Moon's Craters Found To be Less Icy Than Expected

New research on lunar craters indicates that the blemishes and divots on the moon's surface are too young to hold onto ancient reserves of water ice over the long term. According to physicist Norbert Schörghofer of the Planetary Science Institute in the US and astrophysicist Raluca Rufu of the Southwest Research Institute in the US, the majority of the craters that include lasting pockets of shadow — a key focus for future Moon exploration — are younger than 2.2 billion years old.

According to Schörghofer, these results significantly alter estimations of the amount of water ice on the Moon as well as the prediction of where we are likely to discover it. It is no longer expected to find ancient water ice reservoirs on Moon.

Now, we are aware that the Moon has water. There is no serious dispute about that. Researchers are interested in finding out how much water is present up there and where it is hidden. In recent years, investigators have focused more on permanently shadowed areas, or PSRs, such as deep craters. It was once believed that ice might survive in PSRs, which have temperatures that hardly rise beyond -163 degrees Celsius (-260 degrees Fahrenheit), where sunlight may be warm and cause the water to evaporate over billions of years. These craters are thought to be capable of harbouring water ice areas that are several metres thick.

These higher estimates, nevertheless, call for a buildup spanning billions of years. And it appears that the PSRs have not received sufficient protection from the Sun for that accumulation. The revelation follows a study released a year ago that aimed to explain a disparity between the Moon's age (4.5 billion years) and its speed of travel away from Earth (3.8 centimetres, or 1.5 inches, per year). The two figures cannot be compared.

This team discovered that fluctuations in the lunar recession rate would have been caused by resonance between Earth and the Moon. The model took into consideration variations in the lunar axis' orientation. Scientists believe that the inner Solar System was heavily pummelling with comets and asteroids early in the Solar System's history, before roughly 3.8 billion years ago. In this late heavy bombardment, Mercury, Venus, Earth, and Mars were all severely damaged. The Moon would have been there as well, of course.

This would have allowed water to escape from the Moon's interior while it was still hot and pliable from volcanism. The PSRs may have captured a large amount of it if they had been present at that time. However, the PSRs are far more recent based on the most recent theories of the reorientation of the Moon's spin-axis and the evolution of the Earth-Moon distance. According to the researchers, this implies that any ice present must also be more recent.