Starship is a two-stage super heavy lift launch vehicle and spacecraft under development by SpaceX. It is currently the tallest and most powerful space launch vehicle to have flown. Starship is intended to be fully reusable, which means both stages will be recovered after a mission and reused.
The Starship space vehicle is designed to supplant SpaceX's Falcon 9 and Falcon Heavy rockets, build SpaceX's Starlink satellite constellation, and serve crewed spaceflight. SpaceX plans to use Starship vehicles as tankers, refueling other Starships to allow missions to geosynchronous orbit, the Moon, and Mars. A lunar lander variant of Starship is to land astronauts on the Moon as part of NASA's Artemis program. Starship is ultimately meant to enable SpaceX's ambition of colonizing Mars.
Starship is made up of the Super Heavy booster and the Starship spacecraft. The booster and spacecraft are both powered by clusters of Raptor rocket engines, which burn liquid methane and liquid oxygen. Both stages are constructed primarily of stainless steel, a material chosen as an alternative to a series of prior designs. The booster will use its engines to slow itself down before it is caught by a pair of mechanical arms attached to the launch tower. Meanwhile, the Starship spacecraft is protected during atmospheric reentry by its thermal protection system, using a so called ‘belly flop’ manoeuvre where the spacecraft turns from a horizontal into a vertical position, then lands using its engines.
The Starship system aims to achieve frequent space launches at low cost. Development follows an iterative and incremental approach involving frequent, and often destructive, test flights of prototype vehicles. The first flight test of the Starship system took place on 20 April 2023 and ended four minutes after launch with the destruction of the test vehicle.
History
Early design conceptions
Starting with a 2012 announcement of plans to develop a rocket with substantially greater capabilities than SpaceX's existing Falcon 9, the company created a succession of preliminary designs for such a vehicle under various names (Mars Colonial Transporter, Interplanetary Transport System, BFR). Some were substantially different from the current design; the largest one, the Interplanetary Transport System or ITS, massed fully fueled, had a liftoff thrust of and could carry to low Earth orbit while being completely reused. For comparison, the Saturn V had a liftoff thrust of . It also was made of carbon composite. Despite this, they all shared some common features such as being fully reusable and being very large.
In 2019, Starship's structural material was changed from carbon composites to stainless steel. Musk cited the low cost and ease of manufacture, increased strength of stainless steel at cryogenic temperatures, as well as its ability to withstand high heat, as the reasons for the design change. The high temperature at which 300-series steel transitions to plastic deformation would eliminate the need for a heat shield on Starship's leeward side, while the much hotter windward side would be cooled by allowing fuel or water to bleed through micropores in a double-wall stainless steel skin, removing heat by evaporation. However, in July 2019, Musk indicated on Twitter that this would probably not be pursued, instead, thin reusable heat shield tiles which work in a similar way to those of the Space Shuttle would be used. The high melting point of Starship’s stainless steel allows the tiles to be lighter and thinner.
In 2019, SpaceX began to refer to the entire vehicle as Starship, with the second stage being called Starship and the booster Super Heavy. In September 2019, Musk further detailed the lower-stage booster, the upper-stage's method of controlling its descent, the heat shield, orbital refueling capacity, and potential destinations besides Mars. The aft flaps on the spacecraft were reduced from three to two.
In 2019, the design reverted to six Raptor engines, with three optimized for sea-level and three optimized for vacuum. Initial Super Heavy test flights would use fewer engines, perhaps about 20.
Later in 2019 Musk stated that Starship was expected to have an empty mass of and be able to initially transport a payload of , growing to over time. Musk hinted at an expendable variant that could place 250 tonnes into low orbit.
The Raptor design was refined with higher thrust versions. The initial 37 engines were reduced to 31 in 2020. Musk stated that SpaceX would complete hundreds of cargo flights before carrying human passengers. In April 2021, SpaceX publicly forecast that Earth to Earth passenger flights would be common within five years.