SpaceX Starship

The Starship system is a fully reusable, two‑stage‑to‑orbit super heavy‑lift launch vehicle under development by SpaceX. This system is composed of a booster stage named Super Heavy and a second stage, also called "Starship". Unusual for a traditional launch vehicle second stage, the Starship second stage is being designed to be a long‑duration cargo and passenger‑carrying spacecraft. 
Development of the Raptor rocket engine began in 2012, while vehicle development began in 2016 as a self‑funded private spaceflight project. Testing of the Starship second stage began in 2019 as part of an extensive development program to prove out launch‑and‑landing and iterate on a variety of design details, particularly for the vehicle's atmospheric re-entry. The early three prototypes did low‑altitude, low‑velocity flight tests of vertical launches and landings in 2019‑2020. On 9 December 2020, Starship prototype SN8 performed the first high‑altitude test flight, demonstrating most of the atmospheric re‑entry profile in the lower atmosphere. The test was deemed successful by SpaceX, although a hard landing led to the destruction of the vehicle. More prototype Starships have been constructed as the iterative design progresses. Both the Starship upper stage and the Super Heavy booster stage are constructed with a stainless steel hull in diameter.
In June 2019, SpaceX indicated they could potentially launch commercial payloads using Starship as early as 2021. In April 2020, NASA selected a modified crew‑rated Starship system as one of three potential lunar landing system design concepts to receive funding for a 10‑month‑long initial design phase for the NASA Artemis program. As of March 2021, SpaceX is conducting atmospheric flights to altitudes of with the Starship prototypes. On 16 April 2021, NASA contracted SpaceX to develop a modified Starship vehicle to serve as the lunar lander in the Artemis program, although the contract is on hold. 
On 5 May 2021, Starship SN15, the fifth Starship prototype equipped with 3 Raptor engines, completed a test flight to , successfully landed, and was recovered.
Nomenclature.
The name of the vehicle changed many times after its first announcement and during the first several years of development. At least as early as 2005, SpaceX used the codename "BFR" for a conceptual heavy‑lift vehicle, "far larger than the Falcon family of vehicles", with a goal of to orbit. Beginning in mid‑2013, SpaceX referred to both the mission architecture and the vehicle as "Mars Colonial Transporter". By the time a large diameter design concept was unveiled in September 2016, SpaceX had begun referring to the overall system as the Interplanetary Transport System.
With the announcement of a new design in September 2017, SpaceX resumed referring to the vehicle as "BFR", with Musk stating "we are searching for the right name but the code name, at least, is BFR". SpaceX President Gwynne Shotwell subsequently stated that BFR stands for "Big Falcon Rocket". However, Elon Musk had explained in the past that although BFR is the official name, he drew inspiration from the BFG weapon in the "Doom" video games. The BFR had also occasionally been referred to informally by the media and internally at SpaceX as "Big Fucking Rocket". At the time, the second stage/spacecraft was referred to as "BFS" (Big Falcon Ship or Big Fucking Ship). The booster's first stage was also at times referred to as the "BFR" (Big Falcon Rocket or Big Fucking Rocket). 
In November 2018, the spaceship was renamed Starship and the first stage booster was named Super Heavy.
The whole system, with the booster stage and spaceship, is also referred to as "Starship". The combination of Starship spacecraft and Super Heavy booster is called the "Starship system" by SpaceX in their payload users guide. The term "Super Heavy" had also been previously used by SpaceX in a different context. In February 2018, at about the time of the first Falcon Heavy launch, Musk had suggested the possibility of a Falcon Super Heavy—a Falcon Heavy with extra boosters.
History.
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). 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, to fully test the engines under orbital spaceflight conditions; however, any colonization effort was then reported to continue to be "deep into the future".
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). In September 2017, at the 68th annual meeting of the International Astronautical Congress, SpaceX unveiled an updated vehicle design.
