The Economic Geology of Lunar and Asteroid Resources

Dan BrittUniversity of Central Florida

Center for Lunar and Asteroid Surface Science (CLASS)

dbritt@ucf.edu

“You are not in Kansas anymore”

• The geology of extraterrestrial objects is fundamentally different from terrestrial geology.

• Planets and asteroids are large physics and chemistry (and biology) experiments.

• Differences in chemistry, available energy (heat), size (gravity), and processes produce MUCH different results.

• Mineral assemblages evolve and diversify!– The Earth has about 4500 different minerals– Asteroids have less than 250– The moon has about 350

• There is economic value in these objects, but the geologic rules are different.

Goals and Class Mechanics• The focus is Economic Geology…….the geology necessary for

understanding and exploiting the resource.• The core content are a series of topic-focused lectures given by

leaders in the field. • Organization:

– Differences Between Terrestrial and Extraterrestrial Economic Geology • Introduction to Extraterrestrial Economic Geology-Dan Britt (UCF)• Mineral Evolution-Dan Britt (UCF)

– Lunar Geology• Lunar Geology (Lunar origins and crustal development)-Dave Kring (LPI)• The Lunar Highlands-Brett Denevi (APL)• The Lunar Mare-Clive Neal (Notre Dame)• Lunar Polar Water Deposits-Kevin Cannon (UCF)• The Lunar Surface Environment-Clive Neal (Notre Dame)• Operating on the Moon-Phil Metzger (UCF)

– Asteroid Geology• Asteroids: In the Beginning-Steve Desch (ASU)• Physical Evolution of Asteroids-Dan Britt (UCF)• Prospecting Asteroid Resources-Dan Britt (UCF)• Mining in Microgravity-Addie Dove (UCF)• Asteroid Surface Hazards: Dust, Toxic materials, Charging-Josh Colwell (UCF)

– Other Resources• Martian Resources-Angel Abbud-Madrid (CSM)• Simulating Lunar and Asteroid Regoliths-Kevin Cannon (UCF)• Wrap-up: The Geologic Context for a Space Gold Rush-Dan Britt (UCF)

Goals and Class Mechanics• All participants, both in-person and online, are encouraged to ask

questions of the speaker or make comments. • For real-time participants the online the Zoom chat box will be

monitored by the seminar producer and will relay questions to the speaker.

• Participants cover 18 time zones so the lectures and discussions will be recorded for later access.

• Those viewing the recorded sessions can send their questions either to Dr. Britt (dbritt@ucf.edu) or to the individual speakers. Contract information will be provided during each lecture.

• The course website is https://sciences.ucf.edu/class/seminar-series-extraterrestrial-economic-geology/

– Password is isru. • The website has suggested readings for each lecture, a brief

biography of the speaker, the powerpoints used in the lecture, and links to the recorded talk and subsequent discussion.

– It will take a few days before the link to each session is available to be posted on the website.

What is CLASS?• NASA Funded institute “to address basic and applied scientific questions

fundamental to exploration….” https://sciences.ucf.edu/class/• Part of the NASA Solar System Exploration Research Virtual Institute

(SSERVI) https://sservi.nasa.gov/• Designed to attack exploration issues with some the best science talent in

the world.• The access to the best science talent enables smarter, safer, and cheaper

exploration. • The CLASS Team includes scientists and engineers from…..

– 4 NASA Centers and ESA.– 16 Universities (4 continents, 18 time zones).– 14 NewSpace Companies.– 5 Observatories and Research Centers including Arecibo (managed by UCF).

