Lunar Iron Habitat Outline - Lunar Homestead

Version 1.41 August 26, 2019

Phase One – Determine availability and composition of Lunar iron

The first step is to determine if there is enough iron on Luna, where the iron is located, and if it’s in a form we can use to construct habitat pressure hulls. I’m only going to focus on the areas we know the best, the Apollo landing sites. I’m not saying those are the best places for Lunar homesteads, but that’s were we have the most samples over the largest area. Remote sensing is great but physical samples are the best.

Scope of work: This phase will be strictly literature research. No experimentation is anticipated.

Iron composition
- Types of Lunar iron
  - ANSWERS
    - There’s plenty of iron available on Luna. And in forms we can use.
    - Free metallic iron
      - Nanophase iron
      - Iron fines
    - Mineral iron
      - Ilmenite
      - Olivine
      - Spinel
      - Pyroxene
- Chemical composition
  - ANSWERS
    - The iron available on Luna will mostly come in two basic forms, both of which we can use.
    - Elemental iron (Fe⁰)
      - Extracting iron from minerals will yield elemental iron.
      - Nanophase iron particles are mostly pure elemental iron.
    - Iron nickel alloy (FeNi)
      - Deposited by impacting meteoroids and present as native iron. Difficult to determine the origin.
      - Nickel (Ni) and cobalt (Co) contents can range from 0%-50% for Ni and 0%-8% for Co.
      - Traces of other elements can be alloyed with the iron.
Iron distribution and abundance
- Where is the iron located?
  - ANSWERS
    - Free metallic iron is available everywhere.
      - All Lunar samples had metallic iron grains.
      - Meteoroid impacts produce metallic iron. Impacts are evident over the entire surface.
      - Mare sites may have more native iron while highland sites may have more meteoroid contamination iron.
    - Mineral iron is available everywhere.
      - Ilmenite is present in most samples with mare basalts having the highest concentrations.
        
        Ilmenite is the most abundant oxide mineral found in Lunar rocks.
      - Olivine is present in most samples with mare basalts having the highest concentrations.
      - Spinel has been found in all mare basalt samples and some highland samples.
        
        Spinel is the second most abundant opaque mineral found on Luna.
        
        Spinel is most abundant in mare basalt samples.
      - Pyroxene is present in most sample with mare basalts having the highest concentrations.
        
        Pyroxene is the most abundant dark mineral at the Lunar surface.
- How much iron is available?
  - ANSWERS
    - Free metallic iron is thought to be everywhere at about 1% by volume (varies by sample and site).
    - Ilmenite
      - Most samples had <2% ilmentite.
      - Apollo 11 and Apollo 17 mare basalts are up to 15%-20% ilmenite (by volume).
      - Ilmenite abundance is highly variable within a single sample site.
    - Olivine
      - Mare samples showed a range of olivine abundance (0% to >60%).
      - Highland samples averaged around 7%.
    - Spinel
      - Up to 10% (by volume) of some mare basalt samples.
    - Pyroxene
      - Mare basalts are 40%-65% (5%-30% for a few samples) pyroxene.
      - Anorthositic rocks (highland) are 0%-40% pyroxene.

Relevant pages:

Lunar Iron Characterization – Summary of what I’ve learned for this phase of the project.

Phase Two – Determine suitability of Lunar iron for pressure hull construction

Pressurized habitats are critical. There’s no homesteading without them. Since my hypothesis is that Lunar iron can do the job, the next step is to quantify the requirements for habitat pressure hulls and determine if Lunar iron can meet those requirements. If Lunar iron fails this step there’s no point in going further.

Scope of work: This phase will be strictly literature research. No experimentation is anticipated.

Identify material requirements for pressure hull construction
- Habitat Pressure Hull Parameters
- Atmospheric Pressure and Composition
  - ANSWER
    - Lunar iron, when processed, should make excellent pressure hulls. We’ve used them as pressure vessels for a long time now, and at much higher pressures.
    - The habitat pressure hull must be able to handle a range of pressures:
      - One Standard Lunar Homestead Atmosphere of 78% nitrogen/21% oxygen at 70.11 kPa.
      - One standard atmosphere of 78% nitrogen/21% oxygen at 101.325 kPa.
    - The habitat pressure hull must be able to safely contain twice the nominal atmospheric pressure before venting (using pressure relief valves).
      - 101.325 x 2 = 202.65 kPa.
- Pressure Hull Shape, Thickness, and Size
  - ANSWER
    - I’ve decided on an octagonal shape that looks like a square with the corners clipped off.
    - My SWAG (Scientifically Wild Ass Guess) calculations showed that the minimum hull thickness should be 2.58 centimeters. I’m going with 4 centimeters just to be safe.
    - I’ve decided on a hull that is 8 meters high, 8 meters wide, and 10 meters long. I wanted to enclose a significant volume of space because this isn’t a short-term mission. People are going to create lives in these habitats.
- Pressure Hull Durability
  - ANSWER
    - No deal-breakers that I can see. Lunar iron seems like it should be up to the task.
- Iron and Regolith Resource Requirements
  - ANSWER
    - Luna has enough iron for us to build many, many habitats.
    - We’ll need 133.79 metric tons (almost 17 cubic meters) of iron to build a single pressure hull using the above specifications.
    - We’ll need to move and process 7,055 metric tons of regolith if we are only using the available free metallic iron.
    - We’ll need to move and process 1,597.75 metric tons of regolith if we are only using ilmenite.
    - We’ll need to move and process 4,598.2 metric tons of regolith if we are only using olivine.
    - We’ll need to move and process 1,203.5 metric tons of regolith if we are only using ulvöspinel.

