name it "Millennium". In his September 2016 announcement, Musk referred to the vehicle components as the "ITS booster", the "Interplanetary Spaceship", and the "ITS tanker".

In mid-September 2016, Musk noted that the Mars Colonial Transporter name would not continue, as the system would be able to "go well beyond Mars", and that a new name would be needed. The name selected was Interplanetary Transport System (ITS), although in an AMA on Reddit on Oct 23, 2016, Musk stated, "I think we need a new name. ITS just isn't working. I'm using BFR and BFS for the rocket and spaceship, which is fine internally, but...", without stating what the new name might be.

Musk unveiled details of the space mission architecture, launch vehicle, spacecraft, and Raptor engines that power the vehicles at the 67th International Astronautical Congress on September 27, 2016. The first firing of a Raptor engine occurred on a test stand in September 2016 as well.

In October 2016, Musk indicated that the initial prepreg carbon-fiber tank test article, built with no sealing liner, had performed well in initial cryogenic fluid testing, and that a pressure test of the tank at approximately 2/3 of the design burst pressure was slated for later in 2016, with the very large tank placed on an ocean barge for the test. This test was successfully completed in November 2016.

In July 2017, Musk indicated that the architecture had "evolved quite a bit" since the 2016 articulation of the Mars architecture. A key driver of the updated architecture was to be making the system useful for substantial Earth-orbit and cislunar launches so that the system might pay for itself, in part, through economic spaceflight activities in the near-Earth space zone. In September 2018, a less drastic redesign was announced, stretching the second stage slightly and adding radially-steerable forward canards and aft fins, used for pitch control in a new reentry profile resembling a descending skydiver. The aft fins act as landing legs, with a third leg on the top that looks identical but serves no aerodynamic purpose.

Design

The ITS stack was composed of two stages. The first stage was always to be an "ITS booster" while the second stage would have been either an "Interplanetary Spaceship" (for beyond-Earth-orbit missions) or an "ITS tanker" (for on-orbit propellant transfer operations).

Both stages of the ITS were to be powered by Raptor bipropellant liquid rocket engines utilizing the full flow staged combustion cycle with liquid methane fuel and liquid oxygen oxidizer. Both propellants would be fully in the gas phase before entering the Raptor combustion chamber. Both stages were intended to utilize a bleed-off of the high-pressure gas for autogenous pressurization of the propellant tanks, eliminating the problematic high-pressure helium pressurization system used in the Falcon 9 launch vehicle. The self-pressurization gas system is a critical part of SpaceX strategy to reduce launch vehicle fluids from five in their legacy Falcon 9 vehicle family to just two, eliminating not only the helium tank pressurant but all hypergolic propellants as well as nitrogen for cold-gas reaction-control thrusters.

The overall launch vehicle height, first stage and the integrated second-stage/spacecraft, was 122 m (400 ft). Both stages of the ITS were to have been constructed of lightweight-yet-strong carbon fiber, even the deep-cryogenic propellant tanks, a major change from the aluminum-lithium alloy tank and structure material used in SpaceX Falcon 9 family of launch vehicles. Both stages are fully reusable and will land vertically, technology initially developed on the Falcon 9 launch vehicle first stages in 2012–2016. Gross liftoff mass is 10,500 tonnes (23,100,000 lb) at a lift-off thrust of 128 meganewtons (29,000,000 lbf). ITS would be able to carry a payload to low-Earth orbit of 550 tonnes (1,210,000 lb) in expendable-mode and 300 tonnes (660,000 lb) in reusable mode.

ITS booster

The ITS booster was a 12 m-diameter (39 ft), 77.5 m-high (254 ft), reusable first stage, to be powered by 42 sea-level rated Raptor engines producing some 3,024 kilonewtons (680,000 lbf) of thrust in each engine. Total booster thrust would have been approximately 130 MN (29,000,000 lbf), several times the 36 MN (8,000,000 lbf) thrust of the Saturn V Moon mission launch vehicle.

The design engine configuration included 21 engines in an outer ring and 14 in an inner ring, with these 35 engines fixed in place. The center cluster of seven engines were to be gimbaled for directional control, although some directional control to the rocket was to be performed by utilizing differential thrust on the fixed engines. Design thrust on each engine was aiming to be variable between 20 and 100 percent of rated thrust.

Methane/oxygen would also be used to power the control thrusters, as gas thrusters rather than the subcooled liquid used to power the main engines. The methalox control thrusters were to be used to control booster orientation in space, as well as to help provide additional accuracy in landing once the velocity of the descending booster has slowed.

The design was intended to use about 7% of the total propellant load at launch in order to support the reusable aspect and bring the booster back to the launch pad for a vertical landing, assessment, and relaunch, assuming a separation velocity of approximately 8,650 km/h (5,370 mph). The design called for grid fins to be used during atmospheric reentry, once the atmosphere is sufficiently dense, to control the attitude of the rocket and fine tune the landing location. The booster return flights were expected to encounter loads lower than those experienced on the Falcon 9 reentries, principally because the ITS would have both a lower mass ratio and a lower density than Falcon 9. The booster was to be designed for 20 g nominal loads, and possibly as high as 30–40 gs without breaking up.

In contrast to the landing approach used on SpaceX's mid-2010s reusable rocket first stages—either a large, flat concrete pad or downrange floating landing platform used with Falcon 9 and Falcon Heavy—the ITS booster was to be designed to land on the launch mount itself, where it may then be refilled with propellant and checked out for follow-on flights.

Spacecraft that operate briefly as upper stages during launch

The ITS did not have a dedicated and single-function second stage in the way most launch vehicles have had. Instead, the upper stage function of gaining sufficient velocity to place a payload into Earth orbit is provided as a relatively short term role by a spacecraft that has all the requisite systems for long-duration spaceflight. This is not a role that most upper stages have had in launch vehicle designs through the 2010s, as typical upper stage on-orbit life is measured in hours. Previous exceptions to this norm exist, for example the Space Shuttle orbiter provided part of the boost energy and all of the second stage energy for lofting itself into low-Earth orbit. Differences also exist: the Space Shuttle expended its propellant tank and primary launch vehicle structure on ascent, whereas the ITS first- and second-stage options are designed to be fully reusable.

In the 2016 design, SpaceX had identified two spacecraft that would also play the upper stage role on each Earth-away launch: the "Interplanetary Spaceship" and the "ITS tanker". Both spacecraft are the same physical external dimensions: 49.5 m (162 ft)-long and 12 m (39 ft)-diameter 17 m (56 ft) across at the widest point. Both designs were powered by six vacuum-optimized Raptor engines, each producing 3.5 MN (790,000 lbf) thrust, and were to have had three lower-expansion-ratio Raptor engines for in-space maneuvering as well as during descent and landing to allow for reuse on future launches.

Interplanetary Spaceship

The Interplanetary Spaceship was a large passenger-carrying spacecraft design proposed by SpaceX as part of their ITS launch vehicle in September 2016. The ship would operate as a second-stage of the orbital launch vehicle on Earth-ascents—and would also be the interplanetary transport vehicle for both cargo and passengers—capable of transporting up to 450 tonnes (990,000 lb) of cargo per trip to Mars following propellant-refill in Earth orbit.

In addition to use during maneuvering, descent and landing, the three lower-expansion-ratio Raptor engines were also to have been used for initial ascent from the surface of Mars. In 2016, the first test launch of a spaceship was not expected until 2020 or later, and the first flight of the ITS booster was expected to follow a year or more later.

Early Mars flights—in the mid-2020s or later—were expected to carry mostly equipment and few people.

ITS tanker

The ITS tanker is a propellant tanker variant of the ITS second stage. This spacecraft design was to be used exclusively for launch and short-term holding of propellants to be transported to low-Earth orbit. Once on orbit, a rendezvous operation was to have been effected with one of the Interplanetary Spaceships, plumbing connections made, while a maximum of 380 tonnes (840,000 lb) of liquid methane and liquid oxygen propellants would be transferred in one load to the spaceship. To fully fuel an Interplanetary Spaceship for a long-duration interplanetary flight, it was expected that up to five tankers would be required to launch from Earth, carrying and transferring a total of nearly 1,900 tonnes (4,200,000 lb) of propellant to fully load the spaceship for the journey.

Following completion of the on-orbit propellant offloading, the reusable tanker was to reenter the Earth's atmosphere, land, and be prepared for another tanker flight.

Reusability

2016 artist's concept of ITS booster returning to the launch pad

Both stages were to be designed by SpaceX to be fully reusable and were to land vertically, using a set of technologies previously developed by SpaceX and tested in 2013–2016 on a variety of Falcon 9 test vehicles as well as actual Falcon 9 launch vehicles.

