The second stage — which is also referred to as "Starship" :16:20–16:48 — is being designed as a long-duration cargo, and eventually, passenger-carrying spacecraft. It is being used initially without any booster stage at all, as part of an extensive development program to prove out launch-and-landing and iterate on a variety of design details, particularly with respect to the vehicle's atmospheric reentry.
While the spacecraft is currently being tested on its own at suborbital altitudes during 2019–2020, it will later be used on orbital launches with an additional booster stage, the Super Heavy, where the spacecraft will serve as both the second stage on the two-stage-to-orbit launch vehicle and the in-space long-duration orbital spaceship.
SpaceX could potentially launch commercial payloads using Starship no earlier than 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.
While the name of the vehicle has changed many times over the years, the combination of Starship spacecraft and Super Heavy booster is called the "Starship system" by SpaceX in their payload users guide. Sometimes, as on the SpaceX website, the term "Starship" is used as a collective term for both the Starship spacecraft and the Super Heavy booster.
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 100 t (110 tons) to orbit. Beginning in mid-2013, SpaceX referred to both the mission architecture and the vehicle as the Mars Colonial Transporter. By the time a large 12-meter 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 9-meter design in September 2017, SpaceX resumed referring to the vehicle as "BFR". Musk said in the announcement, "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".[a] The booster first stage was also at times referred to as the "BFB".[b] In November 2018, the spaceship was renamed Starship, and the first stage booster was named Super Heavy.
Notably, in the fashion of SpaceX, even that term "Super Heavy" had 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. "We could really dial it up to as much performance as anyone could ever want. If we wanted to we could actually add two more side boosters and make it Falcon Super Heavy".
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, 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".
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 23 October 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. In September 2017, at the 68th annual meeting of the International Astronautical Congress, SpaceX unveiled an updated vehicle design. Musk said, "we are searching for the right name, but the code name, at least, is BFR".
In a September 2018 announcement of a planned 2023 lunar circumnavigation mission, a private spaceflight called dearMoon project, 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. The 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 in the second half of the month that they were "no longer planning to upgrade Falcon 9 second stage for reusability". 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, Elon Musk announced that the Starship would no longer be constructed out of carbon fiber, and that stainless steel would be used instead to build the Starship. Musk cited several reasons including cost, strength, and ease of production to justify making the switch.
In May 2019, the Starship design changed back to just six Raptor engines, with three optimized for sea-level and three optimized for vacuum.
By late May 2019, an initial prototype, Starhopper, was being finished for untethered flight tests at the SpaceX South Texas launch site, while two "orbital prototypes" were under construction, one in South Texas begun in March 2019 and one on the Floridaspace coast begun before May 2019. The build of the first Super Heavy booster stage was projected to be able to start by September 2019. 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. In 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 June 2019, SpaceX publicly announced discussions had begun with three telecommunications companies for using Starship, rather than Falcon 9, for launching commercial satellites for paying customers in 2021. No specific companies or launch contracts were announced at that time.
In July 2019, the Starhopper made its initial flight test, a "hop" of around 20 m (66 ft) altitude, and a second and final "hop" in August 2019, reached an altitude of ~150 m (490 ft)  and landing around 100 m (330 ft) from the launchpad.
SpaceX completed most of the Boca Chica prototype, the Starship Mk1, in time for Musk's next public update in September 2019. Watching the construction in progress before the event, observers online circulated photos and speculated about the most visible change, 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 glass 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. At the time, construction of Mk3 was expected to start in about a month.
In 2019, the cost per launch for Starship was estimated by SpaceX to be as low as US$2 million once the company achieves a robust operational cadence and achieves the technological advance of full and rapid reusability. Full reusability of the second stage of Starship is a fundamental design goal for the entire Starship development program, but success is uncertain. Elon Musk has said in 2020 that, with a high flight rate, they could potentially go even lower, with a fully-burdened marginal cost on the order of US$10 per kilogram of payload launched to low Earth orbit.
