Propellant Supply

The real bottleneck

At Cadence, Propellant Logistics Beats Vehicle Count

Each launch is thousands of tonnes and hundreds of truckloads. Scale that to daily flights and the trucks run out before the pads do.

A Starship launch loads roughly 5,000 t of propellant, about 78% of it liquid oxygen by mass, the rest liquid methane. Each launch currently needs more than 200 tanker trucks of liquid oxygen and nitrogen delivered to the pad. That is manageable at a few flights a year and impossible at the cadence SpaceX is targeting, so the propellant chain is being rebuilt: make the oxygen on site, source the methane next to the gas, and hold a strategic buffer in the tank farm. Beyond Earth orbit the same logic returns as the depot — a place to store propellant that tankers deliver.

This page collects the whole chain; the site pages link back to it. Building

The methalox split

Oxygen Is the Heavy Half; Methane Is the Bought-In Half

The two propellants have completely different supply stories.

Liquid oxygen is about 78% of the load and can be made from air anywhere with enough power, which is why SpaceX is bringing oxygen and nitrogen production on site. Liquid methane is roughly 22% and is bought as commercial liquefied natural gas: Raptor is designed to burn it without an on-site pretreatment plant, so SpaceX dropped its planned gas pretreatment and liquefier in 2022 once Raptor 2 proved commercial LNG worked. That single decision is why methane still arrives by truck while oxygen is going local — and why Louisiana, sited next to Gulf Coast natural gas, changes the methane story too.

Ground supply

From Trucked-In to Made-On-Site

The tank farm, the air separation unit, the Linde plant and the LNG chain.

SpaceX first planned its own air separation plant at the Sanchez site and then at the launch site, abandoned both over power supply and pad proximity, which is why Linde stepped in at Brownsville — and then began the on-pad ASU anyway. The two now overlap, and the ASU’s exact role relative to Linde is not fully settled.

The orbital depot

The Supply Chain Extends Into Orbit

Beyond LEO, propellant supply is the depot, and it has not flown.

Everything above is Earth-side. The moment a mission goes beyond low Earth orbit, propellant supply becomes an orbital problem: a depot filled by tanker flights, holding cryogenic methane and oxygen against boil-off. Ship-to-ship cryogenic transfer — the maneuver that fills the depot — is the single gate on every Moon and Mars variant and has not been demonstrated. It has its own page, Tanker, Depot & Propellant Transfer.

Contested

Deliberately Not Claimed

The load-bearing uncertainties, tagged with the confidence they actually earn.

Record

Provenance and Data Sources