SpaceX Starship

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SpaceX Starship

Artist's concept of the carbon-fiber Starship following stage separation
Manufacturer	SpaceX
Designer	Elon Musk (lead designer) Tom Mueller (engine designer)
Country of origin	United States
Specifications
Spacecraft type	fully reusable, cargo (crewed option later)
Launch mass	1,320,000 kg (2,910,000 lb)
Dry mass	120,000 kg (260,000 lb)(target)
Payload capacity	100,000 kg (220,000 lb)(initially; target is 150,000 kg)
Dimensions
Length	50 m (160 ft)
Diameter	9 m (30 ft)
Production
Status	In development
Built	3 test articles
Engines	3 Raptor (sea-level nozzle) + 3 Raptor vacuum
Thrust	12,000 kN; 2,600,000 lbf (1,200 tf)
Specific impulse	vacuum engine: 380 s sea-level engine: 330 s (at sea level) 355 s (in vacuum)
Fuel	Subcooled CH 4 / LOX

The SpaceX Starship is both the second stage of a reusable launch vehicle and a spacecraft that is being developed by SpaceX, as a private spaceflight project. It is being designed to be a long-duration cargo- and passenger-carrying spacecraft. While it is tested on its own initially, it will be used on orbital launches with an additional booster stage, the Super Heavy, where Starship would serve as the second stage on a two-stage-to-orbit launch vehicle. The combination of spacecraft and booster is called Starship as well.

Beginning in April 2019, a height reduced Starhopper prototype version began test flights. Prototype Starships are under construction and are expected to go through several iterations. Starship is an independent rocket in its own right—without any launch vehicle booster stage at all—as part of an extensive suborbital flight testing program to get launch and landing working and iterate on a variety of design details, particularly with respect to atmospheric reentry of the vehicle.

Integrated system testing of Starship began in March 2019 with the addition of a single Raptor rocket engine to the first flight-capable propellant structure, Starhopper. Starhopper was used through August 2019 for static testing and low-altitude, low-velocity flight testing of vertical launches and landings^[20] in July/August. All test articles have a 9-meter (30 ft)-diameter stainless steel hull.

SpaceX is planning to launch commercial payloads using Starship no earlier than 2021.

History

The initial design of the 9 m (30 ft) ship at the 2017 unveiling was of carbon-composite construction with a delta wing and six Raptor engines (four vacuum and two sea-level)

 

The Starship design concept for the 9-meter rocket was unveiled in September 2017 but work by SpaceX on the engine had begun much earlier and previous larger concepts had been discussed since 2013. 

The Starship engine layout, reentry aerodynamic surface designs, and even the basic material of construction have each changed markedly since the initial public unveiling of the 9-meter (30 ft) diameter rocket in 2017, in order to balance objectives such as payload mass, landing capabilities, and reliability. The initial design at the unveiling showed the ship with six Raptor engines (two sea-level, four vacuum), aerodynamic control surfaces of a delta wing with split flaps, and a plan to build both stages of the launch vehicle out of carbon composite materials.

By late 2017, SpaceX added a third sea-level engine to the conceptual design to increase engine-out capability and allow landings with greater payload mass, bringing the total number of engines to seven. Seven engines, three sea-level and four vacuum, remained the design until September 2018, when a new version of the design was shown at the announcement of the #dearMoon project. SpaceX indicated that early flights would happen with exclusively sea-level nozzle engines and showed animations depicting Starship with seven identical Raptor engines on the planned 2023 mission, the same engines to be used in the design of the booster, now called Super Heavy. By late 2018, the control surface concept for the second stage/spaceship had been redesigned from two small side fin protrusions of the delta wing to three rear fins—two of them actuated and one fixed—and two smaller front fins added for greater control authority during atmospheric entry. All three of the rear fins in the 2018 design were also intended to serve as landing legs.

