SpaceX Starship design process

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

In November 2005, before SpaceX had launched its first rocket the Falcon 1, 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. Later in 2012, Elon Musk first publicly announced plans to develop a rocket surpassing the capabilities of their existing Falcon 9. SpaceX called it the Mars Colonial Transporter, as the rocket was to transport humans to Mars and back. In 2016, the name was changed to Interplanetary Transport System, as the rocket was planned to travel beyond Mars as well. The design called for a carbon fiber structure, 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. By 2017, the concept was temporarily re-dubbed the BFR.

In December 2018, the structural material was announced to change from carbon composites to stainless steel, marking the transition from early design concepts to the current design of Starship. 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. In 2019, SpaceX began to refer to the entire vehicle as Starship, with the second stage being called Starship and the booster Super Heavy. They also announced that Starship would use reusable heat shield tiles similar to those of the Space Shuttle. The second-stage design had also settled on six Raptor engines by 2019; three optimized for sea-level and three optimized for vacuum. 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. 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).