In November 2019, the Mk1 test article in Texas came apart in a tank pressure test, and SpaceX stated they would cease to build the Mk2 prototype under construction in Florida and move on to work on the Mk3 article. A few weeks later, the work on the vehicles in Florida slowed down substantially, with some assemblies that had been built in Florida for those vehicles being transported to the Texas Starship assembly location, and a reported 80% reduction in the workforce at the Florida assembly location as SpaceX pauses activities there. Apparently, at the same time the Mk4 vehicle under construction in Florida was cancelled.
Adopting a new "serial number" nomenclature, the Mk3 article was renamed Starship SN1 by SpaceX to signify the major evolution in building techniques: the rings were now taller and each was made of one single sheet of steel, drastically reducing the welding lines (thus failure points). Also the worksite was expanded with more tents, structures and upgraded machinery to give the workers a much better controlled environment, allowing for better precision work and, more importantly, better quality welds. Smaller articles were made and tested to destruction to validate the new bulkheads design.[better source needed] This was a significant change of pace for SpaceX's approach.
In February 2020, SN1 too was destroyed when undergoing pressurization. The company then focused on resolving the problem that led to SN1's failure by assembling a stripped down version of their next planned prototype, SN2. This time the test was successful and SpaceX began work on SN3. However, in April 2020, SN3 was also destroyed during testing due to a test configuration error. At that time, construction of SN4 was underway.
On 26 April 2020, Starship SN4 became the first full-scale prototype to pass a cryogenic proof test, in which the ship's liquid oxygen and methane was replaced with similarly frigid but non-explosive liquid nitrogen. SN4 was only pressurized to 4.9 bar (~70 psi), which is more than enough to perform a small flight test. On 5 May 2020, SN4 completed a single engine static fire with one mounted Raptor engine and became the first full Starship tank to pass a Raptor static fire. SN4 would complete a total of 4 short static fires (2 to 5 seconds long) before being destroyed in a massive explosion due to a propellant leak from the quick disconnect mechanism occurring at the end of a test fire on 29 May 2020.
SN7 test tank was also tested all the way to leak at around 7.8 bar after which it was repaired and tested to destruction.
On 30 July 2020, Starship SN5 completed a static fire with one mounted Raptor engine. On 3 August 2020, Starship SN5 attempted a 150 meter flight test that was aborted due to a spin start valve on the Raptor engine not opening. At approximately 16:00 UTC on 4 August 2020, SpaceX again attempted a 150 meter flight test, which was also aborted. Later that day, at approximately 23:59 UTC, Starship SN5 completed the 150 meter flight test, landing at an adjacent landing site, thus becoming the first full-scale prototype to perform a successful flight test. After the flight, Elon Musk stated in August that SpaceX would carry out several additional short flights in order to refine the launch process, before attempting a high altitude flight using a vehicle with body flaps.
Starship SN6 completed construction, and was moved to the test stand; static fire testing was to start on 23 August 2020, after 3 attempts on 23 August 2020, they finally had a successful static fire at about 00:43 UTC, 24 August 2020. After unsuccessful hop attempts on 30 August 2020, SN6 completed a maiden 150 meter flight test on 3 September at about 17:45 UTC. Currently, other prototypes are under construction for pressure testing (Starship SN7.1), and flight test articles (Starship SN8 and SN9, the first to have nosecones and aero surfaces).
While the Starship program had a small development team for several years, and a larger development and build team since late 2018, Musk declared in June 2020 that Starship is the top SpaceX priority, except for anything related to reduction of Crew Dragon return risk for the NASA Demo-2 flight to the ISS, and remained so in September 2020.
While Mars has always been a critically important driver of requirements for the Starship system, and Musk had earlier hoped to have an initial orbital test flight by 2020, Musk toned down the expectations when he spoke to the Humans to Mars conference in August 2020. He said that "the first Starship launches to orbit "might not work", saying that SpaceX is in "uncharted territory. ... Nobody has ever made a fully reusable, orbital rocket".