The late-2018 Starship design with seven sea-level Raptor engines and the revised aerodynamic control surface layout

 

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, the first prototype, Starhopper, was preparing for untethered flight tests in South Texas, while two orbital prototypes were under construction, one in South Texas begun in March and one on the Florida space coast begun before May. The build of the first Super Heavy booster stage was projected to be able to start by September. At the time, neither of the two orbital prototypes yet had aerodynamic control surfaces nor landing legs added to the under construction tank structures, and Musk indicated that the design for both would be changing once again. On 21 September 2019, the externally-visible "moving fins" began to be added to the Mk1 prototype, giving a view into the promised mid-2019 redesign of the aerodynamic control surfaces for the test vehicles.

In June 2019, SpaceX publicly announced discussions had begun with three telecom 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, reaching an altitude of around 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.

Description

Starship is a 9-meter-diameter (30 ft), 50-meter-tall (164 ft), fully reusable spacecraft design with a dry mass of 120,000 kg (264,555 lb), powered by six methane/oxygen-propellant Raptor engines. Total Starship thrust is approximately 12,000 kN (2,600,000 lbf). 

Unusual for previous launch vehicle and spacecraft designs, Starship is to function both as a second stage to reach orbital velocity on launches from Earth, and will also be used in space as an on-orbit long-duration spacecraft.

The Starship design is intended to be fully reusable even when used as a second stage for orbital ascent from Earth. 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 reusability.

As announced in May 2019, 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 booster, Super Heavy. Transport use in space is expected to utilize a vacuum-optimized Raptor engine variant to optimize specific impulse (I_sp) to approximately 380 s (3.7 km/s).

Starship is planned to eventually be built in at least three operational variants:

• Spaceship: a large, long-duration spacecraft capable of carrying passengers or cargo to interplanetary destinations, to LEO, or between destinations on Earth.
• 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 2017 early design concept, 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.

Characteristics of Starship are to include:

• 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
• rapid reusability without the need for extensive refurbishment
• automated rendezvous and docking operations
• on-orbit propellant transfers between Starships
• ability of reach the Moon and Mars after on-orbit propellant loading
• stainless steel structure and tank construction. Its strength-to-mass ratio is 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 pressure fed hot gas thrusters for attitude control, including the final pre-landing pitch-up maneuver from belly flop to tail down. Initial prototypes are using cold gas nitrogen thrusters, which have a substantially less-efficient mass efficiency, 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.
• 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 plus 12 unpressurized aft cargo containers of 88 m³ (3,100 cu ft) total.
• flexible design options; for example, a possible design modification to the base Starship—expendable 3-engine Starship with no fairing, rear fins, nor landing legs—to optimize mass ratio for interplanetary exploration with robotic probes.

According to Musk, when Starship is used for 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.

Starship specifications (planned)

Comparison of different heavy launchers

General characteristics

• Crew: ≤ 100
• Length: 118 m (387 ft 2 in)
• Diameter: 9 m (29 ft 6 in)
• Empty mass: 120,000 kg (260,000 lb)
• Payload to low Earth orbit: > 150,000 kg (330,000 lb)

Engine

• Super Heavy: 37 × Raptor rocket engine (sea-level optimized)
  • Thrust: 72 MN (16,000,000 lb_f)
• Starship: 6 × Raptor rocket engine
  • Thrust: c. 12 MN (2,700,000 lb_f)

It is planned for the spacecraft to incorporate life support systems, but as of September 2019, Musk stated that it is yet to be developed, as the first flights will be uncrewed.

Concerning shielding against ionizing radiation, Musk has stated that the radiation will lead to an increased risk of cancer but said he thinks "it's not too big of a deal". Musk has been criticized for not addressing ionizing radiation in more detail.

Prototypes

Two test articles were being built by March 2019, and three by May. The low-altitude, low-velocity Starship test flight rocket 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-metre-diameter (29 ft 6 in) 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, 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' 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.