In September 2018 Musk showed another redesigned concept for the 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. He also announced a planned 2023 lunar circumnavigation mission, a private spaceflight called "dearMoon project". The two major parts of the launch vehicle were given descriptive names in November 2018: "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 January 2019, Musk announced that Starship would no longer be constructed out of carbon fiber and that stainless steel would be used instead, citing several reasons including cost, strength, and ease of production. Later in May SpaceX changed the Starship design back to using just six Raptor engines, with three of the engines optimized for sea‑level and three optimized for vacuum. Later that month, an initial test article, "Starhopper", was being finished for untethered flight tests at the SpaceX South Texas launch site, while two "orbital prototypes" without aerodynamic control surfaces were under construction, one in South Texas and one on the Florida Space Coast. The following month, SpaceX publicly announced that discussions had begun with three telecommunications companies for using Starship, rather than Falcon 9, for launching commercial satellites in 2021. No specific companies or launch contracts were announced at that time.
"Starhopper" made two flights in July 2019, first to an altitude of , and then to . In September 2019, Musk unveiled Starship Mk1, a more advanced test article. Mk1 was destroyed in a tank pressure test that November. SpaceX subsequently abandoned the Mk2 prototype and moved on to Mk3.
Adopting a new "serial number" nomenclature, Mk3 was renamed to Starship SN1. In February 2020, Starship SN1 was also destroyed during a pressurization test. A stripped-down test tank, Starship SN2, was assembled and pressure-tested successfully. The next prototype, Starship SN3, was destroyed due to a test configuration error in April 2020. 
On 26 April 2020, Starship SN4 completed a cryogenic proof test, and on 5 May, SN4 conducted a static fire test with a single Raptor engine. SN4 would perform three more static fire tests (each a few seconds in duration) before it was destroyed in an explosion caused by a propellant leak. 
On 4 August 2020 Starship SN5 completed a flight to an altitude of , landing at an adjacent landing pad. One month later, SN6 would replicate SN5's flight successfully.
Musk declared in June 2020 that Starship was by then the top SpaceX priority, except for anything related to a reduction of Crew Dragon return risk for the upcoming Crew Dragon Demo‑2 flight to the ISS, and remained so in September 2020. In September 2020, Musk clarified that SpaceX intends to exclusively fly cargo transport missions initially and that passenger flights would come only much later.
In July 2020, SpaceX procured two deepwater oil rigs from Valaris for $3.5 million each. These semi‑submersible platforms, later renamed "Deimos" and "Phobos", will be modified into two floating launch platforms for Super Heavy/Starship orbital launches. As of January 2021, a refit is underway on "Deimos" at the Port of Brownsville and "Phobos" at the Port of Galveston.
On 9 December 2020, Starship SN8, the first full-scale Starship prototype fitted with a complement of three Raptor engines as well as body flaps, flew to an altitude of , performed a horizontal descent, but subsequently failed to complete its landing burn, exploding upon collision with the ground. On 2 February 2021, Starship SN9 attempted a flight, but it too was destroyed upon landing when an engine failed to ignite. On 3 March 2021, Starship SN10 successfully landed after a 10 km flight, however, the vehicle was destroyed in an explosion eight minutes later. The next prototype, Starship SN11, launched on 30 March 2021 to an altitude of 10 km, but disintegrated during the landing burn, scattering debris around the launch site. On 5 May 2021, Starship SN15 flew to an altitude of 10 km, landed, and was recovered successfully.
"Starship" upper stage.
The upper stage of Starship is intended to function both as a second stage to reach orbital velocity on launches from Earth and also be used in outer space as an on‑orbit long‑duration spacecraft. This is in contrast to most previous launch vehicle and spacecraft designs. Starship is being designed to be capable of re-entering Earth's atmosphere from orbital velocities and landing vertically, with a design goal of rapid re‑usability without the need for extensive refurbishment.
According to Musk, when Starship is used for beyond Earth orbit (BEO) launches to Mars, the functioning of the overall expedition system will necessarily include propellant production on the Mars surface. This is necessary for the return trip and to reuse the spaceship to keep costs as low as possible. Lunar destinations (circumlunar flybys, orbits, and landings) will be possible without lunar‑propellant depots, so long as the spaceship is refueled in a high‑elliptical orbit before the lunar transit begins. Some lunar flybys will be possible without orbital refueling as evidenced by the mission profile of the "dearMoon project".
