Irradiated Space Dust Carries Water to Earth and Other Planets

Tiny dust particles traveling through the solar system may be capable of delivering water and other organic matter to Earth and other planets, according to scientists.

Interplanetary dust particles, known as IDPs, come from comets, asteroids, and leftover debris from the birth of the solar system.

According to a team of scientists from University of Hawaii-Manoa, Lawrence Livermore National Laboratory, Lawrence Berkeley National Laboratory, and University of California, these IDPs are capable of delivering water to Earth.

In the solar system, winds carrying ionized hydrogen atoms run into the IDPs, can interact with their chemical structure, leaving behind oxygen molecules that are more capable of interacting with hydrogen molecules to form water.

This process may have been the beginning of life on Earth, and possibly other planets as well.

"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," said Hope Ishii, of the Hawaii Institute of Geophysics and Planetology at University of Hawaii-Manoa.

Ishii and her colleagues have published a study detailing this process in the Proceedings of the National Academy of Sciences.

The researchers contend that this dust-raining process could be going on at planets throughout the universe.

Water ice found in permanently shadowed regions of the Moon may have also been delivered there by this raining process, the researchers said.

"Perhaps more exciting, 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," Iishi said. "So we have shown for the first time that water and organics can be delivered together."

The idea that solar wind irradiating cosmic dust and producing water molecules has been around for decades, but whether that actually happens has been hotly debated in the scientific community.

However, part of that debate is rooted in data deficiency that can be linked to inadequate technology available in the past. Newer instruments are more capable of detecting small amounts of water produced on very thin rims on the surfaces of silicate minerals. Older methods of analysis were unable to confirm the presence of water.

But a new state-of-the-art transmission electron microscope has allowed scientists to to detect water produced on these solar-irradiated IDPs.

For now, however, it's unclear how much water this process produced overall.

"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."