Importantly, the "fully and rapidly reusable" aspect of the ITS design was the largest factor in the SpaceX analysis for bringing down the currently huge cost of transporting mass to space, in general, and to interplanetary destinations, in particular. While the transport system under development in 2016-2017 relied on a combination of several elements to make long-duration beyond Earth orbit (BEO) spaceflights possible by reducing the cost per ton delivered to Mars, the reusability aspect of the launch and spacecraft vehicles alone was expected by SpaceX to reduce that cost by approximately 2 1/2 orders of magnitude over what NASA had previously achieved on similar missions. Musk stated that this is over half of the total 4 1/2 orders of magnitude reduction that he believes is needed to enable a sustainable settlement off Earth to emerge.

Operations concept

The concept of operations for ITS launches envisioned the fully loaded second-stage reaching orbit with only minimal propellant remaining in the Interplanetary Spaceship's tanks. Then, while the spaceship remained in Earth orbit, three to five ITS tankers would be launched from Earth carrying additional methane fuel and liquid oxygen oxidizer to rendezvous with, and transfer propellant to, the outgoing spaceship. Once refueled, the spaceship was to perform a trans-Mars injection burn, departing Earth orbit for the interplanetary portion of the journey.

Big Falcon Rocket

File:BFR in orbit, 2017.PNG

2017 artist's concept of BFS cargo

In September 2017, at the 68th annual meeting of the International Astronautical Congress, SpaceX unveiled the updated vehicle design. Musk said, "we are searching for the right name, but the code name, at least, is BFR."

The Big Falcon Rocket (BFR), also known as Big Fucking Rocket, was a 9-meter (30 ft) diameter carbon-composite launch vehicle, using methalox-fueled Raptor rocket engine technology directed initially at the Earth-orbit and cislunar environment, later, for flights to Mars.

The BFR was cylindrical and included a small delta wing at the rear end which included a split flap for pitch and roll control. The delta wing and split flaps were said to be needed to expand the flight envelope to allow the ship to land in a variety of atmospheric densities (none, thin, or heavy atmosphere) with a wide range of payloads (small, heavy, or none) in the nose of the ship. Three versions of the ship were described: BFS cargo, BFS tanker, and BFS crew. The cargo version would be used to launch satellites to low Earth orbit—delivering "significantly more satellites at a time than anything that has been done before"—as well as for cargo transport to the Moon and Mars. After retanking in a high-elliptic Earth orbit the spaceship was being designed to be able to land on the Moon and return to Earth without further refueling.

The engine layout, reentry aerodynamic surface designs, and even the basic material of construction have each changed markedly since the initial public unveiling of the BFR in 2017, in order to balance objectives such as payload mass, landing capabilities, and reliability. The initial design at the unveiling showed the ship with six Raptor engines (two sea-level, four vacuum), aerodynamic control surfaces of a delta wing with split flaps, and a plan to build both stages of the launch vehicle out of carbon composite materials.

By late 2017, SpaceX added a third sea-level engine to the conceptual design to increase engine-out capability and allow landings with greater payload mass, bringing the total number of engines to seven.

Additionally, the BFR was shown to theoretically have the capability to carry passengers and/or cargo in rapid Earth-to-Earth transport, delivering its payload anywhere on Earth within 90 minutes.

By September 2017, Raptor engines had been tested for a combined total of 1,200 seconds of test firing time over 42 main engine tests. The longest test was 100 seconds, which was limited by the size of the propellant tanks at the SpaceX ground test facility. The test engine operates at 20 MPa (200 bar; 2,900 psi) pressure. The flight engine is aimed for 25 MPa (250 bar; 3,600 psi), and SpaceX expects to achieve 30 MPa (300 bar; 4,400 psi) in later iterations. In November 2017, SpaceX president and COO Gwynne Shotwell indicated that approximately half of all development work on BFR was then focused on the Raptor engine.

The aspirational goal in 2017 was to send the first two cargo missions to Mars in 2022, with the goal to "confirm water resources and identify hazards" while deploying "power, mining, and life support infrastructure" in place for future flights, followed by four ships in 2024, two crewed BFR spaceships plus two cargo-only ships bringing additional equipment and supplies with the goal of setting up the propellant production plant.

By early 2018, the first ship using carbon composite structure was under construction, and SpaceX had begun building a new permanent production facility to build the 9-meter vehicles at the Port of Los Angeles. Manufacture of the first ship was underway by March 2018 in a temporary facility at the port, with first suborbital test flights planned for no earlier than 2019. The company continued to state publicly its aspirational goal for initial Mars-bound cargo flights of BFR launching as early as 2022, followed by the first crewed flight to Mars one synodic period later, in 2024, consistent with the no-earlier-than dates mentioned in late-2017.

Back in 2015, SpaceX had been scouting for manufacturing facility locations to build the large rocket, with locations being investigated in California, Texas, Louisiana, and Florida. By September 2017, SpaceX had already started building launch vehicle components: "The tooling for the main tanks has been ordered, the facility is being built, we will start construction of the first ship [in the second quarter of 2018.]"

In March 2018, SpaceX announced that it would manufacture its next-generation, 9-meter-diameter (30 ft) launch vehicle and spaceship at a new facility the company is constructing in 2018–2019 on Seaside Drive at the Port of Los Angeles. The company had leased an 18-acre site for 10 years, with multiple renewals possible, and will use the site for manufacturing, recovery from shipborne landings, and refurbishment of both the booster and the spaceship. Final regulatory approval of the new manufacturing facility came from the Board of Harbor Commissioners in April 2018, and the Los Angeles City Council in May. By that time, approximately 40 SpaceX employees were working on the design and construction of BFR. Over time, the project was expected to have 700 technical jobs. The permanent Port of Los Angeles facility was projected to be a 203,500-square-foot (18,910 m²) building that would be 105 feet (32 m) tall. The fully assembled launch vehicle was expected at that time to be transported by barge, through the Panama Canal, to Cape Canaveral in Florida for launch.

In August 2018, for the first time, the US military publicly discussed interest in using the BFR. The head of USAF Air Mobility Command was specifically interested in BFRs ability to move up to 150 t (330,000 lb) of cargo to anywhere in the world using the projected Earth-to-Earth capability in under 30 minutes, for "less than the cost of a C-5". They projected the large transport capability "could happen within the next five to 10 years."

Starship and Super Heavy

2018 artist's concept of the Starship's former design following stage separation

In a September 2018 announcement of a planned 2023 lunar circumnavigation mission, a private flight called #dearMoon project, Musk showed a redesigned concept for the BFR second stage and spaceship with three rear fins and two front canard fins added for atmospheric entry, replacing the previous delta wing and split flaps shown a year earlier. The revised BFR design was to use seven identically-sized Raptor engines in the second stage; the same engine model as would be used on the first stage. The second stage design had two small actuating canard fins near the nose of the ship, and three large fins at the base, two of which would actuate, with all three serving as landing legs. Additionally, SpaceX also stated later that September that they were "no longer planning to upgrade Falcon 9 second stage for reusability." The two major parts of the re-designed BFR were given descriptive names in November: "Starship" for the upper stage and "Super Heavy" for the booster stage, which Musk pointed out was "needed to escape Earth's deep gravity well (not needed for other planets or moons)."

In May 2019, the final Starship design changed back to six Raptor engines, with three optimized for sea-level and three optimized for vacuum.

Prototypes and testing

Starhopper

On December 2018, nine months after starting construction of some parts of the first test article carbon composite Starship low-altitude test vehicle, Musk announced a "counterintuitive new design approach" would be taken by the company: the primary construction material for the rocket's structure and propellant tanks would be "fairly heavy...but extremely strong" metal, subsequently revealed to be stainless steel. Musk revealed on 23 December 2018 that the initial test article—the Starship Hopper, Hopper, or Starhopper— had been under construction there for several weeks, out in the open on SpaceX property. The Starhopper was being built from a 300-series stainless steel. According to Musk, the reason for using this material is that "it's [stainless steel] obviously cheap, it’s obviously fast—but it's not obviously the lightest. But it is actually the lightest. If you look at the properties of a high-quality stainless steel, the thing that isn’t obvious is that at cryogenic temperatures, the strength is boosted by 50 percent." The high melting point of 300-series still would mean the leeward side of Starship would need no insulation during reentry, while the much hotter windward side would be cooled by allowing fuel or water to bleed through micropores in a double-wall stainless steel skin, removing heat by evaporation. The Starhopper had a single engine and was used for a test flight to develop the landing and low-altitude/low-velocity control algorithms.