Musk clarified that SpaceX intends to fly exclusively cargo transport missions initially, and that passenger flights would come only much later. Starship will fly "hundreds of missions with satellites before we put people on board".
Super Heavy, the booster stage "needed to escape Earth's deep gravity well", is expected to be 72 m (236 ft) long and 9 m (30 ft) in diameter with a gross liftoff mass of 3,680,000 kg (8,110,000 lb). It is to be constructed of stainless steel tanks and structure, holding subcooled liquid methane and liquid oxygen (CH 4/LOX) propellants, powered by ~28 Raptor rocket engines that will provide 72,000 kN (16,000,000 lbf) total liftoff thrust. The specification propellant capacity of Super Heavy was shown as 3,400,000 kg (7,500,000 lb) in May 2020, 3% more than estimated in September 2019.
The initial prototype Super Heavy will be full size. It is expected however, to initially fly with less than the full complement of 28 engines, perhaps approximately 20.
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:26:25–28:35 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.
In September 2016, Elon Musk described the possibility of landing the ITS booster on the launch pad. He re-described this in September 2017 with the Big Falcon Booster (BFB). In 2019, Musk announced that it will initially have landing legs to support the early VTVL development testing of Super Heavy.
Starship upper stage
Artist's concept of an earlier version of Starship upper stage following stage separation
As of September 2019[update], the Starship upper stage is expected to be a 9 m (30 ft) diameter, 50 m (160 ft) tall, fully reusable spacecraft with a dry mass of 120 t (120 long tons; 130 short tons) or less, powered by six methane/oxygen-propellant Raptor engines, three of them will be for use at sea-level while the other three would be used for Vacuum burns. Total Starship thrust will be approximately 11,500 kN (2,600,000 lbf).
Unusual for previous launch vehicle and spacecraft designs, 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. Starship is being designed so as to be capable of reentering Earth's atmosphere from orbital velocities and landing vertically, with a design goal of rapid re-usability.
Starship will use three sea-level optimized Raptor engines and three vacuum-optimized Raptor engines. These 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 (Isp) to approximately 380 s (8,300 mph; 3.7 km/s).
Starship is planned to eventually be built in at least these operational variants:
Spaceship: a large, long-duration spacecraft capable of carrying passengers or cargo to interplanetary destinations, to LEO, or Earth-to-Earth spaceflight.
Satellite delivery spacecraft: a vehicle able to transport and place spacecraft into orbit, or handle the in-space recovery of spacecraft and space debris for return to Earth or movement to another orbit. In the March 2020 users guide, this was shown with a large cargo bay door that can open in space to facilitate delivery and pickup of cargo.
Tanker: a cargo-only propellant tanker to support the refilling of propellants in Earth orbit. The tanker will enable launching a heavy spacecraft to interplanetary space as the spacecraft being refueled can use its tanks twice, first to reach LEO and afterwards to leave Earth orbit. The tanker variant, also required for high-payload lunar flights, is expected to come only later; initial in-space propellant transfer will be from one standard Starship to another.
Lunar-surface-to-orbit transport: a variant of Starship without airbrakes or heat shielding that is required for in-atmosphere-operations. Additionally, the ship will be equipped with a docking port on the nose and have white paint (as opposed to the bare steel planned for regular Starships). On 30 April 2020, NASA selected SpaceX to develop a human-rated lunar lander for the Artemis program, therefore requiring SpaceX to develop an approach for a direct lunar landing.
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 engine-out capability
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."
Methox (methane gas/oxygen gas)pressure fed hot gas reaction control system (RCS) thrusters for attitude control, including the final pre-landing pitch-up maneuver from belly flop to tail down, and stability during high-wind landings up to 60 km/h (37 mph). Initial prototypes are using nitrogen cold gas thrusters, which are substantially less mass efficient, but are expedient for quick building to support early prototype flight testing.
