Lunar South Pole: Water Ice, Permanent Shadow and Future Landing Sites
The lunar south pole is the region of the Moon around 90°S where deep craters stay in permanent shadow and nearby ridges are sunlit for most of the year. The Moon's spin axis is tilted only 1.54° from the perpendicular to the ecliptic, which keeps the Sun very low on the horizon. Crater floors never see direct sunlight and become cold traps for water ice, while high ridges such as Malapert Massif are sunlit for most of the year.
NASA is targeting this region for the first crewed Moon landing since Apollo 17. Artemis III, targeted for mid-2027, is now an Earth-orbit docking test, and the first crewed landing in the south pole region is currently planned for Artemis IV in early 2028.
- Shackleton Crater
- 89.9°S / 0.0°E · 21 km wide
- Measured Water Ice
- 5.6% by mass (LCROSS, Cabeus)
- Moon's Axial Tilt
- 1.54°
- First Crewed Landing
- Artemis IV · targeted early 2028
Last reviewed:
Interactive South Pole Map
Slide the Sun's direction around the pole to see how a changing sun angle affects polar lighting. Hover the cyan dots for ice data. Base map: NASA LRO LOLA topography, polar view.
Illustrative model: the shaded wedge and sunlight percentage are schematic. This is not a terrain-shadow simulation, marker positions are approximate, and it should not be used for landing or navigation planning.
Peaks of Eternal Light
Why the South Pole Changes Everything
Apollo landed near the equator because the orbital mechanics were simpler. The south pole is harder to reach but far more valuable: the Moon's tiny axial tilt puts permanent darkness and near-permanent sunlight within a few kilometres of each other.
Axial Tilt: 1.54°
The Moon's spin axis is tilted just 1.54° from the ecliptic perpendicular, compared with Earth's 23.4°. Near the poles, sunlight arrives at grazing angles. That single geometric fact creates permanent shadow in crater floors and near-continuous illumination on some adjacent ridges, sometimes only a few kilometres apart.
Cold Traps Near 40 Kelvin
Some of the coldest shadowed craters, such as Haworth, stay near or below 40 K (−233°C) in Diviner data, colder than Pluto's roughly 44 K average surface. Shackleton's floor is modelled below about 90 K, still cold enough to hold water ice for very long periods. Water and other volatiles may have arrived through comet and asteroid impacts, solar-wind chemistry and other processes, then migrated into cold traps, preserving a record of the early solar system.
Resources in One Neighbourhood
Power-generating ridges and ice-bearing craters lie within a single exploration radius. No site on Earth combines them this way, which is why a self-sustaining outpost is plausible here.
Communication Constraints
Earth hangs low on the horizon and is often blocked by terrain. Ridge-top sites generally see Earth better than crater floors, and crews will likely rely on relay satellites.
Permanently Shadowed Regions: The Physics
A permanently shadowed region (PSR) is an area that receives no direct sunlight under the Moon's present long-term illumination conditions. Many south polar PSRs have likely stayed cold enough to trap volatiles for extremely long periods.
A PSR forms where crater walls permanently block the Sun from the floor. Because the Moon's axis is tilted only 1.54°, the Sun never climbs more than a couple of degrees above the horizon near the pole, and steep ancient craters keep their floors in unbroken darkness, with no seasons to admit light.
At temperatures near 40 K to 90 K, water molecules that land on the floor have too little thermal energy to escape. Ice delivered in the distant past can remain in place, though how much survives, and in what form, varies from crater to crater.
Key finding: The LCROSS impact at Cabeus on October 9, 2009 measured about 5.6% water by mass in the ejecta plume (±2.9%), higher than many pre-mission estimates (Colaprete et al. 2010, Science 330).
LCROSS sent a spent Centaur rocket stage into Cabeus at roughly 2.5 km/s while a trailing spacecraft analysed the plume. It detected water, hydroxyl, carbon dioxide, methane, ammonia, hydrogen sulphide and sulphur dioxide, a volatile mix that changed models of polar chemistry.
Other instruments point the same way, with caveats. Chandrayaan-1's Moon Mineralogy Mapper found spectral signs of surface ice in south polar PSRs (Li et al. 2018, PNAS), and LRO instruments indicate ice in several craters. SELENE/Kaguya imaging found no exposed pure water ice in Shackleton (Haruyama et al. 2008), which suggests ice there may be thin, buried or mixed with regolith. LCROSS directly detected water in material excavated from Cabeus. Elsewhere, orbital data give strong but indirect evidence, and the abundance, depth and physical form remain uncertain.
