https://en.wikipedia.org/wiki/SpaceX_Starship
Development[edit]
Starship's development is iterative and incremental, using intensive tests on a series of rocket prototypes.[18][19] The first prototype, Starhopper, performed several static fires and low-altitude flights.[20] Seven of Starship's upper stage prototypes were flight tested between August 2020 and May 2021. The last of the seven, a full-size Starship SN15, successfully landed after reaching an altitude of 10 kilometers (6.2 mi).[21] A full-scale orbital test flight of the rocket took place on April 20, 2023.[22]
Starship prototype tests can generally be classified into three main types. In proof pressure tests, the vehicle's tanks are pressurized with either gases or liquids to test their strength—sometimes deliberately until they burst. The vehicle then performs mission rehearsals, with or without propellant, to check the vehicle and ground infrastructure. Before a test flight, SpaceX loads the vehicle prototype with propellant and briefly fires its engines in a static fire test.[23]: 18–19 Alternatively, the engines' turbopump spinning can be tested without firing the engines, referred to as a spin prime test.[24]
After successful testing, uncrewed flight tests and launches may commence. During a suborbital launch, Starship prototypes fly to a high altitude and descend, landing either near the launch site, in the sea, or onto offshore platforms. During an orbital launch, Starship performs procedures as described in its mission profile.[23]: 19–22 Due to SpaceX's relative openness for outsiders to peer into the facilities, Starship rocket tests, flights, and launches have received significant media coverage.[25]
Low-altitude flights[edit]
In September 2019, Musk further detailed the lower-stage booster, the upper stage's method of controlling its descent, its heat shield, orbital refueling capacity, and potential destinations besides Mars.[26] The aft flaps on the spacecraft were reduced from three to two, and Starship's body material was changed from carbon composites to stainless steel for its lower cost, higher melting point, strength at cryogenic temperatures, and ease of manufacture.[27]
SpaceX was already constructing the first full-size Starship Mk1 and Mk2 upper-stage prototypes, at the SpaceX facilities in Boca Chica, Texas and Cocoa, Florida respectively.[26] Neither prototype flew: Mk1 was destroyed in November 2019 during a pressure stress test and Mk2's Florida facility was abandoned and deconstructed throughout 2020.[28][29] After the Mk prototypes, SpaceX began naming its new Starship upper-stage prototypes with the prefix "SN", short for "serial number".[18] No prototypes between SN1 and SN4 flew either—SN1 and SN3 collapsed during pressure stress tests, and SN4 exploded after its fifth engine firing.[30]
In June 2020, SpaceX started construction of a launch pad for orbit-capable Starship rockets.[31] In the next month, the company bought two drilling rigs for $3.5 million each from Valaris plc during the latter's bankruptcy proceedings, to repurpose them as offshore spaceports.[32] The first flight-capable Starship SN5 was cylindrical as it had no flaps or nose cone: just one Raptor engine, propellant tanks, and a mass simulator. On 5 August 2020, SN5 performed a 150 m (500 ft) high flight and successfully landed on a nearby pad.[33] On 3 September 2020, the similar-looking Starship SN6 repeated the hop;[34] later that month, the Raptor Vacuum engine was fired in full duration.[35]
High-altitude flights[edit]
SN8 was the first fully complete Starship upper stage prototype. It underwent four preliminary static fire tests between October and November 2020.[30] On 9 December 2020, SN8 flew, slowly turning off its three engines one by one, and reached an altitude of 12.5 km (7.8 mi). After SN8 dove back to the ground, its engines were hampered by low methane header tank pressure during the landing attempt, which led to a hard impact with the landing pad.[36] Because SpaceX had violated its launch license and ignored warnings of worsening shock wave damage, the Federal Aviation Administration investigated the incident for two months.[37]
On 2 February 2021, Starship SN9 launched to 10 km (6.2 mi) in a flight path similar to SN8. The prototype crashed upon landing because one of its engines did not properly ignite.[38] A month later, on 3 March, Starship SN10 launched on the same flight path as SN8 and 9. The vehicle landed hard and crushed its landing legs, leaning to one side,[39] and a fire was seen at the vehicle's base. It exploded less than ten minutes later,[21] probably due to a propellant tank rupture.[39] On 30 March, Starship SN11 flew into thick fog along the same flight path.[40] The vehicle exploded during descent,[40] possibly due to excess propellant in a Raptor's methane turbopump.[41]