Starship prototypes

Vehicle	Status	Maximum altitude	Build site
Starhopper	Retired	150 m (490 ft)	Boca Chica, Texas
Starship Mk1	Partially destroyed	N/A	Boca Chica, Texas
Starship Mk2	Under construction	N/A	Cocoa, Florida
Starship Mk3	Under construction	N/A	Boca Chica, Texas
Starship Mk4	Under construction	N/A	Cocoa, Florida

Starhopper

Starhopper

 

SpaceX Starhopper configuration as flown in August 2019

 

The construction of the initial test article—the "Starship test flight rocket" "test hopper," "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 two miles (3.2 km) from Boca Chica Beach in South Texas, the external body of the rocket rapidly came together in less than six weeks. Originally thought by watchers of construction 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 meters (30 ft) in diameter and was originally 39 meters (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, 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 two miles (3.2 km) to the launch pad on 8 March. Integrated system testing of the first prototype (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 S/N 2) in early April, 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 S/N 4 was installed in early June for fit checks, but the first test flight that is not tethered was expected to fly with Raptor S/N 5, until it suffered damage during testing at SpaceX Rocket Development and Test Facility, in McGregor, Texas. Subsequently, Raptor S/N 6 was the engine used by Starship Hopper for its untethered flights.

Testing

The hopper test article 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 "test hopper" or 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 test vehicle, 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.

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. 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).

Flight No.	Date and time (UTC)	Vehicle	Launch site	Altitude	Outcome	Duration
1	5 April 2019	Starhopper	South Texas	~ 1 m (3 ft)	Success
	Tethered hop which hit tethered limits. With a single Raptor engine, S/N 2.
2	25 July 2019	Starhopper	South Texas	20 m (66 ft)	Success	~ 22 seconds
	First free flight test. Single Raptor engine, S/N 6. Was previously scheduled for the day before but was aborted. A test flight attempt on 24 July was scrubbed.
3	27 August 2019 22:00	Starhopper	South Texas	150 m (490 ft)	Success	~ 57 seconds
	Single Raptor engine, S/N 6. 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 was scrubbed due to a problem with the Raptor engine igniters. This launch won the SpaceNews Awards Readers’ Choice of Breakthrough of the Year 2019.

High-altitude prototypes

Starship Mk1

 

Two high-altitude prototype ships—referred to as Mk1 and Mk2—were under construction as of May 2019, one in Boca Chica, South Texas and one on the space coast of Florida in Cocoa.

Initial construction was underway by December 2018 when subsections of a Starship prototype—then referred to as the "Starship Mk1 orbital design" were stated to be under construction in California. Planned for high-altitude and high-velocity testing, the prototype was described to be taller than the Starhopper, have thicker skins, and a smoothly curving nose section.

By March 2019, construction of the full external structure and propellant tanks of the first prototype (Mk1) was well underway at the SpaceX "ad-hoc South Texas 'shipyard'," with an expectation that the vehicle could be complete and ready to begin testing as early as June. The new build of additional 9-meter diameter stainless steel structures in South Texas in late February was originally misattributed and thought to be a second and more substantial version of the Starhopper's upper section, following the destruction of the first Starhopper upper section, damaged by high winds in January. The Mk1 prototype will fly with three Raptor engines.

By May 2019, SpaceX revealed that they were building two high-altitude prototypes simultaneously, Mk1 in Texas and a second one, Mk2, in Florida. The two ships were constructed by competing teams—that are required to share progress, insights, and build techniques with the other team, but neither team is required to use the other team's techniques. Construction of a Mk3 prototype began in late-2019. A first orbital flight is not expected until Mk4 or Mk5 in mid 2020. Construction had begun on the Mk4 Starship in Florida by mid-October.

On November 20 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 to an altitude and landed some distance away from the craft. In a statement concerning the test anomaly, SpaceX said they will retire the Mk1 prototype after the incident and focus on Mk2 and Mk3 designs, which are closer to the flight specification. According to SpaceX, there were no injuries.

Characteristics

The Mk1/Mk2 prototype characteristics are:

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

Intended uses

Starship is intended to become the mainline SpaceX orbital vehicle, as SpaceX has announced it intends to fully replace its existing Falcon 9 launch vehicle and Dragon 2 fleet with Starship during the early 2020s.^{[18][22][24]:24:50–27:05} In November 2019 Elon Musk estimated that fuel will cost $900,000 per launch and total launch costs could drop as low as $2 million.^[108]

Starship is designed to be utilized for:^[18][42]

• 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 satellite internet 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.
• long-duration spaceflights in the cislunar region
• Mars transportation, both as cargo ships as well as passenger-carrying transport
• long-duration flights to the outer planets, for cargo and astronauts

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 kilometers (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 & ease of operations."