The Moon has been called a “mine of natural resources” because its very nature, in the words of an early Spanish explorer, is “a spongy rock, with a tendency to absorb anything that falls on it.” Evidence indicates that the Moon was formed from material relatively free of any elements except water. Water (sometimes referred to as liquid water) is found in different forms on Earth – ice, ocean water, and hydrogen. Water (or, more accurately, ice) also occurs in gases which, in turn, give off water vapor – the component most useful for life on Earth.


The concentration of water on the Moon is unknown, although it is calculated by the weight of the moon, and taken with the solar constant, approximately half a percent. The Moon shares its surface with a number of celestial bodies, with many being highly reflective (including the planet Venus, and many stars) or having a nearly complete opposite reflectivity from the Sun. The most well-known natural source of moonlit water is the polar ice fields of Jupiter and Saturn. Ice clouds are also occasionally spotted flying across the moon from the Sun, and there are reports of icy objects being discovered from orbit.

While ice clouds, ice belts, and polar regions certainly provide some mystery, they are not the only things that scientists are discovering from space. Since 1960 NASA has been actively using satellites and other space exploration tools to study the interactions between various space dust particles, gas, and other “asteroids” in space. These space dust clouds can affect the orbits and movement of space dust and even cause holes in the moon’s gravitational field. Although scientists have been aware of these clouds for decades, they continue to study their interaction, and in particular, the impact that Cassini’s Saturn probe had on one of these cloud regions.


This study used data gathered by the NASA’s Lunar Reconnaissance Orbiter (Lunar Reconnaissance Orbiter) and was led by Lauren Kurtz. The team utilized data from the probe’s instruments, and compared this information to pictures posted on the Internet by NASA. By comparing the results of their calculations with pictures posted online, the researchers were able to determine that the ice cloud was produced by a solid body, and was subsequently identified as being a saltshaker.


The study also indicates that the ice cloud formed above and around a small moon-sized rocky body, which NASA calls “the largest moonbound asteroid ever discovered.” This collision resulted in about two and a half times more crate ice than existed around the asteroid before the collision. The crate ice is believed to be made up of silicate and glycine. The research was led by Dr. David R. Williams, an Earth and Space Science Institute researcher. Other scientists involved in the study include: Lauren M. Kurtz from NASA’s Jet Propulsion Laboratory, John J. Goodman from the University of Arizona, and Professor Peter B. Schmere from the Institute for Space and Planetary Exploration, University of London.


This discovery is the first lunar transit discovery to directly detect water ice crystals, and it provides us with a tool to test theories of gravitational instability and to study the Moon in greater detail than ever before. Although the Moon has remained relatively constant throughout its history, it does experience minor wobble which significantly impacts the times that different regions of the Moon are permanently or periodically shadowed. The distribution of permanently darked areas on the Moon will change as the Moon approaches and deviates from its orbit, and these dark areas could have important implications for space exploration. NASA says that the Clementine probe will be on the surface of one of these permanently shadowed areas when it leaves the Earth, and the probe will provide the test needed to determine whether the gravitational instability has caused the observed irregularities in the distribution of the Moon’s gravity.