Some dust in Earth’s atmosphere may hail from beyond Neptune

Author: Lisa Grossman / Source: Science News for Students

an illustration of the Kuiper belt — Some interplanetary dust grains that end up in Earth’s atmosphere may have traveled long distances. They may hail from the Kuiper Belt (illustrated). It is a region of icy objects out beyond Neptune that orbit the sun.

THE WOODLANDS, Texas — Grains of dust from the edge of the solar system could be finding their way to Earth.

And NASA may already have a handful of them, researchers report.

An estimated 40,000 tons of space dust settle in Earth’s atmosphere every year. The U.S. space agency has been flying balloon and aircraft missions since the 1970s to collect samples of the dust. Astronomers had long thought the dust mostly comes from smashups involving comets and asteroids — especially from ones inside the orbit of Jupiter.

In fact, some of the dust grains may come from the Kuiper (KY-pur) Belt. That’s a distant region beyond Neptune of icy objects. Like the planets, they too orbit the sun. Lindsay Keller is a planetary scientist at the Johnson Space Center in Houston, Texas. He reported the findings, here, on March 21 at the Lunar and Planetary Science Conference.

Studying those particles could reveal what distant, mysterious objects in the Kuiper Belt are made of, and perhaps how they formed.

“We’re not going to get a mission out to a Kuiper Belt object to actually collect [dust] samples anytime soon,” Keller said. “But we have samples of these things in the stratospheric dust collections here at NASA.”

One way to find a dust grain’s home is to probe the particle for microscopic tracks. These tracks are typically left as heavy charged particles from solar flares punched through a dust grain. The more tracks a grain has, the longer it has wandered in space — and the more likely it originated far from Earth, Keller explains.