Seen in LRO Diviner data (Paige et al. 2010; Sefton-Nash et al. 2013). Shackleton's floor is modelled below about 90 K (Haruyama et al. 2008), warmer but still cold enough for long-term ice retention.
Direct measurement in the 2009 ejecta plume, with a ±2.9% uncertainty. Observations of the plume indicated an estimated 155 kg of water.
Many deep south polar craters have likely been dark for extremely long periods, so ice delivered early in lunar history could be preserved there.
Mini-SAR on Chandrayaan-1 found ice-consistent radar signatures in more than 40 craters near the lunar north pole (Spudis et al. 2010). South polar evidence comes mainly from LCROSS, LRO and M³.
High-Value Targets: Shackleton and Malapert
Shackleton and the surrounding PSRs hold the ice. Malapert Massif and similar ridges intercept the sunlight. Together they anchor most plans for a permanent south polar outpost.
Shackleton Crater
Named for the Antarctic explorer Ernest Shackleton, this 21 km crater sits almost exactly at the pole (89.9°S). Its floor has likely been in shadow for extremely long periods, while some sections of its rim are lit for a large fraction of the year (roughly 80–90% in illumination models, depending on location).
That geometry puts a near-continuous power source and a cryogenic reservoir within a few kilometres of each other. Orbital data indicates ice in and around Shackleton, but imaging has not shown exposed pure ice, so the amount and form remain open questions that only surface missions can settle.
Malapert Massif
Malapert Massif is a high ridge system near 86°S. Its elevation lets it catch low-angle sunlight for most of the lunar year, so power systems there would face far shorter outages than at equatorial sites, which endure a roughly 14-day night every month.
The height also gives it good line of sight to Earth, which makes it a natural spot for communications relays. Solar access figures vary by model and by the exact point on the massif, so treat 89% as a peak estimate, not a guarantee.
Ice to Propellant: The ISRU Pipeline
In-situ resource utilization (ISRU) would turn polar water ice into drinking water, breathable oxygen and rocket propellant on site. If material elsewhere matched the 5.6% water concentration estimated at Cabeus, and the water could be recovered efficiently, a tonne would contain about 56 kg of water. Actual recoverable yields at any future site remain unknown.
Excavation
Autonomous rovers dig ice-bearing regolith from shadowed floors, working in darkness at cryogenic temperatures.
Sublimation
The material is heated in a sealed unit so ice turns to vapour and separates from dry soil.
Condensation
Vapour is captured in a cold trap and condensed into liquid water for storage.
Electrolysis
Solar or nuclear power splits water into hydrogen and oxygen.
Liquefaction
Gases are chilled into liquid hydrogen (−253°C) and liquid oxygen (−183°C). NASA's SLS core stage burns this same pair.
Water by mass in Cabeus ejecta (±2.9%). Whether other craters hold comparable amounts is not yet known.
Splitting water produces oxygen and hydrogen in an 8:1 mass ratio (16 g of oxygen per 2 g of hydrogen from 18 g of water). Oxygen supports both life support and oxidiser needs; hydrogen serves as fuel.
Every kilogram of water or propellant made on the Moon is a kilogram that does not need to be launched from Earth.
Artemis: Plans for Landing at the Pole
In February 2026, NASA restructured the Artemis campaign. Artemis III, now targeted for mid-2027, is an Earth-orbit test in which Orion rendezvouses and docks with test versions of commercial landers. The first crewed landing in the south pole region moved to Artemis IV, targeted for early 2028, as confirmed in NASA's October 23, 2026 progress update. Schedules have slipped repeatedly, so treat dates as targets.
Nine Candidate Regions (October 2024)
NASA announced these regions on October 28, 2024, for Artemis III, in no priority order. With the landing now planned for Artemis IV, NASA has not confirmed that the same list or a final site applies.
- 01de Gerlache Rim 2
- 02Haworth
- 03Malapert Massif
- 04Mons Mouton Plateau
- 05Mons Mouton
- 06Nobile Rim 1
- 07Nobile Rim 2
- 08Peak Near Cabeus B
- 09Slater Plain
The earlier list of 13 regions from 2022 was narrowed to these nine.
