Chapter 3

📍 Lunar Base Site Selection

Site Selection Criteria

Key factors to consider when choosing a lunar base location. The priorities for water, sunlight, temperature, Earth communication, and landing zone follow WIA-SPACE-011 §4.1; the remaining rows are supplementary criteria used in this book:

Criterion	Importance	Description
Water access	Top priority	Within 10 km of confirmed PSR water ice deposits (§4.1.1)
Sunlight	Very high	At least 70% annual sunlight, target 80-90%; below 70%, nuclear power is required (§4.1.2)
Temperature stability	High	Daily temperature variation below 150°C (§4.1.3)
Radiation shielding	High	Protection from natural terrain
Earth communication	Medium	Direct line of sight to Earth more than 50% of the time (§4.1.4)
Landing zone	High	Slope below 15° within 5 km, boulder coverage below 5%, clear approach corridor (§4.1.5)
Scientific value	Medium	Diversity of research targets

1. South Pole: Shackleton Crater

Location and Characteristics

Advantages

• Permanently shadowed region (PSR): Water ice is expected in the crater's permanently shadowed interior; the standard rates the water resource as excellent (§4.2), although the actual quantity has not been measured
• Peaks of eternal light: The crater rim receives sunlight almost constantly (80-90% of the year)
• Temperature stability: Relatively stable; the standard gives -50°C to -30°C for polar regions (§4.1.3) and -40°C to -20°C for the Shackleton rim (§4.2)
• Earth visibility: From elevated rim sites, Earth is above the horizon for part of each month, allowing direct communication for part of the time
• Scientific value: Enables study of water ice preserved for billions of years

Disadvantages

• Extreme terrain: The crater walls are steep and rugged
• Permanent darkness: The crater interior is always dark, making work difficult
• Low temperatures: The interior of the PSR is extremely cold, below -200°C
• Limited communication: No direct communication from inside the crater; a relay is required

Artemis III Landing Candidate

NASA's candidate landing regions for Artemis III, announced in 2022 and later refined, all lie within a few degrees of the south pole, and several are near Shackleton Crater. The concept assumed in this standard is to build a base on the crater rim and use robots to mine the water ice inside the crater.

2. North Pole: Peary Crater

Location and Characteristics

Advantages

• Water ice: Radar and neutron data indicate ice in north polar shadowed craters; the standard rates Peary's water resource as excellent
• Continuous sunlight: Surrounding peaks receive sunlight more than 85% of the year
• Large crater: Much wider than Shackleton, offering more area to prospect
• Flat areas: Some areas are favorable for landing and construction

Disadvantages

• Low priority: The south pole is the main target of the Artemis program
• Earth communication: As at the south pole, Earth sits low on the horizon
• Insufficient exploration: Less studied than Shackleton

3. Lava Tubes

Locations and Discovery

Beneath the lunar surface lie enormous lava tubes formed by ancient volcanic activity. Major locations:

• Marius Hills: A skylight (pit) discovered by Japan's Kaguya in 2009; the standard's preferred future site (§4.2)
• Near Philolaus Crater: Candidate lava channels identified from orbital imagery
• Mare Tranquillitatis pit: Radar analysis published in 2024 indicated an accessible cave conduit beneath this pit, in the same mare as the Apollo 11 landing site

Advantages

• Radiation shielding: A thick rock ceiling provides near-complete shielding; the standard treats it as 100% GCR shielding (§5.2)
• Micrometeoroid protection: The ceiling protects against impacts
• Temperature stability: Nearly constant year-round (the standard assumes about -20°C)
• Spacious interior: Provides enormous natural living space
• Possible pressurized volume: Sealing sections of a tube to hold pressure has been proposed, but it is unproven; the pressure-vessel requirements of §5.1.1 still apply
• Expandable: The natural volume allows expansion with less structural construction

Disadvantages

• Difficult access: Transporting equipment and materials to the cave entrance is complex
• No solar power: Sunlight does not reach inside, so nuclear power is essential
• Communication blockage: No direct communication with Earth from inside the cave
• Exploration required: The internal structure and stability must be verified in advance
• Structural risk: The possibility of ceiling collapse must be assessed

4. Equatorial Region

Representative Location: Tranquility Base (Apollo 11 Landing Site)

Advantages

• Earth communication: On the near side, Earth is always above the horizon, making communication easy
• Flat terrain: The mare (sea) regions are very flat
• Historical value: The area near the Apollo landing sites is a tourist attraction
• Easy access: Low-latitude sites are easier to reach from equatorial orbits

Disadvantages

• Lack of water: Unlike the polar regions, there is almost no water ice
• 14-day night: No solar power generation during the long night
• Extreme temperatures: +127°C by day, -173°C at night
• Energy problem: Batteries or nuclear power are essential during the night

The equatorial region is suitable for early short-duration visits, but it is inferior to the polar regions as a site for a permanent base.

5. Crater Rim

Concept

The edge (rim) of a deep crater offers unique advantages:

Advantages

• High elevation: Higher than the surroundings, increasing hours of sunlight
• Water access: Access to the ice inside the crater
• Vantage point: A wide field of view benefits exploration and communication
• Natural shielding: Terrain on one side partially blocks radiation

Disadvantages

• Sloping terrain: Construction and movement are difficult
• Stability: Risk of crater wall collapse
• Confined space: Limited room for expansion

Site Comparison and Recommendations

The scores for Shackleton, Peary, and lava tubes are those given in WIA-SPACE-011 §4.2. The equatorial and crater-rim scores and all star ratings are this book's own illustrative assessment.

Location	Water	Sunlight	Temperature	Radiation	Overall score
South Pole: Shackleton	⭐⭐⭐⭐⭐	⭐⭐⭐⭐	⭐⭐⭐⭐	⭐⭐⭐	9.5/10
North Pole: Peary	⭐⭐⭐⭐⭐	⭐⭐⭐⭐	⭐⭐⭐⭐	⭐⭐⭐	9.0/10
Lava tubes	⭐⭐	⭐	⭐⭐⭐⭐⭐	⭐⭐⭐⭐⭐	8.5/10
Equatorial region	⭐	⭐⭐	⭐⭐	⭐⭐	5.0/10
Crater rim	⭐⭐⭐⭐	⭐⭐⭐⭐	⭐⭐⭐	⭐⭐⭐	8.0/10

Phased Development Strategy

Phase 1: Polar Surface Base (2026-2030)

• Small outpost on the rim of Shackleton Crater
• 4-6 crew members, 1-2 month missions
• Water ice mining trials

Phase 2: Permanent Polar Base (2030-2040)

• 10-20 permanent residents
• Full-scale ISRU operations
• Hybrid solar + nuclear energy

Phase 3: Lava Tube Base (2040+)

• Underground city for long-term habitation
• Scale of 100 or more people (§15.1)
• Complete radiation shielding

Conclusion

The area around Shackleton Crater at the lunar south pole is currently the top candidate site, because it combines access to water, near-continuous sunlight, and relatively stable temperatures. In the long term, however, lava tubes may become the preferred habitat.

The next chapter examines the technologies and methods for actually building a lunar base at the chosen location.