As of July 2022, two Starship launch sites (Starbase in Texas and Kennedy Space Center in Florida) and two offshore platforms are under construction. They will be the starting point for many planned space missions, made possible due to the rocket's reduced launch cost and increased launch frequency. In the short term, Starship will deploy satellites and space probes, serve commercial astronauts, and explore the Moon via the Artemis program. In the long term, the rocket may aid SpaceX's ambition of colonizing Mars and enable fast travel between Earth's spaceports.
SpaceX had envisioned a large-capacity launch vehicle concept since as early as 2005. Over the next dozen years, the vehicle's design and construction techniques were refined, specifying the methane fuel in 2012 and stainless-steel construction in 2019. Starship's development program adopted an iterative and incremental methodology, meaning frequent prototype construction, testing, and refinement. As of July 2022, the program has achieved important milestones, such as operating the Raptor engine in vehicles (Starhopper) and demonstrating the use of stabilizing flaps (Starship SN8–SN15). A full-scale orbital test flight is expected to take place in 2022.[2]
In November 2005,[3] before SpaceX launched its first rocket (Falcon 1),[4] CEO Elon Musk first referenced a long-term and high-capacity rocket concept named BFR that would be able to launch 100 t (220,000 lb) to low Earth orbit. It would use the proposed Merlin 2 kerosene-oxygen rocket engine, which is in direct lineage to the Merlin engines used on the Falcon 9. The Merlin 2's thrust would have been comparable to the F-1 engines used on the Saturn V.[3]
In July 2010,[5] after the final launch of Falcon 1 a year prior,[6] SpaceX presented at a conference Mars space tug and heavy-lift launch vehicle concepts, called Falcon X, Falcon X Heavy, and Falcon XX. The largest of these launch vehicles is the Falcon XX with a 140 t (310,000 lb) capacity to low Earth orbit. To deliver such payload, the Falcon XX would have been as tall as the Saturn V and used six Merlin 2 engines.[5] Around 2012,[7] the company first mentioned the Mars Colonial Transporter rocket concept in public, designed for Mars colonization. The rocket was going to be able to carry 100 people or 100 t (220,000 lb) of cargo to Mars and be powered by the in development methane-oxygen Raptor engines.[8] It had seemed that the Raptor engine had superseded the Merlin 2.
SpaceX illustration of the 2016 Interplanetary Transport System
On 26 September 2016, a day before the 67th International Astronautical Congress, the Raptor engine fired for the first time.[9] There, Musk announced the Interplanetary Transport System launch vehicle that uses the Raptor engines. It would have two stages, composing of a booster and a spacecraft. The stages' tanks were proposed to be made from carbon composite for storing liquid methane and liquid oxygen. Despite the rocket's 300 t (660,000 lb) launch capacity to low Earth orbit, it was expected to have a low launch price due to its total reusability. The spacecraft would feature three variants: crew, cargo, and propellant tanker for in-orbit refueling.[10] The Interplanetary Transport System concept garnered a large amount of skepticism, because of the gigantic amount funds and development needed to make it possible.[11]
In September 2017, at the 68th Annual International Astronautical Congress, Musk detailed about the BFR launch vehicle (Big Falcon Rocket),[12] a revision to the Interplanetary Transport System's design. The rocket was still going to be fully reusable, but it was shrunk down and have its low Earth orbit capacity reduced to 150 t (330,000 lb). Unlike its conceptual predecessor, the potential applications for the BFR were more varied. Variants of the BFR would be able to send satellites to orbit, resupply the International Space Station, land on the Moon, travel between spaceports on Earth, and ferry crew to Mars.[13] In April 2018, the Mayor of Los Angeles confirmed plans for a BFR rocket production facility at the Port of Los Angeles,[14] but the plan was abandoned around May 2020.[15]
SpaceX illustration of the 2018 Big Falcon Rocket at stage separation
A year later in September 2018, the BFR's spacecraft received two new forward flaps at the top and three larger aft flaps at the bottom. Both sets of flaps help to control the spacecraft's descent and the aft flaps would also be used as landing legs for the final touchdown. The first contract for the BFR spacecraft was also revealed during the event, which is the dearMoon project led by Japanese billionaire Yusaku Maezawa. The mission, announced as flying in 2023, would have Maezawa and six to eight artists producing artworks onboard a spacecraft, while flying a free-return trajectory around the Moon. This contract had secured crucial funding to the rocket's development.[16] Two months later in November 2018, the rocket booster was first termed Super Heavy and the spacecraft was termed Starship.[12]
Starship's development is iterative and incremental, marked by tests on rocket prototypes.[17][18] The first of such prototypes is called Starhopper, which performed several static fires and low-altitude flights.[19] Then, seven of Starship's upper stage prototypes[a] were flight tested between August 2020 and May 2021. The last of which, a full-size Starship SN15, successfully landing after launching to an altitude of 10 kilometres (6.2 mi).[20] A full-scale orbital test flight of the rocket is currently expected to take place in late 2022.[2]
