Shen Ge : Asteroid Mining Concepts

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
and Propulsion
What resources do NEAs offer?
(water, volatiles)
(silicates, sulfides,
Potential Products from NEAs
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
Semiconductor metals
Space solar arrays
How do we mine them?
Type of Material
Water and other liquids Drillholes.
Frasch process
- 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 deltavs 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
Δv = velocity change
Ve = 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
Example of a Hohmann Transfer
“Apollo-Type” Mission
Low Delta-vs for Many NEAs
Interplanetary Superhighway
Low delta-v trajectories
combined with electric or
solar propulsion can open
the pathway to many more
asteroids previously
considered impossible to
Or maybe bring the asteroid here…
• Use gravity assists to bring
candidates into a stable orbit
around Earth or
• Modify orbits of temporarilycaptured objects (TCOs) to make
them stable orbits.
Diagrams from Mark Sonter
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 [$/kg]
Mmpe is mass of mining and processing equipment [kg]
f is the specific mass throughput ratio for the miner [kg mined / kg equipment /
t is the mining period [days]
r is the percentage recovery of the valuable material from the ore
∆v is the velocity increment needed for the return trajectory [km/s]
ve is the propulsion system exhaust velocity [km/s]
i is the market interest rate
a is semi-major axis of transfer orbit [AU]
Mps is mass of power supply [kg]
Mic is mass of instrumentation and control [kg]
Cmanuf is the specific cost of manufacture of the miner etc. [$/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
Exp NPV = p x NPV
where 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.

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