By late May 2019, while the Starhopper was preparing for untethered flight tests in South Texas, they were building two high-altitude prototypes simultaneously, Mk1 in Texas and Mk2 in Florida. The two ships were constructed by competing teams—that were required to share progress, insights, and build techniques with the other team, but neither team is required to use the other team's techniques. The larger Mk1 and Mk2 test vehicles featured three Raptor methalox engines meant to reach an altitude of no more than 5 km (3.1 mi), and the initial flight was expected no earlier than the first half of 2019. Construction of a Mk3 prototype began in late-2019. A first orbital flight was not expected until Mk4 or Mk5 in mid 2020. The build of the first Super Heavy booster stage was projected to be able to start by September. At the time, neither of the two orbital prototypes yet had aerodynamic control surfaces nor landing legs added to the under construction tank structures, and Musk indicated that the design for both would be changing once again. On 21 September 2019, the externally-visible "moving fins" began to be added to the Mk1 prototype, giving a view into the promised mid-2019 redesign of the aerodynamic control surfaces for the test vehicles.

In July 2019, the Starhopper made its initial flight test, a "hop" of approximately 20 m (66 ft) altitude, and a second and final "hop" in August, reaching an altitude of approximately 150 m (490 ft) and landing approximately 100 m (110 yd) from the launchpad, demonstrating the first use of the Raptor engine in real flight.

Mk1, Mk2, Mk3, Mk4

SpaceX completed the external structure of the Starship Mk1 in time for Musk's public update in September 2019. Watching the construction in progress before the event, observers circulated photos online and speculated about the most visible changes, including a move to two tail fins from the earlier three. During the event, Musk added that landing would now be accomplished on six dedicated landing legs, following a re-entry protected by ceramic heat tiles. Updated specifications were provided: when optimized, Starship was expected to mass at 120,000 kg (260,000 lb) empty and be able to initially transport a payload of 100,000 kg (220,000 lb) with an objective of growing that to 150,000 kg (330,000 lb) over time. Musk suggested that an orbital flight might be achieved by the fourth or fifth test prototype in 2020, using a Super Heavy booster in a two-stage-to-orbit launch vehicle configuration, and emphasis was placed on possible future lunar missions.

In September 2019, Elon Musk unveiled Starship Mk1, and in 20 November 2019, the Mk1 test article came apart in a tank pressure test in Texas. The same day, SpaceX stated they would stop developing Mk1 and Mk2 and move on to work on the Mk3 and Mk4 articles. Construction began on the Starship Mk4 in Florida by mid-October 2019. A few weeks later, the work on the vehicles in Florida paused, with apparent cancellation of Mk4. Some assemblies that had been built in Florida were transported to the Texas assembly location in Boca Chica; there was reportedly an 80% reduction in the workforce at the Florida assembly location as SpaceX paused activities there. SpaceX's Starship development work was now focused on the Texas site.

The Mk1/Mk2 prototype characteristics were:

Mk1/Mk2 prototype characteristics

Size: 9 m (30 ft) diameter by approximately 50 m (160 ft) tall Mk1 empty mass: 200,000 kg (440,000 lb); Gross mass with propellant loaded: 1,400,000 kg (3,100,000 lb) Principal use: prototype test articles for engineering extension of the rocket's powered flight and atmospheric reentry flight envelope, to higher altitudes (>200 meters) and velocities than the two test flights of the Starhopper in summer 2019. Test methodology: vertical-takeoff and vertical-landing suborbital spaceflight. One of many engineering objectives of the early test flights is to recover the test vehicle so that the vehicle can continue to be used on subsequent test flights to further extend the flight envelope. This is a test regime frequently seen with new aircraft, but has rarely been done with orbital spacecraft (the Space Shuttle is an exception), and has never been done on a launch vehicle second stage on powered test flights into the upper atmosphere. Propulsion: (initially) three Raptor methalox engines; may test with up to six engines later in the flight test program Attitude control: For in-atmosphere control: two front actuated fins and two rear actuated fins (also referred to as "moveable fins"). Stability control is via rapid movement of both rear and forward fins during entry and landing, with vernier force control from the attitude control system thrusters. The control surfaces are actuated by "many powerful electric motors and batteries" More specifically, the Mk1 used four Tesla 100 kWh (360 MJ) Lithium-ion battery packs and Tesla Model 3 motors to provide electrohydraulic actuation of the control surfaces. Musk is interested in iterating this to electromechanical actuation in subsequent versions (approximately Mk3) to eliminate the hydraulic accumulator and related inefficiencies. For out-of-atmosphere or upper atmosphere: cold gas nitrogen reaction control system (RCS) thrusters only Nose cone equipment: header tanks for landing, batteries, mounting and reaction control for the front movable fins Starship prototype flight test locations: Texas Florida

Starship SN1 (Mk3) and SN2

On December 2019, Musk announced that the Starship Mk3 would be called "Starship SN1" and there would be at least minor improvements at least through SN20. Musk explained on December 2019, that there was a change in the production of Starship. Some parts are now stamped and TIP TIG welded vs bump-formed and flux core welded. The new production process guarantees stronger joints and a mass reduction of 20%.

In January 2020, SpaceX performed pressurization tests on two test article tanks in Boca Chica. One such test took place on 10 January 2020, when a test tank was intentionally destroyed by over-pressurizing it; the tank achieved pressure of 7.1 bar (710 kPa). Later, another test tank underwent at least two pressurization tests; in the first experiment, on Monday 27 January 2020, the test tank withstand a pressure of 7.5 bar (750 kPa) before springing a leak. The leak was welded and the tank subjected to cryogenic pressure test on 28 January 2020, when the tank was intentionally pressurized until it ruptured and was destroyed at the pressure of 8.5 bar (850 kPa). The test was however considered a success despite the destruction of the tank, as the pressure reached, 8.5 bar (850 kPa), was the pressure the tank needed to hold to be considered safe for human spaceflight; that is, the tank demonstrated a safety factor of 1.4 (1.4 times the operational pressure).

The Starship SN1 (originally known as Starship Mk3) was intended to be "designed for orbit" according to SpaceX. Later on, it was unclear whether this was the case (that SN1 would fly to orbit), and whether Starship SN1 would be used only for static fire testing (with one or more Raptor engines installed) and perhaps for one or more suborbital flights taking the vehicle to a 20 kilometer altitude with a soft landing back to Boca Chica.

SpaceX began construction of internal components for the vehicle in December 2019, and started stacking SN1 at Boca Chica two months later.

SpaceX began stacking SN1 in February 2020 after a series of pressurization tests on propellant tank prototypes. The weld quality of the rings was improved. SN1 failed a pressurization test on 28 February 2020 due to a design failure.

The Starship SN1 vehicle was destroyed while undergoing pressurization testing on 28 February 2020. The vehicle ruptured from the bottom up, with most of the top part of the vehicle sent flying in the air and crashing into ground. At the time of the rupture, the SN1 vehicle had no nose cone or Raptor engines installed, and it was positioned in a test stand. The loss of SN1 was similar to the loss of Starship Mk1 in November 2019, leaving little of the vehicle intact. There were no reports of injuries.

After the incident, SpaceX announced they were focusing their efforts into the next prototype, Starship SN2. SpaceX adjusted their Starship SN2 testing plans to verify that the failure had been corrected, and conducted a successful test using SN2 on 8 March 2020.

Starship SN3 and SN4

In March 2020, Musk discussed SpaceX's future plans for Starship prototype tests. Starship SN3 was planned to be used for static fire tests and short hops, while SN4 will be used for longer flights.

Starship SN3 was destroyed during testing on 3 April 2020.. The cause of the failure was a testing configuration error. The liquid oxygen tanks housed in the lower part of the prototype were pressurised with nitrogen in order to keep them pressurised and structurally capable of withstanding the weight of the full methane tanks undergoing testing. A valve was inadvertently commanded to open resulting in pressure loss and structural failure as the lower portion of the prototype crumbled under the weight of the heavy methane tanks. While Starship SN3 was originally planned to be used for static fire tests and short hops, this setback will end up shifting the future testing timeline. SN4 is being built reusing parts of SN3 not damaged during the mishap.

Starship SN5 and SN6

Later in the spring 2020, SpaceX aims to conduct the long-planned 20 km test flight of Starship. The first orbital test flight of Starship is aspirationally planned to occur before the end of 2020, possibly using SN5 or SN6. Prototyping will continue to accelerate as vehicle production rates increase; SpaceX plans to produce one Starship per week by the end of 2020.