Generally, Starship prototype tests can be classified into three main types. In proof pressure tests, the vehicle's tanks are pressurized with either gases or liquids to test its tank strength. Sometimes, the vehicle is deliberately overpressurized resulting in a burst. The vehicle then performs mission rehearsals, with or without propellant, to check both the vehicle and ground infrastructure. Before a test flight, SpaceX loads the vehicle prototype with propellant and fires its engines briefly, conducting a static fire test.[21]: 18–19 Alternatively, the engines' turbopump spinning can be tested without firing the engines, referred to as a spin prime test.[22]
After these tests are deemed successful, flight tests and launches may commence. During a suborbital launch, Starship prototypes fly to a high altitude and descend, landing back at either near the launch site, sea, or offshore platforms. During an orbital launch, Starship performs procedures as described in its mission profile.[21]: 19–22 Due to the company's openness to the space news industry, Starship rocket tests, flights, and launches have received significant media coverage.[23]
Low-altitude flights
Starhopper under construction, March 2019
A crane lifting Starship SN5, August 2020
The first prototype to fly using a Raptor engine was called Starhopper.[24] The vehicle had three non-retractable legs and was shorter than the final spacecraft design.[25] The craft performed two tethered hops in early April 2019 and three months later, it hopped without a tether to around 25 m (80 ft).[26] In August 2019, the vehicle hopped to 150 m (500 ft) and traveled to a landing pad nearby.[19] As of August 2021, the vehicle has been retired and repurposed; it is now a mounting point for communication, weather monitoring and tracking equipment, and becoming a water tank.[27]
In late September 2019, Musk presented more details about the lower-stage booster, the upper stage's method of controlling its descent, its heat shield, orbital refueling capacity, and potential destinations outside of Mars.[28] The number of aft flaps on the spacecraft was reduced from three to two, and Starship's body material was changed from carbon composites to stainless steel, due to lower cost, higher melting point, strength at cryogenic temperature, and ease of manufacturing.[29]
SpaceX was already constructing the first full-size Starship Mk1 and Mk2 upper-stage prototypes before the presentation. They were located at the SpaceX facilities in Boca Chica, Texas, and Cocoa, Florida, respectively.[28] Neither prototype flew, as Mk1 was destroyed November 2019 during a pressure stress test and Mk2's Florida facility was abandoned and deconstructed throughout 2020.[30][31] After the Mk prototypes, SpaceX began naming its new Starship upper-stage prototypes with the prefix "SN", short for "serial number".[17] No prototypes between SN1 and SN4 flew either, as SN1 and SN3 collapsed during pressure stress tests and SN4 exploded after its fifth engine firing.[27] In January 2020, the company bought two drilling rigs for $3.5 million from Valaris plc each during Valaris's bankruptcy proceedings, with plans to repurpose them as offshore spaceports.[32]
In June 2020, SpaceX started construction of a launch pad for orbit-capable Starship rockets.[33] Starship SN5 was built with no flaps or nose cone, giving it a cylindrical shape. The test vehicle consisted of one Raptor engine, propellant tanks, and a mass simulator. On 5 August 2020, SN5 performed a 150 m (500 ft)-high flight, successfully landing on a nearby pad.[34] On 3 September 2020, the similar-looking Starship SN6 successfully repeated the hop.[35] A week later, SpaceX stress-tested SN7.1 fuel tank, which was constructed from SAE 304L stainless steel rather than SAE 301 by earlier tanks.[27] In the same September, the company fired its Raptor Vacuum engine in full duration.[36]
High-altitude flights
Starship SN9 on a mount with its flaps closed, January 2021
SN8 was the first fully complete Starship upper stage prototype. Before its flight, it underwent four static fire tests between October and November 2020.[27] On 9 December 2020, SN8 flew, slowly turning off its three engines one by one, and reaching to an altitude of 12.5 km (7.8 mi). The craft then performed the belly-flop maneuver and dove back through the atmosphere. As it tried to land, an issue with fuel tank pressure caused the prototype to lose thrust and impact the pad.[37] Because SpaceX had violated its launch license and ignored warnings of worsening shock wave damage, the Federal Aviation Administration performed a two-month investigation of the incident.[38] On 2 February 2021, Starship SN9 launched to 10 km (6.2 mi) in altitude and crashed upon landing, similar to SN8.[39] Unlike the last test flight, the explosion is within the Federal Aviation Administration's safety bounds.[40]
A month later, on 3 March 2021, after an initially aborted launch three hours earlier, Starship SN10 launched on the same flight path as its two predecessors. The vehicle then landed hard and crushed its landing legs, leaning to one side,[41] and a fire was seen at the vehicle's base. Less than ten minutes later,[20] it exploded, probably due to a propellant tank rupture.[41] A few weeks later on 30 March 2021, Starship SN11 flew into thick fog along the same flight path.[42] About twenty-five seconds after lift-off, fire could be spotted at an engine, though it does not impact the ascent.[43] During descent, the vehicle exploded, scattering debris up to 8 km (5 mi) away.[42] It was suspected that a methane leak damaged the vehicle's avionics, causing excess propellant in a Raptor's methane turbopump, leading to the vehicle's explosion.[43]