The SpaceX approach is to tackle the hardest problems first which to Musk is enabling a sustainable human civilization on Mars. That is the major focus of SpaceX resources after 2019. For example, it is planned for the spacecraft to eventually incorporate life support systems but , Musk has stated that it is yet to be developed, as the early flights will all be cargo only.
General characteristics.
, the Starship upper stage is expected to have a diameter, tall, capable of being a fully reusable spacecraft with a dry mass of or less, powered by six Raptor engines.
Starship is designed with the ability to re‑enter Earth's atmosphere and retropropulsively land on a designated landing pad. Landing reliability is projected by SpaceX to ultimately be able to achieve "airline levels" of safety due to the ability to fly with one engine not working ("engine‑out capability"). The spacecraft is also designed to be able to perform automatic rendezvous and docking operations and on‑orbit propellant transfer between Starships.
Starship is also designed with the goal to reach other planets and moons in the solar system after on‑orbit propellant loading. While retropropulsion is intended to be used for the final landing maneuver on the Earth, Moon, or Mars, 99.9% of the energy dissipation on Earth reentry is to be removed aerodynamically and on Mars, 99% aerodynamically even with the much thinner Martian atmosphere, where "body flaps" are used to control attitude during descent and optimize both trajectory and energy dissipation during descent.
As envisioned in the 2017 design unveiling, the Starship is to have a pressurized volume of approximately , which could be configured for up to 40 cabins, large common areas, central storage, a galley and a solar flare shelter for Mars missions.
Propulsion.
The methane/oxygen‑propellant Raptor engines will be the main propulsion system on Starship.
Starship will use three sea‑level optimized Raptor engines and three vacuum‑optimized Raptor engines. The sea‑level engines are identical to the engines on the Super Heavy booster. Transport use in space is expected to use a vacuum‑optimized Raptor engine variant to optimize specific impulse to approximately .
Total Starship thrust will be approximately .
Starship will use pressure fed hot gas reaction control system (RCS) thrusters using methane gas for attitude control, including the final pre‑landing pitch‑up maneuver from belly flop to tail down and for stability during high‑wind landings up to . 
Initial prototypes have used nitrogen cold gas thrusters, which are substantially less mass efficient but are expedient to support early prototype flight testing.
Variants.
Starship is planned to eventually be built in at least these operational variants:
The spaceship design is expected to be flexible. For example, a possible modification to the base Starship would have only an expendable three‑engine Starship with no fairing, rear fins, or landing legs, in order to optimize its mass ratio for interplanetary exploration with robotic probes.
Materials and construction.
Starship has a stainless steel structure and tank construction. Its strength‑to‑mass ratio should be comparable to or better than the earlier SpaceX design alternative of carbon fiber composites across the anticipated temperature ranges, from the low temperatures of cryogenic propellants to the high temperatures of atmospheric reentry
Some parts of the craft will be built with a stainless steel alloy that "has undergone [a type of] cryogenic treatment, in which metals are "... cold‑formed/worked [to produce a] cryo‑treated steel ..." dramatically lighter and more wear‑resistant than traditional hot‑rolled steel."
The spacecraft will also have a thermal protection system against the harsh conditions of atmospheric reentry. This will include hexagonal ceramic tiles that will be used on the windward side of Starship. 
Earlier designs included a double stainless‑steel skin with active coolant flowing in between the two layers, or with some areas additionally containing multiple small pores that would allow for transpiration cooling.
Starship Human Landing System.
A modified Starship vehicle, known as Starship HLS (Starship Human Landing System), was selected by NASA in April 2021 for use in long‑duration crewed lunar landings as part of NASA's Artemis program. This followed a three-team competition begun in April 2020 where NASA wanted to incentivize commercial companies to develop human-capable lunar landing systems.
