Craters near the Moon’s Poles are the only place on our natural satellite where water in the form of ice can exist permanently. Recently, scientists have suggested that we could try looking for microorganisms there as well.
Microbial life at the Moon’s poles
Can microbes survive in permanently shadowed regions of the Moon? A recent study presented at the 56th Lunar and Planetary Science Conference (LPSC 2025) hopes to answer this question, in which a team of researchers from the United States and Canada has investigated the probability of long-term survival of microbes in the PSRs, craters located at the Moon’s poles.
This study may help researchers better understand the unlikely places where they could find life as we know it in the Solar System.
“A few years ago in 2019, I participated in a study looking at the potential for the moon to preserve microbial contamination on spacecraft, led by University of Florida researcher Dr. Andrew Schuerger,” says Dr. John Moores. “At the time, we did not consider the PSRs because of the complexity of modeling the ultraviolet radiation environment here.”
“However, in the years since then, my former student Dr. Jacob Kloos of the University of Maryland has developed a sophisticated lighting model. Furthermore, with the renewed interest in PSR exploration, we decided to take another look at these regions and realized we had all the pieces of the puzzle we needed to understand their ability to preserve terrestrial microbial contamination.”
Shackleton and Faustini craters
For the study, the scientists built a series of models to see if reduced ultraviolet (UV) radiation and increased temperature within the PSRs could contribute to the possible survival of microorganisms in two PSR craters, Shackleton and Faustina. The researchers chose these two craters based on preliminary studies that involved modeling light hitting the craters, and both craters are also current landing sites for future Artemis missions.
As noted, lunar PSRs are deprived of sunlight due to the Moon’s axial tilt, which is approximately 1.5 degrees with respect to the Sun. For comparison, the Earth’s axial tilt is about 23.5 degrees in relation to the Sun, causing the change in the seasons we observe as the Earth orbits the Sun.
As a result of this slight axial tilt, some lunar PSR craters, such as Shackleton and Faustini, have not received sunlight for potentially billions of years. Since the Moon has no atmosphere and is exposed to the cosmic vacuum, this creates very cold pockets that researchers believe can store microbes for long periods of time.
Possibility of introducing microbes from space missions
As noted, the lunar PSRs are target landing sites for NASA’s future Artemis program, especially for Shackleton, due to the potential reserves of water ice contained in the craters of the PSRs, which future astronauts could use for water, fuel, and oxygen. However, all space missions risk bringing undesirable microbes to their destination, thus potentially and unnecessarily contaminating pristine, microbe-deprived terrain. This can lead to the collection of incorrect data and inaccurate results after analyzing the data, which can lead to inaccurate conclusions about the search for life beyond Earth.
This is especially true for human missions to the Moon, as humans are naturally filthy creatures, carrying a myriad of microbes that can travel with them to the Moon. Thus, any microbes that may exist in the PSRs could be exposed to human microbes, which could lead to their death.
To deal with this, NASA’s planetary protection division is tasked with keeping an eye on making sure that the initial spacecraft are sterilized and cleaned of microbes before launch, as well as making sure that returning spacecraft don’t carry unwanted microbes from outside Earth. So, how might the results of this study affect human exploration on the Moon?
Dr. Moores said: “While we can clean robotic spacecraft fairly well, it is more difficult to decontaminate equipment and spacesuits used in human exploration. As a result, humans walking into the PSRs will likely carry considerably more contamination with them, some of which will be left behind and be preserved far longer than anywhere else on the moon.”
Analysis of ice samples from PSR craters
In addition, the study notes that “care should be taken in their exploration,” but does this apply to planetary defense?
Dr. Moores said: “It is less a question of planetary protection than of preserving the PSRs in as close to a pristine state as possible for future scientific analyses. The question then is to what extent does this contamination matter? This will depend on the scientific work being done within the PSRs. One possible goal is to retrieve samples of water ice from within the PSRs to better understand their origins and how they came to be found here. Part of that analysis could include looking at organic molecules present in the ice that are known to occur in other places, for instance within comets. That analysis will be easier if contamination from terrestrial sources is minimized.”
How did microorganisms get to the Moon?
If the lunar PSRs have microbes, it raises the question of how they got there. Given the Moon’s heavily cratered surface, they could have gotten there as a result of a collision with a body from another part of the Solar System or from outside it. However, humans have also sent a number of spacecraft that collided with the lunar surface, including the Ranger spacecraft, which happened before the Apollo missions, but these spacecraft crashed near the moon’s equator and away from the poles.
In 2009, NASA’s Lunar Crater Observation and Sensing Satellite (LCROSS) deliberately crashed its Centaur’s upper stage into Cabeus Crater, a PSR crater located about 100 kilometers (62 miles) from the Moon’s South Pole, in order to measure the amount of water formed in the ejection plume. But how could microbes get into the lunar PSRs and what can this teach us about the formation and evolution of the Moon?
“The chance that there is already terrestrial microbial contamination in the PSRs is low but not zero,” Dr. Moores said. “Several spacecraft have impacted within or near the PSRs. Though they all did so at high speed, past research by others has suggested that small numbers of spores can survive simulated impacts into regolith-like materials. If any microbes survived those impacts, they would have been widely dispersed.”
According to phys.org
