10 December 2013

Students collecting space dust may help find distant planets

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NASA’s fastest spacecraft collects dust like no other scientific instrument. Hurtling through space on its one-way trip toward Pluto, New Horizons is measuring space dust — a technique that could help astronomers find planets in other solar systems.

New Horizons space probe

New Horizons, about the size and shape of a piano, flies through microscopic space debris on its trek toward Pluto. The highlighted Student Dust Counter relays information about these collisions back to Earth. Credit: Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute (JHUAPL/SwRI)

A group of undergraduate and graduate students at the University of Colorado, Boulder designed and built an instrument called the Student Dust Counter, or SDC, for New Horizons, which NASA launched in 2006. Now, Jamey Szalay a graduate student in the physics department at CU Boulder, is analyzing the data the SDC relays back to Earth from more than 4 billion kilometers away. The sensor enables scientists to capture and measure space dust further from the sun than ever before.

“It’s definitely the longest-ranging thing students have ever built. It’s the farthest-reaching dust detector, student built or not,” said Szalay, standing in front of his poster Monday morning at the American Geophysical Union’s Fall Meeting in San Francisco.

Most of the space dust picked up by the SDC is coming from a ring of rocky material at the edge of the solar system known as the Kuiper belt. Here, asteroids and other space fragments are constantly colliding and creating billows of microscopic meteoroids, or dust, that spiral inward toward Jupiter and Saturn.

The SDC, which is about the size of a pizza box, records collisions as New Horizons flies directly through this debris. The sensor is essentially “stuck on the windshield of New Horizons, flying forward, getting hit by lots of tiny micrometeoroids,” said Szalay.

Szalay is using the data from the SDC to determine how dust from the Kuiper Belt is spread across the solar system. He then checks his measurements against a computer model that has predicted this distribution. If researchers can tune the model based on the new data, Szalay said it could help scientists use dust to find planets in other solar systems.

While planets in other solar systems are too distant to see, astronomers can see the clouds of space dust these planets orbit through, Szalay said. By characterizing the dust in Earth’s solar system with instruments like the SDC, researchers can establish how planets push dust around, creating telltale patterns.

“That tells you about planets without even seeing the planets,” said Szalay.

For example, in the computer model for Earth’s solar system, the dust pattern looks like a ringed dartboard with the sun at its bullseye. But an outer ring is missing a chunk and Neptune is responsible. The planet deforms the dust ring into a distinctive C-shape.

In other solar systems, “you wouldn’t see an Earth-sized planet by looking at the dust distribution, but you could see a Neptune-sized planet,” said Szalay.

Matt Davenport is a science communication graduate student at the University of California, Santa Cruz