• CLASS Services– The Exolith Lab: High-mineralogical fidelity regolith simulants

https://sciences.ucf.edu/class/exolithlab/– CLASS Landing Team: https://sciences.ucf.edu/class/landing-team/– CLASS Professional Education: Bringing the right science insights to bear on

exploration issues. https://sciences.ucf.edu/class/graduate-seminars/

Partners in this Seminar• SSERVI: Recognizing that science and human exploration are

mutually enabling, NASA created the Solar System Exploration Research Virtual Institute (SSERVI) to address basic and applied scientific questions fundamental to understanding the Moon, Near Earth Asteroids, the Martian moons Phobos and Deimos, and the near space environments of these target bodies. https://sservi.nasa.gov/

• Center for Lunar Science and Exploration: A collaboration between The Lunar and Planetary Institute (LPI) and the Johnson Space Center (JSC) to better support our new lunar science and exploration activities. https://www.lpi.usra.edu/exploration/

• Florida Space Institute: Supports space research, development, and education activities to aid the development of Florida’s space economy—civil, defense, and commercial. https://fsi.ucf.edu/

• noun (a) The naturally occurring material from which a mineral or minerals of economic value can be extracted at a reasonable profit(Glossary of Geology).– “Ore” is really an economic concept, not

a physical one.• In terrestrial geology an ore usually

implies (or requires) some concentration mechanism, usually igneous, sedimentary or hydrothermal.

• In planetary geology the concentration mechanisms can be very different or non-existent.

What is an Ore?

• Take Platinum• Average crustal

abundance is 0.005 ppm• In the Merensky Reef the

abundance is ~10 ppm, a factor of 2000 concentration.

• This single feature contains around 75% of the world's platinum

What is an Ore?

Concentration is Key to Economic Geology

• Most economic minerals need to be concentrated by geologic processes.

• Even concentrated ores contain huge amounts of waste rock.

Gold-quartz hydrothermal vein860 kg block of gold ore and the 30 g of gold extracted

Terrestrial Concentration Process• Source: The resource is typically finely

disseminated in a source rock at low abundance. It is liberated by some process, usually involving fluids.

• Transport: Required to mobilize and move resource-bearing fluids or solid minerals from the source rock into the ore body.

• Trapping: Required to concentrate the resource via some physical, chemical, or geological mechanism into a mineable ore. Often driven by faulting.

• These processes require fluids (typically brines), heat, high lithostatic pressure, and lots of time.

• The result is highly localized deposits of highly concentrated ores.

• Asteroids got one major heating cycle and were done ~4.5 billion years ago.

• Low-temperature aqueous alteration. – Heating ice + olivine made volatile-rich

asteroids – Resource: water locked in

phyllosilicates• High-temperature complete melting

– Melting chondritic assemblages made iron cores (impacts stripped the crust and mantle)

– Resource: Massive Iron and Siderophile elements disseminated (including Pt-group metals) in ppm amounts.

• Dr. Steve Desch will be addressing the early accretion and evolution of asteroids.

Asteroids

Terrestrial Processes are Typically Driven by Tectonics

• This is the distribution of copper porphyry and epithermal deposits (Richards, 2013).

• It is not hard to puzzle out current and past continental collisions….

Continental Collision

• Provides the heat, the fluids, the pressure, and the faulting for mineralization (Richards, 2013).

“You are not in the Copperbelt anymore”

• On the Moon and asteroids NO plate tectonics, NO continental collision.

• Low lithostatic pressures.• No available fluids after 4.5 billion

years.• Low to no heat internal heat flow. • No hydrothermal systems.• Concentration factors and

processes are fundamentally different.

Terrestrial Processes Result Highly Localized Ore Bodies

• Igneous, sedimentary, or hydrothermal processes mobilize and concentrate ores, but they are typically surrounded by lots of uneconomic rock.

• Typically discrete pods, veins, or zones of enrichment.

• The exploration process is focused on localizing the resource with finer and finer knowledge of the site.

• The better and denser the exploration and modeling, the less rock to move to get to the ore.

Small Asteroids are Typically a Single Mineral Assemblage• We have rendezvous with four small

asteroids. All are a single meteorite type.– Evidence of exogenous materials at the

few percent level, probably from impacts.• Several other lines of independent

evidence for single assemblage asteroids.– Rotational spectroscopy– Meteorites and meteorite showers– Spectroscopy of asteroid dynamical

families

Water in Asteroids • The resource is parent bodies

of hydrated carbonaceous chondrites (CI, CM, C2, CR).