A thermal protection system against the harsh conditions of atmospheric reentry. This will include ceramic tiles, after earlier evaluating a double stainless-steel skin with active coolant flowing in between the two layers or with some areas additionally containing multiple small pores that will allow for transpiration cooling.) Options under study included hexagonal ceramic tiles that could be used on the windward side of Starship.
A novel atmospheric re-entry approach for planets with atmospheres. 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 using 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 1,000 m3 (35,000 cu ft), which could be configured for up to 40 cabins, large common areas, central storage, a galley, and a solar flare shelter for Mars missions.
Flexible design options; for example, a possible design modification to the base Starship – expendable three-engine Starship with no fairing, rear fins, nor landing legs in order to optimize its mass ratio for interplanetary exploration with robotic probes.
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. He says that this is necessary for the return trip and to reuse the spaceship to keep costs as low as possible. He also says that 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, and Musk sees the hardest problem for getting to sustainable human civilization on Mars to be building a fully-reusable orbital Starship, so that is the major focus of SpaceX resources as of 2020. For example, it is planned for the spacecraft to eventually incorporate life support systems, but as of September 2019[update], Musk has stated that it is yet to be developed, as the early flights will all be cargo only.
Starship Human Landing System
A modified version known as the Starship Human Landing System (Starship HLS) was selected by NASA in April 2020 for potential use for long-duration crewed lunar landings as part of NASA's Artemis program. The Starship HLS variant is being designed to stay on and around the Moon and as such both the heat shield and air-brakes – integral parts of the main Starship design – are not included in the Starship HLS design. The variant will use high-thrust methox RCS thrusters located mid-body on Starship HLS during the final "tens of meters" of the terminal lunar descent and landing, and will also include a smaller crew area and a much larger cargo bay, be powered by a solar array located on its nose below the docking port. SpaceX intends to use the same high-thrust RCS thrusters for liftoff from the lunar surface.:50:30 If built, the HLS variant would be launched to Earth orbit via the Super Heavy booster and would use orbital refueling to reload propellants into Starship HLS for the lunar transit and lunar landing operations. In the 2020 mission concept, a NASA Orion spacecraft would carry a NASA crew to the lander where they would depart and descend to the surface in Starship HLS. After Lunar surface operations, it would ascend using the same Starship HLS vehicle and return the crew to the Orion. Although not confirmed yet, the vehicle in theory could be refueled in orbit to carry more crews and cargo to the surface.
SpaceX is one of three organizations developing their lunar lander designs for the Artemis program over a 10-month period in 2020-2021. If SpaceX completes the milestone-based requirements of the design contract, then NASA will pay SpaceX US$135 million in design development funding. The other teams selected are the 'National Team' – led by Blue Origin but including Lockheed Martin, Northrop Grumman, and Draper – with US$579 million in design funding and Dynetics – with SNC and other unspecified companies – with US$253 million in NASA funding. At the end of the ten-month program, NASA will evaluate which contractors will be offered contracts for initial demonstration missions and select firms for development and maturation of lunar lander systems.
Two (Starhopper, Mk1) test articles were being built by March 2019, and three (Starhopper, Mk1, Mk2) by May 2019. 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 9 m ([convert: unknown unit]) 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 combustionmethalox Raptor engine, where the hopper vehicle was flight tested with a single engine in July/August 2019, but could be fitted with up to three engines to facilitate engine-out tolerance testing.
The high-altitude, high-velocity "Starship orbital prototypes" (everything after Starhopper) are planned to be used to develop and flight test thermal protection systems and hypersonic reentry control surfaces. Each orbital prototype is expected to be outfitted with more than three Raptor engines.
Picture of Starhopper before flight
The construction of the initial test article – the Starship Hopper or Starhopper – was begun 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 3.2 km (2.0 mi) 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 9 m (30 ft) in diameter and was originally 39 m (128 ft) tall in January 2019. Subsequent wind damage to the nose cone of the vehicle resulted in a SpaceX decision to scrap the nose section, and fly the low-velocity hopper tests with no nose cone, resulting in a much shorter test vehicle.
