Comet buzzing Mars on Sunday

CAPE CANAVERAL, Fla. - A comet will zoom past Mars Sunday in an event that only happens once in a million years.

Astronaut John Grusfeld calls comet Siding Spring a gift of cosmic science that could unlock many unknowns.

"This particular comet has never before entered the inner solar system, so it will provide a fresh source of clues to our solar system's earliest days" said Grusfeld, astronaut and associate administrator for NASA's Science Mission Directorate in Washington. ...