Asteroid Mining Concepts

Shen Ge

Near-Earth Asteroids• Near-Earth Asteroids (NEAs) of interest due to

the relative ease of reaching them.• All NEAs have distances of less than 1.3 AUs.

Images from William K Hartmann

Known Near-Earth Asteroids

Data from JPL

Asteroid Resources

Chart from Charles Gerlach

Growing Interest in Space Mining

Important Questions

Astrodynamics and Propulsion

Asteroid Composition

Mining Technologies

Economic Analysis

What resources do NEAs offer?

S-typeStony

(silicates, sulfides, metals)

C-typeCarbonaceous

(water, volatiles)

M-typeMetallic(metals)

Potential Products from NEAs

Material Product

Raw silicate Ballast or shielding in space

Water and other volatiles Propellant in space

Nickel-Iron (Ni-Fe) metal Space structures

Platinum Group Metals (PGMs) Catalyst for fuel cells and auto catalyzers

Semiconductor metals Space solar arrays

How do we mine them?

Type of Material ProcessWater and other liquids Drillholes.Sulfur Frasch processMetals - If large, need to grind and crush them with

feeders, crushers, fluid energy mills, hammer mills, etc.

- If small, need to separate the metals by electrostatic or magnetic separation, sieves, carbonyl separation, or cutting.

Required Asteroid Mining System

Chart from Brad R. Blair and Leslie S. Gertsch

How do we get there?• We want to find the asteroids with low delta-

vs to reduce propellant needed.Distribution of specific linear momentum of a Hohmann transfer from low Earth orbit (LEO) to NEAs according to Benner.

1st WARNING: For Virgil and other non-science or engineering majors who apparently gets a headache from seeing equations, please turn your head away from the next slide.

Rocket Equation

whereΔv = velocity changeVe = exhaust velocity

Mo = total mass

Mp = propellant mass

Two Options:1. Reduce delta-v required for trajectories to enable low-thrust

propulsion methods such as electric, solar thermal, or solar sail propulsion.

2. Use chemical propulsion for high thrust trajectories if needed.

Example of a Hohmann Transfer

“Apollo-Type” Mission

Low Delta-vs for Many NEAs

Compare!

Interplanetary Superhighway

Low delta-v trajectories combined with electric or solar propulsion can open the pathway to many more asteroids previously considered impossible to reach.

Or maybe bring the asteroid here…

Diagrams from Mark Sonter

• Use gravity assists to bring candidates into a stable orbit around Earth or

• Modify orbits of temporarily-captured objects (TCOs) to make them stable orbits.

Even NASA is interested…

Can we justify the costs?

• The economic justification for an asteroid mining operation is only the case if the net present value (NPV) is above zero.

• It is NOT just the cost of mining and going there versus the profit obtained from resources.

• Sonter has done extensive work in creating a formula for these calculations.

2nd WARNING: For Virgil and other non-science or engineering majors who apparently gets a headache from seeing equations, please turn your head away from the next slide.

Sonter’s NPV Equation

• Corbit is the per kilogram Earth-to-orbit launch cost [$/kg]

• Mmpe is mass of mining and processing equipment [kg]• f is the specific mass throughput ratio for the miner [kg mined / kg equipment /

day]• t is the mining period [days]• r is the percentage recovery of the valuable material from the ore• ∆v is the velocity increment needed for the return trajectory [km/s]• ve is the propulsion system exhaust velocity [km/s]• i is the market interest rate• a is semi-major axis of transfer orbit [AU]• Mps is mass of power supply [kg]

• Mic is mass of instrumentation and control [kg]

• Cmanuf is the specific cost of manufacture of the miner etc. [$/kg]• B is the annual budget for the project [$/year]• n is the number of years from launch to product delivery in LEO [years].

Expectation Value of NPV

• NPV should take into account the risk of failure.

Exp NPV = p x NPVwhere p = fractional probability of outcome

The Next Steps

• Asteroid Composition. Create database of NEAs of interest for resource extraction with their orbits and compositions.

• Space Mining. Develop potential mining technologies for modified use in space.

• Astrodynamics. Design optimal trajectories and propulsion methods to go there and back.

• Space Economics. Identify costs and returns as well as potential investors.

Questions?