The south pole is a network of sites, not one obvious best location. The Nobile and Mons Mouton regions are high-latitude terrain where lit ridges sit near shadowed ground, and the list pairs them with Malapert, de Gerlache and Haworth so planners can trade off power, communications, slopes and ice access.
Apollo vs. the South Pole Landing
| Apollo | Artemis IV (planned) | |
|---|---|---|
| Location | Equatorial | South pole region |
| Surface stay | 1–3 days | About a week (planned) |
| Crew | 2 on surface | 4 aboard, 2 on surface |
| Water ice | Not targeted | Primary resource of interest |
| Lunar night | ~14-day exposure | Greatly reduced on ridges |
| Power | Batteries, fuel cells | Solar-favoured sites |
- 2009LCROSS detects water in Cabeus plume
- 2018Chandrayaan-1 M³ data shows surface ice signs in polar PSRs
- 2022Artemis I uncrewed flight
- 2024NASA names nine candidate regions
- 2026Artemis III redesigned (February); Artemis II completes its crewed lunar flyby
- 2027–28Artemis III orbit test targeted mid-2027; Artemis IV landing targeted early 2028
What We Still Don't Know About Lunar Ice
Polar water is real, but no deposit has yet been shown to be a practical resource. Four open questions drive the next missions.
LCROSS sampled one spot in Cabeus. Other craters could hold far more or far less.
Pure ice patches, thin frost and grains mixed into regolith look different from orbit and are mined differently.
Ice may be near the surface in some places and buried beneath dry regolith in others.
Excavating and heating regolith at roughly 40 to 90 K, in darkness, has never been done. Yield, power needs and reliability are unproven.
The Boundary Between Exploration and Permanence
By pairing sunlit ridges such as Malapert Massif with ice-bearing cold traps around Shackleton and Cabeus, the south pole offers something no other known lunar location does: a place where crews could arrive, make water and propellant locally, and depend less on Earth for every consumable.
The open questions are practical. How much ice is there, in what form, and how deep? Surface missions and the Artemis IV landing are meant to answer them.
Lunar South Pole FAQ
Short answers on the topography, ice and landing plans at the lunar south pole.
What is the lunar south pole?
The lunar south pole is the region of the Moon around 90°S. Because the Moon's axis is tilted only 1.54°, the Sun stays near the horizon there, which leaves some deep craters in permanent shadow and some high ridges sunlit for most of the year.
Is there water ice on the Moon's south pole?
Yes. NASA's LCROSS mission directly detected water in the Cabeus crater plume in 2009, at about 5.6% by mass with an uncertainty of 2.9%. Orbital instruments also indicate ice in other permanently shadowed regions, though how much exists and in what form is still being studied.
What are the Peaks of Eternal Light?
Peaks of Eternal Light are high spots near the lunar poles that are sunlit for most of the year, with models suggesting roughly 80% to 90% at the best locations. They are good candidates for solar power because they avoid the roughly 14-day night found at the lunar equator. Despite the name, no known peak is lit continuously forever; the term refers to sites with exceptionally high annual illumination.
What are permanently shadowed regions?
Permanently shadowed regions, or PSRs, are areas, usually the floors of deep polar craters, that never receive direct sunlight. Crater walls block the low Sun, creating cold traps where water ice can persist for billions of years.
How cold is the lunar south pole?
Shackleton Crater's floor is modelled at below about 90 kelvin (about −298°F). Some of the coldest permanently shadowed regions, such as Haworth, stay near or below 40 kelvin (−387°F), colder than the average surface of Pluto at about 44 kelvin.
Is Artemis III landing on the Moon?
No. In February 2026 NASA changed Artemis III into an Earth-orbit test in which the Orion spacecraft docks with commercial landers, targeted for mid-2027. The first crewed landing was moved to Artemis IV.
When will astronauts land at the lunar south pole?
NASA currently plans the first crewed south pole landing for Artemis IV, targeted for early 2028. Dates have moved several times and depend on lander readiness and testing.
Where will the Artemis landing happen?
NASA named nine candidate regions near the south pole in October 2024, including Malapert Massif, de Gerlache Rim 2 and Haworth. The final landing site for the first crewed landing depends on the lander and launch window and has not been confirmed.
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