Deep Space 1 visited Comet Borrelly in 2001, and Stardust came within 149 miles of Comet Wild 2 last year, grabbing dust samples that will return to Earth next January. Deep Impact will be the ...

This innovative propulsion concept was first used in 1998 on NASA’s Deep Space 1 mission to Comet Borrelly. In 2004 the Europeans successfully tested their own ion propulsion system on the Smart 1 ...