The Gold We Cannot Reach

Every few years a headline announces that asteroid mining is about to end gold's scarcity for ever, usually attached to a number carrying more zeros than the world economy. It is a good story. It is also, so far, only a story. Humanity has brought back from every asteroid it has ever visited a total of about 127 grams of material, none of it gold. And the largest store of gold anybody has located is not in space at all. It is three thousand kilometres beneath your feet, and it is no more reachable than the asteroid belt.

This deep dive follows directly from the first episode of this series, which set out where gold comes from: not from Earth, but from the violent deaths of stars, delivered here long afterwards. That episode ended with the metal in the ground. This one asks the obvious next question. If the universe is full of gold, why is ours still scarce?

Two vaults, both shut

Start with the nearer one. In May 2025 the University of Göttingen published research opening with a sentence worth reading twice: "Earth's largest gold reserves are not kept inside Fort Knox, the United States Bullion Depository. In fact, they are hidden much deeper in the ground than one would expect. More than 99.999% of Earth's stores of gold and other precious metals lie buried under 3,000 km of solid rock, locked away within the Earth's metallic core and far beyond the reaches of humankind."

When the planet formed and separated four and a half billion years ago, almost all of its gold sank with the iron. What the Göttingen team, Dr Nils Messling and Professor Matthias Willbold, then found is that the door is not perfectly sealed. Analysing lava from the Hawaiian islands, they measured an unusually high signal of a particular ruthenium isotope, 100Ru, slightly more abundant in the core than in the mantle above it. Their conclusion was published in Nature as "Ru and W isotope systematics in ocean island basalts reveals core leakage". Messling's description of the moment is the best line in it: "When the first results came in, we realised that we had literally struck gold! Our data confirmed that material from the core, including gold and other precious metals, is leaking into the Earth's mantle above."

Read that carefully, because it is a scientific result and not a supply. The mechanism Willbold describes is "huge volumes of super-heated mantle material, several hundreds of quadrillion metric tonnes of rock", rising over geological time to build ocean islands. It is a leak measured in isotopes, not in bars.

The second shut vault is the sea. NOAA's answer to whether there is gold in the ocean is yes, followed by the catch: "Gold in the ocean is so dilute that its concentration is on the order of parts per trillion," about one gram for every hundred million metric tons of seawater in the Atlantic and north Pacific. There is more on the seafloor, a mile or two down and locked inside rock, and NOAA's verdict is that there is currently no cost effective way to get any of it out at a profit.

What we have actually brought back

Now the far vault. Two spacecraft have returned samples from asteroids and the totals are exact, because both agencies weighed them.

NASA's OSIRIS-REx delivered its capsule from asteroid Bennu on 24 September 2023. After the sampling head was finally disassembled, NASA announced the bulk mass: "4.29 ounces (121.6 grams) of material from asteroid Bennu", against a mission requirement of at least 60 grams. Japan's Hayabusa2 got there first, returning from asteroid Ryugu on 6 December 2020, and JAXA's curation centre weighed that haul at 5.424 plus or minus 0.217 grams, against a minimum requirement of 0.1 grams.

Add them together and the entire harvest of asteroid material in human history is about 127 grams. Two pieces of arithmetic put that in proportion, and both are ours rather than anyone's estimate. The United States Geological Survey puts world gold mine production in 2025 at an estimated 3,300 tonnes, which is about 105 grams of gold every second of every day. Everything ever returned from an asteroid, of any composition whatsoever, weighs about 1.2 seconds of world gold output.

And the price of it. NASA's own press kit gives the OSIRIS-REx program cost as "Approximately $800 million (excluding launch vehicle)". Divide that by 121.6 grams and the delivered cost is about 6.6 million dollars a gram, for carbonaceous rock. Gold this morning was 141 dollars a gram, or £104.57, on our own markets feed at 07:21 UTC on 7 September 2026. The sample cost roughly forty six thousand times the price of gold, and it is not gold.

The asteroid that is not made of money

Which brings us to 16 Psyche, the object those headline valuations are usually about. The facts, from NASA: it was discovered by the Italian astronomer Annibale de Gasparis on 17 March 1852, measures 280 kilometres across at its widest point and 232 kilometres long, orbits between 378 million and 497 million kilometres from the Sun, and is a mixture of rock and metal with "metal composing 30% to 60% of its volume." NASA's spacecraft launched on 13 October 2023 and begins its prime mission in August 2029, the first ever sent to an asteroid whose surface holds substantial metal rather than rock or ice.

Here is the part the headlines leave out. We searched the mission's own frequently asked questions page on 7 September 2026. The words gold, value and worth do not appear on it once. What does appear is the cost, "approximately $850 million" excluding the launch, and four science objectives, every one of them about planet formation and iron cores. Psyche is a mission to look at a metal world. It will not bring back a gram, and nobody involved has ever said it would.

A law for a place nobody owns

Suppose somebody did. Who would own it? The governing instrument is the Outer Space Treaty, opened for signature on 27 January 1967, and its second article is one sentence: "Outer space, including the moon and other celestial bodies, is not subject to national appropriation by claim of sovereignty, by means of use or occupation, or by any other means."

Nations have since drawn a careful distinction between the rock and what you take off it. United States law now provides that a citizen engaged in commercial recovery "shall be entitled to any asteroid resource or space resource obtained, including to possess, own, transport, use, and sell" it. Luxembourg went further and shorter. Article 1 of its Law of 20 July 2017 is six words long: "Space resources are capable of being owned." The Artemis Accords, which the United Kingdom signed on 13 October 2020 and which had 71 signatories by 31 August 2026, state the position plainly at Section 10: "The Signatories affirm that the extraction of space resources does not inherently constitute national appropriation under Article II of the Outer Space Treaty."

So the legal question is broadly settled and the engineering question is not. You may keep what you catch. Nobody has yet caught more than a teaspoon.

The number that eats itself

One last thought, and it is the reason the quadrillion headlines are self defeating. The World Gold Council puts all the gold ever mined at 222,600 tonnes, worth 29.0 trillion dollars at the end of the second quarter of 2026, with remaining underground reserves put at about 61,000 tonnes by the Council and 66,000 tonnes by the USGS. That 29 trillion is not a property of the metal. It is a price, and a price is what it costs to obtain one more gram.

Any quantity of space metal large enough to justify the journey would, by definition, be large enough to move the number used to justify it. That is not a warning and certainly not a forecast. It is what the word scarce means. Gold has never been rare in the universe. It has only ever been hard to reach, which is the point the 22 metre cube was making: everything humanity has ever won, from every mine, riverbed and reef in history, still fits in a box you could walk around.

Meanwhile the reachable gold is the gold already out of the ground, and a good deal of it is in drawers. A Victorian chain came from a dying star, sank into a planet, was dug back out, refined, and struck with a mark you can still read today. That is the only asteroid mine anybody has ever successfully operated. You can read the marks yourself, or simply look at what came out of it.

This article is history and science reporting, not financial advice. Nothing here is a recommendation to buy or sell any asset, and no figure quoted is a forecast. Figures are stated as at the dates given, and the gold price moves.