Flux of Extraterrestrial Dust through the Late Holocene and Anthropocene

A cryptocrystalline micrometeorite (~0.25 mm) found in Norway. It still preserves its original mineralogy.
Photo Credit: Jon Larsen and Jan Braly Kihle.

Micrometeorites can come from several types of sources. Fully-melted micrometeorites may be sources from ablation (friction and heat-induced eroding) of infalling meteors as they pass through the atmosphere. These particulates do not preserve any textural characteristics of the original source, but another subgroup, called cryptocrystalline micrometeorites do preserve some of their original mineralogy.

Some studies estimate that the Earth gains as much as 40 kilotons of mass from extraterrestrial dust every year, and it is assumed that the variability in the composition of that mass changes over time as Earth passes through different "clouds" of dust in its orbital path.

The micrometeorite collector at McMurdo Station, water well in Antarctica. Image Credit: Cosmic Dust Research Group.

Many micrometeorites have been collected from McMurdo Station in Antarctica. The water well there is drilled into glacial ice, which preserves micrometeorites in layers whose ages are well-known. As more water is collected, the walls of the well melt and deposit more micrometeorites, which sink to the bottom and collect as sediment. This allows scientists to collect micrometeorites with well-constrained ages of deposition (~500-1,000 years old, currently).

Closer to home, a new method of collected micrometeorites from urban rooftops has been developed, and can provide micrometeorites that have been present on Earth for only a few decades at most. This technique allows for the establishment of a dataset of modern extraterrestrial dust compositions.

There's still lots of leftover space dust in our dirty, dirty, Solar System-- but how much?

The availability of both of these sets of data would allow researchers to estimate the change in composition of dust in the Solar System, and form a more accurate picture of how the composition of the Earth's surface can change over shorter timescales. The results of the data may hold implications for other Solar System processes that explain the formation of terrestrial planets, as well.

I propose that the next group of annual Antarctic meteorite hunters (ANTMET) collect micrometeorites at the well and send them to me for analysis. At the same time, I can solicit participation from schools around the U.S. to collect micrometeorites from their facilities' rooftops at virtually no cost and send those to me for analysis as well. The research could have an educational outreach component and involve interested students in STEM activities.