Asteroid Resource Utilisation

A multidisciplinary plan, assessed against the question: should we clean up Earth, or look beyond?

Group 14.1 · HS2907 Earth and Beyond · National University of Singapore
Lim Dillion · Tan Yu Bin · Lau Zong Xuan, Daniel · Jain Tapasya · Evan Jasper Lim

Our position and plan

Develop asteroid resources only where they help clean up Earth.

Test 1

Financially viable after development, transport and operating costs

Test 2

Net environmental benefit for Earth, counting damage caused and avoided

Transport and orbital access

Propellant mass grows exponentially with the velocity change

12

known asteroids retrievable for under 500 m/s into Sun–Earth orbits

To deliver a plant we must leave low Earth orbit and match the asteroid's motion. The rocket equation shows that propellant mass grows exponentially with the velocity change, so delivery cost rises quickly. Solar-electric propulsion uses less propellant, but a proposed 3,000-second system needed a six-to-ten-year mission, and that delay reduces the present value of sales. The plot is our calculation of the Sun–Earth gravity field around Earth, in the restricted three-body model; the Sun is to the left. Each line joins points of equal effective potential; these are not flight paths. [→] The two highlighted contours pass through the Lagrange points L1 and L2, about 1.5 million kilometres either side of Earth. [→] These points are low-energy gateways: an object arriving with just enough energy can pass through them into orbit around Earth's neighbourhood. Using this, García Yárnoz and colleagues identified twelve asteroids retrievable for under 500 metres per second. We would compare targets by transport cost per kilogram of usable water.

Target asteroids: composition from samples and spectra

Resource rights and site access

Outer Space Treaty, Arts. I–II

Exploration and use permitted; national appropriation prohibited

US Commercial Space Launch Competitiveness Act

Citizens may own and sell recovered resources

Artemis Accords, Sec. 11

Temporary safety zones that respect free access

On a small asteroid, overlapping zones can exclude other operators from most usable material.

Proposal

Registered, time-limited zones sized to excavation-debris hazards, with an agreed dispute procedure

Water extraction and propellant production

In microgravity, gas bubbles cling to electrodes and raise power demand.

Iron and nickel recovery without smelting

Below zero the gas forms; above zero it deposits metal and releases CO.

Iron needs pressure

The residue is enriched in non-volatile platinum-group metals.

Without gravity, molten metal will not settle out of slag, so normal smelting fails. We use carbonyl processing instead: carbon monoxide turns nickel and iron into gases, and heating those gases deposits the metal and releases the CO again. The chart shows the Gibbs energy of formation: below zero the carbonyl forms, above zero it decomposes. Nickel crosses zero at about 121 degrees; it forms at 38 to 80 and deposits at 180. [→] Iron at one bar crosses at only 31 degrees, below its 150–200 degree synthesis window. Raising CO pressure to 50 bar, then 300 bar, moves the crossing to 151 and 245 degrees, so formation is favoured across that window. [→] Removing iron and nickel leaves a residue enriched in platinum-group metals, which reduces the mass to return to Earth.

Carbon monoxide losses and resupply

Only CO that is lost must be shipped from Earth.

≥ 1.0–2.2 g

CO per kg of nickel: lower bound, from carbon retained in nickel powder (Boudouard reaction); leaks not included

Every resupply flight counts towards the launch limit.

Environmental comparison per kilogram of platinum

Asteroid metal reduces emissions only if it displaces mining, not recycling.

Launches, soot and re-entry add damage, so launches are capped for each impact (climate, ozone):

Price response in the rhodium market

2025 demand

33.1 t/yr

−21%

price, 1 t/yr added
(one-year elasticities)

−4%

long-run elasticities

Staged investment as a compound real option

Proposed governance: an international authority (ISRMSA)

Why cap returns

Stored supply makes buyers delay purchases (Coase); lower prices reduce catalyst recycling

Rhodium return cap at an agreed price floor

Registry

Time-limited operating areas and safety distances

Return quotas

Annual caps per metal; iridium reviewed against verified electrolyser shortfall

Launch caps and levy

Separate climate and ozone limits; charge for launch damage

Remediation royalty

Share of sales to an audited fund for mine-site repair

Two market effects justify caps. Under the Coase conjecture, buyers who know an operator holds stock in orbit expect more supply later and delay purchases, although high return costs could limit this. And lower prices weaken recycling: WPIC links weak catalyst recycling in 2022 to 2024 partly to low PGM prices. We therefore propose an International Space Resource and Market Stabilization Authority with four rules: a time-limited registry, annual return quotas for each metal, climate and ozone launch caps with a levy, and a royalty paid into an audited fund for mine-site repair. For rhodium, our market model gives the cap directly: the most that can be returned while the price stays above an agreed floor. Following Ostrom, operators, miners and recyclers would vote on quotas, with an independent appeals panel. Over to [Member A].

Launch-cost threshold for asteroid water

Cheaper launches reduce plant cost but also the price of water shipped from Earth.

Also required

Launches below the climate and ozone limits

PGM returns within quota; credit only displaced mining

This brings the analysis together; the chart is illustrative. a is the extra non-launch cost of the asteroid route per kilogram, and the b terms are the Earth-launched mass per kilogram of propellant delivered by each route. As launch prices fall, both lines fall, but Earth delivery falls faster. Asteroid water is cheaper only above the threshold C-star; heavier equipment or lower yields raise it. [→] Being cheaper is not enough. Launches must stay below both the climate and ozone limits, CO resupply must fit within that budget, and PGM returns must stay within quota, counting only the mining they displace. For water, Hein and colleagues estimate 90 kilograms of CO2 per kilogram launched from Earth, and 18 if an asteroid mission returns five times its launch mass.

Recommendation

Alongside, on Earth

Better PGM scrap collection; alkaline electrolysers and lower iridium loadings

Looking beyond is justified when it delivers a demonstrable benefit to Earth.