Lunar Secrets: Unraveling the Ancient Water Mysteries from Earth and Comet Origins

Contrary to all indications, the moon is a realm with water. Water molecules are dispersed throughout the lunar soil, scattered across the surface of the moon. The source of this water has perplexed scientists for years, but a recent study published in PNAS has investigated the sources of the moon’s water, positing that it may have resulted from an intricate array of origins.

“This marks a significant advancement in understanding the origins of lunar water,” remarked Maxwell Thiemens, a co-author of the study and a researcher at Vrije Universiteit Brussel (VUB) in a press statement. “Our data indicate that the moon acquired water dating back to Earth’s formation, followed by later contributions from comets, leading to the water reservoirs we observe today.”

Water Molecules on the Moon

Astronomers previously believed that the moon was a lifeless domain devoid of water. However, recent lunar missions and analyses reveal that water molecules are distributed across the moon’s surface, both frozen and non-frozen, integrated within the soil, concealed inside volcanic glass and mineral fragments, and concentrated in tiny granules.

In 2008, for example, scientists discovered evidence of water in soil samples collected during the Apollo missions. By 2018, they confirmed that ice exists in the moon’s shadowed regions, including its craters, where temperatures drop to approximately minus 410 degrees Fahrenheit. In 2020, it was verified that ice is also present in the sunlit areas of the moon. Although the quantity is modest — according to NASA’s Stratospheric Observatory for Infrared Astronomy (SOFIA), the lunar surface is 100 times drier than the Sahara Desert — it is significantly wetter than initially believed.

But what is the origin of this water? One hypothesis proposes that comets, the cosmic icy bodies orbiting the sun, have impacted the moon, delivering their water to its surface. Another hypothesis suggests that solar winds, which include flows of hydrogen from the sun, have reacted with oxygen on the lunar surface, resulting in water formation.

To evaluate these hypotheses, the researchers examined the water from various soil samples gathered during the Apollo missions. By analyzing the isotopes in these samples, they inferred that the moon’s water likely first originated from substances similar to those found on Earth and secondly from materials resembling those in comets.

---

Read More: Scientists Continue to Explore These Moon Mysteries

---

Isotopic Signature Sourcing

By evaluating the isotopic profiles of the samples through incremental heating, the study authors identified oxygen isotopes similar to those found in enstatite chondrites, meteorites believed to be comprised of the same materials that formed Earth and supplied it with water. By heating the samples to 122 degrees, 302 degrees, and 1,832 degrees Fahrenheit, they also found oxygen isotopes akin to those found in comets.

The findings from this study indicate that the water on the moon may have originated from a mix of sources: firstly, from the substances that may have constituted Earth, and secondly, from the materials found in comets.

Additionally, besides these hints that the moon’s water was derived from a combination of Earth-like and comet-like sources, the analysis unearthed isotopic signatures that question the contributions of solar wind. Therefore, these isotopic indicators cast doubt on the idea that the moon’s water was generated on the lunar surface through interactions with solar wind.

The authors of the study assert that their findings provide significant insights into the moon’s formation and clarify the relationship between the saturated surface of Earth and the dry surface of its satellite. Furthermore, they believe that the results could influence future lunar missions and guide strategies for establishing a permanent presence on the moon.

“The data not only deepen our understanding of the moon’s history but also set the stage for future space exploration and resource utilization,” stated Thiemens in a press release. “These results should transform our perspective on the value of water as a resource for long-term habitation on the moon.”

---

Read More: There’s No Wind or Rain on the Moon, Yet Extreme Temperatures Persist

---

Sources of the Article:

Our authors at Discovermagazine.com utilize peer-reviewed articles and credible sources for crafting our content, and our editorial team ensures adherence to scientific accuracy and editorial standards. Below is a review of the sources referenced in this article:

• NASA. MoonWater and Ices

• PNAS. Triple Oxygen Isotopes of Lunar Water Reveal Native and Cometary Ancestry

• VUB Press. VUB Study Exposes Origins of Lunar Water and Its Connection to Early Earth History

• Science. Earth’s Water May Have Been Acquired From Materials Comparable to Enstatite Chondrite Meteorites

---

Sam Walters is a reporter focusing on archaeology, paleontology, ecology, and evolution for Discover, alongside various other subjects. Prior to becoming part of the Discover team as an assistant editor in 2022, Sam pursued journalism studies at Northwestern University in Evanston, Illinois.