#explainer
Starship consumes a large share of its propellant reaching Earth orbit. A subsequent lunar mission requires an additional velocity-change budget. The planned architecture therefore uses propellant delivered by additional launches.
The oxidizer is replenished too
Refuelling does not mean adding fuel alone. A chemical engine needs methane and oxygen in the correct ratio. Both liquids are cryogenic, and heat input, boil-off and fluid behaviour in microgravity complicate storage. Transfer requires vehicle connection, pressure control and verification of the amount actually moved.
Why there is no fixed tanker count
The number of delivery flights depends on variant payload capability, mission requirements, storage losses and operational reserves. It is a result of a particular design rather than an immutable Starship property. The lunar lander also differs from a spacecraft intended to return to Earth's surface.
Why it is not a car's fuel hose
In orbit, fluid does not settle at the bottom of a tank as on Earth without suitable management. Connecting tanks requires control of liquid and gas phases, pressure and temperature. Experimentally moving a limited quantity between tanks is therefore a different milestone from repeatedly filling a spacecraft for a demanding complete mission.
Follow us
Follow us on social media
New plates, trivia and behind-the-scenes updates as soon as they are ready.
Key points
- Refuelling does not mean adding fuel alone.
- The number of delivery flights depends on variant payload capability, mission requirements, storage losses and operational reserves.
- In orbit, fluid does not settle at the bottom of a tank as on Earth without suitable management.
Sources & further reading
- Tanker, depot and lunar-lander propellant-delivery architecture.
- The lunar lander variant and its distinct mission.
- Two-stage system concept, propulsion and intended applications.
Spaceflightpedia. (n.d.). Why does Starship need orbital refuelling for a Moon mission?. Retrieved 17 October 2026, from https://spaceflightpedia.com/article/starship-orbital-refuelling
article text — CC-BY-SA · ◉ NASA photography — public domain · ✦ AI illustration — marked, generated from sources
More questions on this topic
- How does Starship work?
- Why does Starship have so many engines?
- Why does Starship descend belly-first?
- How can a tower catch a rocket?
