Source of water ice on dark side of the Moon revealed?

Interplanetary dust regularly showers the Earth and other Solar System bodies.

By Max Sonnenberg, The Space Reporter
Saturday, January 25, 2014

According to a news release from the University of Hawaii -  School of Ocean and Earth Science and Technology, researchers have found that interplanetary dust particles, called IDPs, could transport water and organics to the Earth and other Earth-like planets.

Interplanetary dust, dust that has originated from comets, asteroids and the remains from the birth of the solar system, regularly showers the Earth and other Solar System bodies.
These particles are besieged by solar wind, chiefly hydrogen ions. This ion barrage pushes the atoms out of order in the silicate mineral crystal and leaves behind oxygen that is more ready to react with hydrogen, for instance, to produce water molecules.

“It is a thrilling possibility that this influx of dust has acted as a continuous rainfall of little reaction vessels containing both the water and organics needed for the eventual origin of life on Earth and possibly Mars,”
noted co-author Hope Ishii, new Associate Researcher in the Hawaii Institute of Geophysics and Planetology (HIGP) at UHM SOEST, in a statement.

According to researchers, this mechanism of transporting both water and organics at the same time would also work for exoplanets. In fact, these basic ingredients of dust and hydrogen ions from their parents stars would support the mechanism in nearly any planetary system.

The ramifications of this finding are significant: asteroids and the Moon are regularly being exposed to solar wind irradiation that can produce water. In fact, this mechanism of water development offers an explanation for remotely sensed data of the Moon, which found OH and preliminary water, and likely explains the source of water ice in forever shadowed regions of the Moon

“Perhaps more exciting,” posited Ishii, “interplanetary dust, especially dust from primitive asteroids and comets, has long been known to carry organic carbon species that survive entering the Earth’s atmosphere, and we have now demonstrated that it also carries solar-wind-generated water. So we have shown for the first time that water and organics can be delivered together.”

It has long been known that solar wind forces the chemical composition of Moon dust’s surface layer to alter. In fact, the concept that solar wind irradiation might generate water-species is not new, but whether it actually does generate water has been up for debate. Previously, older analytical techniques were unable to confirm the existence of water because the quantity of water generated is tiny and is localized in extremely thin rims on the surfaces of silicate minerals.
Utilizing an advanced electron microscope, the researchers have now identified water generated by solar-wind irradiation in the thin rims on silicate minerals in IDPs. They were also able to determine that the water develops from the interaction of solar wind hydrogen ions with oxygen in the silicate mineral grains.
Researchers aren’t sure exactly how much water was delivered to Earth in this way.
“In no way do we suggest that it was sufficient to form oceans, for example,” said Ishii. “However, the relevance of our work is not the origin of the Earth’s oceans but that we have shown continuous, co-delivery of water and organics intimately intermixed.”
For their next round of research, the researchers will try to approximate how much water was transported to Earth by IDPs.