By Matalin Hansen  
May 7, 2025

Lunar gardening, or impact gardening, is the process of the mixing and overturning of the Moon’s regolith through meteorite impacts. Throughout the billions of years the Moon has been around, these impacts have turned and churned the soil on the topmost layer of the Moon. While not like a Lunar “Mark Watney” with his field of Martian potatoes, this process has an interesting and fascinating record of the Moon’s history while also presenting challenges for any future exploration. 

The Tools - How Meteoroids Do It

The primary tools of this lunar gardening are the minute impacts made by meteoroids, which can range in size from micrometeorites to larger impactors. These impacts eject debris up and out, redistributing the regolith and mixing it with surrounding regolith. Over massive geological timescales, this method can mix regolith to depts of several meters deep [1]. With each impact, underlying bedrock fractures and breaks, blasting material into the exosphere and depositing ejecta across vast lunar distances; because of this, there is a very heterogeneous regolith layer composed of fine dust, rock fragments, and some glass [2]. 

Recently, NASA’s Lunar Atmosphere and Dust Environment Explorer (LADEE) and the Lunar Dust Experiment (LDEX) were able to directly measure the rate of this process: approximately 40 micometers of regolith per million years are redistributed across the surface of the moon due to this micrometeoroid bombardment [3]. This means that, like a good farmer, the uppermost layer of the Moon is perpetually renewed and changed–an important piece of knowledge for any future missions to the moon.

The When - How Long It Takes

Originally, there were estimates that suggested that the topmost centimeter of regolith gets overturned every 10 million years, but of the previously mentioned LDEX mission, the provided data suggests otherwise, approximating 80,000 years [3]. This new rate is widely faster than the former, and it is due to the lack of atmosphere on the Moon; there is nothing impeding the dirt from shifting or the micrometeorites from reaching the surface, allowing any and all impacts to disrupt and change the regolith. This cumulative effect, over the billions of years the Moon has been estimated to have been around, has produced a regolith layer that average 4-5 meters in the flat, plains areas, and up to 10-15 meters thick in older highland regions [1], much like the South Pole, the selected location for the future Lunar Base. 

Recording the Moon’s History

Unlike layers found on the walls of the Grand Canyon, the lunar geological record is continually disturbed. These regolith layers are not useful to read directly about the precise development of the Moon. However, the layers that the impacts have created contain important information regarding the history of the Moon. The layers of regolith contain a stratified, historical record, where every impact contributes to knowledge on the growth of our Moon.

Each impact layer contains important information about the bombardment history of the moon, including the “Late Heavy Bombardment” period that left visible scars in the regolith approximately 3.8 billion years ago [1]. But, as mentioned, the mixing by the meteoroids complicates the interpretations of the layers that can cause some difficulty with interpreting what each layer says. Impact eject can cover and bury other impacts, where they disappear over time. Materials are mixed for separate regions, becoming homogeneous, as it was found that meteorite impact redistributes material to other regions, blurring the material distribution between deposits near the equator and those near the poles [1]. Despite the difficulties with interpretation, isotopic analysis of Apollos samples have helped scientists understand and differentiate these layers, which shed light on the volcanic history of the Moon [4].

Challenges this Poses to Future Exploration

One major issue is that while there were billions of years of meteorite impacts in the past, it absolutely continues to happen and can cause major issues for any long-term above-surface building that could be struck and hit by these flying rocks. The more pressing issue with the impact of lunar gardening on any type of lunar building. The surface will not be very stable, threatening infrastructure and foundations, and could cause issues with structural integrity. Another issue is with resource extraction; under so many layers of loose regolith, harvesting the deeper layers of water ice can become incredibly complicated, dangerous, and costly [1]. These challenges aren’t uncommon on Earth, but it’s difficult to fully understand the limitations and implications of such projects on the Moon. 

Fruits of the Labors - How Understanding Lunar Gardening Can Help Science

It is highly critical to understanding lunar gardening to the betterment of science and expiration. Primarily, in situ analysis and resource utilization would greatly benefit from a better understanding of the Moon’s history of impact ejecta and material mixing [5], so scientists would be able to better understand where to look and how to navigate through the layers of regolith to obtain the material they are looking for. Another important area for science is the simulation studies; understanding how impact formed the moon and changed lunar regolith, laboratories can replicate the impacts [1], which can help us gain better understanding of the impact history of other planets.

Conclusion

Although lunar gardening erases surface features of millions of years, each impact contributes to an extensive geological archive of a billion of years that share the story of our Moon. There are developmental challenges that arise with ever-changing records like these but with modern science, any understanding gained from this study can help shed light on the formation of other planetary bodies, how to best obtain lunar material from the regolith, and continue our scientific endeavors on the lunar surface.