The Starship HLS variant is being designed to stay on and around the Moon. Hence both the heat shield and air‑brakes — integral parts of the main Starship design — are not included in the modified design, as Starship HLS will not return to Earth. Starship HLS is equipped with a complement of thrusters mid-body to be used during the final "tens of meters" of the terminal lunar descent and landing; the same thrusters will be used to liftoff from the lunar surface.. A large solar array is attached to the circumference of the exterior hull for power generation. Once Starship HLS reaches Earth orbit, it will be refueled with tanker Starship vehicles before departing for the Moon. In the Artemis mission architecture, a NASA Orion spacecraft is planned to carry the NASA crew to the lander in lunar orbit where they would depart and descend to the surface in Starship HLS. After lunar surface operations, the Starship HLS vehicle would liftoff from the surface of the Moon and rendezvous with Orion, which would transport the crew back to Earth. Elon Musk stated that Starship HLS will be "capable of at least 100 tons and probably closer to 200 tons of useful payload to the surface of the Moon."
SpaceX originally developed the Starship HLS concept in 2020 as a proposal to NASA for the Artemis program. SpaceX was one of three teams selected to further advance a company-specific lunar lander design for the Artemis program over a year-long period in 2020–2021, starting in May 2020. The other teams considered were Dynetics (in cooperation with Sierra Nevada and other unspecified companies) and the 'National Team'—led by Blue Origin but including Lockheed Martin, Northrop Grumman and Draper. In April 2021, NASA selected Starship HLS for crewed lunar lander development plus two lunar demonstration flights — one uncrewed and one crewed — no earlier than 2024. The contract is valued at over a number of years. Two NASA Artemis astronauts are to land on the second Starship HLS landing. However, NASA put the Starship HLS contract on hold after Blue Origin and Dynetics filed legal challenges with the Government Accountability Office claiming that NASA had improperly evaluated aspects of the proposals.
Prototypes and testing.
The SpaceX testing philosophy, referred to as "test, fly, fail, fix, repeat", is evident in the Starship development and testing program. SpaceX is willing to regularly test prototypes to destruction, counting the data gathered as a successful part of the overall process. This allowance for failures, willingness to build flight articles in view of the public and fast cadence of prototype construction makes the Starship design process unique in the spaceflight industry.
Starship prototypes are subjected to several tests on the launch stand before flight. These include the "ambient-temperature pressure test", "cryogenic proof test" and static fire of the engines. During the "ambient-temperature pressure test" the test article's propellant tanks are filled with benign air‑temperature nitrogen gas. This test checks for leaks, verifies basic vehicle valve and plumbing performance and ensures a basic level of structural integrity. The "ambient-temperature pressure test" is followed by the "cryogenic proof test" where the vehicle's oxygen and methane tanks are loaded with liquid nitrogen. This also tests structural integrity but adds the challenge of thermal stresses to ensure that Starship can safely load, hold and offload supercool liquids. Starship SN9 was the first prototype to arrive at the test stand with engines already installed. For previous test articles with thrust structures, a hydraulic ram was attached to the thrust puck to simulate the thrust of one, two, or three Raptor engines.
Starship SN4 was the first full scale prototype to pass the "cryogenic proof test". Finally a "static fire test" is performed by loading liquid oxygen and liquid methane and firing the Raptor engines briefly while Starship is held down on the test stand.
"Starhopper".
The construction of the initial test article—the "Starship Hopper" or Starhopper—began in early December 2018 and the external frame and skin was complete by 10 January 2019. Constructed outside in the open on a SpaceX property just from Boca Chica Beach in South Texas, the external body of the rocket rapidly came together in less than six weeks from half‑inch (12.5 mm) steel. Originally thought by onlookers at the SpaceX South Texas Launch Site to be the initial construction of a large water tower, the stainless steel vehicle was built by welders and construction workers in more of a shipyard form of construction than traditional aerospace manufacturing. The full "Starhopper" vehicle is in diameter and was originally tall in January 2019. Subsequent wind damage to the nose cone of the vehicle resulted in a SpaceX decision to scrap the nose sectionand fly the low‑velocity hopper tests with no nose cone, resulting in an tall test vehicle.
