Would you believe it if I told you SpaceX is building an expendable version of Starship that has more than twice the payload capacity of NASA’s Saturn V and almost 10 times the payload of the Delta IV Heavy?
Contrary to the core aim of the SpaceX to build a fully reusable transportation system designed to carry both crew and cargo to Earth orbit, the Moon, Mars and beyond’, the company’s CEO, Elon Musk has hinted of a possible expendable version of the Starship.
Although this would be against the initial goal of building a reusable Starship that would enable multiple flights per day while reducing operational costs, an expandable Starship would offer some benefits that not even the Saturn V, the next most capable expendable, would be able to offer.
In response to a question about Starship having an expendable model, Musk replied on Twitter stating that “expendable upper stage may or may not fly, but it is an option”. This gives a clue of a possible version of a SpaceX Starship that might not be reusable like the current Falcon Heavy but rather fully expendable like the Delta IV Heavy. We will compare the expendable Starship to the Delta IV Heavy in a minute to have an idea of how well the Starship performs.
Currently, the 120-metre long Starship which can produce a thrust of 7590 tons at sea level launches up to 150 tons to low Earth orbit. However, SpaceX states that an expendable version of Starship will be able to launch 100 more metric tons to low Earth orbit in a single launch.
SpacesX’s official website confirmed Elon Musk’s earlier comment about the company deciding on building an expendable Starship. According to the website, the expendable Starship would be able launch 250 metric tons to low Earth orbit in a single launch; only NASA’s Saturn V expandable comes close with up to 118 tons to LEO.
However, to achieve an expendable Starship, the current version would need a redesign to reduce the weight and mass of the Starship as much as possible; creating more room for more payloads. This would entail the removal of the heat shield and landing legs that make the Starship reusable.
Elon Musk previously gave a clue about this redesign saying that there could be a lighter version of Starship with no heat shield or legs which confirms the reports of SpaceX already building possible expendables at the company’s Starbase factory.
Although this new design would allow 100 more metric tons of payload onboard, which is obviously an advantage, it also comes with a number of downsides. For example, the whole expendable Starship would have to be discarded after each launch, demanding for extra spendings for later launches.
Just like the regular Spaceship, the engine of the expendable version would also be powered by liquid methane as fuel and liquid oxygen as oxidizer rather than kerosene or RP-1 used in the engines of the Falcon 9 and Falcon Heavy rockets.
Expendable Starship vs Delta IV Heavy
Now let’s have a quick look at how the upcoming expendable Starship performs against one of the most powerful expendable rockets in operation; the Delta IV Heavy. Developed by the United Launch Alliance (ULA), the Delta IV Heavy produces a total thrust of approximately 2.1 million pounds-force at liftoff courtesy of its 3 RS-68 engine system.
The Delta IV Heavy is capable of launching payloads of up to 28.8 metric tons to low Earth orbit and up to 14.2 metric tons to geostationary transfer orbit and has been used to launch a variety of large payloads, including satellites for communication, navigation, and weather monitoring.
The expendable Starship on the other hand will be powered by 6 Raptor engines and equipped with payload capacity of up to 250 metric tons to low Earth orbit, which would be far more efficient than the payload capacity of the Delta IV Heavy.
It would also be able to carry a variety of payloads, including satellites, scientific instruments, and supplies for crewed missions to Earth orbit, the Moon, Mars, and beyond. Considering the payload capacity and the ability for interplanetary travels, do you think an expendable version of the Starship will be more efficient than the Delta IV Heavy?
Expendables Already Being Developed?
This is not the first time Elon Musk and SpaceX are coming up with the idea of a redesigned Starship. Elon in 2019 first mentioned that SpaceX could develop a lighter version of Starship with no flaps on its sides purposely for interplanetary travels.
To answer what Tholins were, Musk suggested that we should send probes to the outer solar system and get high res, true color images of what Tholins were for there might be an alien artefact out there. To do this, he believes there should be a lightened up Starship with no heat shield or fins for the travels which will of course be an expendable version of Starship.
This suggests that an expendable Starship has long been part of the design plans of SpaceX. There are even reports that the company has begun developing two expendables at its manufacturing factory.
Ship 26 and Ship 27, the two prototypes, will be built with no thermal protection, no heat shields and with no flaps; meaning they wouldn’t be reusable.
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