• They are rich in hydrated layered silicates.

• Examples: Bennu and Ryugu• How do we know? Lots of

samples.– CI - 9 meteorites– CM - 641 meteorites– CR - 186 meteorites– C ungrouped - 65 meteorites

• These mineral assemblages are fine-grained and intimately mixed.

• NO CONCENTRATION. The entire asteroid is the resource. From Howard et al, 2011

Alteration Products

Where to find water?Element (wt.%)

Volatile-rich Carbonaceous Chondrites (CI, CM)

Other Carbonaceous (CO, CV, CK, CR, CH)

Ordinary Chondrites(LL, L, H)

Enstatite Chondrites (EL,EH)

Water 15.3 1.9 0 0

Carbon 2.7 0.7 0.1 0.4

Iron 19.6 27.3 22.5 25.5

Magnesium 10.7 14 14.7 12.4

Nickel 1.1 1.4 1.3 1.5

Sulfur 4.6 1.5 2.2 4.6

Oxygen 31 32.7 38.2 29.5

Silicon 11.7 15 18.1 17.7

• Water is locked in hydrated minerals in the CI, CM, C2, and CR carbonaceous chondrite.

• The rest are rocks……

From Hutchison, 2004

Mineralogy of Volatile-Rich CC’s (wt.%)

CI-type

CM-type

CR-type

C2-type

CV-type

Olivine 7 11 32 25 80

Troilite 6.5 2.5 4 8.5 11

Pyroxene 28 7

Vermiculite 9Magnetite 13.5 1 14 22 1Mg Serpentine 48

22 15 30.5

Smectite 5 8

Epsomite 6Kerogen 5 3.5 2 5FeSerpentine

57

Fe-Ni Metal 5 1Total Alteration Products

81.5 80 29 60.5 0

(Red are alteration minerals)

• In this case the “ore” is roughly 80% of the target body.

• Based on ~900 meteorite samples.

• NO CONCENTRATION. The entire asteroid is the resource.

Metallic Asteroids • Fragments of the cores of

asteroids that melted and differentiated in the first ~million years after accretion.

• Differentiated concentrated siderophile and chalcophile elements into the cores.

• How do we know? Abundant samples - 1242 meteorites

• The Widmanstätten pattern is evidence of very slow cooling (at the core of a planetesimal).

• The concentration occurred during formation. The entire asteroid is the resource.

• Lithophile (rock loving) elements remain on or close to the surface because they combine readily with oxygen, forming compounds that do not sink into the core.

• Siderophile (iron loving) elements are the high-density transition metals which tend to sink into the core because they dissolve readily in iron.

• Chalcophile (ore loving) elements that combine readily with sulfur and/or some other chalcogen other than oxygen.

• Atmophile (atmosphere loving) elements are either gases or form volatile hydrides.

Elements concentrated in asteroid cores

Iron Meteorite Elemental Abundances

From Mittlefehldt et al.,1998

• By terrestrial standards these are not bad ore grades for platinum, gold, or nickel (or iron).

• No veins, no other concentration mechanism. • Materials are disseminated in the bulk metal. The entire asteroid is the ore body.

A Few Definitions• Mineral Resource: concentration of minerals that has reasonable

prospects for economic extraction.• Inferred Mineral Resource: that part of the resource or which quantity

in grade or quality can be estimated from geologic evidence, limited sampling, and reasonably assumed geologic and grade continuity.

• Indicated Mineral Resource: that part of a resource for which quality, grade or quality can be estimated with sufficient confidence to support mine planning and evaluation of economic viability.

• Measured Mineral Resource: that part of the resource for which quantity, greater quality can be estimated with sufficient confidence to allow production planning and evaluation of economic viability.