From mid-January to early-March 2019, a major focus of the manufacture of the test article was to complete the pressure vessel construction for the liquid methane and liquid oxygen tanks, including plumbing up the system, and moving the lower tank section of the vehicle 3.2 km (2.0 mi) to the launch pad on 8 March 2019. Integrated system testing of the Starhopper – with the newly built ground support equipment (GSE) at the SpaceX South Texas facilities – began in March 2019. "These tests involved fueling Starhopper with LOX and liquid methane and testing the pressurization systems, observed via icing of propellant lines leading to the vehicle and the venting of cryogenic boil off at the launch/test site. During a period of over a week, StarHopper underwent almost daily tanking tests, wet dress rehearsals and a few pre-burner tests."
Following initial integrated system testing of the Starhopper test vehicle with Raptor engine serial number 2 (Raptor SN2) in early April 2019, the engine was removed for post-test analysis and several additions were made to the Starhopper. Attitude control system thrusters were added to the vehicle, along with shock absorbers for the non-retractable landing legs, and quick-disconnect connections for umbilicals. Raptor SN4 was installed in early June for fit checks, but the first test flight that is not tethered was expected to fly with Raptor SN5, until it suffered damage during testing at SpaceX Rocket Development and Test Facility, in McGregor, Texas. Subsequently, Raptor SN6 was the engine used by Starhopper for its untethered flights.
By December 2018, initial construction of two low-altitude prototype ships had begun, referred to as Mk1 at Boca Chica, Texas, and Mk2 at the space coast of Florida in Cocoa. Planned for high-altitude and high-velocity testing, the prototypes were described to be taller than the Starhopper, have thicker skins, and a smoothly curving nose section. Both prototypes measured 9 m (30 ft) in diameter by approximately 50 m (160 ft) in height.
On 20 November 2019, the Starship Mk1 was partially destroyed during max pressure tank 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. In a statement concerning the test anomaly, SpaceX said they will retire the Mk1 and Mk2 prototypes after the incident, and focus on Mk3 and Mk4 designs, which are closer to the flight specifications.
Construction had begun on the Mk2 Starship in Florida by mid-October 2019, but work then ceased in Florida (with apparent cancellation of Mk2) and focused on the Texas site. The prototype in Texas (Mk3) was renamed to SN1 (serial number 1). It was destroyed during a pressure test on 28 February 2020. After this incident, SpaceX announced they would focus on the next prototype, the Starship SN2. SN2 successfully went through a pressure and cryo test, but was not used for a static fire or hop. Instead, SpaceX moved on to SN3, the next prototype. SN3's cryo test then failed, the result being the LOX (Liquid Oxygen) Tank collapsing due to underpressurisation. On 26 April 2020, SN4 successfully completed a cryogenic pressure test. On 20 May 2020, SN4 exploded after a successful engine test when SpaceX tested a new "quick disconnect" design as part of ground support equipment testing. On 4 August 2020, SN5 completed a 150 m hop, its first successful launch and landing.
SN5 prototype being moved by a crane onto a stand before test flight.
The Starhopper was used to flight test a number of subsystems of the Starship and to begin to expand the flight envelope as the Starship design is iterated. Initial tests began in March 2019. All test flights of the Starhopper were at low altitude. On 3 April 2019, SpaceX conducted a successful static fire test in Texas of its Starhopper vehicle, which ignited the engine while the vehicle remained tethered to the ground.
The first static fire test of the Starhopper, with a single Raptor engine attached, occurred on 3 April 2019. The firing was a few seconds in duration, and was classed as successful by SpaceX. A second tethered test followed just two days later, on 5 April 2019.
By May 2019, SpaceX was planning to conduct flight tests both in South Texas and on the Florida space coast. The FAA issued a one-year experimental permit in June 2019 to fly Starhopper at Boca Chica, including pre-flight and post-flight ground operations.
