ARCHITECTURE CONCEPT 

REVIEW 2022 White Paper

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National Aeronautics and 

Space Administration

WHY ARTEMIS WILL FOCUS ON THE 

LUNAR SOUTH POLAR REGION

INTRODUCTION

This paper will highlight the unique value to 

exploring the south polar region of the Moon. 

In 2019 NASA was directed to land astronauts 

in the lunar south polar region. The lunar polar 

regions are of unique value in part due to the 

lighting conditions, which include locations 

with nearly continuous sunlight throughout a 

year, ranging to continuous darkness. Long 

duration lighting provides thermal stability 

for human exploration hardware and solar 

power generation, while permanent shadow 

protects the surface from the solar wind 

and creates environments where volatiles 

could be trapped as ices. Access to these 

ices will yield scientific knowledge about the 

role of volatile processes across the inner 

solar system throughout Earth’s history that 

cannot be gained elsewhere, which is critical 

knowledge for understanding life in general. 

Furthermore, these ices might yield resources 

that enable future astronauts to live off the land 

and put NASA on a path towards sustainable 

exploration. Ices that are trapped in the south 

polar region are located within some of the 

oldest terranes on the Moon, which provides opportunity to collect samples to help understand 

the history of the Moon, the Sun, and our home planet of Earth, where samples and knowledge 

from this era of Solar System development have largely been lost through plate tectonics, or 

greatly altered by the very environment that supports the existence of life here. The south polar 

region is located near the South Pole Aitken Basin, the largest impact basin in the Solar System. 

Studying samples from the south polar region will help us understand when this basin formed, 

which is a high science priority to help us understand how and when collisions between large 

objects occurred during the birth and evolution of the Solar System. 

LUNAR LIGHTING

Our view of the Moon, as seen from Earth and during the Apollo surface missions, is of an 

object whose appearance changes regularly and reliably over time. Humans have long defined 

these lunar cycles or phases and how they relate to life here on Earth. However, the lunar poles 

Figure 1. Lunar Reconnaissance Orbiter (LRO) 

Narrow Angle Camera image M1432398306LR 

showing the Malapert Massif in the south polar region 

of the Moon. Malapert is a high elevation feature that 

is Sunlit, but surrounded by areas of darkness cast by 

shadows from other high elevation features such as 

impact crater rims.Credit: NASA/GSFC/Arizona State 

University
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are different from what we see of the Earthfacing side of the Moon (Fig. 1), and as a 

result they are scientifically unique and 

compelling locations to explore [1]. Like 

the Earth, the Moon experiences seasons. 

These seasons are less dramatic than 

what we experience on Earth because the 

lunar polar axis has less of a tilt than the 

Earth relative to its orbit around the Sun. 

This difference has critical implications 

for the lunar polar environment, its impact 

on human exploration systems, and the 

science that we will be able to conduct 

when we go there. In addition, we know that 

the south pole of the Moon is geologically 

distinct from areas explored by Apollo, 

presenting an opportunity to unravel the 

earliest history of the Earth-Moon system.

The lighting conditions in the lunar south 

pole enable unique opportunities. Unlike 

equatorial locations, such as the Apollo 

sites, the polar day-night cycle is irregular 

and heavily influenced by the lunar 

seasons. At Apollo sites there are ~14.5 

Earth days of light, followed by ~14.5 

Earth days of night. At polar locations, this 

rhythm is distinct, due to both the inclination to the lunar equator to the ecliptic plane (1.54°) as well as the 

topography of the surface. These factors create one of the most unique aspects of the poles: that there are 

regions that never receive direct sunlight, as well as areas that are illuminated for longer than the 14.5 days 

experienced at equatorial locations, and are in darkness for much shorter times than those equatorial areas 

(Fig. 2). Lunar landings during Apollo took advantage of the equatorial lighting conditions, landing early in the 

day/night cycle in order to experience many Earth days of exposure to continuous light. Furthermore, at these 

more equatorial locations, the entire region is exposed to sunlight as the sun slowly tracks overhead from one 

horizon to the next. Near the poles, a person would observe the sun circle their location, never rising more than 

a few degrees above the horizon, and sometimes sinking below the horizon, completely out of sight. At the 

poles, the sun never rises overhead of an observer. The result is a breathtaking scene of contrasting light and 

darkness, creating oases of light surrounded by extensive stretches of shadow (Fig. 1). 

These lighting conditions provide operational benefits. The oases of light offer locations where hardware will 

experience more constant thermal conditions and can generate solar power for longer periods of time than 

at the equator, while requiring less battery power to survive stretches of shadow and darkness. Taking into 

consideration the timing of astronaut or robotic activities, travel between oases of light is possible along 

sunlit ridges. An additional benefit from the south pole is the connection with the Earth. Like Apollo sites, 

there are areas on the Earth-facing hemisphere that have constant and nearly constant view of the Earth (Fig. 

3), obviating the need for additional communication assets for short duration missions early in Artemis. The 

corollary to this is that there are areas that don’t see the Earth, which enable opportunities for lunar-based 

radio astronomy assets that can observe the universe in a radio-quiet environment [1] all within fairly short 

distances of single to 10s of kilometers.