In March 2021, the company sent a public construction plan that had two sub-orbital launch pads, two orbital launch pads, two landing pads, two test stands, and a large propellant tank farm. In the same month, the company proposed developing the surrounding Boca Chica village into a company town named Starbase,[44] raising concerns about SpaceX's authority, power, and potential abuse for eviction.[45] In early April 2021, the orbital launch pad's fuel storage tanks began mounting.[33] A few weeks later, on 16 April 2021, NASA selected Starship HLS as the crewed lunar lander.[46]Blue Origin, a bidding competitor to SpaceX, disputed the decision and began a legal case in August 2021,[47] and it was later dismissed by the Court of Federal Claims three months later.[48]
Starship prototypes SN12, SN13, and SN14 were scrapped before completion, and Starship SN15 was selected to fly instead.[49] The prototype features general improvement on its avionics, structure, and engines, learning from the failures of prior prototypes.[20] On 5 May 2021, SN15 launched, completed the same maneuvers as older prototypes, and landed softly[49] after six minutes. Even though SN15 had a small fire in the engine area after landing, like SN10, it was extinguished, completing the first successful high-altitude test.[20] Further prototypes such as Starship SN16 were built, but plans for flying them were abandoned.[50]
From left to right: Booster 4, Ship 15, Ship 22, and Ship 20 displayed at Starbase, June 2022
In July 2021, Super Heavy BN3 conducted its first full-duration static firing, lighting three engines.[51] Around this time, SpaceX changed their naming scheme from "SN" to "Ship" for Starship crafts,[50] and from "BN" to "Booster" for Super Heavy boosters.[52] A month later, using cranes, Ship 20 was stacked atop Booster 4 for the first time. Ship 20 was the first to include a body-tall heat shield, made of standardized hexagonal heat tiles.[53] In October 2021, the catching mechanical arms were installed onto the integration tower, and the first tank farm's construction was completed.[33] Two weeks later, NASA and SpaceX announced their plans to construct Kennedy Space Center's Launch Complex 49.[54]
At the start of 2022, the Raptor 2 engine was first spotted by the public. Raptor 2 is intended to be a upgrade to the original engine with a much more simplified design, decrease in mass, widening of the throat, and increase in main combustion chamber pressure from 250 bar (3,600 psi) to 300 bar (4,400 psi). This lead to an increase in thrust from 1.85 MN (420,000 lbf) to 2.3 MN (520,000 lbf), with a 3 seconds of specific impulse decrease trade off.[55] In February 2022, after stacking Ship 20 on top of Booster 4 using mechanical arms,[56] Elon Musk gave a presentation on Starship development at Starbase; he updated progress on Raptor 2 production, mentioned a possible move to the Florida facility, and confirmed many technical information speculations.[57]
In June 2022, the Federal Aviation Administration determined that Starbase did not need a full environmental impact assessment, though the company must address issues outlined in the final assessment document.[58] One month later on 11 July 2022, Booster 7 tested spinning the liquid oxygen turbopumps on all of its thirty-three Raptor engines, referred to as a spin prime test. The test resulted in a violent explosion at the prototype's base, though the prototype's body remains somewhat intact.[59] As of July 2022, Booster 7 is expected to pair up with Ship 24 for the first orbital flight.[22]
Although SpaceX has not received an orbital launch license as of 13 June 2022,[60] the company had described the planned trajectory in a report sent to the Federal Communications Commission. During the orbital test flight, the rocket is planned to launch from Starbase, after which the Super Heavy booster will separate and perform a soft water landing around 30 km (20 mi) from the Texas shoreline. The spacecraft will continue flying with its ground track passing through the Straits of Florida and then softly land in the Pacific Ocean around 100 km (60 mi) northwest of Kauai in the Hawaiian Islands. The spaceflight will last ninety minutes.[61]: 2–4
Design
Starship is designed to be a fully reusable and orbital rocket, aiming to drastically reduce launch costs and maintenance between flights.[62]: 2 The rocket will consist of a Super Heavy first stage or a booster and a Starship second stage or spacecraft,[1] powered by Raptor and Raptor Vacuum engines.[63] The bodies of both rocket stages are made from stainless steel, giving Starship its shine and strength for atmospheric entry.[64] The rocket's reusability and stainless-steel construction has influenced other rockets such as the Terran R[65] and Project Jarvis.[66]