List of vehicles

Starship

A Starship prototype in launch configuration: Starship spacecraft S24 stacked on Super Heavy B7.
Function	General purpose Super-heavy lift launch vehicle
Project cost	At least US$5 billion
Cost per launch	$100 million (expendable)
Size
Height	121.3 m (398 ft)
Diameter	9 m (30 ft)
Mass	5,000,000 kg (11,000,000 lb)
Capacity
Payload to LEO
Mass	100,000–150,000 kg (220,000–330,000 lb)
Volume	1,000 m3 (35,000 cu ft)
Associated rockets
Derivative work	Starship HLS
Comparable	N1 Saturn V Space Shuttle Falcon Heavy Space Launch System Long March 9
Launch history
Status	In development
Launch sites	Starbase, OLM-A Starbase, OLM-B (under construction) Kennedy, LC-39A (under construction) Cape Canaveral, SLC-37 (planned)
Total launches	4
Success(es)	2 (IFT-3 , IFT-4)
Failure(s)	2 (IFT-1, IFT-2)
First flight	20 April 2023 (2023-04-20)
Last flight	6 June 2024 (2024-06-06)
First stage – Super Heavy
Height	71 m (233 ft)
Diameter	9 m (30 ft)
Empty mass	200,000 kg (440,000 lb)
Gross mass	3,600,000 kg (7,900,000 lb)
Propellant mass	3,400,000 kg (7,500,000 lb)
Powered by	33 × Raptor engines
Maximum thrust	74,400 kN (16,700,000 lbf)
Specific impulse	SL: 327 s (3.21 km/s)
Propellant	CH4 / LOX
Second stage – Starship
Height	50.3 m (165 ft)
Diameter	9 m (30 ft)
Empty mass	~100,000 kg (220,000 lb)
Gross mass	1,300,000 kg (2,900,000 lb)
Propellant mass	1,200,000 kg (2,600,000 lb)
Powered by	3 × Raptor engines 3 × Raptor vacuum engines
Maximum thrust	12,300 kN (2,800,000 lbf)
Specific impulse	SL: 327 s (3.21 km/s) vac: 380 s (3.7 km/s)
Propellant	CH4 / LOX

Starship is a two-stage fully reusable super heavy-lift launch vehicle under development by SpaceX. As of September 2024, it is the most massive and powerful vehicle ever to fly. SpaceX has developed Starship with the intention of lowering launch costs using economies of scale. SpaceX aims to achieve this by reusing both rocket stages, increasing payload mass to orbit, returning both stages to be "caught" by the launch tower, increasing launch frequency, creating a mass-manufacturing pipeline and adapting it to a wide range of space missions. Starship is the latest project in SpaceX's reusable launch system development program and plan to colonize Mars.

Starship has two stages: the Super Heavy booster and the Starship spacecraft. Both stages are equipped with Raptor engines, the first mass-produced full-flow staged combustion cycle engines, which burn liquid methane (natural gas) and liquid oxygen. The main structure is made from a special stainless steel alloy that SpaceX has dubbed "30X".

As of 2024, Starship is in development with an iterative and incremental approach, involving test flights of prototype vehicles. As a successor to SpaceX's Falcon 9 and Falcon Heavy rockets, Starship will perform a wide range of space missions. SpaceX plans versions of the Starship spacecraft including: cargo (satellite deployment), tankers to act as depots for in-orbit refueling of other Starships, human spaceflight, landing on the Moon, and eventually landing on Mars. For missions to further destinations, such as geosynchronous orbit, the Moon, and Mars, Starship will rely on orbital refueling from the tanker variant; a ship-to-ship propellant transfer demonstration is expected to occur in 2025 to prove out this critical capability. Starship will deploy SpaceX's second-generation Starlink satellite constellation, and the Starship HLS variant will land astronauts on the Moon as part of the Artemis program, starting with Artemis 3 in 2026.

Description

When stacked and fully fueled, Starship has a mass of approximately 5,000 t (11,000,000 lb), a diameter of 9 m (30 ft) and a height of 121.3 m (398 ft). The rocket has been designed with the goal of being fully reusable to reduce launch costs; it consists of the Super Heavy first-stage booster and the Starship spacecraft which are powered by Raptor and Raptor Vacuum engines. The bodies of both rocket stages are made from stainless steel and are manufactured by stacking and welding stainless steel cylinders. These cylinders have a diameter of 9 m (30 ft) a height of 1.8 m (5 ft 11 in), a thickness of 4 mm (0.16 in) and a mass of 1,600 kg (3,500 lb) each. Domes inside the spacecraft separate the methane and oxygen tanks. SpaceX has stated that Starship, in its "baseline reuseable design", will have a payload capacity of 100–150 t (220,000–331,000 lb) to low earth orbit and 27 t (60,000 lb) to geostationary transfer orbit.

Super Heavy booster

Main article: SpaceX Super Heavy

The first-stage booster, named Super Heavy, is 71 m (233 ft) tall and 9 m (30 ft) wide. It contains 33 Raptor engines arranged in three concentric rings. The outermost ring of 20 engines lack gimbal actuators and onboard startup hardware to save weight. These engines are started using attachments on the launch mount and are not reignited for later burns. At full power, all engines combined produce 74,400 kN (16,700,000 lb_f) of thrust, more than double that of the Saturn V first stage. The 33 individual plumes interact to produce gigantic shock diamonds in the exhaust.

The booster uses four electrically actuated grid fins for control, each with a mass of 3 t (6,600 lb). The booster is lifted from protruding hardpoints, which are located between gridfins. Above the grid fins is the vented interstage, used for hot staging; in which the upper stage fires its engines during stage separation rather than after.

Starship spacecraft

Main article: SpaceX Starship (spacecraft)

The Starship spacecraft is 50.3 m (165 ft) tall and 9 m (30 ft) in diameter. It uses 6 Raptor engines, three of which are optimized for use in vacuum. The engines produce 14,700 kN (3,300,000 lb_f) of thrust. The vehicle's payload bay is planned to measure 17 m (56 ft) tall and 8 m (26 ft) in diameter with an internal volume of 1,000 m³ (35,000 cu ft); slightly larger than the ISS's pressurized volume. Starship has a total propellant capacity of 1,200 t (2,600,000 lb) across its main tanks and header tanks. According to Elon Musk in 2019, the header tanks are better insulated due to their position and are reserved for use to flip and land the spacecraft following reentry. A set of reaction control thrusters, which use the pressure in the fuel tank, control attitude while in space.

Diagram of a V1 Starship's internal structure. Not shown in this diagram are the flaps: the aft flaps are placed at the bottom (or left in this orientation), and the forward flaps are placed at the top (here, right) portion of the spaceship.

The spacecraft has four body flaps to control the spacecraft's orientation and help dissipate energy during atmospheric entry, composed of two forward flaps and two aft flaps. According to SpaceX, the flaps replace the need for wings or tailplane, and reduce the fuel needed for landing. Under the forward flaps, hardpoints are used for lifting and catching the spacecraft via mechanical arms. The flap's hinges are sealed in aero-covers because otherwise, they would be easily damaged during reentry.

Starship is planned to be able to be refueled by docking with separately launched Starship propellant tanker spacecraft in orbit. Doing so could allow it to reach higher-energy targets, such as geosynchronous orbit, the Moon, and Mars. A propellant depot could store methane and oxygen on-orbit, and could be used by Starship HLS to replenish its fuel tanks.

Heat shield

Starship's heat shield is composed of eighteen thousand hexagonal black tiles that can withstand temperatures of 1,400 °C (2,600 °F). It is designed to protect the vehicle during atmospheric entry and to be used multiple times with minimal maintenance between flights. The silica-based tiles are attached to Starship with pins and have small gaps in between to allow for heat expansion. After IFT-4, SpaceX added a secondary ablative layer under the primary heat shield.

Variants

For satellite launch, Starship is planned to have a large cargo door that will open to release payloads, similar to NASA's Space Shuttle, and close upon reentry, instead of using a jettisonable fairing. Instead of a cleanroom, payloads would be integrated directly into Starship's payload bay, which requires purging the payload bay with temperature-controlled ISO class 8 clean air. To deploy Starlink satellites, the cargo door is to be replaced with a slot and dispenser rack, whose mechanism has been compared to a Pez candy dispenser.

Starship HLS

Main article: Starship HLS

Starship Human Landing System (HLS) is a crewed lunar lander variant of the Starship vehicle under development that would be modified for landing, operation, and takeoff from the lunar surface. HLS features landing legs, a body-mounted solar array, a set of thrusters mounted mid-body to assist with final landing and takeoff, two airlocks, and an elevator to lower crew and cargo onto the lunar surface.

In 2021, Musk said that between "four and eight" tanker launches would be required to fully fuel HLS. The same year, the Government Accountability Office said that SpaceX would "require 16 launches overall", and in 2023, a NASA official estimated the number of Starship launches required for one lunar landing to be "in the high teens". In 2024, SpaceX vice president of customer operations estimated that the number of launches would be "10-ish", though this number is subject to change. These launches will reportedly have to be in "rapid succession" in order to manage schedule constraints and cryogenic fuel boil-off. When fully fueled, Starship HLS is designed to land 100 t (220,000 lb) of payload on the Moon.

