SpaceX CEO Elon Musk says that the company could eventually develop an expendable version of its next-generation Starship rocket.
Starship is extraordinarily ambitious. Even before considering the unproven concepts of orbital propellant refilling and full, rapid reusability that are central to the full system, Starship is a beast. The rocket measures 120 meters (~390 ft) tall and is theoretically capable of producing up to 7590 tons (~16.7M lbf) of thrust at sea level. It’s larger, taller, heavier, and more powerful than any other launch vehicle in history. 33 Raptor 2 engines power Starship’s Super Heavy booster – also more than any other rocket.
Once optimized, SpaceX says that Starship can launch up to 150 tons (330,000 lbs) to low Earth orbit while still recovering the orbital ship and suborbital booster for reuse. CEO Elon Musk has stated that Starship reuse will eventually take hours, enabling multiple flights per day for each ship and booster and dropping the marginal cost of each launch to just a few million dollars.
In comparison, SpaceX’s workhorse Falcon 9 rocket uses simpler Merlin 1D engines, has just 10 of those engines to Starship’s 39 Raptors, produces about 10 times less thrust at liftoff, and can launch about 11% as much payload to orbit while expending its upper stage. Even then, Musk reported in mid-2020 that the marginal cost of a Falcon 9 launch was $15 million – impressively low but still a vivid demonstration of just how far Starship has to go.
Simply ensuring that Starship can reach orbit at all is a major challenge. Successfully recovering Starship and Super Heavy after the fact may be an even bigger challenge and cannot be fully demonstrated until the rocket can consistently reach orbit. SpaceX won’t be able to reuse Starship until it can consistently recover ships and boosters from orbital launches. And there’s no guarantee that early prototypes will be reusable even if they’re recovered.
Until reusability is demonstrated, every “Starship upper stage” will be functionally expendable whether or not Elon Musk wants it to be. Musk likely means that SpaceX may or may not decide to develop a Starship upper stage custom-built for expendable missions. Such a stage would likely take Starship, remove everything extraneous, and reduce its mass as much as possible. Musk has proposed something similar before, noting that SpaceX could develop a “lightened” version of Starship “with no heat shield or fins/legs” for expendable, interplanetary launches.
Further to the contrary, SpaceX’s Starbase factory is already building multiple intentionally-expendable Starships. Ship 26 and Ship 27 feature no thermal protection, have no heat shield tiles, and will not be fitted with flaps, making them impossible to recover or reuse. More likely than not, they will be used to test other crucial Starship technologies like orbital refilling and cryogenic fluid management.
Meanwhile, SpaceX’s multibillion-dollar contract to use Starship to return NASA astronauts to the Moon revolves around a depot ship variant that will store propellant in orbit and cannot return to Earth. The first few Starship Moon landers may also be functionally expendable and only used for one astronaut landing apiece. In short, SpaceX already has extensive plans to build variants of Starship that are either fully expendable or can only be reused in orbit.
In early 2023, SpaceX updated the Starship section of its website, revealing that an expendable version of the rocket will be able to launch up to 250 metric tons (~550,000 lbs) to low Earth orbit in a single launch. Saturn V, the next most capable expendable rocket, could launch up to 118 tons (~260,000 lbs) to LEO and cost $1-2 billion per launch. SpaceX publicly advertising the expendable performance of Starship unsurprisingly confirms that the company is considering all of the capabilities its new launch system will offer.
And Starship’s expendable capabilities are significant. Constructed piece by piece over dozens of launches, the International Space Station weighs about 420 tons (~925,000 lbs). Two expendable Starships could launch more usable mass to LEO – truly revolutionary if SpaceX can make Starship launches frequent and routine.