When stacked and fueled, Starship is about 5,000 t (11,000,000 lb) by mass,[b] 9 m (30 ft) wide,[69] and 120 m (390 ft) high.[c] It is taller than the Saturn V by 9 m (30 ft), a rocket that was used for the NASA Apollo program of the 1960s and 1970s.[70]: 6 With Super Heavy's peak thrust of 72 MN (16,000,000 lbf),[71] the rocket has a thrust-to-weight ratio of about 1.45 at liftoff.[d] One launch may deliver 100 t (220,000 lb) to low Earth orbit,[72] which would formally classify the rocket as a super heavy-lift launch vehicle.[e]
According to Eric Berger from Ars Technica in March 2020, manufacturing of the Starship rocket starts with rolls of steel. They are then unrolled, cut, and welded along the cut edge to create a cylinder 9 m (30 ft) in diameter, 2 m (7 ft) in height, and around 1,600 kg (4,000 lb) in mass. To make the outer layer of the Starship spacecraft, seventeen of these cylinders and nose cones are stacked and welded along their edges. Between the methane and oxygen tanks are domes, made by robots welding at a rate of ten minutes per seam, equal to four hours per dome. These welds are later inspected with an X-ray machine.[75]
Raptor is a family of rocket engines used in Starship, made by SpaceX. The Raptor engines burn liquid oxygen and methane, which is chosen because they are cheap, produce little soot[76] and can be made on Mars via the Sabatier reaction.[77] The engines run at an oxygen-to-methane mixture ratio of between 3.5 : 1 and 3.7 : 1, which is somewhat more fuel-rich or lower than the stoichiometric mixture. Combusting propellant in the stoichiometric mixture would overheat and damage the Raptor engines.[67]
The engine structure is mostly made out of aluminum, copper, steel and SpaceX's proprietary SX500superalloy, with a small number of 3D printed parts. As of July 2022, the company aims to produce each engine for about $250,000. The Raptor's gimbaling or rotation range is 15°, higher than the RS-25's 12.5° and the Merlin's 5°. The main combustion chamber ignites the gas via its own temperature and pressure[55] and is able to contain 300 bar (4,400 psi) of pressure, the highest of all rocket engines.[76] A Raptor engine can produce 2.3 MN (520,000 lbf) of thrust with a fuel efficiency or specific impulse of 327 seconds.[55]
SpaceX builds many other variants of Raptor. The Raptor Vacuum, designed to be fired in space, is equipped with a nozzle extension made from brazed steel tubes. This and other modifications to the engine increase its throat-to-exit-area ratio to 1:90 and specific impulse to 380 seconds.[67] Another engine variant, Raptor Boost, is used in the outer ring of Super Heavy's engine cluster and unable to steer.[78] Future versions of the engine would have its thrust and main combustion chamber pressure increased.[55]
The Raptor engine family is the only full-flow staged combustion cycle engine currently in production. In the past, the Soviet Union and the United States tried to construct such an engine, but neither product has been put in a rocket.[76] A general full-flow staged combustion cycle engine has two preburners connected to their matching turbopumps. One of the preburners is fed with an oxidizer-rich mixture and the other is fed with a propellant-rich mixture, which both combust slightly to spin the matching turbines. The cycle then feeds all the oxidizer-rich and propellant-rich gaseous mixture into the combustion chamber, unlike other engine cycles that waste some propellant. This increases the engine's chamber pressure, making the engine able to produce more thrust and being more efficient overall.[76][79][80]
Super Heavy booster
Super Heavy's underside without any Raptor engines mounted
Super Heavy is a first stage or booster stage, forming the lower part of the rocket. The booster is 70 m (230 ft) tall, 9 m (30 ft) wide,[69] and houses up to thirty-three sea level-optimized Raptor engines.[71] The engine cluster is composed of an inner ring of three engines, surrounded by ten in the middle ring and twenty in the outer ring.[81] The engines in the inner and middle ring can steer or thrust vector control, but those in the outer ring cannot. This is because the engines in the outer ring belong to a different Raptor variant, called Raptor Boost.[78] Collectively, they produce 72 MN (16,000,000 lbf) at full power, more than twice as powerful as the Saturn V.[71]
The booster's tanks can hold 3,600 t (7,900,000 lb) of propellant, consisting of 2,800 t (6,200,000 lb) of liquid oxygen and 800 t (1,800,000 lb) of liquid methane.[f] Super Heavy also stores 280 L (74 US gal) of hydraulic fluid for its operations.[21]: 158 The final design of Super Heavy is estimated to have a dry mass between 160 t (350,000 lb) and 200 t (440,000 lb), with the tanks weighing 80 t (180,000 lb) and the interstage 20 t (44,000 lb).[67]
The booster is equipped with four grid fins powered by electricity, each of which has a mass of 3 t (6,600 lb). The grid fins are unevenly spaced to allow the craft to obtain more pitch control and can only rotate in the roll axis.[67] Between the grid fins are Super Heavy's hardpoints, which are used for lifting and catching by the mechanical arms on the integration tower.[33] The booster's orientation can be controlled using cold gas thrusters, fed with evaporated propellant inside the tanks. The booster's separation from the spacecraft is done by the Raptors engines and releasing the latches.[67]
Starship spacecraft
Leeward angle of Starship SN16 spacecraft