Raptor engine

Main article: SpaceX Raptor

Sea level-optimized Raptor 1 engine, May 2020

Raptor is a family of rocket engines developed by SpaceX for use in Starship and Super Heavy vehicles. It burns liquid oxygen and methane in an efficient and complex full-flow staged combustion power cycle. The Raptor engine uses methane as fuel rather than kerosene because methane gives higher performance and prevents the build-up of deposits in the engine from coking. Methane can also be produced from carbon dioxide and water using the Sabatier reaction. The engines are designed to be reused many times with little maintenance.

Raptor operates with an oxygen-to-methane mixture ratio of about 3.6:1, lower than the stoichiometric mixture ratio of 4:1 necessary for complete combustion, since operating a higher temperatures would melt the engine. The propellants leave the pre-burners and get injected into the main combustion chamber as hot gases instead of liquid droplets allowing a higher power density as the propellants mix rapidly via diffusion. The methane and oxygen are at high enough temperatures and pressures that they ignite on contact, eliminating the need for igniters in the main combustion chamber. The engine structure itself is mostly aluminum, copper, and steel; oxidizer-side turbopumps and manifolds subject to corrosive oxygen-rich flames are made of an Inconel-like SX500 superalloy. Some components are 3D printed.

At sea level, a Raptor 2 engine produces 2.3 MN (520,000 lbf) at a specific impulse of 327 seconds (3.21 km/s) at sea level and 350 seconds (3.4 km/s) in a vacuum. Raptor Vacuum, used on the Starship upper stage, is modified with a regeneratively cooled nozzle extension made of brazed steel tubes, increasing its expansion ratio to about 90 and its specific impulse in vacuum to 380 seconds (3.7 km/s). The main combustion chamber operates at a pressure of 350 bar (5,100 psi) exceeding that of any prior operational rocket engine. The Raptor's gimbaling range is 15°, higher than the RS-25's 12.5° and the Merlin's 5°. SpaceX has stated they aim to achieve a per unit production cost of US$250,000 upon starting mass-production.

Versions

Performance

Starship metrics	Block 1	Block 2	Block 3
Payload to Orbit (t)	N/A	100+	200+
Booster Prop Load (t)	3300	3650	4050
Ship Prop Load (t)	1200	1500	2300
Booster Liftoff Thrust (tf)	7130	8240	10000
Ship Initial Thrust (tf)	1250	1600	2700
Ship SL Engines	3	3	3
Ship VAC Engines	3	3	6
Booster Height (m)	71	72.3	80.2
Ship Height (m)	50.3	52.1	69.8
Total Height (m)	121.3	124.4	150

On 4 April 2024, Elon Musk provided an update on Starship at Starbase, where two new versions of Starship were announced, Starship 2 and Starship 3.

Starship 1

As of 6 June 2024, Starship 1 has been used for all 4 Integrated Flight Tests.

Starship 2

As of April 2024, exact specifications are not known for the Starship 2 vehicle; however, the V2 ships will feature a thinner forward flap design, a 25% increase in propellant capacity, integrated vented interstage, and an increase in thrust. The vehicle will be a total of 3.1 m (10 ft) taller than the previous V1 vehicle, and is planned to have a payload capacity of at least 100 tons to orbit when reused. Additionally, the engine type will switch to Raptor 3, which removes the need for secondary engine shielding. The capacity to manufacture version 2 became possible as a large portion of the Starfactory was commissioned in 2024.

Starship 3

As of June 2024, the Starship 3 final configuration is unknown. The most recent configuration, as described in regulatory filings submitted to the FAA, has a height of 150 m (490 ft). The Starship second stage will feature 9 Raptor engines, while the Super Heavy booster will have up to 35. It is planned to have a payload capacity of at least 200 tons to orbit when reused.

Planned launch and landing profile

Animation of Super Heavy's integration to the launch mount, using mechanical arms.

Payloads are planned to be integrated into Starship at a separate facility and then rolled out to the launch site. Super Heavy and Starship are then to be stacked onto their launch mount and loaded with fuel via the ship quick disconnect (SQD) arm and booster quick disconnect (BQD). The SQD and BQD retract, all thirty-three engines of Super Heavy ignite, and the rocket lifts off.

A short animation of Super Heavy's landing on mechanical arms. The actual landing speed is a few times slower.

At approximately 159 seconds after launch at an altitude of roughly 64 km (40 mi), Super Heavy cuts off all but three of its center gimbaling rocket engines. Starship then ignites its engines while still attached to the booster, and separates. During hot-staging, the booster throttles down its engines. The booster then rotates, before igniting ten additional engines for a "boostback burn" which stops all forward velocity. 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, it ignites its inner 13 engines, then shuts off all but the inner 3, to perform a landing burn which slows it sufficiently to be caught by a pair of hydraulic actuating arms attached to the launch tower.

Meanwhile, the Starship spacecraft continues to accelerate to orbital velocity with its six Raptor engines. Once in orbit, the spacecraft is planned to be able to be refueled by another Starship tanker variant. Musk has estimated that 8 launches would be needed to completely refuel a Starship in low Earth orbit. NASA has estimated that 16 launches in short succession (due to cryogenic propellant boil-off) would be needed to partially refuel Starship for one lunar landing. To land on bodies without an atmosphere, such as the Moon, Starship will fire its engines to slow down. To land on bodies with an atmosphere, such as the Earth and Mars, Starship first slows by entering the atmosphere via a heat shield. The spacecraft would then perform a "belly-flop" maneuver by diving back through the atmosphere body at a 60° angle to the ground, controlling its fall using four flaps at the front and aft of the spacecraft. Shortly before landing, the Raptor engines fire, using fuel from the header tanks, to perform a "landing flip" maneuver to return to a vertical orientation, with the Raptor engines' gimbaling helping to maneuver the craft. Lunar and tanker variants do not reenter the atmosphere and thus do not have a thermal protection system.

If Starship's second stage lands on a pad, a mobile hydraulic lift will move it to a transporter vehicle. If it lands on a floating platform, it will be transported by a barge to a port and then transported by road. The recovered Starship will either be positioned on the launch mount for another launch or refurbished at a SpaceX facility.

Development

See also: List of Starship launches

Early design concepts (2012–2019)

Main article: SpaceX Starship design history

SpaceX CEO Elon Musk holding a model of BFR.

In November 2005, before SpaceX had launched its first rocket the Falcon 1, CEO Elon Musk first mentioned a high-capacity rocket concept able to launch 100 t (220,000 lb) to low Earth orbit, dubbed the BFR. Later in 2012, Elon Musk first publicly announced plans to develop a rocket surpassing the capabilities of their existing Falcon 9. SpaceX called it the Mars Colonial Transporter, as the rocket was to transport humans to Mars and back. In 2016, the name was changed to Interplanetary Transport System, as the rocket was planned to travel beyond Mars as well. The design called for a carbon fiber structure, a mass in excess of 10,000 t (22,000,000 lb) when fully fueled, a payload of 300 t (660,000 lb) to low Earth orbit while being fully reusable. By 2017, the concept was temporarily re-dubbed the BFR.

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, and the booster Super Heavy. They also announced that Starship would use reusable heat-shield tiles similar to those of the Space Shuttle. The second-stage design had also settled on six Raptor engines by 2019: three optimized for sea-level and three optimized for vacuum. In 2019 SpaceX announced a change to the second stage's design, reducing the number of aft flaps from three to two in order to reduce weight. In March 2020 SpaceX released a Starship Users Guide, in which they stated the payload of Starship to LEO would be in excess of 100 t (220,000 lb), with a payload to GTO of 21 t (46,000 lb).

Low-altitude flight tests (2019–2021)

Further information: SpaceX Starship (spacecraft) § Hops (SN3–SN6), and SpaceX Starship (spacecraft) § High-altitude test flights (SN8–SN15)

Starhopper to SN6

Starhopper under construction, March 2019

A crane lifting Starship SN5, August 2020

The first tests started with the construction of the first prototype in 2018, Starhopper, which performed several static fires and two successful low-altitude flights in 2019. SpaceX began constructing the first full-size Starship Mk1 and Mk2 upper-stage prototypes before 2019, at the SpaceX facilities in Boca Chica, Texas, and Cocoa, Florida, respectively. Neither prototype flew: Mk1 was destroyed in November 2019 during a pressure stress test and Mk2's Florida facility was deconstructed throughout 2020.