The low‑altitude, low‑velocity "Starhopper" was used for initial integrated testing of the Raptor rocket engine with a flight‑capable propellant structure and was slated to also test the newly designed autogenous pressurization system that is replacing traditional helium tank pressurization as well as initial launch and landing algorithms for the much larger diameter rocket. SpaceX originally developed their reusable booster technology for the 3‑meter‑diameter Falcon 9 from 2012 to 2018. The "Starhopper" prototype was also the platform for the first flight tests of the full‑flow staged combustion methalox Raptor engine. Only one engine was installed but Starhopper could have been fitted with up to three engines to facilitate engine‑out tolerance testing.
"Starhopper" was also used to flight test a number of subsystems of Starship to begin to expand the flight envelope of the Starship design. "Starhopper" testing ran from March to August 2019 with all "Starhopper" test flights at low altitude. 
The maiden flight test of the "Starhopper" test vehicle and also the maiden flight test of any full‑flow staged combustion rocket engine, was on 25 July 2019 and attained a height of . This was not a full‑duration burn but a 22‑second test. SpaceX is developing their next‑generation rocket to be reusable from the beginning, just like an aircraft and thus needs to start with narrow flight test objectives, while still aiming to land the rocket successfully to be used subsequently in further tests to expand the flight envelope. The second and final untethered test flight of the "Starhopper" test article was carried out on 27 August 2019, to a VTVL altitude of .
Low‑altitude prototypes.
Construction of the Mark 1 (Mk1) in Boca Chica, Texas and Mark 2 (Mk2) in Cocoa, Florida began in December 2018. Like Starhopper, the vehicles measured in diameter but were full‑height at approximately , making them the first full‑size Starship prototypes. On 20 November 2019, the Starship Mk1 was partially destroyed during pressure testing, when the forward LOX tank ruptured along a weld line of the craft's steel structure, propelling the bulkhead several meters upwards. The upper bulkhead went airborne and landed some distance away from the craft. No injuries were reported. After the incident, SpaceX decided not to repair and retest Mk1. Both Mk1 and Mk2 were scrapped and focus turned to the Mk3 and Mk4 builds which were designed for orbit.
The second Texas prototype (Mk3) was renamed to Starship SN1 (serial number 1). It was destroyed in February 2020 during a pressure test when the tank ruptured near the thrust puck. The thrust puck serves as both the lower dome of the fuel tank and the mount for the Raptor engines. After this incident, SpaceX built Starship SN2 as a scaled down test tank to focus testing on the structure of the thrust puck. Starship SN2 successfully passed the pressure and cryogenic tests proving the design changes. SpaceX returned to full size prototype testing with Starship SN3 which failed the cryogenic proof test. During testing the LOX (Liquid Oxygen) Tank experienced a loss of pressure and collapsed due to an error in the test sequence. Starship SN4 successfully completed a cryogenic pressure test on 26 April 2020. but exploded a few weeks later after a successful engine test when SpaceX tested a new "quick disconnect" design as part of ground support equipment testing. After passing all pad tests, Starship SN5 completed a 150 m hop on 4 August 2020, descending to a nearby landing pad. This marked the first successful launch and landing of a prototype with full‑height propellant tanks. Starship SN6 performed the same flight test plan just one month later.
High‑altitude prototypes.
High‑altitude prototypes include installation of the nose cone and aerodynamic surfaces allowing testing of ascent, controlled engine cutoff, vehicle reorientation, controlled descent, the flip maneuver and landing. 
Starship SN8 was the first high‑altitude prototype to perform a test flight. On 9 December 2020, Starship SN8 launched and ascended to an altitude of . During ascent, the three Raptor engines were cut one by one allowing the rocket to perform a successful and novel skydiver‑like horizontal descent. As the vehicle neared the ground, it used a combination of aerodynamic surfaces and engine gimbaling to rotate back to a vertical position for a propulsive landing attempt. Lower than expected pressure in the methane header tank following the rapid rotation caused inadequate final deceleration and a hard landing resulted in an explosion on the landing pad and total destruction of the test vehicle. 
