So, let’s explore what we know and what we don’t about lunar water, and how Artemis II is setting the stage for the missions that will eventually turn this potential resource into an operational one.

Forms of Lunar Water

Lunar water exists in two primary forms, and the distinction between them is central to any discussion of resource utilization.

Surface-Bound Water (Hydroxyl and Molecular H₂O)

A portion of lunar water is present in the Moon’s surface material, known as regolith, which is a layer of loose dust and fragmented rock.

In 2020, observations from the NASA-operated SOFIA infrared telescope confirmed the presence of molecular water (H₂O) at low latitudes and in sunlit regions of the Moon. The formation process is driven by solar wind implantation: hydrogen ions continuously interact with oxygen-bearing minerals in the regolith, producing hydroxyl (OH) and, under certain conditions, molecular water (H₂O). Some of this water may also be trapped inside tiny glass-like structures formed by micrometeorite impacts.

However, concentrations are low, about 100 to 400 parts per million (ppm). This is equivalent to only a few drops of water per cubic meter of soil. From an engineering standpoint, this is not a viable primary resource and is not considered a primary target for large-scale in situ resource utilization. Extracting meaningful quantities would require heating and processing large volumes of soil, resulting in high energy costs.

Water Ice in Permanently Shadowed Regions (PSRs)

A more promising form of water exists near the lunar poles, inside craters that receive no direct sunlight. These are known as permanently shadowed regions (PSRs). Temperatures in these regions remain below approximately −160°C, with some areas significantly colder, allowing volatile compounds, including water, to accumulate and remain stable over geological timescales.

Measurements from the Lunar Reconnaissance Orbiter detected elevated hydrogen concentrations in PSRs using neutron spectroscopy. While hydrogen detection is not direct proof of water, hydrogen abundance measured in this way is widely interpreted as a strong proxy in the lunar environment due to the absence of alternative hydrogen-bearing reservoirs.

More direct evidence came from the LCROSS mission. In this experiment, a spacecraft was deliberately crashed into a shadowed crater. The material expelled from the surface, known as ejecta, was analyzed, and instruments detected water vapor and ice particles in the plume, providing direct confirmation that water is present in these regions.

Estimates suggest that PSRs may contain on the order of tens to hundreds of millions of tons of water ice.

Constraints on Resource Utilization

The limiting factor in lunar water utilization is characterization. Current estimates of total water content are derived from indirect measurements and carry substantial uncertainty. More importantly, parameters that determine extraction feasibility remain poorly constrained. These include deposit depth, lateral continuity, grain size distribution, and the degree of mixing with regolith.

From an engineering perspective, this information is critical since the difficulty of accessing and processing this material will determine whether it can be used efficiently.

At present, no in situ extraction has been demonstrated at an operational scale. As a result, the economic and logistical viability of lunar water as a resource remains a theoretical frontier.

Role of Water in Exploration Architectures

In space exploration architectures, water is a high-value resource due to its multifunctionality. Through electrolysis, it can be separated into hydrogen and oxygen. Oxygen sustains breathable environments, while hydrogen and oxygen together provide an efficient rocket propellant.

Water also serves as an effective radiation shielding material, particularly against solar particle events.

These properties make water central to in-situ resource utilization (ISRU) strategies. The objective is to reduce dependence on Earth-supplied mass, which carries significant energy and cost penalties. Even partial substitution with locally sourced water can significantly alter mission architecture, reducing launch mass and enabling more flexible, sustainable, and long-term operations.

Why Artemis II Matters in Exploration Architecture

Utilizing water on the Moon is a system-level problem. It depends on sustained transport between Earth and lunar orbit, stable habitation in extreme environments, and continuous operational capability at the lunar surface.

Artemis II is testing the foundations of that system. The mission is designed to validate crewed deep-space operations, including life support, navigation, radiation protection, long-duration system performance, and communications systems aboard the Orion spacecraft. By proving these systems function reliably in an integrated flight environment, Artemis II will provide the critical validation step toward sustained lunar operations and the conditions required for resource utilization.

References & Resources