After the Mk prototypes, SpaceX began naming its new Starship upper-stage prototypes with the prefix "SN", short for "serial number". No prototypes between SN1 and SN4 flew either—SN1 and SN3 collapsed during pressure stress tests, and SN4 exploded after its fifth engine firing.

In June 2020, SpaceX started constructing a launch pad for orbital Starship flights. The first flight-capable prototype, SN5, was cylindrical as it had no flaps or nose cone: just one Raptor engine, fuel tanks, and a mass simulator. On 5 August 2020, SN5 performed a 150 m (500 ft) high flight and successfully landed on a nearby pad. On 3 September 2020, the similar-looking Starship SN6 repeated the hop; later that month, a Raptor Vacuum engine underwent its first full duration firing at McGregor, Texas.

SN8 to SN15

SN8 shortly after taking off, December 2020

Computer animation depicting a successful high-altitude flight test

Starship SN8 was the first full-sized upper-stage prototype, though it lacked a heat shield. It underwent four preliminary static fire tests between October and November 2020. On 9 December 2020, SN8 flew, slowly turning off its three engines one by one, and reached an altitude of 12.5 km (7.8 mi). After SN8 dove back to the ground, its engines were hampered by low methane header tank pressure during the landing attempt, which led to a hard impact with the landing pad and subsequent explosion of the vehicle.

Because SpaceX had violated its launch license and ignored warnings of worsening shock wave damage, the Federal Aviation Administration investigated the incident for two months. During the SN8 launch, SpaceX ignored FAA warnings that the flight profile posed a risk of explosion. FAA space division chief Wayne Monteith said SpaceX's violation was “inconsistent with a strong safety culture", and criticized the company for proceeding with the launch "based on 'impressions' and 'assumptions,' rather than procedural checks and positive affirmations".

On 2 February 2021, Starship SN9 launched to 10 km (6.2 mi) in a flight path similar to SN8. The prototype crashed upon landing because one engine did not ignite properly. A month later, on 3 March, Starship SN10 launched on the same flight path as SN9. The vehicle landed hard and crushed its landing legs, leaning to one side. A fire was seen at the vehicle's base and it exploded less than ten minutes later, potentially due to a propellant tank rupture. On 30 March, Starship SN11 flew into thick fog along the same flight path. The vehicle exploded during descent, possibly due to excess propellant in a Raptor's methane turbopump.

In March 2021, the company disclosed a public construction plan for two sub-orbital launch pads, two orbital launch pads, two landing pads, two test stands, and a large propellant tank farm. The company soon proposed developing the surrounding Boca Chica Village, Texas, into a company town named Starbase. Locals raised concerns about SpaceX's authority, power, and a potential threat for eviction through eminent domain.

In early April, the orbital launch pad's fuel storage tanks began mounting. SN12 through SN14 were scrapped before completion; SN15 was selected to fly instead, due to improved avionics, structure, and engines. On 5 May 2021, SN15 launched, completed the same maneuvers as older prototypes, and landed safely. SN15 had a fire in the engine area after landing but it was extinguished. According to a later report by SpaceX, SN15 experienced several issues while landing, including the loss of tank pressure and an engine.

Integrated flight tests (2023–)

First integrated flight test

Main article: Starship flight test 1

Starship during the first integrated flight attempt. Several engines failed on the first stage.

In July 2021, Super Heavy BN3 conducted its first full-duration static firing and lit three engines. Around this time, SpaceX changed their naming scheme from "SN" to "Ship" for Starship crafts, and from "BN" to "Booster" for Super Heavy boosters. A month later, using a large crane, Ship 20 was stacked atop Booster 4 to form the full launch vehicle for the first time; Ship 20 was also the first craft to have a body-tall heat shield. In October 2021, the catching mechanical arms, also known as "chopsticks", were installed onto the integration tower and the first tank farm's construction was completed.

In June 2022, the Federal Aviation Administration determined that SpaceX must address more than 75 issues identified in the preliminary environmental assessment. In July, Booster 7 tested the liquid oxygen turbopumps on all thirty-three Raptor engines, resulting in an explosion at the vehicle's base, which destroyed a pressure pipe and caused minor damage to the launchpad. By the end of November, Ship 24 had performed 2- and full 6-engine static test fires, while Booster 7 had performed static fires with 1, 3, 7, 14, 11 engines and finally on 9 February 2023, a static fire with 31 engines at 50% throttle. In January 2023, the whole Starship stack underwent a full wet dress rehearsal.

After a launch attempt aborted on 17 April 2023, Booster 7 and Ship 24 lifted off on 20 April 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 booster later lost thrust vectoring control of the Raptor engines, which led to the rocket spinning out of control. The vehicle reached a maximum altitude of 24 mi (39 km). Approximately 3 minutes after lift-off the rocket's autonomous flight termination system was activated, though the vehicle tumbled for another 40 seconds before disintegrating. The first flight test blasted large amounts of sand and soil in the air, reaching communities within a 10.7 km (6.6 mi) radius. A brushfire on nearby state parkland also occurred, burning 3.5 acres of state parkland.

Second integrated flight test

Main article: Starship flight test 2

Starship during the second integrated flight attempt

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.

In August, SpaceX submitted to the FAA the 63 corrective actions they had to take before another launch could take place. Following SpaceX's final report, the FAA closed the investigation on 8 September 2023. By 31 October 2023, the FAA had concluded the safety review portion of the launch license.

On 18 November 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 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.

The second stage continued until it reached an altitude of ~149 kilometres (93 mi), after over eight minutes of flight; prior to engine cutoff, telemetry was lost on the second stage. SpaceX said that a safe command based on flight performance data triggered the flight termination system and destroyed the second stage, prior to achieving its planned orbit or attempting re-entry. It appeared to re-enter a few hundred miles north of the Virgin Islands, according to NOAA weather radar data.

Third integrated flight test

Main article: Starship flight test 3

Video of Starship during the third integrated flight attempt

Following the second flight test (which saw the loss of both stages), significant changes were implemented, including upgrading Starship's thrust vector control system to electric thrust vector control (TVC) and measures to delay liquid oxygen (LOX) venting until after Starship engine cutoff (SECO) has taken place.

IFT-3 launched from the SpaceX Starbase facility along the South Texas coast around 8:25 CDT on 14 March 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 in the Gulf of Mexico was not successful, as it exploded at 462 m (1,516 ft) above the surface.

The Starship spacecraft itself – after reaching space and orbital velocity – conducted several tests after engine cutoff, including initiating a propellant transfer demo and payload dispenser test. It attempted to re-enter the atmosphere, and at an altitude of around 65 km (40 mi), all telemetry from Ship 28 stopped, indicating a loss of the vehicle. This flight test demonstrated a cryogenic propellant transfer, by transferring propellant from the Ship's header tanks into its main tanks while in space, a technology which is required for Starship HLS to exit low earth orbit (LEO). The result of this test was declared successful by NASA and SpaceX. Additional data analysis is occurring on the fluid dynamics such as slosh and boil-off of the propellant.

Fourth integrated flight test

Main article: Starship flight test 4

The fourth integrated flight test of the full Starship configuration launched on 6 June 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, and for the Ship to survive peak heating during atmospheric reentry. The flight test was successful in both regards, with Super Heavy achieving a soft splashdown and Ship surviving atmospheric reentry and a controlled splashdown.

Fifth integrated flight test

Main article: Starship flight test 5

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. As of September 2024, IFT-5 is expected to occur in September. A tower catch of the Super Heavy booster is planned for this flight. SpaceX claimed that B12 and S30 were ready to launch in early August, in advance of regulatory approval.

Sixth integrated flight test

Main article: Starship flight test 6

Vehicle testing commenced in May 2024, and in July Ship 31, slated for flight 6, completed a successful cryogenic test.

Cost and funding

SpaceX develops the Starship primarily with private funding. SpaceX Chief Financial Officer Bret Johnsen disclosed in court that SpaceX has invested more than $3 billion into the Starbase facility and Starship systems from July 2014 to May 2023. Elon Musk stated in April 2023 that SpaceX expected to spend about $2 billion on Starship development in 2023.

Musk has theorized that a Starship orbital launch might eventually cost SpaceX only $1 million to launch. Eurospace's director of research Pierre Lionnet stated in 2022 that Starship's launch price to customers would likely be higher because of the rocket's development cost.

As part of the development of the Human Landing System for the Artemis program, SpaceX was awarded in April 2021 a $2.89 billion fixed-price contract from NASA to develop the Starship lunar lander for Artemis III. Blue Origin, a bidding competitor to SpaceX, disputed the decision and began a legal case against NASA and SpaceX in August 2021, causing NASA to suspend the contract for three months until the case was dismissed in the Court of Federal Claims. Two years later Blue Origin was awarded a $3.4 billion fixed-price contract for their lunar lander.

