By Ron Cowen
Pummeled by dusty debris traveling six times as fast as a rifle bullet, a NASA spacecraft last week snatched up dust samples while taking the sharpest images ever of the icy core of a comet. Comets are considered to be pristine leftovers from the formation of the solar system some 4.6 billion years ago, and if all goes according to plan, the NASA craft Stardust will carry bits of that original material to Earth in January 2006.
Transporting samples of the comet, known as Wild 2 (pronounced vilt 2), remains Stardust’s primary mission, but planetary scientists this week were marveling at the images radioed by the craft from its encounter with the 5-kilometer-diameter comet on Jan. 2. Coming within 240 km of the comet’s core and discerning features as small as 30 meters across, the craft unveiled a surprisingly pocked and varied terrain.