Researchers have discovered that interplanetary dust particles (IDPs) could deliver water and organics to the Earth and other terrestrial planets.

 

Interplanetary dust, dust that has come from comets, asteroids, and leftover debris from the birth of the solar system, continually rains down on the Earth and other Solar System bodies. These particles are bombarded by solar wind, predominately hydrogen ions. This ion bombardment knocks the atoms out of order in the silicate mineral crystal and leaves behind oxygen that is more available to react with hydrogen, for example, to create water molecules.

 

Implications of this work are potentially huge: Airless bodies in space such as asteroids and the Moon, with ubiquitous silicate minerals, are constantly being exposed to solar wind irradiation that can generate water. In fact, this mechanism of water formation would help explain remotely sensed data of the Moon, which discovered OH and preliminary water, and possibly explains the source of water ice in permanently shadowed regions of the Moon.

 

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 now it has been demonstrated that it also carries solar-wind-generated water. So for the first time it has been shown that water and organics can be delivered together.

 

The idea that solar wind irradiation might produce water-species has been around for a long time, but whether it actually does produce water has been debated. The reasons for the uncertainty are that the amount of water produced is small and it is localized in very thin rims on the surfaces of silicate minerals so that older analytical techniques were unable to confirm the presence of water.