Tech Digest

History of solar system studied in comet dust

FOR THE LAST FOUR YEARS University physics professor Bob Pepin and his colleagues have studied dust particles collected from Comet Wild-2 in an effort to trace the history of our solar system. The results of that research were published in a recent issue of Science.

Professor Bob Pepin holds a piece of aerogel containing comet dust from the Stardust probe.

By studying gases trapped in the dust, Pepin and his colleagues found evidence that after being generated near—but not in—the infant sun, the gases blasted their way into nearby dust particles. Previous work by other researchers suggests that the dust was later flung out past Neptune, where it helped form comets.

Planetary scientists regard comets as the most pristine remnants of the ancIent cloud of gas and dust that condensed into the sun and the myriad bodies that orbit it.

“We want to establish what the solar system looked like in the very early stages,” Pepin said. “If we establish the starting conditions, we can tell what happened in between then and now.” One early event was the birth of Earth’s moon, about 50 million years after the solar system formed, he said.

The comet dust was collected on NASA’s Stardust mission in January 2004, when the Spacecraft visited the comet, veering as close as 149 miles from its nucleus and flying through the stream of particles blowing off it. During the encounter, the spacecraft sponged up some of the dust with an ultralight glass-fiber material called aerogel, held in a supporting framework.