Dusting off old research at planetary sciences meeting in Tucson

Posted by Rich Talcott
on Tuesday, November 11, 2014

Most of the researchers attending the 46th annual meeting of the Division for Planetary Sciences of the American Astronomical Society in Tucson, Arizona, are reporting on their latest observations and models of our solar system as well as those around other stars. Yesterday, reports on late-breaking science about Comet 67P/Churyumov-Gerasimenko, Saturn’s largest moon, Titan, and a plethora of exoplanets filled the sessions.

But one planetary scientist was dusting off his research from the 1970s. William Hartmann of the Planetary Science Institute in Tucson and a member of Astronomy’s Editorial Advisory Board showed a movie of experiments he conducted at NASA’s Ames Research Center four decades ago. He was looking at what happens when projectiles make low-speed impacts into powdery substances in a vacuum, all in an effort to see what might have happened in the early solar system when small fragments of the planet-building process collided with bigger, debris-covered objects.

But in one “accidental experiment,” he filled the target (a bucket) with a relatively dense and coarse powder instead of the fine pumice he had been using. Instead of a small crater with little ejecta, the new experiment delivered a veritable eruption that lasted close to a minute. Hartmann suggests that such impacts could explain outbursts from comets such as 29P/Schwassmann-Wachmann. Although this object has a nearly circular orbit that lies six times as far from the Sun as Earth, it experiences powerful eruptions at irregular intervals.

The original film got damaged in a projector in the early 1980s, and Hartmann had it restored just recently. The refurbished film made its debut at yesterday’s meeting. Check it out below.

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