The maiden flight test of the Starhopper test vehicle, and also the maiden flight test of any full-flow staged combustion rocket engine ever, was on 25 July 2019, and attained a height of 18 m (59 ft). This was not a full-duration burn but a 22-second test. It accidentally ignited nearby vegetation. 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 150 m (490 ft).
On 4 August 2020, prototype SN5 with full-height propellant tanks and a single Raptor engine, conducted a test flight to a height of about 150 m (490 ft), descending to a nearby landing pad.
Single Raptor engine, SN6. SpaceX called this the "150 meter Starhopper Test" on their livestream. Starhopper was retired after this launch, with some parts being reused for other tests. The test flight attempt on 26 August 2019 was scrubbed due to a problem with the Raptor engine igniters.
Single Raptor engine, SN27. A successful static fire test was carried out on 30 July 2020. Following 2 separate aborted attempts, a successful 150-meter flight was completed on 4 August 2020.
Single Raptor engine, SN29. A successful test hop took place on 3 September 2020. A static fire test of SN6 occurred on 24 August 2020 at 00:43 UTC. This also became the shortest duration between test flights, with less than 30 days after SN5's test hop. Elon Musk tweeted later that it was "a much smoother and faster operation" than SN5.
Three Raptor engines, SN30, SN32, and SN39. SpaceX conducted a static fire on 20 October 2020, and Musk states that they will then complete another static fire prior to attempting the hop. Unlike previous flights, SN8 has body flaps and a nosecone with front flaps installed.
2022 or 2023
Potential Earth-to-Earth test flight, according to Elon Musk.
Starship is intended to become the primary SpaceX orbital vehicle, as SpaceX has announced it intends to eventually replace its existing Falcon 9 launch vehicle 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, whether from SpaceX or other launch service provider.:24:50–27:05 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.
Starship 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 after humans put technology into space.:30:10–31:30 Specifically, Starship is designed to be used for:
Earth-orbit satellite delivery market. In addition to the standard external 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 only ~60.
Reusable lunar lander, for use transporting astronauts and cargo to and from the Moon's surface and Gateway in lunar orbit via Starship Human Landing System (Starship HLS); as well as more advanced heavy cargo lunar use cases that are envisioned by SpaceX but are not any part of the HLS variant that NASA has contracted with SpaceX for early design work.:13:34–20:10
In 2017, SpaceX mentioned the theoretical ability of using a boosted Starship to carry passengers on suborbital flights between two points on Earth in under one hour, providing commercial long-haul transport on Earth, 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 10,000 km (6,200 mi) on Earth-to-Earth flights at speeds approaching Mach 20 (25,000 km/h; 15,000 mph) 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".
SpaceX has been developing the Starship with private funding, including the Raptor rocket engine used on both stages of the vehicle, since 2012. In 2020, SpaceX has contracted with NASA to do limited early design work for 10 months on a human lunar lander variant Starship – Starship HLS – that might be used to land astronauts on the lunar surface as part of the NASA Artemis program after 2024.
The development work on the new two-stage launch vehicle design is 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.
Elon Musk said that there is no expectation of receiving NASA contracts for any of the ITS system work SpaceX was doing. He also indicated that such contracts, if received, would be good.
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, further lowering build costs. By late 2019, SpaceX projected that, with company private investment funding, including contractual funds from Yusaku Maezawa who had recently contracted for a private lunar mission in 2023, they have sufficient funds to advance the Earth-orbit and lunar-orbit extent of flight operations, although they may 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 design and initial development over a 10-month design period for a variation of the Starship second-stage vehicle and spaceship – a "Starship Human Landing System", or Starship HLS – as a Lunar human landing system for the NASA Artemis program; NASA is paying US$579 million and US$253 million to other contractors developing competing lunar landing designs.
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 tanks on the Starship vehicle.
The Starship vehicle 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 brief to lead to an increased risk of cancer, saying "it's not too big of a deal".
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