The world runs on rock · Story 5 of 12

The Rocket the metals that survive launch

A rocket has to be light enough to fly and tough enough to hold a controlled explosion. That takes lithium in its tanks, niobium and hafnium in its engines, chromium and nickel in its steel, and germanium under the solar cells of what it carries.

Scroll to take one apart

Take it apart

Seventy metres, two stages

A Falcon 9 stands 70 m tall and 3.7 m wide. Its first stage carries nine Merlin engines; its second stage one more, built for vacuum. The payload rides on top under a fairing of carbon composite.¹

Light as possible

Tanks aluminium-lithium alloy, friction-stir welded¹
Grid fins cast and machined titanium, to steer the stage home²
Fairing carbon-fibre composite¹

Lithium is the lightest metal of all. A little of it in aluminium makes the alloy lighter and stiffer, so the tanks weigh less.

Coming home

A Falcon 9 first stage descending on its engine flame toward a landing pad beyond the trees

Close view of the bright plume of a Falcon 9's engines at night lift-off

Left: a first stage lands at Cape Canaveral after the Crew-13 launch, 1 October 2026 (NASA/John Kraus). Right: CRS-27 lift-off, March 2023 (NASA/Kevin Davis and Kevin O'Connell). Public domain.

The first stage turns round, relights its engines and lands upright to fly again.¹ The engines fan out here so you can see all nine.

The hottest metal on board

A nozzle that glows red

The second-stage engine ends in a long, thin nozzle extension. Nothing cools it but its own glow: it sheds heat as light, red-hot in flight. It is made of C-103, a niobium alloy (89% niobium, 10% hafnium, 1% titanium) that stays strong at about 1,700 K.^3,4

NbHfTiAlLiCuCrNi

Long-exposure photo of a Falcon 9 launch at night: a bright curving streak of light rising from the pad over the water — Falcon 9 launching Firefly's Blue Ghost lunar lander from Kennedy Space Center, 15 January 2025, long exposure. NASA/Frank Michaux (public domain).

Lift-off

A controlled explosion, upwards

From the pad to orbit takes minutes. In that time the metal must hold freezing liquid oxygen on one side and engine fire on the other.

The next rocket

Starship is made of steel

For Starship, SpaceX dropped carbon fibre for stainless steel. Elon Musk's reasons: steel is far cheaper (he put carbon fibre at about $135 a kilogram against $3 for steel), and it stays strong both when frozen by propellant and when heated on re-entry.⁵ SpaceX began with ordinary 301 steel and moved to an alloy of its own.⁶

What makes it stainless

Chromium, at least 10.5%

Steel is iron with a little carbon. Stainless steel must contain at least 10.5% chromium; nickel is added to keep it tough, especially in the cold.⁷

The trick

A skin that heals

The chromium reacts with oxygen in the air to form an invisible film of chromium oxide only a few nanometres thick. Scratch it and, as long as there is oxygen around, it grows back.⁷

Follow the supply

1 · Niobium

Brazil mined 93% of the world's niobium in 2025, Canada 5.4%.⁸ One company, CBMM, at Araxá in Minas Gerais, supplies over 80% of the world's niobium products.⁹ Most niobium goes into steel; rocket nozzles are a tiny, demanding corner of the market.

2 · Chromium

South Africa mined 45% of the world's chromium ore, Türkiye 18% and Kazakhstan 14%.⁸

3 · Nickel

Indonesia mined 67% of the world's nickel in 2025, the same nickel that goes into batteries and stainless steel.⁸

4 · Gallium and germanium

China refined 99% of the world's primary gallium in 2025, and 68% of its germanium in 2021.⁸ Both go into the solar cells that power satellites.

5 · To the pad

The metals meet in the factory at Hawthorne, California, and fly from Florida and California; Starship is built and launched at Starbase in Texas.

What it carries

More than 10,000 satellites

Among much else, Falcon 9 launches SpaceX's own Starlink satellites. By March 2026 more than 10,000 Starlink satellites were in orbit, according to astronomer Jonathan McDowell's count.¹⁰ One dot here is one satellite.

Sunlight to power

Solar cells on germanium

Satellites need the most power from the least area. Many use triple-junction cells: thin layers of indium gallium phosphide and indium gallium arsenide grown on a wafer of germanium, each layer catching a different colour of light, above 30% efficient.¹¹

The squeeze

Aug 2023China requires export licences for gallium and germanium.¹²
Dec 2024China bans gallium, germanium and antimony exports to the US.¹²
Nov 2025The US ban is suspended until November 2026.¹³

Satellite makers buy cells, not metal, but every cell begins with a wafer of germanium.

Why "critical"

Light, hot, hard to replace

Most of these metals go into ordinary things: niobium into bridges and pipelines, chromium and nickel into kitchen sinks, lithium into batteries. Spaceflight takes a small share of each, but needs the best grades, and each comes mostly from one or two countries.

NbNiobiumBrazil 93% HfHafniumfrom zirconium TiTitaniumChina 34% CrChromiumSouth Africa 45% NiNickelIndonesia 67% LiLithiumAl-Li tanks GeGermaniumChina 68% GaGalliumChina 99%

Next in the series: The Signal, the glass and metal under the sea. Before this: The Magnet, The Battery, The Mind and The Chip.

Sources

Shares of world output are from USGS Mineral Commodity Summaries 2026 via our minerals data; other figures are cited where they appear. The rocket is an illustration in the shape of a Falcon 9, from public descriptions, not a SpaceX drawing; SpaceX has not published every material it uses. Photos: NASA, public domain.