Starship is a second stage or long-duration spacecraft, forming the upper part of the rocket.[82] The spacecraft is 50 m (160 ft) tall[69] and has a dry mass of less than 100 t (220,000 lb).[67] Starship's payload volume is about 1,000 m3 (35,000 cu ft),[72] larger than the International Space Station's pressurized volume by 80 m3 (2,800 cu ft),[83] and can be even bigger with an extended 22 m (72 ft)-tall volume.[84]: 2 By refueling the Starship spacecraft in orbit using tanker spacecraft, Starship will be able to transport larger payloads and more astronauts to other Earth orbits, the Moon, and Mars.[84]: 5
Starship has a total propellant capacity of 1,200 t (2,600,000 lb),[85] divided into main tanks and header tanks.[86] The header tanks are better insulated due to their position and are reserved for use to flip and land the spacecraft following reentry.[87] About 130 L (34 US gal) of hydraulic fluid is used for the spacecraft's operations.[21]: 158 At the aft end of the Starship spacecraft are six Raptor engines, three of which are designed for operation in the lower atmosphere, and the other three Raptor Vacuum engines are optimized to operate in the vacuum of space.[18] A set of reaction control thrusters mounted at the spacecraft's exterior control the spacecraft's attitude while in space.[37]
The spacecraft has four body flaps to control the spacecraft's orientation and help to dissipate energy during atmospheric entry,[88] composed of two forward flaps and two aft flaps.[89] Under the forward flaps are hardpoints, used for lifting and catching the spacecraft via mechanical arms.[33] The flap's hinges are sealed with metal because they are easily damaged during reentry otherwise.[67]
Starship's heat shield, composed of thousands[53] of hexagonal black tiles,[18] is designed to be used many times, ultimately with no maintenance between flights.[62]: 2 The tiles are made of silica[90] and are more uniform in shape than the Space Shuttle's heat shield tiles. They are attached, not glued,[18] with small gaps in between to counteract heat expansion.[67] Their hexagonal shape is designed to enable mass production[67] and prevent hot plasma from causing severe damage, allowing the tiles to withstand temperatures of 1,400 °C (2,600 °F).[91]
Variants
According to Starship's user guide written in March 2020, the generic cargo spacecraft variant will feature a large door replacing conventional payload fairings. The payload door would be closed during launch, opened to release its payload once in orbit, and closed again during reentry. It may be possible to mount the payload on the inside of the payload bay's sidewalls using trunnions, suitable for payloads on ride-share missions. Payloads are going to be integrated into a vertical rocket inside temperature-controlled, ISO class 8 clean air.[84]: 2–4 A specialized dispenser will be fitted for those tasked with deploying Starlink v2.0 satellites, releasing pairs of satellites through a slot akin to a Pez candy dispenser.[92]
The user guide also detailed about the crewed spacecraft variant, which is designed for missions to the Moon, Mars, etc. Each spacecraft will be able to carry around one hundred people, with "private cabins, large communal areas, centralized storage, solar storm shelters, and a viewing gallery".[84]: 5 Starship's life-support system is expected to be regenerative, which resources inside are constantly recycled. Other than that, little information about the system is provided to the public.[93]
The tanker spacecraft variant can be used to refuel another Starship in orbit, allowing the ship to transport larger payloads and more astronauts to other Earth orbits, the Moon, and Mars.[94] Up to fourteen launches of Starship tanker variant are needed to send a spacecraft to the Moon, though according to Musk only four to eight tanker launches are needed.[95] Another Starship orbital propellant depot variant is in development, used to receive propellant from tanker Starships and refuel Starship HLS.[96]: 4, 52 As of October 2020, the Starship variant is under development for conducting a large-scale flight demonstration, transferring 10 t (22,000 lb) of propellant between two spacecraft.[97]
Starship HLS is a crewed lunar lander variant of the Starship spacecraft for NASA's Artemis program. The lunar lander may have windows and airlocks far away from the lunar surface,[98] along with an elevator and a set of thrusters to land on the Moon's surface.[99] The lunar lander may be able to carry a large amount of payload between outer space and the Moon. On an Artemis mission, it may launch ahead of the crew by up to a hundred days, accompanied with launches of refueling Starship tankers. Another variant of the lunar lander may be used for the Commercial Lunar Payload Services program,[98] where scientific, exploration, and commercial payloads are sent to the Moon.[100]
Mission profile
Animation of Super Heavy's integration to the launch mount, using mechanical arms
The payload will first integrate onto Starship at a separate facility and then roll out to the launch site.[21]: 36 After Super Heavy and Starship are stacked onto a launch mount by lifting from hardpoints, they will be loaded with propellant via the quick disconnect arm and mount.[33] Roughly four hundred truck deliveries are needed for one launch, though some commodities will be provided on-site via an air separation unit.[21]: 161–162 Then, the arm and mount will be detached, all thirty-three engines of Super Heavy fire, and the rocket lifts off.[33]
A short animation of Super Heavy's landing on mechanical arms. The actual landing speed is a few times slower.