• Mineral Reserve: economically mineable part of a measured or indicated resource demonstrated at least at PFS that includes adequate information on mining, processing, metallurgical factors etc. to demonstrate the economic extraction can currently be justified

• Probable Mineral Reserve: economically mineable part of an indicated (occasionally measured) resource.

• Proven Mineral Reserve: economically mineable part of a measured resource.

Ore Identification and Reserves• The process of turning a

potential resource into a reserve.

– Requires increasing knowledge of the geology.

– Increasing localization of the ore zones.

• This process is designed with the assumption of highly localized ore bodies surrounded by lots of gangue (waste rock) and overburden.

Resource to Reserve• This can be understood as a

probably distribution. • Increasing knowledge and

localization results in higher probably of the economicrecovery of an amount of the resource.

• Economic is the key term!– The calculus is not just

geological but also financial, environmental, regulatory, legal, governmental and many others.

Amount of Resource Increasing

Resource to Reserve on Asteroids• Still a probably distribution, but

since the entire body is the ore the localization imperative is largely irrelevant.

• Resource identification on asteroids are likely to be more of a step function. – Meteorite mineralogy and

remote sensing can identify high probably resources.

– Remotely identify meteorite analog, mineralogy, resource potential, size, mass, physical properties, rotation state.

– Sample return or in-situ analysis can verify the mineralogy to high confidence.

• Lack of concentration processes means no need for “high-grading” or traditional localization surveys (kriging).

Amount of Resource Increasing

Asteroid Remote Sensing

In-Situ Analysis

Resource Evaluation ProcessTerrestrial Process Asteroid Equivalent

Collect geological information Remote sensing to identify meteorite analog, mineralogy, resource potential, size, mass, physical properties, rotation state.

Build 3D geological model N/A-resource is single assemblage

Bill block model and extrapolate drill data to produce grade model

N/A-resource is single assemblage

Determine resource Based on meteorite mineralogy and asteroid mass

Acquire mining, metallurgical, economic information (prefeasibility study)

Sample return or in-situ analysis gives ore grade and reserve to high confidence

Determine reserve Grade and asteroid mass give reserve

Feasibility study Feasibility study

There is a need to develop a Lunar and asteroid-specific resource evaluation processes.

• The moon was the product of a giant impact that ripped off the crust and some of mantle of the early Earth.

• The moon got two extra cycles of heating, but the basic mineralogy is fundamentally different from the Earth.

• Dr. David Kring will address the origin and early evolution of the Moon.

• The lunar highlands (85% of the surface) are the product of a magma ocean.

• Dr. Brett Denevi will address the geology of the Lunar Highlands.

The Moon

Lunar Basalt ≠ Terrestrial Basalt

• Lunar basalts are lower in silicon and aluminum, and much higher in iron and titanium

• 85% of the lunar surface is Anorthosite!

OxideMare Basalt

Low-TI (A-15)Mare Basalt

High-TI (A-17)Terrestrial

MORBOcean Island

BasaltsBlack

Point-1Anorthosite

(A-15)

SiO2 44.1 40.6 50 49 47.2 44.1TiO2 2.28 10.8 1.11 2.4 2.3 0.02Al2O3 8.38 9.67 16.3 14.5 16.7 35.5FeO 22.7 18 9.7 11.8 12.1 0.23MgO 11.3 7.05 8.7 8 6.5 0.09CaO 9.27 12.4 11.8 9.6 9.2 19.7Na2O 0.27 0.43 2.5 2.8 3.5 1.34K2O 0.04 0.08 0.05 0.83 1.1

From Taylor and McLennan (2009)

Surface Processes • The surfaces of the moon and asteroids

are dominated by impacts at all scales.• Small asteroids are typically piles of

rubble bound by gravity and interparticle forces (sand bars in space).

• The moon’s surface is covered by impact ejecta to at least 1000’s of meters.

• Lunar impact “gardening” will disperse and mix the surface ejecta to 10’s of meters depth. Gardening will affect lunar polar ice deposits.

• Gardening will be more intense on older surfaces….like the poles. This will mix and scatter polar ice.

