Dr. Matt Siegler from the Planetary Science Institute in Tucson, Arizona, led a group of researchers that studied pictures and measurements taken of the moon by two spaceships. The team studied a group of spots on the satellite which they thought were ice deposits.
In the past, scientists identified ice beneath the moon’s poles, but these deposits are a little distant from them which led the scientists to think that maybe the satellite had shifted its axis in the past. They calculated the axis changed on 5.5 degrees and they theorize that the reason was an internal distribution of mass.
Using models, the scientists found a possible point where the mass distribution changed. On the near side of the moon, there is a volcanic zone which was active millions of years ago. The volcanoes might have heated the moon’s surface to such an extreme that an almost unnoticeable shift in its axis took place. The change happened around three billion years ago.
Why is this important?
These ancient ice deposits are the former poles of the moon. On the other hand, Earth has changed itself several times and there is nothing in it that is as old as the ice on the moon. Which makes these ice spots time capsules. Experts say that by studying them, we could understand how water originated on our planet. They have called it “The Moon’s tilt for gold”
“The ice at the poles of the moon records the interior evolution of the moon, which seems crazy — that is the last place you would think to look,” said Siegler. “Also, that means the ice has to be really old, and therefore may record the ancient delivery of ice to the inner solar system,” he told Space.com via email.
The Lunar Prospector which orbited the moon from January 1998 until July 1999 and the Lunar Reconnaissance Orbiter, which is still orbiting the moon, provided the data for the study. The paper was published online in Nature on November 26, 2015.