After two minutes,[101] at an altitude of 65 km (40 mi), Super Heavy is going to cut off its engines and[21]: 21 release the latches, causing the rocket stages to separate.[67] The booster will then flip its orientation and ignite its engines briefly. As the booster returns to the launch site via a controlled descent, similar to the Falcon 9's first stage,[21]: 21 it is going to be caught by a pair of mechanical arms.[102] After six minutes in flight,[101] about 20 t (44,000 lb) of propellant will remain inside the booster.[67]
Meanwhile, the Starship spacecraft accelerates to orbital velocity. Once in orbit, the spacecraft can be refueled by one or more tanker variant Starships, increasing the spacecraft's capacity.[72] To land on bodies without an atmosphere such as the Moon, Starship would turn on its engines and thrusters to slow down.[99] To land on bodies with an atmosphere such as Earth and Mars, Starship is going to slow down first by entering the atmosphere, protected by its heat shield.[62]: 1 The spacecraft will then perform the belly-flop maneuver, by diving back through the atmosphere body first in a 60° angle to the ground[29] and control its fall using the four flaps.[37]
Near touchdown, the Raptor engines will fire,[37] using propellant from the header tanks,[87] causing the spacecraft to flip back to a vertical orientation. At this stage, Raptor engines' gimbaling, throttle, and reaction control system's firing will help precisely maneuver the craft.[37] A pseudospectral optimal control algorithm by the German Aerospace Center predicted that the landing flip would tilt up to 20° from the ground's perpendicular line, and the angle would be reduced to zero on touchdown.[103]: 10–12 In the future, Starship is envisioned to be caught by mechanical arms, like the booster.[33]
If Starship's rocket stages land on a pad, a mobile hydraulic lift will then move them to a transporter vehicle. If the rocket stages land on a floating platform, they will be transported by a barge to a port and move the rest of the distance by road. After recovery, Super Heavy and Starship will either be positioned on the launch mount for another launch, or refurbished at a SpaceX facility.[21]: 22
Starship's reusability is expected to reduce launch costs, expanding space access to more payloads and entities.[104] Musk has stated that a Starship orbital launch will eventually cost $1 million (or $10 per kilogram). However, Eurospace's director of research Pierre Lionnet stated that Starship's launch cost will likely be higher because of the rocket's high development cost.[94] Starship is also expected to be able to launch up to three times per day[94] and replace the company's Falcon 9 and Falcon Heavy rockets.[105] Such a launch cadence is necessary for Starship's profitability and may cause the current space industry to become saturated.[94] One way for Starship to meet its demand is to launch rideshare missions that carry many satellites at once.[106]
Commercial and defense
SpaceX illustration of a violin performance in a space tourism mission, demonstrating Starship's large internal volume
Starship is also planned to launch the second satellite generation of SpaceX's Starlink constellation, used for delivering global high-speed internet.[107] A space analyst at financial services company Morgan Stanley stated development of Starship and Starlink are intertwined, with Starship launch capacity enabling cheaper Starlink launches, and Starlink's profits financing Starship's development costs.[108] When Starlink satellites reach end of life, they can be recovered by the spacecraft to reduce space debris.[109]
As of 19 August 2022, the Superbird-9 communication satellite is Starship's first and only known contract for externally made commercial satellites. The satellite weighs 21 t (46,000 lb) and plans to launch in 2024 to a geostationary orbit.[110] Also in the near term, the crewed variant of the spacecraft can be used for space tourism activities. An example is the dearMoon project announced by Japanese entrepreneur Yusaku Maezawa, which consists of a flight around the Moon aboard Starship with a crew comprising Maezawa and eight others.[111] Another example is the third flight of the Polaris program announced by Jared Issacman.[112]
In the farther future, Starship may host point-to-point flights, coined "Earth to Earth" by SpaceX, traveling anywhere on Earth in under one hour.[113] SpaceX resident and chief operating officer Gwynne Shotwell predicted point-to-point travel could become cost-competitive with conventional business class flights.[114] Contrariwise, John Logsdon, an academic on space policy and history, said point-to-point travel is unrealistic, as the craft would go back and forth from weightlessness to 5 g of acceleration.[115] As of January 2022, SpaceX was awarded a $102 million, five-year contract to develop under the Rocket Cargo program.[116]
Space exploration
Artemis 3 launch profile of a human landing on the Moon, involving Starship HLS, Starship tanker variants, and Orion spacecraft
