NASA’s Artemis program plans to return humans to the Moon for the first time in over 50 years. The Artemis III mission, currently targeted for 2026, will land the first woman and next man near the lunar south pole. In preparation, NASA established the Artemis III Science Definition Team to define compelling and executable science objectives for this historic mission.
The team’s report, released in December 2020, lays out a comprehensive plan encompassing seven key science objectives:
- Understanding planetary processes
- Understanding the character and origin of lunar polar volatiles
- Interpreting the impact history of the Earth-Moon system
- Revealing the record of the ancient sun and our astronomical environment
- Observing the universe and the local space environment from a unique location
- Conducting experimental science in the lunar environment
- Investigating and mitigating exploration risks
By addressing these objectives, Artemis III aims to make significant advances in lunar and planetary science, paving the way for a sustainable human presence on the Moon.
Understanding Planetary Processes
The Moon preserves a record of fundamental planetary processes. Artemis III will allow astronauts to make detailed observations of the lunar surface and collect carefully documented samples. Key goals include sampling a diverse range of rock types, determining the ages of different landforms and geologic units, and characterizing the composition and physical properties of the regolith (soil).
The south polar region may provide access to some of the Moon’s most ancient terrains. The South Pole-Aitken basin, the largest and oldest impact structure on the Moon, may have excavated material from the upper mantle. Collecting samples from this basin could yield insights into the Moon’s primordial differentiation and evolution. Other high-priority targets include the Schrödinger basin, which may host samples of the lunar farside crust, and small, young craters that could provide absolute age calibration points for the lunar cratering record.
In addition to sampling surface rocks and soils, the astronauts will also deploy geophysical instrument packages. These could include passive seismic and heat flow experiments to probe the Moon’s interior structure and thermal evolution. Magnetometers and electromagnetic sounding instruments could shed light on the presence of a metallic core and the Moon’s magnetic history. Laser retroreflectors would enable precise measurements of the Earth-Moon distance, constraining models of the Moon’s formation and orbital evolution.
Understanding the Character and Origin of Lunar Polar Volatiles
The lunar poles host permanently shadowed regions (PSRs) that are among the coldest places in the solar system. Remote sensing data indicate these regions contain enhanced concentrations of water ice and other volatiles, which could provide a valuable resource for future exploration. However, the distribution, abundance, and physical state of these volatiles remains poorly constrained.
Artemis III will allow direct sampling and in-situ analysis of polar volatiles. The highest priority is obtaining samples from a PSR that can be returned to Earth for detailed characterization. These samples could yield crucial insights into the origins of the volatiles (e.g. solar wind implantation, delivery by comets or asteroids) and their evolution over geologic time (e.g. migration, loss, and redeposition).
The astronauts will also deploy volatile-monitoring stations to measure the abundance and variability of volatiles in the near-surface regolith. These measurements will help determine the feasibility of extracting water and other resources. Thermal and geotechnical properties of PSR regolith will also be investigated to inform future landing site selection and construction of lunar habitats.
Interpreting the Impact History of the Earth-Moon System
The Moon’s heavily cratered surface records a history of bombardment dating back to the formation of the Earth-Moon system. Obtaining an absolute chronology of this impact record is a key goal of lunar science, as it would provide a reference for interpreting the early impact histories of Earth, Mars, and other terrestrial planets.
Artemis III will target previously unsampled young craters (Copernican age) to help anchor the recent end of the lunar impact flux. Radiometric dating of samples from these craters will help calibrate the crater size-frequency distributions used to estimate the ages of planetary surfaces across the solar system.
Sampling ejecta from larger craters and basins can also provide insights into the impact history. Many of the Moon’s largest impact basins formed during a period of intense bombardment around 3.9 billion years ago, an event known as the Late Heavy Bombardment (LHB). The existence and timing of the LHB has major implications for the habitability of the early Earth and the emergence of life. Artemis III will seek to obtain impact melt samples that can be radiometrically dated to constrain the timing and duration of the LHB.
Another goal is to characterize the physical and chemical properties of impact ejecta to better understand crater formation and modification processes. The south polar region contains a diverse range of impact structures, from small simple craters to large complex and multi-ring basins. Comparing the morphologies and ejecta characteristics of these craters can yield insights into the mechanics of crater formation and the role of target properties.
Revealing the Record of the Ancient Sun and Our Astronomical Environment
The Moon’s ancient regolith may contain a record of solar and galactic processes extending back billions of years. Solar wind particles and cosmic rays interacting with the lunar surface can produce measurable changes in the regolith’s isotopic and elemental composition. Sampling and analyzing ancient regolith deposits could thus provide a window into the history of the Sun and our local galactic environment.
A key objective for Artemis III is collecting samples of paleoregolith, regolith that was buried and preserved beneath lava flows or impact ejecta billions of years ago. The south polar region contains numerous exposures of buried regolith layers in the walls of craters and scarps. The astronauts will target these exposures to obtain samples with a range of ages, ideally spanning much of solar system history.
Another goal is to emplace solar wind composition collectors and cosmic ray detectors for retrieval by future missions. These experiments will measure the present-day fluxes of solar and galactic particles, providing a baseline for interpreting the paleoregolith record. The south pole’s unique lighting conditions, with some areas in near-permanent shadow while nearby regions remain illuminated for extended periods, provide an ideal location for these long-duration experiments.