In March 2021, the company disclosed a public construction plan for two sub-orbital launch pads, two orbital launch pads, two landing pads, two test stands, and a large propellant tank farm. The company soon proposed developing the surrounding Boca Chica village into a company town named Starbase;[42] locals raised concerns about SpaceX's authority, power, and potential threat for eviction through eminent domain.[43] In early April, the orbital launch pad's fuel storage tanks began mounting.[31] A few weeks later, on 16 April, NASA selected Starship Human Landing System (HLS) as the crewed lunar lander.[44] Blue Origin, a bidding competitor to SpaceX, disputed the decision and began a legal case in August 2021,[45] which was dismissed by the Court of Federal Claims three months later.[46]
Starship prototypes SN12, SN13, and SN14 were scrapped before completion; SN15 was selected to fly instead.[47] SN15 had better avionics, structure, and engines.[21] On 5 May 2021, SN15 launched, completed the same maneuvers as older prototypes, and landed safely.[47] Even though SN15, like SN10, had a small fire in the engine area after landing, it was extinguished, completing the first successful high-altitude test.[21] According to a later report by SpaceX, SN15 experienced several issues while landing, including the loss of tank pressure and an engine.[48]: 2
Development towards first orbital launch[edit]
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In July 2021, Super Heavy BN3 conducted its first full-duration static firing and lit three engines.[49] 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.[51] A month later, using cranes, Ship 20 was stacked atop Booster 4 to form the full launch vehicle for the first time; Ship 20 was also the first craft to have a body-tall heat shield.[52] In October 2021, the catching mechanical arms, also known as "chopsticks", were installed onto the integration tower and the first tank farm's construction was completed.[31] Two weeks later, NASA and SpaceX announced plans to construct Kennedy Space Center's Launch Complex 49.[53]
The Raptor 2 engine was spotted by the public at the start of 2022. Raptor 2 has a simpler design, less mass, wider throat, and increase in main combustion chamber pressure from 250 bar (3,600 psi) to 300 bar (4,400 psi). These changes yielded an increase in thrust from 1.85 MN (420,000 lbf) to 2.3 MN (520,000 lbf), but a decrease of 3 seconds (~0.9%) of specific impulse.[54] In February 2022, after stacking Ship 20 on top of Booster 4 using mechanical arms, Elon Musk gave a presentation on Starship, Raptor engine and Florida spaceport development at Starbase.[55]
In June 2022, the Federal Aviation Administration determined that Starbase did not need a full environmental impact assessment, but that SpaceX must address issues identified in the preliminary environmental assessment.[56] In July, Booster 7 tested spinning the liquid oxygen turbopumps on all thirty-three Raptor engines, and an explosion occurred at the base of the vehicle, destroying a pressure pipe and causing minor damage to the launchpad.[57] By the end of November, Ship 24 had performed 2- and full 6-engine static fires,[58]: 20 while Booster 7 had performed static fires with 1, 3, 7, 11, 14 engines[59][58]: 20 and finally on 9th February 2023 a static fire with 31 engines at 50% throttle (33 was attempted but one engine was disabled pre-firing, and another engine aborted). In January 2023, Starship underwent a full wet dress rehearsal at Starbase, where it was filled with more than 4,500 t (10,000,000 lb) of propellant.[60]
First attempted orbital test flight[edit]
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After a cancelled launch attempt on April 17 due to a frozen valve,[61] Booster 7 and Ship 24 lifted off on 20 April 2023 at 14:33 UTC in the first orbital flight test that ended in failure.[62] Even though it lost several engines through the spaceflight, the vehicle reached a maximum altitude of 39 km (24 mi). The spacecraft was unable to separate from the booster and the rocket was intentionally destroyed by commanding the flight termination system.[63][64] Had everything proceeded as planned, the spacecraft would have continued to fly with its ground track passing through the Straits of Florida, with a hard splashdown in the Pacific Ocean around 100 km (60 mi) northwest of Kauai in the Hawaiian Islands, having made nearly one revolution around the Earth.[65][66]: 2–4
