Deep Impact Full of Surprises

NASA: Data from Deep Impact’s instruments indicate an immense cloud of fine powdery material was released when the probe slammed into the nucleus of comet Tempel 1 at 6.3 miles per second. The cloud indicated the comet is covered in the powdery stuff. The Deep Impact science team continues to wade through gigabytes of data collected during the July 4 encounter with the 3-mile-wide by 7-mile-long comet.

“The major surprise was the opacity of the plume the impactor created and the light it gave off,” said Deep Impact Principal Investigator Dr. Michael A’Hearn of the University of Maryland, College Park. “That suggests the dust excavated from the comet’s surface was extremely fine, more like talcum powder than beach sand. And the surface is definitely not what most people think of when they think of comets — an ice cube.”

How can a comet hurtling through our solar system be made of a substance with less strength than snow or even talcum powder? “You have to think of it in the context of its environment,” said Pete Schultz, Deep Impact scientist from Brown University, Providence, R.I. “This city-sized object is floating around in a vacuum. The only time it gets bothered is when the sun cooks it a little or someone slams an 820-pound wakeup call at it at 23,000 miles per hour.”