4 days ago
Moon could be a $1 trillion treasure trove of precious metals
The moon has inspired myth-makers, stargazers and astronauts. In the future, it may tempt miners.
Scientists believe that billions of years of asteroid impacts have seeded the lunar surface with a fortune hiding in plain sight: precious metals potentially worth $1 trillion.
The estimate — described by the team behind it as 'conservative' — stems from a study that surveyed the moon's pockmarked terrain and calculated how many of its craters were likely to have been formed by asteroids rich in platinum group metals (PGMs): ruthenium, rhodium, palladium, osmium, iridium and platinum itself.
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Forged during the cataclysmic collisions of neutron stars, these elements are now indispensable to catalytic converters, electronics and the green economy.
'On cosmic timescales, over several generations of stellar birth and death, they get mixed with other elements and end up in planet-forming discs and then within planets and asteroids,' said Jayanth Vyasanakere, the study's lead author.
'Metallic asteroids have a significant fraction of iron, and the PGMs are found bound to it. When these asteroids strike a body such as the moon, depending on the impact velocity some of it may survive.'
Unlike Earth, the moon has no atmosphere to incinerate incoming space rocks, and no plate tectonics to bury their remnants deep underground. So much of what hits the surface should, in theory, remain there.
Vyasanakere and his co-authors estimate the moon may contain up to 30 million kilograms of PGMs. The true figure will depend on the size, speed and angle of asteroid impacts, and how much of their precious cargo survived the blast. But if the new study is even remotely accurate the moon would be by far the richest known reserve of PGMs beyond Earth. For context, terrestrial annual production is about 600 tonnes (600,000kg).
How concentrated the lunar deposits would be is uncertain, but Vyasanakere notes that PGMs in their parent asteroids are thought to be present at concentrations of 10 to 100 parts per million — on a par with, or better than, many terrestrial mines.
However, mining on the moon would present formidable technical hurdles. With only a sixth of Earth's gravity, traditional extraction techniques that rely on weight, pressure or fluid dynamics would be difficult to apply. There is also no liquid water — a particular challenge, since most terrestrial PGM refining methods are water-intensive. Engineers would need to radically rethink how to extract and process ore in a dry vacuum.
Yet our satellite offers logistical advantages that asteroids — another potential source of mineral wealth — cannot. It is close enough for near real-time remote operation of machinery. Robots could be directed from Earth with just a few seconds' communications delay, avoiding the need for fully autonomous systems, which would probably be essential for asteroid mining.
And unlike individual asteroids, which must be tracked and intercepted by spacecraft, the moon is a stationary target. Its entire surface can be mapped from orbit. In large part, it already has been.
'The lack of gravity also makes it impossible for a spacecraft to 'land' on an asteroid,' Vyasanakere said. 'And many asteroids are 'rubble piles' — their surface is not stable.'
So should investors brace for a collapse in the price of platinum?
'Prices could fall if, say, 100 tonnes of PGMs are brought back from the moon in one go,' Vyasanakere said. 'But this is very unlikely. The best-case scenario — at least in the early days of lunar mining — is that someone might be able to bring back a few tonnes per year, which shouldn't affect prices much.'
The study, whose authors include researchers from the the Harvard & Smithsonian Center for Astrophysics and the University of Birmingham, has been published in the journal Planetary and Space Science.