Starship SN9 and Starship SN10 both followed the same general test flight plan. SN9's flight took it to , on 2 February 2021. The flight went well up until the landing, where one of the Raptor engines did not relight causing a failure to counteract the momentum of the landing flip maneuver. This failure caused SN9 to slam into the ground diagonally and explode. Starship SN10 performed the same test profile but used all three engines for the final flip maneuver successfully decelerating enough to land intact. Several minutes after the landing the Starship exploded and was tossed in the air, before slamming down on its side on the landing pad. SpaceX CEO Elon Musk later revealed that the single Raptor engine that was used for the final landing burn couldn't reach high thrust despite being commanded to do so, thus SN10's landing was harder than intended. The cause of the low thrust is probably due to partial helium ingestion from the fuel header tank.
Starship SN11 was launched to 10 km on 30 March 2021, as heavy fog covered the launch site. Telemetry was lost about 5 minutes and 49 seconds after launch as the vehicle disintegrated during its landing attempt. The explosion was caused by a methane leak in one of the Raptor engines, which led to a malfunction when it attempted to relight for the landing burn.
Starship SN15 featured numerous upgrades over its predecessors, including improved avionics, an upgraded aft skirt plumbing system, and a new Raptor engine design. On 5 May 2021, Starship SN15 flew to an altitude of , transitioned to a horizontal descent, and completed its landing maneuver successfully. A small fire near the base occurred shortly after landing, but was later extinguished. Subsequently, Starship SN15 was lifted onto the launch pad in preparation for a second flight.
Orbital flights.
Starship SN20, as well as Super Heavy booster BN3, are believed to be used for the first orbital flight of the Starship system no earlier than June 2021. FCC filings in May 2021 by SpaceX stated that the orbital flight will launch from Boca Chica. After separation, Super Heavy will perform a return and touch down at a point offshore, while Starship will enter orbit and eventually splash down off the coast of Kauai in Hawaii.
"Super Heavy" booster.
The booster stage Super Heavy is expected to be long and in diameter.
It is to be constructed of stainless steel tanks and structure, holding subcooled liquid methane and liquid oxygen (/LOX) propellants, powered by 28 Raptor rocket engines that will provide total liftoff thrust. 
The specification propellant capacity of Super Heavy was shown as in May 2020, 3% more than in the earlier high-level design as of September 2019.
The initial prototype Super Heavy will be full size. It is expected to initially fly with less than the full complement of 28 engines.
The Super Heavy external design changed throughout 2019/2020 as the detailed design was iterated and the Raptor engines were tested and achieved higher power levels. In September 2019, a design change for the booster stage to have six fins that serve exclusively as fairings to cover the six landing legs and four diamond‑shaped welded steel grid fins to provide aerodynamic control on descent, was discussed. In August 2020, as the first build of "booster prototype 1" was to get underway, Musk noted that the leg design had been modified to just four landing legs and fins, to improve supersonic engine plume re‑circulation margins.
Landing.
In September 2016, Elon Musk described the possibility of landing the ITS booster on the launch mount. He re‑described this concept in September 2017 with the Big Falcon Booster (BFB). In 2019, Musk announced that the booster would initially have landing legs to support the early VTVL development testing of Super Heavy. More recently, Musk had again expressed the long term goal of landing on the launch mount. In December 2020, Musk added the possibility of catching the booster by the grid fins using the launch tower arm, eliminating the need for landing legs entirely and simplifying recovery processes.
Prototypes.
In late 2020, the segments of the first booster, codenamed BN1, were observed at Boca Chica. In March 2021, Elon Musk indicated he was hopeful that the first orbital flight could be made as early as July 2021. The two segments of BN1 were stacked together in the High Bay for the first time on 18 March 2021. The first booster is a production pathfinder and will also help develop transport processes from the Boca Chica build area to the launch/landing area.
Intended uses.
Orbital launches.
Starship is intended to become the primary SpaceX orbital vehicle. 