Observing the Universe and the Local Space Environment from a Unique Location
The lunar surface provides a stable platform for astronomical observations, free from the interference of Earth’s atmosphere and ionosphere. Artemis III will conduct a series of astrophysical and heliophysical experiments, leveraging the unique observing conditions at the south pole.
One objective is to deploy a small radio telescope to conduct low-frequency radio astronomy observations. The far side of the Moon is shielded from terrestrial radio interference, enabling observations at frequencies that cannot be accessed from Earth. A radio telescope deployed in a permanently shadowed crater near the south pole could remain operational for extended periods, powered by batteries or a small nuclear reactor.
Another goal is to install a suite of instruments to monitor the local space environment, including the solar wind, magnetotail, and ionized rarefied exosphere. These measurements will help characterize the radiation and plasma environment at the lunar surface, which can vary significantly depending on location and time. Understanding this environment is critical for designing systems to protect astronauts and equipment during extended lunar stays.
Artemis III will also deploy retroreflectors and laser ranging equipment as part of the Next Generation Lunar Laser Ranging (NGLR) experiment. By bouncing laser pulses off the retroreflectors, scientists can precisely measure the Earth-Moon distance, yielding insights into the Moon’s orbit, interior structure, and gravitational field. The NGLR could enable tests of general relativity and other theories of gravity with unprecedented precision.
Conducting Experimental Science in the Lunar Environment
The Moon’s low gravity, hard vacuum, and extreme temperature variations provide a unique environment for conducting experimental science. Artemis III will perform a variety of investigations to study the behavior of materials and biological systems under these conditions.
One area of focus is in-situ resource utilization (ISRU), the use of local materials for construction, manufacturing, and life support. The astronauts will test techniques for extracting oxygen and water from the lunar regolith, which could reduce the need for supplies from Earth. They will also experiment with using regolith as a raw material for 3D printing, which could enable on-demand fabrication of spare parts and structures.
Another goal is to study the effects of the lunar environment on biological systems. The astronauts will deploy small payloads containing microorganisms, plants, and small animals to investigate how they respond to reduced gravity and radiation exposure. These studies could provide insights into the challenges of sustaining life beyond Earth and the potential for lunar agriculture.
Artemis III will also conduct fundamental physics experiments that exploit the Moon’s unique conditions. For example, the astronauts may deploy torsion balances to test theories of gravity with high precision, or set up experiments to study quantum entanglement and other exotic phenomena over long distances. The Moon’s seismic quietness and stable environment could enable measurements that are difficult or impossible to perform on Earth.
Investigating and Mitigating Exploration Risks
Artemis III will serve as a critical test of the systems and operations needed to support a sustained human presence on the Moon. In addition to the scientific investigations, the astronauts will conduct a variety of experiments and technology demonstrations to validate the capabilities needed for future missions.
One key objective is to assess the performance of the Extravehicular Mobility Units (EMUs), the spacesuits that will enable astronauts to explore the lunar surface. The south pole’s challenging terrain and lighting conditions will provide a rigorous test of the EMUs’ mobility, visibility, and thermal control systems. The astronauts will also evaluate tools and techniques for navigating, sampling, and manipulating objects in the lunar environment.
Another goal is to study the effects of lunar dust on human health and equipment. Lunar regolith is highly abrasive and can cause damage to spacesuits, seals, and other hardware. Inhaling lunar dust may also pose risks to astronaut health. Artemis III will test technologies for mitigating dust, such as electrostatic filters and dust-repellent coatings. The astronauts will also assess decontamination procedures and study the behavior of lunar dust in habitats and airlocks.
Artemis III will also demonstrate technologies for power generation, energy storage, and thermal management. The south pole’s extended periods of sunlight provide an opportunity to test high-efficiency solar arrays and regenerative fuel cells. The astronauts will also deploy experiments to study the performance of batteries and other energy storage systems in the lunar environment.
Finally, Artemis III will validate the capabilities needed for long-duration lunar habitation. The astronauts will test life support systems, including water recycling and waste management technologies. They will also assess the habitability of lunar modules and evaluate protocols for maintaining crew health and performance during extended missions.
Summary
The Artemis III Science Definition Team report presents a comprehensive plan for conducting high-priority science investigations during NASA’s first crewed lunar landing in over 50 years. By addressing key questions in planetary science, heliophysics, and astrobiology, Artemis III will make significant contributions to our understanding of the Moon and the solar system.
The mission’s science objectives are ambitious but achievable, leveraging the unique capabilities of human explorers to collect samples, deploy instruments, and conduct experiments. The south polar region offers a wealth of opportunities for scientific discovery, from ancient impact basins to permanently shadowed craters hosting volatile deposits.
Artemis III will also serve as a critical stepping stone toward a sustained human presence on the Moon. By testing technologies and operations for lunar exploration and habitation, the mission will validate the systems needed for future Artemis missions and long-term lunar surface operations.
As NASA prepares to return humans to the Moon, the Artemis III Science Definition Team report provides a roadmap for maximizing the scientific return of this historic mission. By delivering on the report’s objectives, Artemis III will not only advance our understanding of the Moon and the solar system but also inspire a new generation of scientists and explorers to push the boundaries of human knowledge and presence in space.