Figure 2. Map of the lunar south polar solar illumination, averaged over 

hourly timesteps spanning 18.6 years, for the south polar region. Shown 

over 85S-90S (60m/px). Black shows locations that never see sunlight in 

depressions and impact craters whereas lighter toned colors can see > 

50% sunlight especially along crater rims and high topographic ridges.
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LUNAR VOLATILES

These unusual environments result in 

perhaps the most compelling science 

we can accomplish at the Moon with 

Artemis. After Apollo, the science 

community believed that the lunar 

surface was dry; that the temperature 

extremes on the Moon would not 

support stable volatiles (specifically 

H2O and OH) at the lunar surface. It 

was hypothesized that the poles could 

harbor surface volatiles due to the cold 

surface environment, specifically areas 

that are in permanent shadow. We now 

know that large areas of permanent 

darkness in the polar regions preserve 

volatiles collected throughout the 

Moon’s past. Recent remote sensing 

data paint a complex picture of volatile 

distribution in the lunar poles-- not all 

areas of permanent shadow contain 

volatiles, and there are areas that are 

partially illuminated and still appear to 

retain volatiles at or near the surface. 

Crewed and robotic exploration of these regions will constrain the controls on volatile distribution, transport, 

and retention. With careful sampling and return to Earth of these volatiles, we will learn about their origin and 

age, gaining insight into the processes that distribute water throughout the Solar System. There are competing 

theories for the origin of lunar water; some water may have originated from the lunar interior, reflecting water 

remnant during the formation of the Moon over 4.5 billion years ago; water may originate from comets and 

asteroids that have impacted the Moon over its entire history; some water may be forming today because 

of solar wind interacting with the surface. Ultimately these processes may have each contributed to what is 

observed at the surface today, but only once we have samples in labs on the Earth, will we be able to fully 

interpret the lunar volatile history.

The sampling and analyses of volatiles will not only reveal the rich history of the Solar System, but also 

may provide the very material to sustain a presence on the Moon and enable exploration deeper into space. 

Identifying the abundance, form, and small-scale distribution of volatiles at and near the surface directly feeds 

into how we will utilize resources available at the south pole. Artemis missions will directly contribute to our 

understanding of volatiles and their resource utility, starting with the collection of samples in early missions 

to understand the presence of volatiles, leading to more complex samples and sampling methods as Artemis 

missions mature. It will be the early Artemis missions that establish the necessary guidelines for sampling, 

collecting, and eventually utilizing those resources.

ANCIENT SURFACES

Those very volatiles are imprinted on some of the oldest surfaces on the Moon. Mapping of the south pole (Fig. 

4) suggests that regions in the Artemis exploration zone will have surfaces older than ~3.85 billion years (and in 

some places older than that), older than any of the Apollo sites. The south polar region includes the margins of 

the South Pole-Aitken Basin (SPA), the largest and oldest impact basin in the solar system, which formed as a 

result of a collision between the Moon and another large solar system object. Determining when the SPA event 

occurred is a high priority for the science community as it could mark the beginning of collisions between solar 

system debris of such large sizes, after which life could begin to gain a foothold on planets. The proximity of 

the south pole to the SPA basin increases the chances of collecting samples from that event relative to landing 

Figure 3: Map of average Earth-visibility over 18.6 years, centered on the 

south pole with the Earth-facing hemisphere at top. Figure from [3]
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in the north polar region. Much of the region within the Artemis exploration zone is dominated by materials 

from the formation of SPA and materials that have been modified by subsequent impacts. Well-documented 

samples collected by Artemis from this region will record these multiple impact events, determining their ages 

unambiguously via laboratory analysis will vastly improve our knowledge of the dynamics of the early history 

of the Solar System, most importantly the Earth-Moon system.

The ancient material at the South Pole not only records the bombardment history of the Moon, it also is a 

witness plate to billions of years of interactions with the Sun and galactic cosmic rays. Apollo samples are 

used to identify changes in the Sun’s output over hundreds of millions of years as well as contributions from 

outside our Solar System, but are limited to the ages of those units. The ancient surfaces explored during 

Artemis will allow us vastly improved insight into the history of the Sun and interactions with the galaxy over 

several billion years. This history is directly relevant to interpreting the history of the Earth and its interactions 

with the Sun and the space environment, a record that is largely absent or erased from the Earth.

Figure 4. Geologic map [3] of the lunar south pole, illustrating the distribution of ancient surfaces (brown colors) around the pole. 

These ancient units are associated with the South Pole-Aitken basin, the oldest recognized crater in the Earth-Moon system. The 

green circle marks the Artemis exploration zone.
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KEY TAKE-AWAYS

The lighting conditions in the south polar region contribute to unique scientific and operational 

opportunities. Sites of permanent darkness in the polar regions provide locations that are not exposed 

to the solar wind and could preserve volatiles collected throughout the Moon’s past. Conversely, long 

exposure to sunlight creates environments that are suitable to long duration survivability of hardware 

and for solar power generation. The south polar region is also among the oldest parts of the Moon. 

Sample collection in the south polar region will help identify the age of the largest impact basin in 

the solar system, helping identify when life might have been able to survive on Earth. Volatiles, likely 

trapped as ice in areas of permanent shadow, could reveal valuable knowledge about the history of 

the inner solar system, including when life gained a foothold on the Earth after the significant impacts 

that formed the large basins. Just as ancient ices hold scientific value, lunar samples from this area will 

increase our knowledge of the history of the Moon itself and of the solar processes that have impacted 

the Earth and Moon. Additionally, these ices could serve as valuable resources for use during future 

exploration.

REFERENCES AND ADDITIONAL BACKGROUND

[1] NASA, (2020) Artemis III Science Definition Team Report, SP-20205009602.

[2] Mazarico, E., et al. (2011), Icarus, Vol. 211, pp. 1066-1081

[3] Krasilnikov, S. S., et al., (2023) Icarus, 394, 115422.

This white paper was developed as part of NASA’s 2022 strategic analysis cycle to address topics of frequent discussion. For 

the latest white papers or other architectural documents related to human missions to the Moon and Mars, please visit:

www.nasa.gov/MoonToMarsArchitecture.