SpaceX intends to eventually replace its existing Falcon 9 and SpaceX Dragon 2 fleet with Starship, which is expected to take cargo to orbit at far lower cost than any other existing launch vehicle. 
In November 2019, Elon Musk estimated that fuel will cost US$900,000 per launch and total launch costs could drop as low as US$2 million.
In addition to the commercial launch market that SpaceX has been servicing since 2013, the company intends to use Starship to launch the largest portion of its own internet satellite constellation, Starlink, with more than 12,000 satellites intended to be launched by 2026, more than six times the total number of active satellites on orbit in 2018. An orbital launch of Starship could place ~400 Starlink satellites into orbit with a single launch, whereas the Falcon 9 flights in 2019‑2020 can launch a maximum of 60.
Beyond the low-Earth orbit launches performed by Falcon 9 and Falcon Heavy in the 2010s, the Starship system is an architecture designed to do many diverse spaceflight missions, principally due to the very low marginal cost per mission that the fully‑reusable spaceflight vehicles bring to spaceflight technology that were absent in the first six decades humans put technology into space. Starship is designed to be used for: 
Long‑haul Earth transport.
In 2017, SpaceX mentioned the theoretical possibility of using Starship to carry passengers on suborbital flights between two points on Earth. Any two points on Earth could be connected in under one hour, providing commercial long‑haul transport competing with long‑range aircraft. SpaceX however announced no concrete plans to pursue the two stage "Earth‑to‑Earth" use case.
Over two years later, in May 2019, Musk floated the idea of using single‑stage Starship to travel up to on Earth‑to‑Earth flights at speeds approaching with an acceptable payload saying it "dramatically improves cost, complexity and ease of operations". 
In June 2020, Musk estimated that Earth‑to‑Earth test flights could begin in "2 or 3 years", i.e. 2022 or 2023 and that planning was underway for "floating superheavy‑class spaceports for Mars, Moon and hypersonic travel around Earth".
In April 2021, COO Gwynne Shotwell clarified that she believes SpaceX "will be flying large numbers of people on Starship in five years ... including point-to-point transportation between two locations on Earth".
Funding.
SpaceX has been developing the Starship system with private funding, including the Raptor rocket engine used on both stages of the vehicle, since 2012. In later years, after 2016, SpaceX has also contracted to supply specific Starship system development and operational work for the US government, including building a single custom-order prototype Raptor engine for the USAF in 2016-2018 and in 2020/21, NASA contracting for SpaceX to do specific work for a modified Starship second stage that could be used for Lunar passenger and cargo transport from the NASA Lunar Gateway space station to the surface of the Moon and return.
The actual development work on the new two-stage launch vehicle design has been nearly entirely privately funded by SpaceX. The entire project is possible only as a result of SpaceX's multi-faceted approach focusing on the reduction of launch costs. However, the full build-out of the Mars colonization plans—after Starship initial development—has been envisioned by Musk since 2016 to be ultimately funded by both private and public funds. The speed of commercially available Mars transport for both cargo and humans will be driven, in large part, by market demand as well as constrained by the technology development and development funding. 
In 2016, Musk said that the company had no expectation of receiving NASA contracts for any of the development work SpaceX was doing. He also indicated then that such contracts, if received, would be good. In January 2016 the US Air Force contracted with SpaceX US$33.7 million to develop a prototype Raptor engine for a methalox upper stage for Falcon 9 and Falcon Heavy, with up to a further US$61.4 million available for additional USAF requirements. SpaceX has no plans to develop a methalox second stage for the Falcon launch vehicles but the Air Force wanted this technology to be developed.
In 2017, the company settled on a 9-meter diameter design and commenced procuring equipment for vehicle manufacturing operations. In late 2018, they switched the design from carbon composite materials for the main structures to stainless steel motivated by ordinary company economic incentives to further lower build costs, without requiring review by NASA or US government sources.