However, there are differing opinions about how Starship's low launch cost will affect future science payloads' cost. According to Waleed Abdalati, former NASA Chief Scientist, the low launch cost will make satellite replacement cheaper and enable more ambitious missions for budget-limited programs. Though according to Lionnet, low launch cost may not reduce the overall cost of a science mission significantly. He cited the Rosetta space probe and Philae lander's mission cost of $1.7 billion, which the launch cost only composed less than ten percent.[109]
Starship's lunar lander variant, Starship HLS, is critical to the Artemis program, a current NASA human exploration program of the Moon.[98] The lander is accompanied by Starship tankers and Starship propellant depot variants. The tankers transfer propellant to a depot till it is full, then the depot fuels Starship HLS. By doing so, the lunar lander has enough thrust to place itself into a lunar orbit. Then, the crews on board the Orion spacecraft are launched with the Space Launch System. Orion then docks with Starship HLS and the crews transfer into the lander. After landing and returning, the lunar crews transfer back to Orion and return to Earth.[96]: 4, 5
Illustration of a Starship spacecraft heading towards Mars
The Starship spacecraft's Mars variant is expected to be able to land on Mars and return to Earth.[118]: 120 First, the main spacecraft is launched to low Earth orbit, then gets refueled by around five tanker spacecraft before heading towards Mars.[119] After landed on Mars, the Sabatier reaction is used to create liquid methane and liquid oxygen, Starship's propellant, in a power-to-gas plant. The plant's raw resources are taken from the Martian water and carbon dioxide.[77] On Earth, similar technologies can be used to create carbon-neutral propellant for the rocket.[120]
SpaceX and Musk have stated their goal of colonizing Mars to ensure the long-term survival of humanity,[94][121] with an ambition of sending thousand Starship spacecraft to Mars during a Mars launch window.[122] This goal has been evident since before SpaceX's founding, when Musk in 2001 joined the Mars Society and researched about Mars-related space experiments.[123] In 2011, SpaceX proposed robotic scientific missions to Mars using the Red Dragon capsule adapted from its Dragon capsule,[124] but the proposal was eventually abandoned around 2017.[125]
Musk has made many tentative predictions about Starship's first crewed Mars landing,[64] the most recent one being 2029, made in March 2022.[126] However, it is unlikely that SpaceX will meet the prediction, as the company has not detailed technical plans about Starship's life-support systems, radiation protection,[93] and in-orbit refueling.[119]
A bay at Starbase build site, hosting construction of prototypes
Starbase consists of a manufacturing facility and launch site,[127] and is located at Boca Chica, Texas. Both facilities operate for twenty-four hours a day,[75] and a maximum of 450 full-time employees may be onsite.[21]: 28 The site is planned to consist of two launch sites, one payload processing facility, one seven-acre solar farm, and other facilities.[21]: 34–36 As of April 2022, the expansion plan's permit has been withdrawn by the United States Army Corps of Engineers, citing lack of information provided.[128] The company leases Starbase's land for the STARGATE research facility owned by the University of Texas Rio Grande Valley, and uses part of it for Starship development.[129]
At McGregor, Texas, the Rocket Development facility tests all Raptor engines. The facility has two main test stands: one horizontal stand for both engine types and one vertical stand for sea-level-optimized rocket engines. Other test stands are used for checking Starship's reaction control thrusters and Falcon's Merlin engines. In the past, the McGregor facility hosted test flights of landable first stages; Grasshopper and F9R Dev1. 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.[130]
At Florida, a facility at Cocoa purifies silica for Starship heat-shield tiles, producing a slurry which is then shipped to another facility at Cape Canaveral. In the past, workers at this facility constructed the Starship Mk2 prototype in competition with Starbase's crews.[90] Within the state, the Kennedy Space Center is planned to host other Starship facilities, such as Starship launch sites at Launch Complex 39A, planned Launch Complex 49, and a production facility at Roberts Road. The production facility is being expanded from Hangar X, Falcon rocket boosters' storage and maintenance facility. Roberts Road facility will include a 30,000 m2 (320,000 sq ft) building, loading dock, and a place for constructing integration tower sections.[131]
Launch sites
A launch site at Starbase, showing a tank farm and an integration tower in construction
Starbase is planned to host two launch sites, named Pad A and B.[21]: 34 A launch site at Starbase has large facilities, such as a tank farm, launch pad, and an integration tower. Smaller facilities are present at the launch site: tanks surrounding the area contain methane, oxygen, nitrogen, helium, hydraulic fluid, etc.;[21]: 161 subcoolers near the tank farm cool propellant using liquid nitrogen; and various pipes are installed at large facilities.[33] Each tank farm consists of eight tanks, enough for one orbital launch. The launch pad has a water sound suppression system, twenty clamps that hold down the booster, and a quick disconnect mount that provides the rocket with commodities and electricity.[33]
