space.comWater on Earth and Moon May Have Common Origin
by Katia Moskvitch, Space.com Contributor | April 01, 2014 07:22am ET
The traces of water in ancient moon rocks may share a common source with water on Earth, scientists say.
If confirmed, the potential moon-Earth water link would add more support to thetheorythat the moon's material came from the proto-Earth, and that water in this material survived the aftermath of the giant impact thought to have formed Earth's large natural satellite, researchers explained earlier this month at the Lunar and Planetary Science Conference in Houston.
Until now, most studies of moon rocks have focused on assessing the water contents of the younger basalts and volcanic glasses, which are partially meltedsubstancesofthe lunar mantle. Researchers have access to the lunar rocks thanks to NASA's six Apollo moon landing missions and the three Russian robotic sample-return missions. The Apollo missions returned to Earth with a huge load of 842 pounds (382 kilograms) of lunar rock and soil samples. [Photos: The Search for Moon Water]
Water on the moon
The recent research instead concentrated on the possible sources of water in rocks from the lunar highlands. These samples make up some of the oldest moon rocks available for study and are thought to have directly formed from the moon magma ocean. Jessica Barnes, a PhD student in planetary and space sciences at the Open University in the United Kingdom, led the research.
The rocks are of volcanic origin and contain apatite, a calcium phosphate mineral that has the same volatile elements as those found in many igneous rocks on Earth. Volatile elements, which include hydrogen, chlorine and sulfur, are the elements that most easily escape from magma. [10 Strange Moon Facts]
The presence of these volatile elements in magmatic rocks tellsscientists about the composition of the crust, mantle and atmosphere of a planet or moon. And because apatite is hydrogen rich, it suggests that water was present on the moon in the past.
Researchers have found apatite in various types of lunar rocks.And whileprevious studies have analyzed this mineral in younger lunar rocks and pyroclastic glasses, these samples did not provide ideal material for understanding the original volatile composition of the moon soon after its formation, said Barnes' co-author Mahesh Anand, also of the Open University. "Because of their relatively younger age, [the rocks] could have been derived from portions of the lunar interior that had received additional water after the moon's formation," he said.
* * *Read more ...