Mining the Moon

Prospecting comes before mining

A mine needs a known deposit, and on the Moon nobody yet has one. ESA's Prospect package is designed to start answering that question. ESA says it will drill to a depth of at least one metre, extract samples and analyse them in a miniature laboratory called ProSPA, looking for volatiles trapped at temperatures down to minus 150 degrees Celsius and testing resource extraction processes. In 2024 ESA announced that Prospect would fly to the Moon's south polar region on a commercial lander under NASA's CLPS initiative, with a 2027 target. Measurements like these turn a promising orbital map into data an engineer could use to design extraction equipment.

Pulling oxygen out of rock

Even dry regolith is rich in oxygen, but it is locked inside minerals. Announcing the team for its first experimental oxygen-extraction payload, ESA said lunar regolith is 40 to 45% oxygen by weight, bound chemically as oxides in minerals or glass. The industrial team ESA selected, led from the UK, is working on an electrolysis-based process that separates simulated regolith into metals and oxygen. ESA set the demonstrator a goal of extracting 50 to 100 grams of oxygen, and 70% of the oxygen available in its sample, within a 10-day period of lunar daylight. The quantities are small, but success on the Moon would show whether larger plants are worth building.

The robots between the ground and the tank

Extraction is a chain of machines, and every link has to run with little human help. Excavators must loosen and lift regolith or icy soil, haulers must carry it to a processing unit, and the processor must heat, split or electrolyse it before the product is stored. Each step faces abrasive dust, extreme cold in shadowed areas and limited power, and each must recover from faults without a technician. For water ice, processing also means capturing vapour before it escapes into space. Designers are therefore as interested in reliability, maintenance and energy use as in raw digging speed, since a stalled excavator stops the whole chain.

Who may take resources from the Moon

International principles set the frame. The Artemis Accords, adopted on 13 October 2020, include a section on space resources in which signatories state that extraction should comply with the Outer Space Treaty and affirm that extracting space resources does not in itself amount to national appropriation under the treaty's Article II. Signatories also commit to tell the United Nations Secretary-General, the public and the scientific community about their resource extraction activities, and to contribute to multilateral work on rules, including through the UN Committee on the Peaceful Uses of Outer Space. The Accords bind only the nations that sign them, so expect the law on lunar mining to keep developing alongside the technology.

Sources and further reading

• European drill and mini lab secure ride to the Moon — European Space Agency (ESA).
  ESA on Prospect, a drill and miniature lab due to search for ice and other volatiles near the lunar south pole.
• Team chosen to make first oxygen on the Moon — European Space Agency (ESA).
  ESA's oxygen-extraction demonstrator: how much oxygen regolith holds and what the payload aims to produce.
• The Artemis Accords: Principles for Cooperation in the Civil Exploration and Use of the Moon, Mars, Comets, and Asteroids for Peaceful Purposes — NASA.
  Full text of the Accords, including Section 10 on extracting and using space resources.

Common questions

How soon could mining on the Moon begin?

Prospecting comes first. ESA is targeting 2027 for its Prospect drill and laboratory, and extraction then has to be demonstrated at small scale before anyone builds a plant. Commercial-scale mining depends on what these missions find and on whether extraction can run reliably with the power available.

Could water from the Moon be turned into rocket fuel?

In principle, yes. Water can be split into hydrogen and oxygen, which many rocket engines burn as propellants, so polar ice draws strong interest. Robots first have to show how much ice exists, how it is mixed with soil and how much energy extraction takes.