An integration tower or launch tower consists of steel truss sections, a lightning rod on top,[132] and a pair of mechanical arms that can lift, catch and recover the booster called "Mechazilla". The mechanical arms are attached onto 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, the carriage and mechanical arms can move vertically, with support from bearings attached at the sides of the carriage. A linear hydraulic actuator is used to move the arms side by side. Tracks are mounted on top of arms, which are used to position the booster or spacecraft precisely. The tower is mounted with a quick disconnect arm that can extend to and contract from the booster; its functions are similar to the quick disconnect mount.[33]
Other launch sites are in construction or being planned. Phobos and Deimos are the names of two Starship offshore launch platforms, both of which were in renovation as of March 2022.[133] Before being purchased from Valaris plc in June 2020, they were nearly-identical oil platforms named Valaris 8501 and Valaris 8500.[32] Their main decks are 78 m (260 ft) long by 73 m (240 ft) wide; their four columns are 15 m (49 ft) long and 14 m (46 ft) wide; and their helicopter decks are 22 m (72 ft) in diameter.[134] In February 2022, Musk stated Phobos and Deimos are not yet in SpaceX's focus. He then said in the far future, most Starship launches would start from offshore platforms.[56]
Since 2021,[135] the company is constructing a Starship launch pad in Cape Canaveral, Florida in Kennedy Space Center's Launch Complex 39A,[131] which is currently used to launch Crew Dragon capsules to the International Space Station.[135] SpaceX plans to make a separate pad at 39A's north, named Launch Complex 49.[131] Because of Launch Complex 39A's Crew Dragon launches, the company is studying how to strengthen the pad against the possibility of a Starship explosion and proposed to retrofit Cape Canaveral Space Launch Complex 40 instead. According to Musk, these launch sites at Cape Canaveral will become the primary ones, and Starbase in Texas will be used for research and development.[135] The towers and mechanical arms at the Florida launch sites should be similar to one at Starbase with improvements.[131]
Reception
Starship SN15 and SN16 juxtaposed with a local tiki bar
Reception to Starship's development among local communities has been mixed, especially from cities near the Starbase spaceport. Proponents of SpaceX's arrival said the company would provide money, education, and job opportunities to the country's poorest areas. Fewer than one-fifth of those twenty-five or older in the Rio Grande Valley have a bachelor's degree, in comparison to the national average of one-third.[136] The local government has stated that the company boosted the local economy by hiring local residents and investing, aiding three-tenths of the population who are living in poverty.[137]
Opponents of the development said the company encourages Brownsville's gentrification, with an ever-increasing property valuation.[137] Though Starbase had been originally planned to launch Falcon rockets when the original environmental assessment was completed in 2014,[138] the site in 2019 was subsequently used to develop Starship which ultimately required a revised environmental assessment.[139] The assessment was completed in June 2022, where the Federal Aviation Administration determined the changes would have "no significant impact".[58] Some of the tests have resulted in large explosions, causing major disruption to nearby wildlife reserves and residents' life. The disruption to the residents is further compounded by SpaceX's frequent beach and road closures for vehicle testing.[139] Because of this, some have moved away or requested financial reparations from the company.[137]
Notes
^SN5, SN6, SN8, SN9, SN10, SN11, and SN15. Search the article for their respective citations.
^Super Heavy dry mass: 160 t (350,000 lb) – 200 t (440,000 lb); Starship dry mass: <100 t (220,000 lb); Super Heavy propellant mass: 3,600 t (7,900,000 lb);[67] Starship propellant mass: 1,200 t (2,600,000 lb).[68] The total of these masses is about 5,000 t (11,000,000 lb).
^Super Heavy is 70 m (230 ft) tall and Starship spacecraft is 50 m (160 ft) tall,[69] sum up to 120 m (390 ft).
^72 MN (16,000,000 lbf) of thrust[71] divide by 5,000 t (11,000,000 lb) of weight gives 1.44, round up to 1.45.
^100 t (220,000 lb) to low Earth orbit fits with both the Russian's[73] and United States's[74]: TA01-6 super heavy-lift classification.
^78% of 3,600 t (7,900,000 lb)[67] is 2,800 t (6,200,000 lb) of liquid oxygen.
^McConnaughey, Paul K.; Femminineo, Mark G.; Koelfgen, Syri J.; Lepsch, Roger A.; Ryan, Richard M.; Taylor, Steven A. (November 2010). Draft Launch Propulsion Systems roadmap – Technology Area 01(PDF) (Report). Archived(PDF) from the original on 4 April 2022. Retrieved 9 June 2022.
This article incorporates text from this source, which is in the 