Determine if Lunar iron is a suitable material to construct pressure hulls.
- Are there usable forms of Lunar iron?
  - ANSWER – YES
- Can Lunar iron be found in reasonable concentrations?
  - ANSWER – YES
- Can a reasonable amount of refined Lunar iron be used to make a habitat pressure hull?
  - ANSWER – YES
- Can this pressure hull contain a usable atmosphere safely?
  - ANSWER – YES

Phase 3 – Lunar regolith (and mega-regolith) mining and moving equipment

OK, we’ve identified the regolith, and mega-regolith, we want and where it is. Now we need to get it from the surface into a hopper (I’m assuming) so it can be processed. Unfortunately, it’s not as simple as grabbing a shovel and getting it done. Or maybe it is!

Scope of work: Here’s where the fun begins! Literature research and then experiments!

Lunar Homestead Experimental Location
- ANSWER – Apollo 12 landing site
  - Honestly, it doesn’t really matter. SPORE needs to be able to operate anywhere and iron is available everywhere.
  - But all future Lunar Homestead research will use Apollo 12 site parameters to keep things simple.
Apollo 12 Site Regolith Characterization
- ON HOLD – I’ll get back to this once I’ve hammered out SPORE. If SPORE is feasible then many of the characteristics of the Lunar regolith will become irrelevant or will change.
Regolith and mega-regolith mining options
- SPORE project – Using a shielded pressurized structure to conduct Lunar mining operations instead of conducting exposed surface mining. SPORE might also make Iron Pressure Hulls unnecessary.
Regolith and mega-regolith moving options
- - We need to get the raw materials from the mine to the refining equipment.

Phase 4 – Lunar free metallic iron separation

The easiest iron to retrieve is are the particles of free metallic iron.

Scope of work: Literature research and experiments.

Separation options (literature research)
- Benefication
- Electro-static separation

Lunar iron separation experiments (scale prototypes)

Phase 5 – Lunar mineral iron extraction

OK, we’ve got all the free iron out of our regolith. Now we need to extract the rest from the rocks.

Scope of work: Literature research and experiments.

Benefication of raw regolith to separate out iron-rich ores
Reduction options
Lunar iron extraction experiments (scale prototypes)

Phase 6 – Lunar iron refining

Now we have a pile of nickel-iron pebbles and a pile (?) of elemental iron. We need to change our raw iron into something more usable.

Scope of work: Literature research and experiments.

Refining options
- Melting
- Hot forging
- Cold forging
Lunar iron refining experiments (scale prototypes)

Phase 7 – Lunar iron working

Once we have access to refined iron (bars, ingots, whatever) we’re going to want to DO something with them.

Scope of work: Literature research and experiments.

Iron working options
- Casting
- Forging
- Welding
- Sintering
- 3D metal printing
Lunar iron working experiments (scale prototypes)

Phase 8 – Adapt successful scale prototypes to in-situ produced scale prototypes

OK, we’ve got working scale propotypes built from commercially sourced materials. The next step is to build them from scratch using Lunar regolith simulant, just like our Homesteaders will. By the end of this phase we should have enough knowledge to be able to take raw Lunar regolith and make iron habitats.

Scope of work: Purely experimental.

In this phase we’ll tweak the designs to reflect 100% in-situ production. Then we’ll start from the beginning:

Working scale prototypes of regolith moving equipment. Constructed exclusively from iron extracted from Lunar regolith simulant.
Working scale prototypes of regolith benefication and separation equipment. Constructed exclusively from iron extracted from Lunar regolith simulant.
Working scale prototypes of mineral iron extraction equipment. Constructed exclusively from iron extracted from Lunar regolith simulant.
Working scale prototypes of iron refining equipment. Constructed exclusively from iron extracted from Lunar regolith simulant.
Working scale prototypes of iron working equipment. Constructed exclusively from iron extracted from Lunar regolith simulant.
Working scale prototype of a pressure habitat hull. Constructed exclusively from iron extracted from Lunar regolith simulant.

Phase 9 – Preliminary uses for refined Lunar iron

We’ve got the iron. We know how to make it into pressure hulls and other usable items. Now let’s figure out what else we can make. This phase is actually the lead-in to the next project. I’ll use this phase to determine what the next project (or projects) need to be.

Scope of work: Literature research only. I’ll save the experiments for when I’m working the next project.

I’m thinking the next project should be on of the following:

Shelter construction – We’ve got a pressure hull for our habitat. But that’s not the only shelter our Homesteader’s will need.
- Unpressurized – Vacuum usually isn’t the biggest problem. Radiation, impacts, dust, and thermal swings are harder to defend against. Our habitat also could use a shelter to protect it from the regolith shielding (I’m calling it a shieldwall for now).
- Semi-pressurized – Some functions won’t require a full habitable atmosphere.
Storage construction – We need a way to store all the resources our Homesteaders are going to extract from the Lunar surface.
- Unpressurized gas storage tanks – I’m not sure this will be a priority.
- Pressurized gas storage tanks – Oxygen and nitrogen will be the first two we need.
- Liquid storage tanks – Storing water comes to mind.
Tool and Parts construction – We’re going to need these to build everything else.

That’s it for now. I’ll refine this outline as I come up with more ideas or get more information. Any suggestions would be most appreciated. You can contact me at ben@lunarhomestead.com. Thanks!

Please check out the Get Involved! page if you find this project as exciting as I do!