Beginning in 2019, SpaceX began to offer specific services to potential future customers using Starship/Super Heavy/Raptor technology. In June 2019, SpaceX indicated they could potentially launch commercial payloads using Starship as early as 2021, which can result in the recognition of revenue before a flight is launched. By late 2019, SpaceX projected that, with company private investment funding, including contractual funds from Yusaku Maezawa who had contracted for a private lunar mission, they had sufficient funds to advance the Earth‑orbit and lunar‑orbit extent of Starship flight operations, although they could choose to raise additional funds in order "to go to the Moon or landing on Mars".
In April 2020, NASA announced they would pay SpaceX US$135 million for initial design work of a variation of the Starship second‑stage vehicle and spaceship—a "Starship Human Landing System", or Starship HLS—as one of three potential Lunar human landing systems for the NASA Artemis program
In October 2020, NASA awarded SpaceX US$53.2 million to conduct a large scale flight demonstration to transfer 10 metric tons of cryogenic propellant between the tanks of two Starship vehicles.
On 16 April 2021, NASA selected SpaceX's Starship for the Artemis human landing system. The contract is valued at over a number of years.
Criticism.
The Starship vehicle design has been criticized for not adequately protecting astronauts from ionizing radiation on Mars missions; Musk has stated that he thinks the transit time to Mars will be too insignificant for a crewed Mars mission, saying "it's not too big of a deal". The lifetime cancer risk increase caused by the dose incurred on a multi‑year Mars mission has been estimated to amount to a 5% increase in total cancer risk, a number which can be greatly reduced through simple shielding measures.
Eugene Parker had stated in 2006 that several meters of water completely surrounding the crew would be needed to protect astronauts on the journey: "If the material is water, it has to be ﬁve meters deep. So a spherical water tank encasing a small capsule would have a mass of about 500 tons. Larger, more comfortable living quarters would require even more." Elon Musk responded: "...you don't need to have that, you can just have a column of water pointed at the Sun and make sure that you stay in front of that column." Astrophysicist Jarrah White disputed this, arguing that solar flare particles are not directional and fall along the magnetic field lines: "You need to shelter all sides of the capsule because the solar flares are deflected in all directions by the Sun's magnetic field." He cited the January 27, 2012, Solar Proton Event, the particles of which were carried to the vicinity of both Mars and Earth despite the initial eruption on the Sun being pointed away from these planets.
During Musk's 2016 unveiling of his original Interplanetary Transport System, one of the slides infamously depicted astronauts walking on the surface of Jupiter's moon Europa. White argued that Europa's orbit is within Jupiter's radiation belt and calculated that astronauts walking on Europa would be subjected to a lethal dose of radiation. He said proposing to land astronauts on Europa was "the biggest indication that Musk doesn't have a clue what he's getting himself into [and] has greatly underestimated the hazard." Phil Mason concurred: "You just look like kind of a melon who doesn't really know what they're talking about, when you then go onto explain how radiation in space isn't that big of a deal in Mars or elsewhere when you're sat in front of a picture where everyone traveling on your solar system exploring rocket has just been exposed to a fatal dose of radiation." Mason also argued that the solar panels would not be adequate to power the spacecraft in the outer solar system: "If these solar panels generate some 200kW when they are by the Earth, that means that by the time they get out at Saturn they are generating about 2kW of power. Meaning that you need to sustain everyone on that spaceship with less than the power it takes to run a kettle." 
Responding to these criticisms, Musk's 2017 revision included a "solar storm shelter." He also retracted his claim that solar flares were directional at the 2017 ISS R&D Conference: "I always thought of the particles from the sun as going straight at [you] from the sun, but they follow the magnetic field lines and so you actually can get the particles coming at you from the side. So you do need some protection on four or five sides." However, as of May 2021, Musk has not officially unveiled any interior designs showing how the solar storm shelter is incorporated into the Starship.
Critics have also attacked the Starship test campaign at the SpaceX South Texas launch site. Debris from launch explosions has traveled over five miles downwind, leading residents to argue that it damages the surrounding ecosystems. Environmental activists accuse SpaceX of not adhering to the conditions outlined in their original Environmental Impact Statement and have urged the Environmental Protection Agency to require an updated EIS.