In 2022, NASA awarded SpaceX a $1.15 billion fixed-price contract for a second lunar lander for Artemis 4. The same year, SpaceX was awarded a $102 million five-year contract to develop the Rocket Cargo program for the United States Space Force.

Launch History

Starship vehicles have been launched 4 times over 1 year, resulting in 2 full successes (50%), and two in-flight failures (IFT-1, IFT-2).

Starship 1 has been launched four times between April 2023 to June 2024, and will be replaced by Starship 2 after another two flights.

Launch sites

1

2

2023

2024

2025

•   Starbase, OLM-A
•   Starbase, OLM-B
•   Kennedy, LC-39A
•   Cape Canaveral, SLC-37

Launch outcomes

2

4

2023

2024

2025

•   Failure
•   Partial failure
•   Success
•   Planned

Booster landings

1

2

2023

2024

2025

•   Precluded
•   Ocean failure
•   Tower failure
•   Ocean success
•   Tower success
•   No attempt

Spacecraft landings

1

2

2023

2024

2025

•   Precluded
•   Ocean failure
•   Tower failure
•   Ocean success
•   Tower success
•   No attempt

Vehicle variants

1

2

2023

2024

2025

•   Starship 1
•   Starship 1.5
•   Starship 2
•   Starship 3
•   Starship Crew
•   Starship HLS

Potential missions

Starlink

SpaceX plans to use Starship to launch the second generation of satellites for SpaceX's Starlink system, which currently delivers high-speed internet to over 70 countries. An analyst at financial services company Morgan Stanley stated development of Starship and Starlink are intertwined, with Starship's planned launch capacity enabling cheaper Starlink launches, and Starlink's profits financing Starship's development costs. In deficit from its inception until the end of 2022, Starlink was first reported to be cash flow positive in the first quarter of 2023, though Elon Musk said that Starlink had only reached "break-even cashflow" in 2023. In December 2023, the FCC issued a final denial of a $885M Starlink subsidy because of Starlink's "continuing inability to successfully launch on the Starship rocket".

Artemis 3 launch profile of a human landing on the Moon, involving Starship HLS, Starship tanker variants, and Orion spacecraft

Artemis Program

Starship HLS was initially chosen by NASA as the sole lunar Human Landing System for the planned Artemis 3 and Artemis 4 crewed missions, as part of the Artemis program. Starship HLS is to be launched into a low Earth orbit, and refueled by multiple Starship tanker spacecraft. Once fueled, it would perform a trans lunar injection burn and enter a near-rectilinear halo orbit around the Moon, with a perilune of 1,500 km (930 mi) occurring over the north pole and an apolune of 70,000 km (43,000 mi) occurring over the south pole. The Orion spacecraft would then dock with Starship HLS and two of its four crew would transfer into Starship HLS. Starship HLS would then use its engines to make a powered descent and land near the lunar south pole. After the crew performs the surface portion of their mission, the HLS would ascend with the crew. The crew would then transfer into the Orion spacecraft and return to Earth.

Astronomy

Astronomers have called to consider Starship's larger mass to orbit and wider cargo bay for proposed space telescopes such as LUVOIR, and to develop larger telescopes to take advantage of these capabilities. Starship's 9 m (30 ft) fairing width could hold an 8 m (26 ft) wide space telescope mirror in a single piece, alleviating the need for complex unfolding such as that of the JWST's 6.5 m (21 ft) mirror, which added cost and delays. Ariane 5 imposed a ~6,500 kg limit on the telescope's weight. Whereas Starship's low launch cost could also allow probes to use heavier, more common, cheaper materials, such as glass instead of beryllium for large telescope mirrors. With a 5 t (11,000 lb) mirror built using similar methods to the Hubble Space Telescope's mirror, the JWST would represent only 10% of the mass deliverable by a (refueled) Starship to the Sun–Earth L2 point, and therefore minimizing the weight of the telescope would not have been a dominant design consideration.

The National Academies of Science's 2020 survey recommended the Habitable Worlds Observatory (HWO); the space observatory, requiring a super heavy lift launch vehicle, will search for signs of life on exoplanets. The HWO's team hope for the success of big launchers due to their critical importance to the HWO's mission. Lee Feinberg, NASA HWO lead architect and JWST manager, stays in communication with SpaceX to track Starship's progress and has visited them in 2024 for that same purpose. The NASA Habitable Worlds Observatory will have a 6-8 meter mirror for now, but its design should be flexible to leverage launchers with potentially double the mass and volume by the time it launches in the 2040s. Former NASA JPL architect Casey Handmer believes the HWO to be far too conservative compared to what is possible with Starship. Handmer argues that Starship enables telescopes to scale up to the point of surface-level exoplanet imaging, perhaps big enough to detect seasonal migration patterns.

Rocket cargo

Main article: Rocket Cargo

In January 2022, SpaceX was awarded a $102 million five-year contract to develop the Rocket Cargo program for the United States Space Force. The five-year contract is intended to "determine exactly what a rocket can achieve when used for cargo transport", and will see the Air Force Research Laboratory collect data during commercial launches of Starship. The contract includes an eventual demonstration mission with the launch and landing of a cargo-laden Starship in a point-to-point flight.

The Department of Defense has planned a test with Starship as part of their program to demonstrate the ability to rapidly deploy up to 100 tons of cargo and supplies, a capability it calls point to point delivery (P2PD). The test is envisioned to take place in FY25 or FY26.

Mars Sample Return

In 2024, the NASA-ESA Mars Sample Return project, one of NASA's highest priority flagship projects, suffered a setback when an independent review board assessing the project's feasibility concluded that the project could not complete under its mission profile. In April 2024, the Administrator of NASA then announced that a new mission profile was needed for the project and that NASA would turn to industry for proposals, with responses due in fall 2024, and high emphasis on lower total cost and lower risk. Starship was widely seen as a leading candidate to serve as a central component of the new mission profile architecture.

Other missions

One future payload is the Superbird-9 communication satellite, which was Starship's first contract for externally made commercial satellites. Another planned payload is the Starlab space station, which Starship will launch in a single piece.

In the future, the spacecraft's crewed version could be used for space tourism—for example, for the third flight of the Polaris program.

Research conducted by Project Lyra determined that with refueling in LEO, a Starship could send a spacecraft to Oumuamua with a journey taking 20 years. A gravity assist would be required at Jupiter.

Potential use cases

Space science

Opinions differ on how Starship's planned low launch cost could affect the cost of space science. According to Waleed Abdalati, former NASA Chief Scientist, the planned low launch cost could reduce the cost of satellite replacement and enable more ambitious missions for budget-limited programs due to the higher percentage of the total budget taken up by launch costs for lower budget missions. According to Lionnet, low launch cost might not reduce the overall cost of a science mission significantly: of the Rosetta space probe and Philae lander's mission cost of $1.7 billion, the cost of launch (by the expendable Ariane 5) only made up ten percent. Similarly the Juno mission had a total budget of $1.13 billion, with launch cost of $190 million making up only seventeen percent of the budget.

A fully refueled Starship could launch 100 t (220,000 lb) observatories to the Moon and the Sun–Earth L2 Lagrange point. A fully refueled Starship might also be capable of launching probes to Neptune, Jupiter's moon Io, or large sample-return missions. Astrophysicists have noted Starship could deploy multiple antennae up to 30 m (98 ft) in length, opening up radio astronomy to frequencies below 30 MHz and wavelengths greater than 10 m (33 ft). This would give the ability to study the Universe's Dark Ages, unfeasible on Earth due to the atmosphere and human radio background.

Transportation

One possible future use of Starship that SpaceX has proposed is point-to-point flights (called "Earth to Earth" flights by SpaceX), traveling anywhere on Earth in under an hour. Musk stated that SpaceX would complete hundreds of cargo flights before launching with human passengers.

Space colonization

Further information: SpaceX ambition of colonizing Mars

According to SpaceX, Starship is intended to be able to land crews on Mars, though SpaceX has not published technical plans or designs about Starship's life support systems, radiation protection, docking system, or in-orbit refueling system for Mars. The spacecraft would be launched to low Earth orbit and refueled in orbit before heading to Mars. After landing on Mars, the Sabatier reaction could be used to synthesize liquid methane and liquid oxygen, Starship's fuel, in a power-to-gas plant. The plant's raw resources would be Martian water and Martian carbon dioxide. On Earth, similar technologies could be used to make carbon-neutral propellant for the rocket. To date, there has been one proof of concept experiment (MOXIE) demonstrating the extraction of oxygen from Martian carbon dioxide, with George Dvorsky writing for Gizmodo commenting that we are not "remotely close" to turning this "into something practical".