• Dr. Clive Neal will address the Lunar surface environment.

Prospecting on the Moon• Remote sensing actually works

pretty well for many lunar resources.

• Iron and Titanium: Remote sensing has used ground truth samples and done a great job of mapping Fe and Ti…..prospecting done.

• But….. iron and titanium on the Moon are quite poor resources by terrestrial standards.

– Ore-grade Ti on Earth is 55 wt.% TiO2, – Fe on the Moon is mostly in silicates

and quite difficult to get out compared to Earth where you have nearly pure hematite/magnetite horizons.

• Dr. Clive Neal will be speaking on the geology of the Lunar Mare.

Prospecting on the Moon• Where you need local prospecting is for

ice at the poles. • We know where the shadowed

regions are, but not much about the amount and distribution of the ice.

• Remember that regolith gardening will have mixed the stratigraphy and distribution of the ice. Do not expect large coherent ice “ore bodies”.

• Dr. Kevin Cannon will address the Lunar Polar Water deposits.

Lunar Samples• Like asteroids, prospecting is

aided by a substantial collection of Lunar samples.

• Apollo: 2200 samples, 382 Kg• Luna: 301 grams• Lunar meteorites: ~398

samples, ~200 Kg

NWA5000

Allan Hills 81005

Apollo 15 Regolith Breccia Apollo 15 Basalt

Prospecting on the Moon

From Korotev (2018)

You can learn a lot from ~2700 samples

Lunar Trafficability• One of the poorly discussed

issues in the Apollo missions was the effect prolonged traffic had on the lunar regolith.

• Prolonged activity seriously degrades lunar soil compaction.

• The soil around the Apollo Modules had been swept clean of loose material by the descent engines, but after a few days the crew’s boots had worked it into a loose quagmire of material.

• Also landing/takeoff plumes turn regolith into high-velocity ejecta.

• Dr. Phil Metzger will be speaking on these issues.

Trafficability on Ice-Rich Areas

• Remember that the ice is also holding up the surface. Any removal or volatilization will change the surface.

• Mining will cause terrain collapse.• Any rover will probably be much

warmer than its surroundings. Repeated movement will cause volatilization and compaction.

• It is worth remembering that a common feature of rural areas is the “sunken lane”. Nobody excavated these roads or paths. Repeated traffic compacted the soil and cause the road to sink relative to the fields.

Prospecting Asteroids• Remote sensing actually works pretty

well for asteroids.• Water: Water-rich meteorites/asteroids

are much darker than water-poor asteroids. Just look at the albedo…..prospecting done.

• Metal: High radar albedo = metal• You don’t need to prospect at a small

asteroid.– Ores are not concentrated on small

asteroids….there are no concentration processes.

– You don’t get significant mineralogical variation in a small asteroid. The whole asteroid is the ore body.

– “High-grading” is a useless concept for asteroids since there are no local concentration mechanisms.

• We will have a whole lecture on asteroid prospecting (by me).

To Wrap Up

• Mineral evolution and geology are fundamentally different on the Moon and Asteroids vs. the Earth

• Geological concentration mechanisms that we depend on terrestrially do not exist on the moon and asteroids.

• No plate tectonics, no high heat flow, no available fluids, no hydrothermal systems for the last ~4.5 billion years.

• Useful asteroids contain volatiles or metal. The rest are rocks.

• Prospecting for “ore” asteroids can be done remotely.

• Small asteroids are overwhelmingly a single mineral assemblage. Once at an asteroid prospecting and “high-grading” is a waste of time.

To Wrap Up

• Regolith processes (i.e. gardening) produce interesting results.

• Remote sensing works pretty well on the moon for concentrations of Fe and Ti.

• Remember that an ore is an economic concept, everything depends on cost.

• Resource evaluation standards need to be revised for the realities of Lunar and asteroid geology and processes.

• Ore geology on the Moon and asteroids is different but very understandable given knowledge of the geologic context.

• That is the objective of this course.