SpaceX Starship design history

Before settling on the 2018 Starship design, SpaceX successively presented a number of reusable super-heavy lift vehicle proposals.^[1][2] These preliminary spacecraft designs were known under various names (Mars Colonial Transporter, Interplanetary Transport System, BFR).

In November 2005,^[3] before SpaceX had launched its first rocket the Falcon 1,^[4] CEO Elon Musk first mentioned a high-capacity rocket concept able to launch 100 t (220,000 lb) to low Earth orbit, dubbed the BFR.^[3] Later in 2012, Elon Musk first publicly announced plans to develop a rocket surpassing the capabilities of their existing Falcon 9.^[5] SpaceX called it the Mars Colonial Transporter, as the rocket was to transport humans to Mars and back.^[6] In 2016, the name was changed to Interplanetary Transport System, as the rocket was planned to travel beyond Mars as well.^[7] The design called for a carbon fiber structure,^[8] a mass in excess of 10,000 t (22,000,000 lb) when fully-fueled, a payload of 300 t (660,000 lb) to low Earth orbit while being fully reusable.^[8] By 2017, the concept was temporarily re-dubbed the BFR.^[9]

In December 2018, the structural material was changed from carbon composites^[10][8] to stainless steel,^[11][12] marking the transition from early design concepts of the Starship.^[11][13][14] Musk cited numerous reasons for the design change; low cost, ease of manufacture, increased strength of stainless steel at cryogenic temperatures, and ability to withstand high temperatures.^[15][13] In 2019, SpaceX began to refer to the entire vehicle as Starship, with the second stage being called Starship and the booster Super Heavy.^[16][17][18] They also announced that Starship would use reusable heat shield tiles similar to those of the Space Shuttle.^[19][20] The second-stage design had also settled on six Raptor engines by 2019; three optimized for sea-level and three optimized for vacuum.^[21][22] In 2019 SpaceX announced a change to the second stage's design, reducing the number of aft flaps from three to two in order to reduce weight.^[23] In March 2020, SpaceX released a Starship Users Guide, in which they stated the payload of Starship to LEO would be in excess of 100 t (220,000 lb), with a payload to GTO of 21 t (46,000 lb).^[24]