SpaceX and Musk have stated their goal of colonizing Mars to ensure the long-term survival of humanity, with an ambition of having sent one million people to Mars by 2050. In March 2022, he estimated that the first crewed Mars landing could occur in 2029. This timeline has been criticized as unrealistic by Kevin Olsen, a physicist at the University of Oxford who has said that "colony needs to become a factory" to produce air, fuel and water as it is "fundamentally impossible to create a completely closed environment in space", and that the technology to do so is "far, far behind the technology of space flight and habitation construction". Serkan Saydam, a mining engineering professor from the University of New South Wales stated that humanity currently lacks the necessary technology to establish a Martian colony, and will likely lack the capacity to establish a Martian city with one million people by 2050.

Facilities

Further information: SpaceX Starbase and SpaceX facilities

Testing and manufacturing

Ship 27, Ship 26 and Booster 10 forward section under construction in Starbase build site, March 2023

Starbase consists of a manufacturing facility and launch site, and is located at Boca Chica, Texas. Both facilities operate twenty-four hours a day. A maximum of 450 full-time employees may be onsite. The site is planned to consist of two launch sites, one payload processing facility, one seven-acre solar farm, and other facilities. The company leases Starbase's land for the STARGATE research facility, owned by the University of Texas Rio Grande Valley. It uses part of it for Starship development.

Raptor engines are tested at the Rocket Development facility in McGregor, Texas. The facility has two main test stands: one horizontal stand for both engine types and one vertical stand for sea-level-optimized rocket engines. In the future, a nearby factory, which as of September 2021 was under construction, will make the new generation of sea-level Raptors while SpaceX's headquarters in California will continue building the Raptor Vacuum and test new designs.

At Florida, a facility at Cocoa purifies silica for Starship heat-shield tiles, producing a slurry that is then shipped to a facility at Cape Canaveral. In the past, workers constructed the Starship Mk2 prototype in competition with Starbase's crews. The Kennedy Space Center, also in Florida, is planned to host other Starship facilities, such as a Starship launch site at Launch Complex 39A and a production facility at Roberts Road. This production facility is being expanded from "Hangar X", the Falcon rocket boosters' storage and maintenance facility. It will include a 30,000 m² (320,000 sq ft) building, loading dock, and a place for constructing integration tower sections. Adjacent to the Kennedy Space Center will be an additional launch site at Cape Canaveral Space Launch Complex 37, likely to service missions for the complex owner, the United States Space Force.

Launch sites

Starbase

The orbital launch mount under construction in Starbase, August 2021

Starbase is planned to host two launch sites, named Pad A and Pad B. A launch site at Starbase has large facilities, such as a tank farm, an orbital launch mount, and an integration tower. Smaller facilities are present at the launch site: tanks surrounding the area containing methane, oxygen, nitrogen, helium, hydraulic fluid, etc.; subcoolers near the tank farm cool propellant using liquid nitrogen; and various pipes are installed at large facilities. Each tank farm consists of eight tanks, enough to support one orbital launch. The current launch mount on Pad A has a water-powered flame diverter, twenty clamps holding the booster, and a quick disconnect mount providing liquid fuel and electricity to the Super Heavy booster before it lifts off.

The integration tower or launch tower consists of steel truss sections, a lightning rod on top, and a pair of mechanical arms that can lift, catch and recover the booster. The decision to catch the booster with the arms rather than landing with landing legs was made to enable flights and reduce the rocket's mass and part count. The mechanical arms are attached to a carriage and controlled by a pulley at the top of the tower. The pulley is linked to a winch and spool at the base of the tower using a cable. Using the winch and the carriage, the mechanical arms can move vertically, with support from bearings attached at the sides of the carriage. A linear hydraulic actuator moves the arms horizontally. Tracks are mounted on top of arms, which are used to position the booster or spacecraft. The tower is mounted with a quick disconnect arm extending to and contracting from the Starship spacecraft; its functions are similar to the quick disconnect mount that powers the booster.

Florida

Starship launch tower construction can be seen (right) at LC-39A in January 2024 as Falcon 9 launches continue to take place

SpaceX has been constructing a Starship launch pad at Kennedy Space Center Launch Complex 39A (LC-39A) since 2021. The site was leased to the company in 2014 and is used to launch Falcon 9 rockets. In 2024, the Federal Aviation Administration began the process of preparing an environmental impact statement (EIS) evaluating the potential impacts of the new infrastructure and a higher launch cadence of up to 44 per year at LC-39A.

In June 2024, Blue Origin and United Launch Alliance (ULA) provided comments as part of the EIS process, both objecting to the impact that Starship launch operations may have on their own activities at the site. Blue Origin suggested several mitigations, including allowing other operators to object to a Starship launch that would conflict with one of its own, limiting Starship operations to particular times, or expanding the number of launchpads in the area to reduce the impact of conflicting launches. ULA suggested regulators prevent Starship from launching in Florida altogether because a fully fueled Starship would require an evacuation zone so large that it would prevent other operators from using their facilities, and the noise generated by repetitive launches could be injurious to those who live or work nearby. Elon Musk suggested that the two companies' comments were disingenuous and that their true motivation was to impede SpaceX’s progress by lawfare.

The company has also proposed building another Starship launch pad at the nearby Cape Canaveral Space Launch Complex 37 (SLC-37) which became vacant in 2024 after the retirement of the Delta IV rocket. That year, the United States Space Force began the process of preparing an EIS evaluating the potential impacts of new infrastructure and a launch cadence of up to 76 times per year at SLC-37.

Both EIS processes must be complete before SpaceX will be cleared to launch Starship from Florida, which likely won't occur until late 2025. The towers and mechanical arms at the sites should be similar to the one at Starbase, with improvements gained from the experience at Boca Chica.

Responses to Starship development

Further information: SpaceX Starbase § Impact

In order to compete with SpaceX and close their technological gap with the company, the China Aerospace Science and Tech Corp and other aerospace actors in China have reportedly been working on their own equivalent of Starship – the Long March 9 super-heavy lift rocket, which is also designed to eventually be fully reusable. In 2021, the China Academy of Launch Vehicle Technology (CALT) showed a rendered video of a rocket noted to be "strikingly" similar to Starship in appearance and function. In a 2022 event organized by the International Astronautical Federation and the Chinese Society of Astronautics, the CALT communicated performing research on a crewed launch vehicle powered by LOX-methane propellant, with a second stage that was very similar to Starship's.

SpaceNews noted that the Chinese start-up Space Epoch and engine maker Jiuzhou Yunjian were developing a smaller Starship-like rocket with a methane-LOX engine similar to Raptor, stainless steel tanks and an iterative design. Starship's reusability and stainless-steel construction might also have inspired Project Jarvis, a reusable upper stage for Blue Origin's New Glenn heavy-lift launch vehicle intended to replace New Glenn's expendable upper stage in the future.

In 2021, members of Congress voiced concerns about the FAA's response to SpaceX's launch license violations following the explosion of SN8, calling on the FAA to "resist any potential undue influence on launch safety decision-making". In 2023, prior to Starship's second orbital test flight, SpaceX's vice president and ex-NASA engineer Bill Gerstenmaier made statements at the U.S. Senate on the importance of innovation in light of "strategic competition from state actors like China". He said SpaceX was under a contract with NASA to use Starship to land American astronauts on the moon before China does, and that the Starship test flights campaign was being held up by "regulatory headwinds and unnecessary bureaucracy" unrelated to public safety.

Following the second integrated flight test of Starship, the Government Accountability Office (GAO) made recommendations to the FAA to "improve its mishap investigation process", finding that historically they have allowed the launch operator to conduct their own investigation with the FAA supervising.

Several environmental groups have filed lawsuits against the FAA and SpaceX, claiming that environmental reviews were bypassed due to Musk's political and financial influence.

See also

• Comparison of orbital launch systems
• Comparison of orbital launcher families
• SpaceX reusable launch system development program

External links

• Programmatic Environmental Assessment by the Federal Aviation Administration
• Starship of SpaceX on eoPortal directory, administered by the European Space Agency
• Ringwatchers Frequently updated reporting on the Starship program
• Tim Dodd's Starship interviews with Elon Musk on YouTube:
  • A conversation with Elon Musk about Starship, 2019
  • Starbase and Starship tour, 2021: part 1, part 2, and part 3
  • Launch tower and Raptor engine tour, 2022: overview, launch infrastructure, Raptor engine
  • Starfactory tour, 2024: [1]
  • IFT-4 Pre- and post-launch interview: [2]

See also

• List of Starship flights
• SpaceX Starship