By Ron Cowen
When NASA’s EPOXI spacecraft whizzed past Comet Hartley 2 on November 4 (SN Online: 11/4/10), it passed through a storm of fluffy ice bodies at least as large as golf balls, researchers reported at a November 18 press briefing. “This whole thing looks like a snow globe that you’ve shaken,” said EPOXI scientist Peter Schultz of Brown University in Providence, R.I.
Pictures from the craft’s high-resolution camera, which took extra time for scientists to process because the instrument was out of focus, show for the first time chunks of ice ejected from a comet by jets of carbon dioxide, said EPOXI principal scientist Michael A’Hearn of the University of Maryland in College Park.
“We were astounded,” he said, because in 2005, when the same spacecraft hurled a projectile into Comet Tempel 1, it kicked up only tiny, micrometer-sized ice grains — not large chunks.